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    <link:label id="lab_ofc_RealEstatePropertiesStatusAxis_CCC17BB868D9968323F69F84AEE169DD_terseLabel_en-US" xlink:label="lab_ofc_RealEstatePropertiesStatusAxis_CCC17BB868D9968323F69F84AEE169DD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Real Estate Properties Status [Axis]</link:label>
    <link:label id="lab_ofc_RealEstatePropertiesStatusAxis_CCC17BB868D9968323F69F84AEE169DD_label_en-US" xlink:label="lab_ofc_RealEstatePropertiesStatusAxis_CCC17BB868D9968323F69F84AEE169DD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Properties Status [Axis]</link:label>
    <link:label id="lab_ofc_RealEstatePropertiesStatusAxis_CCC17BB868D9968323F69F84AEE169DD_documentation_en-US" xlink:label="lab_ofc_RealEstatePropertiesStatusAxis_CCC17BB868D9968323F69F84AEE169DD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Information by status of the property.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstatePropertiesStatusAxis" xlink:label="loc_ofc_RealEstatePropertiesStatusAxis_CCC17BB868D9968323F69F84AEE169DD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstatePropertiesStatusAxis_CCC17BB868D9968323F69F84AEE169DD" xlink:to="lab_ofc_RealEstatePropertiesStatusAxis_CCC17BB868D9968323F69F84AEE169DD" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstatePropertiesStatusDomain_C61385C01D4B9E08EF669F84AEE10C39_terseLabel_en-US" xlink:label="lab_ofc_RealEstatePropertiesStatusDomain_C61385C01D4B9E08EF669F84AEE10C39" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Real Estate Properties Status [Domain]</link:label>
    <link:label id="lab_ofc_RealEstatePropertiesStatusDomain_C61385C01D4B9E08EF669F84AEE10C39_label_en-US" xlink:label="lab_ofc_RealEstatePropertiesStatusDomain_C61385C01D4B9E08EF669F84AEE10C39" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Properties Status [Domain]</link:label>
    <link:label id="lab_ofc_RealEstatePropertiesStatusDomain_C61385C01D4B9E08EF669F84AEE10C39_documentation_en-US" xlink:label="lab_ofc_RealEstatePropertiesStatusDomain_C61385C01D4B9E08EF669F84AEE10C39" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the status of the property.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstatePropertiesStatusDomain" xlink:label="loc_ofc_RealEstatePropertiesStatusDomain_C61385C01D4B9E08EF669F84AEE10C39" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstatePropertiesStatusDomain_C61385C01D4B9E08EF669F84AEE10C39" xlink:to="lab_ofc_RealEstatePropertiesStatusDomain_C61385C01D4B9E08EF669F84AEE10C39" xlink:type="arc" />
    <link:label id="lab_ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember_9B90EAD2A063FB21E3369F84AEE16F76_terseLabel_en-US" xlink:label="lab_ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember_9B90EAD2A063FB21E3369F84AEE16F76" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Office properties under, or contractually committed for, construction or approved for redevelopment [Member]</link:label>
    <link:label id="lab_ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember_9B90EAD2A063FB21E3369F84AEE16F76_label_en-US" xlink:label="lab_ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember_9B90EAD2A063FB21E3369F84AEE16F76" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Office Properties Under Construction, Redevelopment or Contractually Committed for Construction [Member]</link:label>
    <link:label id="lab_ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember_9B90EAD2A063FB21E3369F84AEE16F76_documentation_en-US" xlink:label="lab_ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember_9B90EAD2A063FB21E3369F84AEE16F76" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents office properties under, or contractually committed for, construction or approved for redevelopment.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember" xlink:label="loc_ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember_9B90EAD2A063FB21E3369F84AEE16F76" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember_9B90EAD2A063FB21E3369F84AEE16F76" xlink:to="lab_ofc_OfficePropertiesUnderConstructionRedevelopmentOrContractuallyCommittedForConstructionMember_9B90EAD2A063FB21E3369F84AEE16F76" xlink:type="arc" />
    <link:label id="lab_ofc_OperatingOfficePropertiesMember_494EE9A0C65D4072F9489F84AEE10B2E_terseLabel_en-US" xlink:label="lab_ofc_OperatingOfficePropertiesMember_494EE9A0C65D4072F9489F84AEE10B2E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Operating office properties [Member]</link:label>
    <link:label id="lab_ofc_OperatingOfficePropertiesMember_494EE9A0C65D4072F9489F84AEE10B2E_label_en-US" xlink:label="lab_ofc_OperatingOfficePropertiesMember_494EE9A0C65D4072F9489F84AEE10B2E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Office Properties [Member]</link:label>
    <link:label id="lab_ofc_OperatingOfficePropertiesMember_494EE9A0C65D4072F9489F84AEE10B2E_documentation_en-US" xlink:label="lab_ofc_OperatingOfficePropertiesMember_494EE9A0C65D4072F9489F84AEE10B2E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents operating office properties owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_OperatingOfficePropertiesMember" xlink:label="loc_ofc_OperatingOfficePropertiesMember_494EE9A0C65D4072F9489F84AEE10B2E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_OperatingOfficePropertiesMember_494EE9A0C65D4072F9489F84AEE10B2E" xlink:to="lab_ofc_OperatingOfficePropertiesMember_494EE9A0C65D4072F9489F84AEE10B2E" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstatePropertiesAxis_C265E40B089AC6BD135F9F84AEE123A3_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstatePropertiesAxis_C265E40B089AC6BD135F9F84AEE123A3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Real Estate Property Ownership [Axis]</link:label>
    <link:label id="lab_us-gaap_RealEstatePropertiesAxis_C265E40B089AC6BD135F9F84AEE123A3_label_en-US" xlink:label="lab_us-gaap_RealEstatePropertiesAxis_C265E40B089AC6BD135F9F84AEE123A3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Property Ownership [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstatePropertiesAxis" xlink:label="loc_us-gaap_RealEstatePropertiesAxis_C265E40B089AC6BD135F9F84AEE123A3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstatePropertiesAxis_C265E40B089AC6BD135F9F84AEE123A3" xlink:to="lab_us-gaap_RealEstatePropertiesAxis_C265E40B089AC6BD135F9F84AEE123A3" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstatePropertiesDomain_EEA82A47418C9B7BBD189F84AEE1B95F_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstatePropertiesDomain_EEA82A47418C9B7BBD189F84AEE1B95F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Real Estate Properties [Domain]</link:label>
    <link:label id="lab_us-gaap_RealEstatePropertiesDomain_EEA82A47418C9B7BBD189F84AEE1B95F_label_en-US" xlink:label="lab_us-gaap_RealEstatePropertiesDomain_EEA82A47418C9B7BBD189F84AEE1B95F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Properties [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstatePropertiesDomain" xlink:label="loc_us-gaap_RealEstatePropertiesDomain_EEA82A47418C9B7BBD189F84AEE1B95F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstatePropertiesDomain_EEA82A47418C9B7BBD189F84AEE1B95F" xlink:to="lab_us-gaap_RealEstatePropertiesDomain_EEA82A47418C9B7BBD189F84AEE1B95F" xlink:type="arc" />
    <link:label id="lab_ofc_NewlyConstructedPropertiesPlacedInServiceMember_4370DDC9873A00CA80399F84AEE1323F_terseLabel_en-US" xlink:label="lab_ofc_NewlyConstructedPropertiesPlacedInServiceMember_4370DDC9873A00CA80399F84AEE1323F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Newly-constructed properties placed in service [Member]</link:label>
    <link:label id="lab_ofc_NewlyConstructedPropertiesPlacedInServiceMember_4370DDC9873A00CA80399F84AEE1323F_label_en-US" xlink:label="lab_ofc_NewlyConstructedPropertiesPlacedInServiceMember_4370DDC9873A00CA80399F84AEE1323F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Newly Constructed Properties Placed in Service [Member]</link:label>
    <link:label id="lab_ofc_NewlyConstructedPropertiesPlacedInServiceMember_4370DDC9873A00CA80399F84AEE1323F_documentation_en-US" xlink:label="lab_ofc_NewlyConstructedPropertiesPlacedInServiceMember_4370DDC9873A00CA80399F84AEE1323F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents properties with newly constructed square feet placed in service during the reporting period.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NewlyConstructedPropertiesPlacedInServiceMember" xlink:label="loc_ofc_NewlyConstructedPropertiesPlacedInServiceMember_4370DDC9873A00CA80399F84AEE1323F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NewlyConstructedPropertiesPlacedInServiceMember_4370DDC9873A00CA80399F84AEE1323F" xlink:to="lab_ofc_NewlyConstructedPropertiesPlacedInServiceMember_4370DDC9873A00CA80399F84AEE1323F" xlink:type="arc" />
    <link:label id="lab_ofc_SingletenantDataCentersMember_DDC3C508B281004768A49F84AEE18CCD_terseLabel_en-US" xlink:label="lab_ofc_SingletenantDataCentersMember_DDC3C508B281004768A49F84AEE18CCD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Single-tenant data centers [Member]</link:label>
    <link:label id="lab_ofc_SingletenantDataCentersMember_DDC3C508B281004768A49F84AEE18CCD_label_en-US" xlink:label="lab_ofc_SingletenantDataCentersMember_DDC3C508B281004768A49F84AEE18CCD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Single-tenant Data Centers [Member]</link:label>
    <link:label id="lab_ofc_SingletenantDataCentersMember_DDC3C508B281004768A49F84AEE18CCD_documentation_en-US" xlink:label="lab_ofc_SingletenantDataCentersMember_DDC3C508B281004768A49F84AEE18CCD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents single-tenant data centers owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SingletenantDataCentersMember" xlink:label="loc_ofc_SingletenantDataCentersMember_DDC3C508B281004768A49F84AEE18CCD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_SingletenantDataCentersMember_DDC3C508B281004768A49F84AEE18CCD" xlink:to="lab_ofc_SingletenantDataCentersMember_DDC3C508B281004768A49F84AEE18CCD" xlink:type="arc" />
    <link:label id="lab_ofc_NewlyRedevelopedPropertiesPlacedInServiceMember_36BD51B4E8B1B10867529F84AEE13726_terseLabel_en-US" xlink:label="lab_ofc_NewlyRedevelopedPropertiesPlacedInServiceMember_36BD51B4E8B1B10867529F84AEE13726" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Newly redeveloped properties placed In service [Member]</link:label>
    <link:label id="lab_ofc_NewlyRedevelopedPropertiesPlacedInServiceMember_36BD51B4E8B1B10867529F84AEE13726_label_en-US" xlink:label="lab_ofc_NewlyRedevelopedPropertiesPlacedInServiceMember_36BD51B4E8B1B10867529F84AEE13726" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Newly Redeveloped Properties Placed In Service [Member]</link:label>
    <link:label id="lab_ofc_NewlyRedevelopedPropertiesPlacedInServiceMember_36BD51B4E8B1B10867529F84AEE13726_documentation_en-US" xlink:label="lab_ofc_NewlyRedevelopedPropertiesPlacedInServiceMember_36BD51B4E8B1B10867529F84AEE13726" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Newly Redeveloped Properties Placed In Service [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NewlyRedevelopedPropertiesPlacedInServiceMember" xlink:label="loc_ofc_NewlyRedevelopedPropertiesPlacedInServiceMember_36BD51B4E8B1B10867529F84AEE13726" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NewlyRedevelopedPropertiesPlacedInServiceMember_36BD51B4E8B1B10867529F84AEE13726" xlink:to="lab_ofc_NewlyRedevelopedPropertiesPlacedInServiceMember_36BD51B4E8B1B10867529F84AEE13726" xlink:type="arc" />
    <link:label id="lab_ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember_1D8FC7A93953A377D02B9F84AEE1DBED_terseLabel_en-US" xlink:label="lab_ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember_1D8FC7A93953A377D02B9F84AEE1DBED" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Properties under construction or contractually committed for construction [Member]</link:label>
    <link:label id="lab_ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember_1D8FC7A93953A377D02B9F84AEE1DBED_label_en-US" xlink:label="lab_ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember_1D8FC7A93953A377D02B9F84AEE1DBED" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Properties under Construction or Contractually Commited for Construction [Member]</link:label>
    <link:label id="lab_ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember_1D8FC7A93953A377D02B9F84AEE1DBED_documentation_en-US" xlink:label="lab_ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember_1D8FC7A93953A377D02B9F84AEE1DBED" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents real estate office properties under construction or contractually committed for construction.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember" xlink:label="loc_ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember_1D8FC7A93953A377D02B9F84AEE1DBED" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember_1D8FC7A93953A377D02B9F84AEE1DBED" xlink:to="lab_ofc_PropertiesUnderConstructionOrContractuallyCommitedForConstructionMember_1D8FC7A93953A377D02B9F84AEE1DBED" xlink:type="arc" />
    <link:label id="lab_ofc_PropertiesCompletedHeldforFutureLeaseMember_848D34F416F3860566EE9F84AEE2B0D0_terseLabel_en-US" xlink:label="lab_ofc_PropertiesCompletedHeldforFutureLeaseMember_848D34F416F3860566EE9F84AEE2B0D0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Properties completed Held-for-future lease [Member]</link:label>
    <link:label id="lab_ofc_PropertiesCompletedHeldforFutureLeaseMember_848D34F416F3860566EE9F84AEE2B0D0_label_en-US" xlink:label="lab_ofc_PropertiesCompletedHeldforFutureLeaseMember_848D34F416F3860566EE9F84AEE2B0D0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Properties Completed, Held for Future Lease [Member]</link:label>
    <link:label id="lab_ofc_PropertiesCompletedHeldforFutureLeaseMember_848D34F416F3860566EE9F84AEE2B0D0_documentation_en-US" xlink:label="lab_ofc_PropertiesCompletedHeldforFutureLeaseMember_848D34F416F3860566EE9F84AEE2B0D0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Properties Completed, Held for Future Lease [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PropertiesCompletedHeldforFutureLeaseMember" xlink:label="loc_ofc_PropertiesCompletedHeldforFutureLeaseMember_848D34F416F3860566EE9F84AEE2B0D0" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PropertiesCompletedHeldforFutureLeaseMember_848D34F416F3860566EE9F84AEE2B0D0" xlink:to="lab_ofc_PropertiesCompletedHeldforFutureLeaseMember_848D34F416F3860566EE9F84AEE2B0D0" xlink:type="arc" />
    <link:label id="lab_ofc_PropertiesUnderorApprovedforRedevelopmentMember_42EE12A8535FD317E8309F84AEE219A2_terseLabel_en-US" xlink:label="lab_ofc_PropertiesUnderorApprovedforRedevelopmentMember_42EE12A8535FD317E8309F84AEE219A2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Properties under redevelopment [Member]</link:label>
    <link:label id="lab_ofc_PropertiesUnderorApprovedforRedevelopmentMember_42EE12A8535FD317E8309F84AEE219A2_label_en-US" xlink:label="lab_ofc_PropertiesUnderorApprovedforRedevelopmentMember_42EE12A8535FD317E8309F84AEE219A2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Properties Under or Approved for Redevelopment [Member]</link:label>
    <link:label id="lab_ofc_PropertiesUnderorApprovedforRedevelopmentMember_42EE12A8535FD317E8309F84AEE219A2_documentation_en-US" xlink:label="lab_ofc_PropertiesUnderorApprovedforRedevelopmentMember_42EE12A8535FD317E8309F84AEE219A2" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents real estate office properties under, or approved for, redevelopment.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PropertiesUnderorApprovedforRedevelopmentMember" xlink:label="loc_ofc_PropertiesUnderorApprovedforRedevelopmentMember_42EE12A8535FD317E8309F84AEE219A2" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PropertiesUnderorApprovedforRedevelopmentMember_42EE12A8535FD317E8309F84AEE219A2" xlink:to="lab_ofc_PropertiesUnderorApprovedforRedevelopmentMember_42EE12A8535FD317E8309F84AEE219A2" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstatePropertyClassificationAxis_15838045DA83B0337AA89F84AEE2A141_terseLabel_en-US" xlink:label="lab_ofc_RealEstatePropertyClassificationAxis_15838045DA83B0337AA89F84AEE2A141" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Real Estate Property Classification [Axis]</link:label>
    <link:label id="lab_ofc_RealEstatePropertyClassificationAxis_15838045DA83B0337AA89F84AEE2A141_label_en-US" xlink:label="lab_ofc_RealEstatePropertyClassificationAxis_15838045DA83B0337AA89F84AEE2A141" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Property Classification [Axis]</link:label>
    <link:label id="lab_ofc_RealEstatePropertyClassificationAxis_15838045DA83B0337AA89F84AEE2A141_documentation_en-US" xlink:label="lab_ofc_RealEstatePropertyClassificationAxis_15838045DA83B0337AA89F84AEE2A141" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents information regarding classification of real estate properties.</link:label>
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    <link:label id="lab_ofc_RegionalOfficeMember_1F0C779E4DE6CDB3A5A49F84AEE24DD4_documentation_en-US" xlink:label="lab_ofc_RegionalOfficeMember_1F0C779E4DE6CDB3A5A49F84AEE24DD4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Regional Office [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RegionalOfficeMember" xlink:label="loc_ofc_RegionalOfficeMember_1F0C779E4DE6CDB3A5A49F84AEE24DD4" xlink:type="locator" />
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    <link:label id="lab_ofc_FortMeadeandBaltimoreWashingtonCorridorMember_3391AA44257BAF0730539F84AEE25C1E_documentation_en-US" xlink:label="lab_ofc_FortMeadeandBaltimoreWashingtonCorridorMember_3391AA44257BAF0730539F84AEE25C1E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Fort Meade and Baltimore Washington Corridor [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_FortMeadeandBaltimoreWashingtonCorridorMember" xlink:label="loc_ofc_FortMeadeandBaltimoreWashingtonCorridorMember_3391AA44257BAF0730539F84AEE25C1E" xlink:type="locator" />
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    <link:loc xlink:href="ofc-20171231.xsd#ofc_DefenseandTechnologyLocationsMember" xlink:label="loc_ofc_DefenseandTechnologyLocationsMember_D1B81983983051C568AB9F84AEE27969" xlink:type="locator" />
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    <link:label id="lab_ofc_RegionalOfficeandOtherMember_15DD98F3FF9F636344DF9F84AEE25100_documentation_en-US" xlink:label="lab_ofc_RegionalOfficeandOtherMember_15DD98F3FF9F636344DF9F84AEE25100" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Regional Office and Other [Member]</link:label>
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    <link:label id="lab_ofc_RealEstatePropertyDisposalAxis_09BF2E152EB7BC31CA029F84AEE8BDE3_label_en-US" xlink:label="lab_ofc_RealEstatePropertyDisposalAxis_09BF2E152EB7BC31CA029F84AEE8BDE3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Property Disposal [Axis]</link:label>
    <link:label id="lab_ofc_RealEstatePropertyDisposalAxis_09BF2E152EB7BC31CA029F84AEE8BDE3_documentation_en-US" xlink:label="lab_ofc_RealEstatePropertyDisposalAxis_09BF2E152EB7BC31CA029F84AEE8BDE3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents information regarding disposal of operating properties aggregated according to factors such as location, number of properties and acquisition date.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstatePropertyDisposalAxis" xlink:label="loc_ofc_RealEstatePropertyDisposalAxis_09BF2E152EB7BC31CA029F84AEE8BDE3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstatePropertyDisposalAxis_09BF2E152EB7BC31CA029F84AEE8BDE3" xlink:to="lab_ofc_RealEstatePropertyDisposalAxis_09BF2E152EB7BC31CA029F84AEE8BDE3" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstatePropertyDisposalDomain_60A0C709AE2B87B817C79F84AEE8417E_terseLabel_en-US" xlink:label="lab_ofc_RealEstatePropertyDisposalDomain_60A0C709AE2B87B817C79F84AEE8417E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Real Estate Property Disposal [Domain]</link:label>
    <link:label id="lab_ofc_RealEstatePropertyDisposalDomain_60A0C709AE2B87B817C79F84AEE8417E_label_en-US" xlink:label="lab_ofc_RealEstatePropertyDisposalDomain_60A0C709AE2B87B817C79F84AEE8417E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Property Disposal [Domain]</link:label>
    <link:label id="lab_ofc_RealEstatePropertyDisposalDomain_60A0C709AE2B87B817C79F84AEE8417E_documentation_en-US" xlink:label="lab_ofc_RealEstatePropertyDisposalDomain_60A0C709AE2B87B817C79F84AEE8417E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents operating property disposal.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstatePropertyDisposalDomain" xlink:label="loc_ofc_RealEstatePropertyDisposalDomain_60A0C709AE2B87B817C79F84AEE8417E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstatePropertyDisposalDomain_60A0C709AE2B87B817C79F84AEE8417E" xlink:to="lab_ofc_RealEstatePropertyDisposalDomain_60A0C709AE2B87B817C79F84AEE8417E" xlink:type="arc" />
    <link:label id="lab_ofc_Number11751MeadowvilleLaneMember_B7C257FF6AC8B57AF4CD9F84AEE88A88_terseLabel_en-US" xlink:label="lab_ofc_Number11751MeadowvilleLaneMember_B7C257FF6AC8B57AF4CD9F84AEE88A88" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">11751 Meadowville Lane [Member]</link:label>
    <link:label id="lab_ofc_Number11751MeadowvilleLaneMember_B7C257FF6AC8B57AF4CD9F84AEE88A88_label_en-US" xlink:label="lab_ofc_Number11751MeadowvilleLaneMember_B7C257FF6AC8B57AF4CD9F84AEE88A88" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 11751 Meadowville Lane [Member]</link:label>
    <link:label id="lab_ofc_Number11751MeadowvilleLaneMember_B7C257FF6AC8B57AF4CD9F84AEE88A88_documentation_en-US" xlink:label="lab_ofc_Number11751MeadowvilleLaneMember_B7C257FF6AC8B57AF4CD9F84AEE88A88" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 11751 Meadowville Lane, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number11751MeadowvilleLaneMember" xlink:label="loc_ofc_Number11751MeadowvilleLaneMember_B7C257FF6AC8B57AF4CD9F84AEE88A88" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number11751MeadowvilleLaneMember_B7C257FF6AC8B57AF4CD9F84AEE88A88" xlink:to="lab_ofc_Number11751MeadowvilleLaneMember_B7C257FF6AC8B57AF4CD9F84AEE88A88" xlink:type="arc" />
    <link:label id="lab_ofc_Number3120FairviewParkDriveMember_B81EBE68A293248F9EF79F84AEE83AD8_terseLabel_en-US" xlink:label="lab_ofc_Number3120FairviewParkDriveMember_B81EBE68A293248F9EF79F84AEE83AD8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">3120 Fairview Park Drive [Member]</link:label>
    <link:label id="lab_ofc_Number3120FairviewParkDriveMember_B81EBE68A293248F9EF79F84AEE83AD8_label_en-US" xlink:label="lab_ofc_Number3120FairviewParkDriveMember_B81EBE68A293248F9EF79F84AEE83AD8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 3120 Fairview Park Drive [Member]</link:label>
    <link:label id="lab_ofc_Number3120FairviewParkDriveMember_B81EBE68A293248F9EF79F84AEE83AD8_documentation_en-US" xlink:label="lab_ofc_Number3120FairviewParkDriveMember_B81EBE68A293248F9EF79F84AEE83AD8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 3120 Fairview Park Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number3120FairviewParkDriveMember" xlink:label="loc_ofc_Number3120FairviewParkDriveMember_B81EBE68A293248F9EF79F84AEE83AD8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number3120FairviewParkDriveMember_B81EBE68A293248F9EF79F84AEE83AD8" xlink:to="lab_ofc_Number3120FairviewParkDriveMember_B81EBE68A293248F9EF79F84AEE83AD8" xlink:type="arc" />
    <link:label id="lab_ofc_Number1334AshtonRoadMember_810A96C295E81B0E17839F84AEE84237_terseLabel_en-US" xlink:label="lab_ofc_Number1334AshtonRoadMember_810A96C295E81B0E17839F84AEE84237" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1334 Ashton Road [Member]</link:label>
    <link:label id="lab_ofc_Number1334AshtonRoadMember_810A96C295E81B0E17839F84AEE84237_label_en-US" xlink:label="lab_ofc_Number1334AshtonRoadMember_810A96C295E81B0E17839F84AEE84237" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1334 Ashton Road [Member]</link:label>
    <link:label id="lab_ofc_Number1334AshtonRoadMember_810A96C295E81B0E17839F84AEE84237_documentation_en-US" xlink:label="lab_ofc_Number1334AshtonRoadMember_810A96C295E81B0E17839F84AEE84237" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1334 Ashton Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1334AshtonRoadMember" xlink:label="loc_ofc_Number1334AshtonRoadMember_810A96C295E81B0E17839F84AEE84237" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1334AshtonRoadMember_810A96C295E81B0E17839F84AEE84237" xlink:to="lab_ofc_Number1334AshtonRoadMember_810A96C295E81B0E17839F84AEE84237" xlink:type="arc" />
    <link:label id="lab_ofc_Number201TechnologyDriveMember_E9C83D3392D7DD07A35D9F84AEE92274_terseLabel_en-US" xlink:label="lab_ofc_Number201TechnologyDriveMember_E9C83D3392D7DD07A35D9F84AEE92274" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">201 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number201TechnologyDriveMember_E9C83D3392D7DD07A35D9F84AEE92274_label_en-US" xlink:label="lab_ofc_Number201TechnologyDriveMember_E9C83D3392D7DD07A35D9F84AEE92274" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 201 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number201TechnologyDriveMember_E9C83D3392D7DD07A35D9F84AEE92274_documentation_en-US" xlink:label="lab_ofc_Number201TechnologyDriveMember_E9C83D3392D7DD07A35D9F84AEE92274" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 201 Technology Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number201TechnologyDriveMember" xlink:label="loc_ofc_Number201TechnologyDriveMember_E9C83D3392D7DD07A35D9F84AEE92274" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number201TechnologyDriveMember_E9C83D3392D7DD07A35D9F84AEE92274" xlink:to="lab_ofc_Number201TechnologyDriveMember_E9C83D3392D7DD07A35D9F84AEE92274" xlink:type="arc" />
    <link:label id="lab_ofc_Number7320ParkwayDriveMember_F7D18C43C91AA4B764F09F84AEE919C8_terseLabel_en-US" xlink:label="lab_ofc_Number7320ParkwayDriveMember_F7D18C43C91AA4B764F09F84AEE919C8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7320 Parkway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7320ParkwayDriveMember_F7D18C43C91AA4B764F09F84AEE919C8_label_en-US" xlink:label="lab_ofc_Number7320ParkwayDriveMember_F7D18C43C91AA4B764F09F84AEE919C8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7320 Parkway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7320ParkwayDriveMember_F7D18C43C91AA4B764F09F84AEE919C8_documentation_en-US" xlink:label="lab_ofc_Number7320ParkwayDriveMember_F7D18C43C91AA4B764F09F84AEE919C8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7320 Parkway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7320ParkwayDriveMember" xlink:label="loc_ofc_Number7320ParkwayDriveMember_F7D18C43C91AA4B764F09F84AEE919C8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7320ParkwayDriveMember_F7D18C43C91AA4B764F09F84AEE919C8" xlink:to="lab_ofc_Number7320ParkwayDriveMember_F7D18C43C91AA4B764F09F84AEE919C8" xlink:type="arc" />
    <link:label id="lab_ofc_ArborcrestCorporateCampusMember_795E9474C2771327ED9A9F84AEE9FB0E_terseLabel_en-US" xlink:label="lab_ofc_ArborcrestCorporateCampusMember_795E9474C2771327ED9A9F84AEE9FB0E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Arborcrest Corporate Campus [Member]</link:label>
    <link:label id="lab_ofc_ArborcrestCorporateCampusMember_795E9474C2771327ED9A9F84AEE9FB0E_label_en-US" xlink:label="lab_ofc_ArborcrestCorporateCampusMember_795E9474C2771327ED9A9F84AEE9FB0E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Arborcrest Corporate Campus [Member]</link:label>
    <link:label id="lab_ofc_ArborcrestCorporateCampusMember_795E9474C2771327ED9A9F84AEE9FB0E_documentation_en-US" xlink:label="lab_ofc_ArborcrestCorporateCampusMember_795E9474C2771327ED9A9F84AEE9FB0E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Arborcrest Corporate Campus [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ArborcrestCorporateCampusMember" xlink:label="loc_ofc_ArborcrestCorporateCampusMember_795E9474C2771327ED9A9F84AEE9FB0E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ArborcrestCorporateCampusMember_795E9474C2771327ED9A9F84AEE9FB0E" xlink:to="lab_ofc_ArborcrestCorporateCampusMember_795E9474C2771327ED9A9F84AEE9FB0E" xlink:type="arc" />
    <link:label id="lab_ofc_Number8003CorporateDriveMember_05AEC6345C901F0381089F84AEE9EF2B_terseLabel_en-US" xlink:label="lab_ofc_Number8003CorporateDriveMember_05AEC6345C901F0381089F84AEE9EF2B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">8003 Corporate Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8003CorporateDriveMember_05AEC6345C901F0381089F84AEE9EF2B_label_en-US" xlink:label="lab_ofc_Number8003CorporateDriveMember_05AEC6345C901F0381089F84AEE9EF2B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 8003 Corporate Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8003CorporateDriveMember_05AEC6345C901F0381089F84AEE9EF2B_documentation_en-US" xlink:label="lab_ofc_Number8003CorporateDriveMember_05AEC6345C901F0381089F84AEE9EF2B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 8003 Corporate Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number8003CorporateDriveMember" xlink:label="loc_ofc_Number8003CorporateDriveMember_05AEC6345C901F0381089F84AEE9EF2B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number8003CorporateDriveMember_05AEC6345C901F0381089F84AEE9EF2B" xlink:to="lab_ofc_Number8003CorporateDriveMember_05AEC6345C901F0381089F84AEE9EF2B" xlink:type="arc" />
    <link:label id="lab_ofc_Number1341and1343AshtonRoadMember_D840F5B6C2BED809A3B89F84AEE97462_terseLabel_en-US" xlink:label="lab_ofc_Number1341and1343AshtonRoadMember_D840F5B6C2BED809A3B89F84AEE97462" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1341 and 1343 Ashton Road [Member]</link:label>
    <link:label id="lab_ofc_Number1341and1343AshtonRoadMember_D840F5B6C2BED809A3B89F84AEE97462_label_en-US" xlink:label="lab_ofc_Number1341and1343AshtonRoadMember_D840F5B6C2BED809A3B89F84AEE97462" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1341 and 1343 Ashton Road [Member]</link:label>
    <link:label id="lab_ofc_Number1341and1343AshtonRoadMember_D840F5B6C2BED809A3B89F84AEE97462_documentation_en-US" xlink:label="lab_ofc_Number1341and1343AshtonRoadMember_D840F5B6C2BED809A3B89F84AEE97462" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 1341 and 1343 Ashton Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1341and1343AshtonRoadMember" xlink:label="loc_ofc_Number1341and1343AshtonRoadMember_D840F5B6C2BED809A3B89F84AEE97462" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1341and1343AshtonRoadMember_D840F5B6C2BED809A3B89F84AEE97462" xlink:to="lab_ofc_Number1341and1343AshtonRoadMember_D840F5B6C2BED809A3B89F84AEE97462" xlink:type="arc" />
    <link:label id="lab_ofc_Number8007801380158019and80238027CorporateDriveMember_B19D017F8959B5966FFD9F84AEE9156C_terseLabel_en-US" xlink:label="lab_ofc_Number8007801380158019and80238027CorporateDriveMember_B19D017F8959B5966FFD9F84AEE9156C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">8007, 8013, 8015, 8019 and 8023-8027 Corporate Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8007801380158019and80238027CorporateDriveMember_B19D017F8959B5966FFD9F84AEE9156C_label_en-US" xlink:label="lab_ofc_Number8007801380158019and80238027CorporateDriveMember_B19D017F8959B5966FFD9F84AEE9156C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 8007, 8013, 8015, 8019 and 8023-8027 Corporate Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8007801380158019and80238027CorporateDriveMember_B19D017F8959B5966FFD9F84AEE9156C_documentation_en-US" xlink:label="lab_ofc_Number8007801380158019and80238027CorporateDriveMember_B19D017F8959B5966FFD9F84AEE9156C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 8007, 8013, 8015, 8019 and 8023-8027 Corporate Drive [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number8007801380158019and80238027CorporateDriveMember" xlink:label="loc_ofc_Number8007801380158019and80238027CorporateDriveMember_B19D017F8959B5966FFD9F84AEE9156C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number8007801380158019and80238027CorporateDriveMember_B19D017F8959B5966FFD9F84AEE9156C" xlink:to="lab_ofc_Number8007801380158019and80238027CorporateDriveMember_B19D017F8959B5966FFD9F84AEE9156C" xlink:type="arc" />
    <link:label id="lab_ofc_Number130213041306ConcourseDriveMember_8336A5F47FCC291D64219F84AEE97EF6_terseLabel_en-US" xlink:label="lab_ofc_Number130213041306ConcourseDriveMember_8336A5F47FCC291D64219F84AEE97EF6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1302, 1304 &amp; 1306 Concourse Drive [Member]</link:label>
    <link:label id="lab_ofc_Number130213041306ConcourseDriveMember_8336A5F47FCC291D64219F84AEE97EF6_label_en-US" xlink:label="lab_ofc_Number130213041306ConcourseDriveMember_8336A5F47FCC291D64219F84AEE97EF6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1302, 1304 &amp; 1306 Concourse Drive [Member]</link:label>
    <link:label id="lab_ofc_Number130213041306ConcourseDriveMember_8336A5F47FCC291D64219F84AEE97EF6_documentation_en-US" xlink:label="lab_ofc_Number130213041306ConcourseDriveMember_8336A5F47FCC291D64219F84AEE97EF6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 1302, 1304 &amp; 1306 Concourse Drive [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number130213041306ConcourseDriveMember" xlink:label="loc_ofc_Number130213041306ConcourseDriveMember_8336A5F47FCC291D64219F84AEE97EF6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number130213041306ConcourseDriveMember_8336A5F47FCC291D64219F84AEE97EF6" xlink:to="lab_ofc_Number130213041306ConcourseDriveMember_8336A5F47FCC291D64219F84AEE97EF6" xlink:type="arc" />
    <link:label id="lab_ofc_Number2900TowerviewRoadMember_0BB59A0CF297F2D09C229F84AEE9D7CE_terseLabel_en-US" xlink:label="lab_ofc_Number2900TowerviewRoadMember_0BB59A0CF297F2D09C229F84AEE9D7CE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2900 Towerview Road [Member]</link:label>
    <link:label id="lab_ofc_Number2900TowerviewRoadMember_0BB59A0CF297F2D09C229F84AEE9D7CE_label_en-US" xlink:label="lab_ofc_Number2900TowerviewRoadMember_0BB59A0CF297F2D09C229F84AEE9D7CE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2900 Towerview Road [Member]</link:label>
    <link:label id="lab_ofc_Number2900TowerviewRoadMember_0BB59A0CF297F2D09C229F84AEE9D7CE_documentation_en-US" xlink:label="lab_ofc_Number2900TowerviewRoadMember_0BB59A0CF297F2D09C229F84AEE9D7CE" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 2900 Towerview Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2900TowerviewRoadMember" xlink:label="loc_ofc_Number2900TowerviewRoadMember_0BB59A0CF297F2D09C229F84AEE9D7CE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2900TowerviewRoadMember_0BB59A0CF297F2D09C229F84AEE9D7CE" xlink:to="lab_ofc_Number2900TowerviewRoadMember_0BB59A0CF297F2D09C229F84AEE9D7CE" xlink:type="arc" />
    <link:label id="lab_ofc_Number4940CampbellDriveMember_15D75F1CA2D291F393779F84AEE9FFD9_terseLabel_en-US" xlink:label="lab_ofc_Number4940CampbellDriveMember_15D75F1CA2D291F393779F84AEE9FFD9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">4940 Campbell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number4940CampbellDriveMember_15D75F1CA2D291F393779F84AEE9FFD9_label_en-US" xlink:label="lab_ofc_Number4940CampbellDriveMember_15D75F1CA2D291F393779F84AEE9FFD9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 4940 Campbell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number4940CampbellDriveMember_15D75F1CA2D291F393779F84AEE9FFD9_documentation_en-US" xlink:label="lab_ofc_Number4940CampbellDriveMember_15D75F1CA2D291F393779F84AEE9FFD9" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 4940 Campbell Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number4940CampbellDriveMember" xlink:label="loc_ofc_Number4940CampbellDriveMember_15D75F1CA2D291F393779F84AEE9FFD9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number4940CampbellDriveMember_15D75F1CA2D291F393779F84AEE9FFD9" xlink:to="lab_ofc_Number4940CampbellDriveMember_15D75F1CA2D291F393779F84AEE9FFD9" xlink:type="arc" />
    <link:label id="lab_ofc_Number1560AAndBCableRanchRoadMember_3B0473DCFDE6A958D6D89F84AEE965C8_terseLabel_en-US" xlink:label="lab_ofc_Number1560AAndBCableRanchRoadMember_3B0473DCFDE6A958D6D89F84AEE965C8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1560 A and B Cable Ranch Road [Member]</link:label>
    <link:label id="lab_ofc_Number1560AAndBCableRanchRoadMember_3B0473DCFDE6A958D6D89F84AEE965C8_label_en-US" xlink:label="lab_ofc_Number1560AAndBCableRanchRoadMember_3B0473DCFDE6A958D6D89F84AEE965C8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1560 A And B Cable Ranch Road [Member]</link:label>
    <link:label id="lab_ofc_Number1560AAndBCableRanchRoadMember_3B0473DCFDE6A958D6D89F84AEE965C8_documentation_en-US" xlink:label="lab_ofc_Number1560AAndBCableRanchRoadMember_3B0473DCFDE6A958D6D89F84AEE965C8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 1560 A And B Cable Ranch Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1560AAndBCableRanchRoadMember" xlink:label="loc_ofc_Number1560AAndBCableRanchRoadMember_3B0473DCFDE6A958D6D89F84AEE965C8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1560AAndBCableRanchRoadMember_3B0473DCFDE6A958D6D89F84AEE965C8" xlink:to="lab_ofc_Number1560AAndBCableRanchRoadMember_3B0473DCFDE6A958D6D89F84AEE965C8" xlink:type="arc" />
    <link:label id="lab_ofc_Number1331AshtonRoadMember_C43E24CFA7AD9306132D9F84AEEAC9AB_terseLabel_en-US" xlink:label="lab_ofc_Number1331AshtonRoadMember_C43E24CFA7AD9306132D9F84AEEAC9AB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1331 Ashton Road [Member]</link:label>
    <link:label id="lab_ofc_Number1331AshtonRoadMember_C43E24CFA7AD9306132D9F84AEEAC9AB_label_en-US" xlink:label="lab_ofc_Number1331AshtonRoadMember_C43E24CFA7AD9306132D9F84AEEAC9AB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1331 Ashton Road [Member]</link:label>
    <link:label id="lab_ofc_Number1331AshtonRoadMember_C43E24CFA7AD9306132D9F84AEEAC9AB_documentation_en-US" xlink:label="lab_ofc_Number1331AshtonRoadMember_C43E24CFA7AD9306132D9F84AEEAC9AB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1331 Ashton Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1331AshtonRoadMember" xlink:label="loc_ofc_Number1331AshtonRoadMember_C43E24CFA7AD9306132D9F84AEEAC9AB" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1331AshtonRoadMember_C43E24CFA7AD9306132D9F84AEEAC9AB" xlink:to="lab_ofc_Number1331AshtonRoadMember_C43E24CFA7AD9306132D9F84AEEAC9AB" xlink:type="arc" />
    <link:label id="lab_ofc_Number900ElkridgeLandingRoadMember_54E331337F8B398C5D089F84AEEA2DA5_terseLabel_en-US" xlink:label="lab_ofc_Number900ElkridgeLandingRoadMember_54E331337F8B398C5D089F84AEEA2DA5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">900 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number900ElkridgeLandingRoadMember_54E331337F8B398C5D089F84AEEA2DA5_label_en-US" xlink:label="lab_ofc_Number900ElkridgeLandingRoadMember_54E331337F8B398C5D089F84AEEA2DA5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 900 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number900ElkridgeLandingRoadMember_54E331337F8B398C5D089F84AEEA2DA5_documentation_en-US" xlink:label="lab_ofc_Number900ElkridgeLandingRoadMember_54E331337F8B398C5D089F84AEEA2DA5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 900 Elkridge Landing Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number900ElkridgeLandingRoadMember" xlink:label="loc_ofc_Number900ElkridgeLandingRoadMember_54E331337F8B398C5D089F84AEEA2DA5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number900ElkridgeLandingRoadMember_54E331337F8B398C5D089F84AEEA2DA5" xlink:to="lab_ofc_Number900ElkridgeLandingRoadMember_54E331337F8B398C5D089F84AEEA2DA5" xlink:type="arc" />
    <link:label id="lab_ofc_Number1550WestbranchDriveMember_D7987EDEDD58E084E13F9F84AEEA51A1_terseLabel_en-US" xlink:label="lab_ofc_Number1550WestbranchDriveMember_D7987EDEDD58E084E13F9F84AEEA51A1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1550 Westbranch Drive [Member]</link:label>
    <link:label id="lab_ofc_Number1550WestbranchDriveMember_D7987EDEDD58E084E13F9F84AEEA51A1_label_en-US" xlink:label="lab_ofc_Number1550WestbranchDriveMember_D7987EDEDD58E084E13F9F84AEEA51A1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1550 Westbranch Drive [Member]</link:label>
    <link:label id="lab_ofc_Number1550WestbranchDriveMember_D7987EDEDD58E084E13F9F84AEEA51A1_documentation_en-US" xlink:label="lab_ofc_Number1550WestbranchDriveMember_D7987EDEDD58E084E13F9F84AEEA51A1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1550 Westbranch Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1550WestbranchDriveMember" xlink:label="loc_ofc_Number1550WestbranchDriveMember_D7987EDEDD58E084E13F9F84AEEA51A1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1550WestbranchDriveMember_D7987EDEDD58E084E13F9F84AEEA51A1" xlink:to="lab_ofc_Number1550WestbranchDriveMember_D7987EDEDD58E084E13F9F84AEEA51A1" xlink:type="arc" />
    <link:label id="lab_ofc_Number15000and15010ConferenceCenterDriveMember_AD0B2BAEEDCA1BC554B29F84AEEAEEDD_terseLabel_en-US" xlink:label="lab_ofc_Number15000and15010ConferenceCenterDriveMember_AD0B2BAEEDCA1BC554B29F84AEEAEEDD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">15000 and 15010 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number15000and15010ConferenceCenterDriveMember_AD0B2BAEEDCA1BC554B29F84AEEAEEDD_label_en-US" xlink:label="lab_ofc_Number15000and15010ConferenceCenterDriveMember_AD0B2BAEEDCA1BC554B29F84AEEAEEDD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 15000 and 15010 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number15000and15010ConferenceCenterDriveMember_AD0B2BAEEDCA1BC554B29F84AEEAEEDD_documentation_en-US" xlink:label="lab_ofc_Number15000and15010ConferenceCenterDriveMember_AD0B2BAEEDCA1BC554B29F84AEEAEEDD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 15000 and 15010 Conference Center Drive [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number15000and15010ConferenceCenterDriveMember" xlink:label="loc_ofc_Number15000and15010ConferenceCenterDriveMember_AD0B2BAEEDCA1BC554B29F84AEEAEEDD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number15000and15010ConferenceCenterDriveMember_AD0B2BAEEDCA1BC554B29F84AEEAEEDD" xlink:to="lab_ofc_Number15000and15010ConferenceCenterDriveMember_AD0B2BAEEDCA1BC554B29F84AEEAEEDD" xlink:type="arc" />
    <link:label id="lab_ofc_Number13200WoodlandParkRoadMember_F18686916B06ADCE1BBA9F84AEEAF7C9_terseLabel_en-US" xlink:label="lab_ofc_Number13200WoodlandParkRoadMember_F18686916B06ADCE1BBA9F84AEEAF7C9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">13200 Woodland Park Road [Member]</link:label>
    <link:label id="lab_ofc_Number13200WoodlandParkRoadMember_F18686916B06ADCE1BBA9F84AEEAF7C9_label_en-US" xlink:label="lab_ofc_Number13200WoodlandParkRoadMember_F18686916B06ADCE1BBA9F84AEEAF7C9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 13200 Woodland Park Road [Member]</link:label>
    <link:label id="lab_ofc_Number13200WoodlandParkRoadMember_F18686916B06ADCE1BBA9F84AEEAF7C9_documentation_en-US" xlink:label="lab_ofc_Number13200WoodlandParkRoadMember_F18686916B06ADCE1BBA9F84AEEAF7C9" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 13200 Woodland Park Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number13200WoodlandParkRoadMember" xlink:label="loc_ofc_Number13200WoodlandParkRoadMember_F18686916B06ADCE1BBA9F84AEEAF7C9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number13200WoodlandParkRoadMember_F18686916B06ADCE1BBA9F84AEEAF7C9" xlink:to="lab_ofc_Number13200WoodlandParkRoadMember_F18686916B06ADCE1BBA9F84AEEAF7C9" xlink:type="arc" />
    <link:label id="lab_ofc_Number990099109920FranklinSquareDriveMember_3C7B7A64ED9D644871D99F84AEEA5C14_terseLabel_en-US" xlink:label="lab_ofc_Number990099109920FranklinSquareDriveMember_3C7B7A64ED9D644871D99F84AEEA5C14" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">9900, 9910, 9920 Franklin Square Drive [Member]</link:label>
    <link:label id="lab_ofc_Number990099109920FranklinSquareDriveMember_3C7B7A64ED9D644871D99F84AEEA5C14_label_en-US" xlink:label="lab_ofc_Number990099109920FranklinSquareDriveMember_3C7B7A64ED9D644871D99F84AEEA5C14" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 9900, 9910, 9920 Franklin Square Drive [Member]</link:label>
    <link:label id="lab_ofc_Number990099109920FranklinSquareDriveMember_3C7B7A64ED9D644871D99F84AEEA5C14_documentation_en-US" xlink:label="lab_ofc_Number990099109920FranklinSquareDriveMember_3C7B7A64ED9D644871D99F84AEEA5C14" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 9900, 9910, 9920 Franklin Square Drive [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number990099109920FranklinSquareDriveMember" xlink:label="loc_ofc_Number990099109920FranklinSquareDriveMember_3C7B7A64ED9D644871D99F84AEEA5C14" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number990099109920FranklinSquareDriveMember_3C7B7A64ED9D644871D99F84AEEA5C14" xlink:to="lab_ofc_Number990099109920FranklinSquareDriveMember_3C7B7A64ED9D644871D99F84AEEA5C14" xlink:type="arc" />
    <link:label id="lab_ofc_Number9690DeerecoRoadand375WPadoniaRoadMember_F71C865F03D519E5DA379F84AEEA322E_terseLabel_en-US" xlink:label="lab_ofc_Number9690DeerecoRoadand375WPadoniaRoadMember_F71C865F03D519E5DA379F84AEEA322E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">9690 Deereco Road and 375 W Padonia Road [Member]</link:label>
    <link:label id="lab_ofc_Number9690DeerecoRoadand375WPadoniaRoadMember_F71C865F03D519E5DA379F84AEEA322E_label_en-US" xlink:label="lab_ofc_Number9690DeerecoRoadand375WPadoniaRoadMember_F71C865F03D519E5DA379F84AEEA322E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 9690 Deereco Road and 375 W Padonia Road [Member]</link:label>
    <link:label id="lab_ofc_Number9690DeerecoRoadand375WPadoniaRoadMember_F71C865F03D519E5DA379F84AEEA322E_documentation_en-US" xlink:label="lab_ofc_Number9690DeerecoRoadand375WPadoniaRoadMember_F71C865F03D519E5DA379F84AEEA322E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 9690 Deereco Road and 375 W Padonia Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number9690DeerecoRoadand375WPadoniaRoadMember" xlink:label="loc_ofc_Number9690DeerecoRoadand375WPadoniaRoadMember_F71C865F03D519E5DA379F84AEEA322E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number9690DeerecoRoadand375WPadoniaRoadMember_F71C865F03D519E5DA379F84AEEA322E" xlink:to="lab_ofc_Number9690DeerecoRoadand375WPadoniaRoadMember_F71C865F03D519E5DA379F84AEEA322E" xlink:type="arc" />
    <link:label id="lab_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0722EBBE3EE01977CEA99F84AEEAE11C_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0722EBBE3EE01977CEA99F84AEEAE11C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Disposal Group Name [Axis]</link:label>
    <link:label id="lab_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0722EBBE3EE01977CEA99F84AEEAE11C_label_en-US" xlink:label="lab_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0722EBBE3EE01977CEA99F84AEEAE11C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Disposal Group Name [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0722EBBE3EE01977CEA99F84AEEAE11C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0722EBBE3EE01977CEA99F84AEEAE11C" xlink:to="lab_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_0722EBBE3EE01977CEA99F84AEEAE11C" xlink:type="arc" />
    <link:label id="lab_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_D5662E1E9F7FE33263259F84AEEAEA9A_terseLabel_en-US" xlink:label="lab_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_D5662E1E9F7FE33263259F84AEEAEA9A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Disposal Group Name [Domain]</link:label>
    <link:label id="lab_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_D5662E1E9F7FE33263259F84AEEAEA9A_label_en-US" xlink:label="lab_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_D5662E1E9F7FE33263259F84AEEAEA9A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Disposal Group Name [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_D5662E1E9F7FE33263259F84AEEAEA9A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_D5662E1E9F7FE33263259F84AEEAEA9A" xlink:to="lab_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_D5662E1E9F7FE33263259F84AEEAEA9A" xlink:type="arc" />
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    <link:label id="lab_ofc_ScheduleOfLimitedLiabilityCompanyLlcOrLimitedPartnershipLpManagingMemberOrGeneralPartnerOwnershipInterestTable_FDD7F89EE88D89E81394485A081AD56C_terseLabel_en-US" xlink:label="lab_ofc_ScheduleOfLimitedLiabilityCompanyLlcOrLimitedPartnershipLpManagingMemberOrGeneralPartnerOwnershipInterestTable_FDD7F89EE88D89E81394485A081AD56C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Schedule of Limited Liability Company LLC or Limited Partnership LP Managing Member or General Partner Ownership Interest [Table]</link:label>
    <link:label id="lab_ofc_ScheduleOfLimitedLiabilityCompanyLlcOrLimitedPartnershipLpManagingMemberOrGeneralPartnerOwnershipInterestTable_FDD7F89EE88D89E81394485A081AD56C_label_en-US" xlink:label="lab_ofc_ScheduleOfLimitedLiabilityCompanyLlcOrLimitedPartnershipLpManagingMemberOrGeneralPartnerOwnershipInterestTable_FDD7F89EE88D89E81394485A081AD56C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Schedule of Limited Liability Company LLC or Limited Partnership LP Managing Member or General Partner Ownership Interest [Table]</link:label>
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    <link:label id="lab_us-gaap_ConsolidatedEntitiesAxis_204C5426A77671B4790C485A081A0E2A_label_en-US" xlink:label="lab_us-gaap_ConsolidatedEntitiesAxis_204C5426A77671B4790C485A081A0E2A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Consolidated Entities [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidatedEntitiesAxis" xlink:label="loc_us-gaap_ConsolidatedEntitiesAxis_204C5426A77671B4790C485A081A0E2A" xlink:type="locator" />
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    <link:label id="lab_us-gaap_ConsolidatedEntitiesDomain_0D789A6411F2785DD810485A081A1B4B_terseLabel_en-US" xlink:label="lab_us-gaap_ConsolidatedEntitiesDomain_0D789A6411F2785DD810485A081A1B4B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Consolidated Entities [Domain]</link:label>
    <link:label id="lab_us-gaap_ConsolidatedEntitiesDomain_0D789A6411F2785DD810485A081A1B4B_label_en-US" xlink:label="lab_us-gaap_ConsolidatedEntitiesDomain_0D789A6411F2785DD810485A081A1B4B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Consolidated Entities [Domain]</link:label>
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    <link:label id="lab_us-gaap_SubsidiariesMember_52671B7EC406B3DE0A33485A081A321A_label_en-US" xlink:label="lab_us-gaap_SubsidiariesMember_52671B7EC406B3DE0A33485A081A321A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Subsidiaries [Member]</link:label>
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    <link:label id="lab_ofc_UnitsClassDomain_A39D10A145E722B9B0EC485A081B9610_documentation_en-US" xlink:label="lab_ofc_UnitsClassDomain_A39D10A145E722B9B0EC485A081B9610" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Type or class of preferred units or special units.</link:label>
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    <link:label id="lab_ofc_CommonUnitsMember_519027F30DAD72DB1B39485A081B63BD_label_en-US" xlink:label="lab_ofc_CommonUnitsMember_519027F30DAD72DB1B39485A081B63BD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Common Units [Member]</link:label>
    <link:label id="lab_ofc_CommonUnitsMember_519027F30DAD72DB1B39485A081B63BD_documentation_en-US" xlink:label="lab_ofc_CommonUnitsMember_519027F30DAD72DB1B39485A081B63BD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Common units representing ownership interest in the operating partnership.</link:label>
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    <link:label id="lab_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest_3D99BF70AAF7EAD79EF3485A081B2115_terseLabel_en-US" xlink:label="lab_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest_3D99BF70AAF7EAD79EF3485A081B2115" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Percentage ownership in operating partnership</link:label>
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    <link:label id="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain_BE8505F1FCC04DCE6BA69B3DCE5BC3CA_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain_BE8505F1FCC04DCE6BA69B3DCE5BC3CA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Property, Plant and Equipment, Type [Domain]</link:label>
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    <link:label id="lab_us-gaap_LandMember_C4FF07D45648B8B5EBC99B3DCE5B8D89_verboseLabel_en-US" xlink:label="lab_us-gaap_LandMember_C4FF07D45648B8B5EBC99B3DCE5B8D89" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Land [Member]</link:label>
    <link:label id="lab_us-gaap_LandMember_C4FF07D45648B8B5EBC99B3DCE5B8D89_label_en-US" xlink:label="lab_us-gaap_LandMember_C4FF07D45648B8B5EBC99B3DCE5B8D89" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Land [Member]</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LandMember_C4FF07D45648B8B5EBC99B3DCE5B8D89" xlink:to="lab_us-gaap_LandMember_C4FF07D45648B8B5EBC99B3DCE5B8D89" xlink:type="arc" />
    <link:label id="lab_us-gaap_BuildingAndBuildingImprovementsMember_9A01E1C3BF9FD21F97AC9B3DCE5C8739_terseLabel_en-US" xlink:label="lab_us-gaap_BuildingAndBuildingImprovementsMember_9A01E1C3BF9FD21F97AC9B3DCE5C8739" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Buildings and improvements [Member]</link:label>
    <link:label id="lab_us-gaap_BuildingAndBuildingImprovementsMember_9A01E1C3BF9FD21F97AC9B3DCE5C8739_label_en-US" xlink:label="lab_us-gaap_BuildingAndBuildingImprovementsMember_9A01E1C3BF9FD21F97AC9B3DCE5C8739" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Building and Building Improvements [Member]</link:label>
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    <link:label id="lab_us-gaap_RealEstatePropertiesLineItems_630F86ABC29EAC883DF29B3DCE5C2284_verboseLabel_en-US" xlink:label="lab_us-gaap_RealEstatePropertiesLineItems_630F86ABC29EAC883DF29B3DCE5C2284" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Properties</link:label>
    <link:label id="lab_us-gaap_RealEstatePropertiesLineItems_630F86ABC29EAC883DF29B3DCE5C2284_label_en-US" xlink:label="lab_us-gaap_RealEstatePropertiesLineItems_630F86ABC29EAC883DF29B3DCE5C2284" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Properties [Line Items]</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstatePropertiesLineItems_630F86ABC29EAC883DF29B3DCE5C2284" xlink:to="lab_us-gaap_RealEstatePropertiesLineItems_630F86ABC29EAC883DF29B3DCE5C2284" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateGrossAtCarryingValue_A82A20276671F91F79459B3DCE5C111C_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateGrossAtCarryingValue_A82A20276671F91F79459B3DCE5C111C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Gross</link:label>
    <link:label id="lab_us-gaap_RealEstateGrossAtCarryingValue_A82A20276671F91F79459B3DCE5C111C_label_en-US" xlink:label="lab_us-gaap_RealEstateGrossAtCarryingValue_A82A20276671F91F79459B3DCE5C111C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate, Gross</link:label>
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    <link:label id="lab_us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation_B6CE1F34BFE1C5F0B2D59B3DCE5D1F0E_negatedLabel_en-US" xlink:label="lab_us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation_B6CE1F34BFE1C5F0B2D59B3DCE5D1F0E" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Less: accumulated depreciation</link:label>
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    <link:label id="lab_us-gaap_RentalProperties_ACDD25DBD5596BA3A47B9B3DCE5D15D2_totalLabel_en-US" xlink:label="lab_us-gaap_RentalProperties_ACDD25DBD5596BA3A47B9B3DCE5D15D2" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Operating properties, net</link:label>
    <link:label id="lab_us-gaap_RentalProperties_ACDD25DBD5596BA3A47B9B3DCE5D15D2_label_en-US" xlink:label="lab_us-gaap_RentalProperties_ACDD25DBD5596BA3A47B9B3DCE5D15D2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Rental Properties</link:label>
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    <link:label id="lab_us-gaap_StatementGeographicalAxis_33D614A1A4B12F3B88F79A1E18A3FE4E_label_en-US" xlink:label="lab_us-gaap_StatementGeographicalAxis_33D614A1A4B12F3B88F79A1E18A3FE4E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Geographical [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_33D614A1A4B12F3B88F79A1E18A3FE4E" xlink:type="locator" />
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    <link:label id="lab_us-gaap_SegmentGeographicalDomain_6597D5F859208083468A9A1E18A32877_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentGeographicalDomain_6597D5F859208083468A9A1E18A32877" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Geographical [Domain]</link:label>
    <link:label id="lab_us-gaap_SegmentGeographicalDomain_6597D5F859208083468A9A1E18A32877_label_en-US" xlink:label="lab_us-gaap_SegmentGeographicalDomain_6597D5F859208083468A9A1E18A32877" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Geographical [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_6597D5F859208083468A9A1E18A32877" xlink:type="locator" />
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    <link:label id="lab_ofc_NumberofRealEstatePropertiesAssetsHeldforsale_3B3FB47034AD138BFAB09A1E18A32435_terseLabel_en-US" xlink:label="lab_ofc_NumberofRealEstatePropertiesAssetsHeldforsale_3B3FB47034AD138BFAB09A1E18A32435" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of land parcels held-for-sale</link:label>
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    <link:label id="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertiesNet_3E8FA9066C442381A9A19A1E18A39CB7_terseLabel_en-US" xlink:label="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertiesNet_3E8FA9066C442381A9A19A1E18A39CB7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Properties, net</link:label>
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    <link:label id="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertiesNet_3E8FA9066C442381A9A19A1E18A39CB7_documentation_en-US" xlink:label="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertiesNet_3E8FA9066C442381A9A19A1E18A39CB7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Properties, Net</link:label>
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    <link:label id="lab_ofc_DisposalGroupIncludingDiscontinuedOperationDeferredRentReceivable_2613BAFFFC26489AF14C9A1E18A3980F_terseLabel_en-US" xlink:label="lab_ofc_DisposalGroupIncludingDiscontinuedOperationDeferredRentReceivable_2613BAFFFC26489AF14C9A1E18A3980F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Deferred rent receivable</link:label>
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    <link:label id="lab_ofc_CreditFacilityMember_E29E5C6699188A8A9BA69B3DCB9C938C_documentation_en-US" xlink:label="lab_ofc_CreditFacilityMember_E29E5C6699188A8A9BA69B3DCB9C938C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the credit facility which includes the aggregate borrowings of the following facilities: line of credit, letter of credit, and a swingline facility.</link:label>
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    <link:label id="lab_ofc_TermCreditFacilityEffectiveFebruary2012Member_B1211831507EE557CAE89B3DCB9C2DC0_terseLabel_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveFebruary2012Member_B1211831507EE557CAE89B3DCB9C2DC0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective February 2012 [Member]</link:label>
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    <link:label id="lab_ofc_TermCreditFacilityEffectiveFebruary2012Member_B1211831507EE557CAE89B3DCB9C2DC0_documentation_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveFebruary2012Member_B1211831507EE557CAE89B3DCB9C2DC0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective February 2012 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_TermCreditFacilityEffectiveFebruary2012Member" xlink:label="loc_ofc_TermCreditFacilityEffectiveFebruary2012Member_B1211831507EE557CAE89B3DCB9C2DC0" xlink:type="locator" />
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    <link:label id="lab_ofc_TermLoanFacilitiesMaturing2020Member_81E49AE670BD46ABA1AE9B3DCB9C4664_label_en-US" xlink:label="lab_ofc_TermLoanFacilitiesMaturing2020Member_81E49AE670BD46ABA1AE9B3DCB9C4664" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Term Loan Facilities Maturing 2020 [Member]</link:label>
    <link:label id="lab_ofc_TermLoanFacilitiesMaturing2020Member_81E49AE670BD46ABA1AE9B3DCB9C4664_documentation_en-US" xlink:label="lab_ofc_TermLoanFacilitiesMaturing2020Member_81E49AE670BD46ABA1AE9B3DCB9C4664" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Term Loan Facilities Maturing 2020 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_TermLoanFacilitiesMaturing2020Member" xlink:label="loc_ofc_TermLoanFacilitiesMaturing2020Member_81E49AE670BD46ABA1AE9B3DCB9C4664" xlink:type="locator" />
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    <link:label id="lab_ofc_TermCreditFacilityEffectiveDecember2015Member_F3DB9AF04C7C5446DA869B3DCB9CD793_terseLabel_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveDecember2015Member_F3DB9AF04C7C5446DA869B3DCB9CD793" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective December 2015 [Member]</link:label>
    <link:label id="lab_ofc_TermCreditFacilityEffectiveDecember2015Member_F3DB9AF04C7C5446DA869B3DCB9CD793_label_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveDecember2015Member_F3DB9AF04C7C5446DA869B3DCB9CD793" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective December 2015 [Member]</link:label>
    <link:label id="lab_ofc_TermCreditFacilityEffectiveDecember2015Member_F3DB9AF04C7C5446DA869B3DCB9CD793_documentation_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveDecember2015Member_F3DB9AF04C7C5446DA869B3DCB9CD793" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective December 2015 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_TermCreditFacilityEffectiveDecember2015Member" xlink:label="loc_ofc_TermCreditFacilityEffectiveDecember2015Member_F3DB9AF04C7C5446DA869B3DCB9CD793" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_TermCreditFacilityEffectiveDecember2015Member_F3DB9AF04C7C5446DA869B3DCB9CD793" xlink:to="lab_ofc_TermCreditFacilityEffectiveDecember2015Member_F3DB9AF04C7C5446DA869B3DCB9CD793" xlink:type="arc" />
    <link:label id="lab_ofc_TermCreditFacilityEffectiveDecember2016Member_C64856B71E0C227444EF9B3DCB9DD3DD_terseLabel_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveDecember2016Member_C64856B71E0C227444EF9B3DCB9DD3DD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective December 2016 [Member]</link:label>
    <link:label id="lab_ofc_TermCreditFacilityEffectiveDecember2016Member_C64856B71E0C227444EF9B3DCB9DD3DD_label_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveDecember2016Member_C64856B71E0C227444EF9B3DCB9DD3DD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective December 2016 [Member]</link:label>
    <link:label id="lab_ofc_TermCreditFacilityEffectiveDecember2016Member_C64856B71E0C227444EF9B3DCB9DD3DD_documentation_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveDecember2016Member_C64856B71E0C227444EF9B3DCB9DD3DD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective December 2016 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_TermCreditFacilityEffectiveDecember2016Member" xlink:label="loc_ofc_TermCreditFacilityEffectiveDecember2016Member_C64856B71E0C227444EF9B3DCB9DD3DD" xlink:type="locator" />
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    <link:label id="lab_ofc_TermCreditFacilityEffectiveAugust2012Member_CD066E55C41AD4CB617B9B3DCB9DEEA7_terseLabel_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveAugust2012Member_CD066E55C41AD4CB617B9B3DCB9DEEA7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective August 2012 [Member]</link:label>
    <link:label id="lab_ofc_TermCreditFacilityEffectiveAugust2012Member_CD066E55C41AD4CB617B9B3DCB9DEEA7_label_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveAugust2012Member_CD066E55C41AD4CB617B9B3DCB9DEEA7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective August 2012 [Member]</link:label>
    <link:label id="lab_ofc_TermCreditFacilityEffectiveAugust2012Member_CD066E55C41AD4CB617B9B3DCB9DEEA7_documentation_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveAugust2012Member_CD066E55C41AD4CB617B9B3DCB9DEEA7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective August 2012 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_TermCreditFacilityEffectiveAugust2012Member" xlink:label="loc_ofc_TermCreditFacilityEffectiveAugust2012Member_CD066E55C41AD4CB617B9B3DCB9DEEA7" xlink:type="locator" />
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    <link:label id="lab_ofc_TermCreditFacilityEffectiveSeptember2011Member_439D5D6EC72100C2AF6D9B3DCB9D05CD_terseLabel_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveSeptember2011Member_439D5D6EC72100C2AF6D9B3DCB9D05CD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective September 2011 [Member]</link:label>
    <link:label id="lab_ofc_TermCreditFacilityEffectiveSeptember2011Member_439D5D6EC72100C2AF6D9B3DCB9D05CD_label_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveSeptember2011Member_439D5D6EC72100C2AF6D9B3DCB9D05CD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective September 2011 [Member]</link:label>
    <link:label id="lab_ofc_TermCreditFacilityEffectiveSeptember2011Member_439D5D6EC72100C2AF6D9B3DCB9D05CD_documentation_en-US" xlink:label="lab_ofc_TermCreditFacilityEffectiveSeptember2011Member_439D5D6EC72100C2AF6D9B3DCB9D05CD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Term Credit Facility Effective September 2011 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_TermCreditFacilityEffectiveSeptember2011Member" xlink:label="loc_ofc_TermCreditFacilityEffectiveSeptember2011Member_439D5D6EC72100C2AF6D9B3DCB9D05CD" xlink:type="locator" />
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    <link:label id="lab_ofc_FivePercentSeniorNotesMember_451148CBAEF073B5D46E9B3DCB9D67F5_label_en-US" xlink:label="lab_ofc_FivePercentSeniorNotesMember_451148CBAEF073B5D46E9B3DCB9D67F5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Five Percent Senior Notes [Member]</link:label>
    <link:label id="lab_ofc_FivePercentSeniorNotesMember_451148CBAEF073B5D46E9B3DCB9D67F5_documentation_en-US" xlink:label="lab_ofc_FivePercentSeniorNotesMember_451148CBAEF073B5D46E9B3DCB9D67F5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Five Percent Senior Notes [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_FivePercentSeniorNotesMember" xlink:label="loc_ofc_FivePercentSeniorNotesMember_451148CBAEF073B5D46E9B3DCB9D67F5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_FivePercentSeniorNotesMember_451148CBAEF073B5D46E9B3DCB9D67F5" xlink:to="lab_ofc_FivePercentSeniorNotesMember_451148CBAEF073B5D46E9B3DCB9D67F5" xlink:type="arc" />
    <link:label id="lab_ofc_A3.70SeniorNotesMember_70584FFB213EE5EC49619B3DCB9D0714_terseLabel_en-US" xlink:label="lab_ofc_A3.70SeniorNotesMember_70584FFB213EE5EC49619B3DCB9D0714" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">3.70% Senior Notes [Member]</link:label>
    <link:label id="lab_ofc_A3.70SeniorNotesMember_70584FFB213EE5EC49619B3DCB9D0714_label_en-US" xlink:label="lab_ofc_A3.70SeniorNotesMember_70584FFB213EE5EC49619B3DCB9D0714" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">3.70% Senior Notes [Member]</link:label>
    <link:label id="lab_ofc_A3.70SeniorNotesMember_70584FFB213EE5EC49619B3DCB9D0714_documentation_en-US" xlink:label="lab_ofc_A3.70SeniorNotesMember_70584FFB213EE5EC49619B3DCB9D0714" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">3.70SeniorNotes [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_A3.70SeniorNotesMember" xlink:label="loc_ofc_A3.70SeniorNotesMember_70584FFB213EE5EC49619B3DCB9D0714" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_A3.70SeniorNotesMember_70584FFB213EE5EC49619B3DCB9D0714" xlink:to="lab_ofc_A3.70SeniorNotesMember_70584FFB213EE5EC49619B3DCB9D0714" xlink:type="arc" />
    <link:label id="lab_ofc_A3.60SeniorNotesMember_D9F1DE8DC802B48BA3AD9B3DCB9DC2D4_terseLabel_en-US" xlink:label="lab_ofc_A3.60SeniorNotesMember_D9F1DE8DC802B48BA3AD9B3DCB9DC2D4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">3.60% Senior Notes [Member]</link:label>
    <link:label id="lab_ofc_A3.60SeniorNotesMember_D9F1DE8DC802B48BA3AD9B3DCB9DC2D4_label_en-US" xlink:label="lab_ofc_A3.60SeniorNotesMember_D9F1DE8DC802B48BA3AD9B3DCB9DC2D4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">3.60% Senior Notes [Member]</link:label>
    <link:label id="lab_ofc_A3.60SeniorNotesMember_D9F1DE8DC802B48BA3AD9B3DCB9DC2D4_documentation_en-US" xlink:label="lab_ofc_A3.60SeniorNotesMember_D9F1DE8DC802B48BA3AD9B3DCB9DC2D4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">3.60% Senior Notes [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_A3.60SeniorNotesMember" xlink:label="loc_ofc_A3.60SeniorNotesMember_D9F1DE8DC802B48BA3AD9B3DCB9DC2D4" xlink:type="locator" />
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    <link:label id="lab_ofc_A5.250SeniorNotesMember_B003AFCB22AEB61008B69B3DCB9DB9A1_terseLabel_en-US" xlink:label="lab_ofc_A5.250SeniorNotesMember_B003AFCB22AEB61008B69B3DCB9DB9A1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">5.250% Senior Notes [Member]</link:label>
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    <link:label id="lab_ofc_FixedRateSecuredDebtMember_B302D6D100A67E0E13F59B3DCBA34D05_terseLabel_en-US" xlink:label="lab_ofc_FixedRateSecuredDebtMember_B302D6D100A67E0E13F59B3DCBA34D05" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Fixed rate mortgage loans [Member]</link:label>
    <link:label id="lab_ofc_FixedRateSecuredDebtMember_B302D6D100A67E0E13F59B3DCBA34D05_label_en-US" xlink:label="lab_ofc_FixedRateSecuredDebtMember_B302D6D100A67E0E13F59B3DCBA34D05" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Fixed Rate Secured Debt [Member]</link:label>
    <link:label id="lab_ofc_FixedRateSecuredDebtMember_B302D6D100A67E0E13F59B3DCBA34D05_documentation_en-US" xlink:label="lab_ofc_FixedRateSecuredDebtMember_B302D6D100A67E0E13F59B3DCBA34D05" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">A collateralized debt obligation (backed by pledge, mortgage or other lien on the entity's assets) bearing fixed interest rates.</link:label>
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    <link:label id="lab_us-gaap_VariableRateAxis_53B39112A8B40DF4E5399B3DCBA3C587_label_en-US" xlink:label="lab_us-gaap_VariableRateAxis_53B39112A8B40DF4E5399B3DCBA3C587" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Rate [Axis]</link:label>
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    <link:label id="lab_us-gaap_VariableRateDomain_DD2D39F29389E31A1ED59B3DCBA32D54_label_en-US" xlink:label="lab_us-gaap_VariableRateDomain_DD2D39F29389E31A1ED59B3DCBA32D54" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Rate [Domain]</link:label>
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    <link:label id="lab_ofc_AdjustedTreasuryMember_34ABC5EE5A5691A668BE9B3DCBA7790E_terseLabel_en-US" xlink:label="lab_ofc_AdjustedTreasuryMember_34ABC5EE5A5691A668BE9B3DCBA7790E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Adjusted Treasury [Member]</link:label>
    <link:label id="lab_ofc_AdjustedTreasuryMember_34ABC5EE5A5691A668BE9B3DCBA7790E_label_en-US" xlink:label="lab_ofc_AdjustedTreasuryMember_34ABC5EE5A5691A668BE9B3DCBA7790E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Adjusted Treasury [Member]</link:label>
    <link:label id="lab_ofc_AdjustedTreasuryMember_34ABC5EE5A5691A668BE9B3DCBA7790E_documentation_en-US" xlink:label="lab_ofc_AdjustedTreasuryMember_34ABC5EE5A5691A668BE9B3DCBA7790E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Adjusted Treasury [Member]</link:label>
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    <link:label id="lab_us-gaap_LondonInterbankOfferedRateLIBORMember_A8ACD459B58BAEBFA8C99B3DCBA7AB38_terseLabel_en-US" xlink:label="lab_us-gaap_LondonInterbankOfferedRateLIBORMember_A8ACD459B58BAEBFA8C99B3DCBA7AB38" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">London Interbank Offered Rate (LIBOR) [Member]</link:label>
    <link:label id="lab_us-gaap_LondonInterbankOfferedRateLIBORMember_A8ACD459B58BAEBFA8C99B3DCBA7AB38_label_en-US" xlink:label="lab_us-gaap_LondonInterbankOfferedRateLIBORMember_A8ACD459B58BAEBFA8C99B3DCBA7AB38" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">London Interbank Offered Rate (LIBOR) [Member]</link:label>
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    <link:label id="lab_us-gaap_DebtInstrumentLineItems_3BE2E18D800DEBA3DE949B3DCBA89C7C_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentLineItems_3BE2E18D800DEBA3DE949B3DCBA89C7C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Debt Instrument [Line Items]</link:label>
    <link:label id="lab_us-gaap_DebtInstrumentLineItems_3BE2E18D800DEBA3DE949B3DCBA89C7C_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentLineItems_3BE2E18D800DEBA3DE949B3DCBA89C7C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt Instrument [Line Items]</link:label>
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    <link:label id="lab_ofc_Basispointsusedindeterminingredemptionpricepriortomaturity_83318AA4AFE1DB3B38F69B3DCBA89B57_terseLabel_en-US" xlink:label="lab_ofc_Basispointsusedindeterminingredemptionpricepriortomaturity_83318AA4AFE1DB3B38F69B3DCBA89B57" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Basis points used in determining redemption price prior to maturity</link:label>
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    <link:label id="lab_ofc_Basispointsusedindeterminingredemptionpricepriortomaturity_83318AA4AFE1DB3B38F69B3DCBA89B57_documentation_en-US" xlink:label="lab_ofc_Basispointsusedindeterminingredemptionpricepriortomaturity_83318AA4AFE1DB3B38F69B3DCBA89B57" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Basis points added to adjusted treasury note used in determining the redemption price of the debt instrument prior to maturity.</link:label>
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    <link:label id="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_6988D43EA70FEE14C7489B3DCBA8D1C0_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_6988D43EA70FEE14C7489B3DCBA8D1C0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Maximum availability</link:label>
    <link:label id="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_6988D43EA70FEE14C7489B3DCBA8D1C0_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_6988D43EA70FEE14C7489B3DCBA8D1C0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Line of Credit Facility, Maximum Borrowing Capacity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_6988D43EA70FEE14C7489B3DCBA8D1C0" xlink:type="locator" />
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    <link:label id="lab_ofc_LineOfCreditExpansionRightMaximumBorrowingAvailabiliity_669E3D54BC40B9D4292F9B3DCBA88082_terseLabel_en-US" xlink:label="lab_ofc_LineOfCreditExpansionRightMaximumBorrowingAvailabiliity_669E3D54BC40B9D4292F9B3DCBA88082" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Expansion right, maximum borrowing capacity</link:label>
    <link:label id="lab_ofc_LineOfCreditExpansionRightMaximumBorrowingAvailabiliity_669E3D54BC40B9D4292F9B3DCBA88082_label_en-US" xlink:label="lab_ofc_LineOfCreditExpansionRightMaximumBorrowingAvailabiliity_669E3D54BC40B9D4292F9B3DCBA88082" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Line Of Credit Expansion Right Maximum Borrowing Availabiliity</link:label>
    <link:label id="lab_ofc_LineOfCreditExpansionRightMaximumBorrowingAvailabiliity_669E3D54BC40B9D4292F9B3DCBA88082_documentation_en-US" xlink:label="lab_ofc_LineOfCreditExpansionRightMaximumBorrowingAvailabiliity_669E3D54BC40B9D4292F9B3DCBA88082" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Maximum borrowing availability to which the credit facility may be expanded as per the terms of the agreement, which is the right of the reporting entity.</link:label>
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    <link:label id="lab_ofc_LineofCreditFacilityMaturityDateExtensionNumberofExtensions_68E0F1ACA9DF2A7CDAFE9B3DCBA93A9A_terseLabel_en-US" xlink:label="lab_ofc_LineofCreditFacilityMaturityDateExtensionNumberofExtensions_68E0F1ACA9DF2A7CDAFE9B3DCBA93A9A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of extensions</link:label>
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    <link:label id="lab_ofc_DebtInstrumentExtensionOptionTerm_81F51A5AE1DFFC2FFAE59B3DCBA9D400_terseLabel_en-US" xlink:label="lab_ofc_DebtInstrumentExtensionOptionTerm_81F51A5AE1DFFC2FFAE59B3DCBA9D400" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Extension option period (in years)</link:label>
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    <link:label id="lab_ofc_DebtInstrumentExtensionOptionTerm_81F51A5AE1DFFC2FFAE59B3DCBA9D400_documentation_en-US" xlink:label="lab_ofc_DebtInstrumentExtensionOptionTerm_81F51A5AE1DFFC2FFAE59B3DCBA9D400" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the period over which the debt may be extended at the option of the entity, subject to certain conditions.</link:label>
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    <link:label id="lab_ofc_LineofCreditFacilityExtensionFeePercentage_1482CFDFE19E28FFE1199B3DCBA98EEF_terseLabel_en-US" xlink:label="lab_ofc_LineofCreditFacilityExtensionFeePercentage_1482CFDFE19E28FFE1199B3DCBA98EEF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Line of credit facility, extension fee percentage</link:label>
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    <link:label id="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_CE03BDF93F2329D52CEA9B3DCBA97434_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_CE03BDF93F2329D52CEA9B3DCBA97434" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Variable rate, spread (as a percent)</link:label>
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    <link:label id="lab_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_857C2E1463A47E4AEC429B3DCBA93390_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_857C2E1463A47E4AEC429B3DCBA93390" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Commitment fee percentage</link:label>
    <link:label id="lab_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_857C2E1463A47E4AEC429B3DCBA93390_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_857C2E1463A47E4AEC429B3DCBA93390" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Line of Credit Facility, Commitment Fee Percentage</link:label>
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    <link:label id="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_2E775FC7616237E796589B3DCBAA9A72_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_2E775FC7616237E796589B3DCBAA9A72" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Remaining borrowing capacity</link:label>
    <link:label id="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_2E775FC7616237E796589B3DCBAA9A72_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_2E775FC7616237E796589B3DCBAA9A72" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Line of Credit Facility, Remaining Borrowing Capacity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_2E775FC7616237E796589B3DCBAA9A72" xlink:type="locator" />
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    <link:label id="lab_us-gaap_LineOfCreditFacilityAverageOutstandingAmount_55D71E33FCAC3DB5483F9B3DCBAA3278_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityAverageOutstandingAmount_55D71E33FCAC3DB5483F9B3DCBAA3278" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Weighted average borrowings</link:label>
    <link:label id="lab_us-gaap_LineOfCreditFacilityAverageOutstandingAmount_55D71E33FCAC3DB5483F9B3DCBAA3278_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityAverageOutstandingAmount_55D71E33FCAC3DB5483F9B3DCBAA3278" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Line of Credit Facility, Average Outstanding Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityAverageOutstandingAmount" xlink:label="loc_us-gaap_LineOfCreditFacilityAverageOutstandingAmount_55D71E33FCAC3DB5483F9B3DCBAA3278" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DebtWeightedAverageInterestRate_8DB217937EE832403F4C9B3DCBAA7586_terseLabel_en-US" xlink:label="lab_us-gaap_DebtWeightedAverageInterestRate_8DB217937EE832403F4C9B3DCBAA7586" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Weighted average interest rate (as a percent)</link:label>
    <link:label id="lab_us-gaap_DebtWeightedAverageInterestRate_8DB217937EE832403F4C9B3DCBAA7586_label_en-US" xlink:label="lab_us-gaap_DebtWeightedAverageInterestRate_8DB217937EE832403F4C9B3DCBAA7586" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt, Weighted Average Interest Rate</link:label>
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    <link:label id="lab_ofc_LineofCreditFacilityIncreasetoMaximumBorrowingCapacity_C428EAE87E27DE445D169B3DCBAA6A2E_terseLabel_en-US" xlink:label="lab_ofc_LineofCreditFacilityIncreasetoMaximumBorrowingCapacity_C428EAE87E27DE445D169B3DCBAA6A2E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Increase to maximum borrowing capacity</link:label>
    <link:label id="lab_ofc_LineofCreditFacilityIncreasetoMaximumBorrowingCapacity_C428EAE87E27DE445D169B3DCBAA6A2E_label_en-US" xlink:label="lab_ofc_LineofCreditFacilityIncreasetoMaximumBorrowingCapacity_C428EAE87E27DE445D169B3DCBAA6A2E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Line of Credit Facility, Increase to Maximum Borrowing Capacity</link:label>
    <link:label id="lab_ofc_LineofCreditFacilityIncreasetoMaximumBorrowingCapacity_C428EAE87E27DE445D169B3DCBAA6A2E_documentation_en-US" xlink:label="lab_ofc_LineofCreditFacilityIncreasetoMaximumBorrowingCapacity_C428EAE87E27DE445D169B3DCBAA6A2E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Line of Credit Facility, Accordion Feature, Increase Limit</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_LineofCreditFacilityIncreasetoMaximumBorrowingCapacity" xlink:label="loc_ofc_LineofCreditFacilityIncreasetoMaximumBorrowingCapacity_C428EAE87E27DE445D169B3DCBAA6A2E" xlink:type="locator" />
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    <link:label id="lab_us-gaap_RepaymentsOfLongTermDebt_A6B696F4967B5DA688979B3DCBAAB310_terseLabel_en-US" xlink:label="lab_us-gaap_RepaymentsOfLongTermDebt_A6B696F4967B5DA688979B3DCBAAB310" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Repayments of term loan</link:label>
    <link:label id="lab_us-gaap_RepaymentsOfLongTermDebt_A6B696F4967B5DA688979B3DCBAAB310_label_en-US" xlink:label="lab_us-gaap_RepaymentsOfLongTermDebt_A6B696F4967B5DA688979B3DCBAAB310" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Repayments of Long-term Debt</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_A6B696F4967B5DA688979B3DCBAAB310" xlink:type="locator" />
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    <link:label id="lab_us-gaap_RepaymentsOfDebt_4BE43EE76D907AA4D3539B3DCBAAEB45_terseLabel_en-US" xlink:label="lab_us-gaap_RepaymentsOfDebt_4BE43EE76D907AA4D3539B3DCBAAEB45" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Repayments of debt</link:label>
    <link:label id="lab_us-gaap_RepaymentsOfDebt_4BE43EE76D907AA4D3539B3DCBAAEB45_label_en-US" xlink:label="lab_us-gaap_RepaymentsOfDebt_4BE43EE76D907AA4D3539B3DCBAAEB45" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Repayments of Debt</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RepaymentsOfDebt" xlink:label="loc_us-gaap_RepaymentsOfDebt_4BE43EE76D907AA4D3539B3DCBAAEB45" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DebtInstrumentFaceAmount_BAAEA1436447A0260C289B3DCBABC0EC_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentFaceAmount_BAAEA1436447A0260C289B3DCBABC0EC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Loan amount</link:label>
    <link:label id="lab_us-gaap_DebtInstrumentFaceAmount_BAAEA1436447A0260C289B3DCBABC0EC_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentFaceAmount_BAAEA1436447A0260C289B3DCBABC0EC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt Instrument, Face Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_BAAEA1436447A0260C289B3DCBABC0EC" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentFaceAmount_BAAEA1436447A0260C289B3DCBABC0EC" xlink:to="lab_us-gaap_DebtInstrumentFaceAmount_BAAEA1436447A0260C289B3DCBABC0EC" xlink:type="arc" />
    <link:label id="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_A28386BF20AAA18CB6829B3DCBAB33FB_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_A28386BF20AAA18CB6829B3DCBAB33FB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Stated interest rate (as a percent)</link:label>
    <link:label id="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_A28386BF20AAA18CB6829B3DCBAB33FB_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_A28386BF20AAA18CB6829B3DCBAB33FB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt Instrument, Interest Rate, Stated Percentage</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_A28386BF20AAA18CB6829B3DCBAB33FB" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DebtInstrumentRedemptionPricePercentage_9693AB857CEBEFC662219B3DCBAB7F0C_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPricePercentage_9693AB857CEBEFC662219B3DCBAB7F0C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Redemption price (percent)</link:label>
    <link:label id="lab_us-gaap_DebtInstrumentRedemptionPricePercentage_9693AB857CEBEFC662219B3DCBAB7F0C_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPricePercentage_9693AB857CEBEFC662219B3DCBAB7F0C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt Instrument, Redemption Price, Percentage</link:label>
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    <link:label id="lab_ofc_Debtissuanceasapercentageofprincipalamount_30BC040941DC39A72F509B3DCBABE6F3_terseLabel_en-US" xlink:label="lab_ofc_Debtissuanceasapercentageofprincipalamount_30BC040941DC39A72F509B3DCBABE6F3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Debt issuance as a percentage of principal amount</link:label>
    <link:label id="lab_ofc_Debtissuanceasapercentageofprincipalamount_30BC040941DC39A72F509B3DCBABE6F3_label_en-US" xlink:label="lab_ofc_Debtissuanceasapercentageofprincipalamount_30BC040941DC39A72F509B3DCBABE6F3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt issuance as a percentage of principal amount</link:label>
    <link:label id="lab_ofc_Debtissuanceasapercentageofprincipalamount_30BC040941DC39A72F509B3DCBABE6F3_documentation_en-US" xlink:label="lab_ofc_Debtissuanceasapercentageofprincipalamount_30BC040941DC39A72F509B3DCBABE6F3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the debt instrument issuance price, expressed as a percentage of the principal amount of the debt instrument.</link:label>
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    <link:label id="lab_us-gaap_DebtInstrumentUnamortizedDiscount_7C87D24E636349D989CD9B3DCBAB5AE2_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentUnamortizedDiscount_7C87D24E636349D989CD9B3DCBAB5AE2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Unamortized discount included in carrying value</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_7C87D24E636349D989CD9B3DCBAB5AE2" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DebtInstrumentInterestRateEffectivePercentage_B672AB848215B75701849B3DCBAB2312_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateEffectivePercentage_B672AB848215B75701849B3DCBAB2312" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt Instrument, Interest Rate, Effective Percentage</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_B672AB848215B75701849B3DCBAB2312" xlink:type="locator" />
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    <link:loc xlink:href="ofc-20171231.xsd#ofc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsSharesissuedforAwardsVestedinPeriod" xlink:label="loc_ofc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsSharesissuedforAwardsVestedinPeriod_D62260B53F9C1CE9F4549A845C67A0CF" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsSharesissuedforAwardsVestedinPeriod_D62260B53F9C1CE9F4549A845C67A0CF" xlink:to="lab_ofc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsSharesissuedforAwardsVestedinPeriod_D62260B53F9C1CE9F4549A845C67A0CF" xlink:type="arc" />
    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost_C53CBCD4B65FD65FE1FB9AD448E81836_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost_C53CBCD4B65FD65FE1FB9AD448E81836" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Grant date fair value</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost_C53CBCD4B65FD65FE1FB9AD448E81836" xlink:type="locator" />
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    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_C52B38247560AF312F0C9A845C680A22_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_C52B38247560AF312F0C9A845C680A22" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Aggregate intrinsic value of options exercised</link:label>
    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_C52B38247560AF312F0C9A845C680A22_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_C52B38247560AF312F0C9A845C680A22" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_C52B38247560AF312F0C9A845C680A22" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_4C5862AE9E8943B7E6529A845C695DDF_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_4C5862AE9E8943B7E6529A845C695DDF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Executive transition costs</link:label>
    <link:label id="lab_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_4C5862AE9E8943B7E6529A845C695DDF_label_en-US" xlink:label="lab_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_4C5862AE9E8943B7E6529A845C695DDF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Deferred Compensation Arrangement with Individual, Compensation Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_4C5862AE9E8943B7E6529A845C695DDF" xlink:type="locator" />
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    <link:label id="lab_ofc_GICOPTDCPartnershipLLCMember_8F256DE8A98A0198C7EA9BE4B09039E3_terseLabel_en-US" xlink:label="lab_ofc_GICOPTDCPartnershipLLCMember_8F256DE8A98A0198C7EA9BE4B09039E3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">GI-COPT [Member]</link:label>
    <link:label id="lab_ofc_GICOPTDCPartnershipLLCMember_8F256DE8A98A0198C7EA9BE4B09039E3_label_en-US" xlink:label="lab_ofc_GICOPTDCPartnershipLLCMember_8F256DE8A98A0198C7EA9BE4B09039E3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">GI-COPT DC Partnership LLC [Member]</link:label>
    <link:label id="lab_ofc_GICOPTDCPartnershipLLCMember_8F256DE8A98A0198C7EA9BE4B09039E3_documentation_en-US" xlink:label="lab_ofc_GICOPTDCPartnershipLLCMember_8F256DE8A98A0198C7EA9BE4B09039E3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">GI-COPT DC Partnership LLC [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_GICOPTDCPartnershipLLCMember" xlink:label="loc_ofc_GICOPTDCPartnershipLLCMember_8F256DE8A98A0198C7EA9BE4B09039E3" xlink:type="locator" />
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    <link:label id="lab_ofc_LandControlledforFutureDevelopmentMember_793D20BAE41C5C15CDE19BE4B091F3EE_terseLabel_en-US" xlink:label="lab_ofc_LandControlledforFutureDevelopmentMember_793D20BAE41C5C15CDE19BE4B091F3EE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Land controlled for future development [Member]</link:label>
    <link:label id="lab_ofc_LandControlledforFutureDevelopmentMember_793D20BAE41C5C15CDE19BE4B091F3EE_label_en-US" xlink:label="lab_ofc_LandControlledforFutureDevelopmentMember_793D20BAE41C5C15CDE19BE4B091F3EE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Land Controlled for Future Development [Member]</link:label>
    <link:label id="lab_ofc_LandControlledforFutureDevelopmentMember_793D20BAE41C5C15CDE19BE4B091F3EE_documentation_en-US" xlink:label="lab_ofc_LandControlledforFutureDevelopmentMember_793D20BAE41C5C15CDE19BE4B091F3EE" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents land controlled by the entity for future development.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_LandControlledforFutureDevelopmentMember" xlink:label="loc_ofc_LandControlledforFutureDevelopmentMember_793D20BAE41C5C15CDE19BE4B091F3EE" xlink:type="locator" />
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    <link:label id="lab_ofc_OtherLandMember_3ECB26493E3F9A2720A49BE4B09175F1_terseLabel_en-US" xlink:label="lab_ofc_OtherLandMember_3ECB26493E3F9A2720A49BE4B09175F1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other land [Member]</link:label>
    <link:label id="lab_ofc_OtherLandMember_3ECB26493E3F9A2720A49BE4B09175F1_label_en-US" xlink:label="lab_ofc_OtherLandMember_3ECB26493E3F9A2720A49BE4B09175F1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Land [Member]</link:label>
    <link:label id="lab_ofc_OtherLandMember_3ECB26493E3F9A2720A49BE4B09175F1_documentation_en-US" xlink:label="lab_ofc_OtherLandMember_3ECB26493E3F9A2720A49BE4B09175F1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Other Land [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_OtherLandMember" xlink:label="loc_ofc_OtherLandMember_3ECB26493E3F9A2720A49BE4B09175F1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_OtherLandMember_3ECB26493E3F9A2720A49BE4B09175F1" xlink:to="lab_ofc_OtherLandMember_3ECB26493E3F9A2720A49BE4B09175F1" xlink:type="arc" />
    <link:label id="lab_ofc_WholesaleDataCenterMember_11563BF680FE77F8990F9BE4B09197DF_terseLabel_en-US" xlink:label="lab_ofc_WholesaleDataCenterMember_11563BF680FE77F8990F9BE4B09197DF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Operating wholesale data centers [Member]</link:label>
    <link:label id="lab_ofc_WholesaleDataCenterMember_11563BF680FE77F8990F9BE4B09197DF_label_en-US" xlink:label="lab_ofc_WholesaleDataCenterMember_11563BF680FE77F8990F9BE4B09197DF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Wholesale Data Center [Member]</link:label>
    <link:label id="lab_ofc_WholesaleDataCenterMember_11563BF680FE77F8990F9BE4B09197DF_documentation_en-US" xlink:label="lab_ofc_WholesaleDataCenterMember_11563BF680FE77F8990F9BE4B09197DF" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the wholesale data center segment of the entity.</link:label>
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    <link:label id="lab_ofc_OfficePropertiesMember_4370ABA678F71A168BE09BE4B091AD8A_terseLabel_en-US" xlink:label="lab_ofc_OfficePropertiesMember_4370ABA678F71A168BE09BE4B091AD8A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Office Properties [Member]</link:label>
    <link:label id="lab_ofc_OfficePropertiesMember_4370ABA678F71A168BE09BE4B091AD8A_label_en-US" xlink:label="lab_ofc_OfficePropertiesMember_4370ABA678F71A168BE09BE4B091AD8A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Office Properties [Member]</link:label>
    <link:label id="lab_ofc_OfficePropertiesMember_4370ABA678F71A168BE09BE4B091AD8A_documentation_en-US" xlink:label="lab_ofc_OfficePropertiesMember_4370ABA678F71A168BE09BE4B091AD8A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Office Properties [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_OfficePropertiesMember" xlink:label="loc_ofc_OfficePropertiesMember_4370ABA678F71A168BE09BE4B091AD8A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_OfficePropertiesMember_4370ABA678F71A168BE09BE4B091AD8A" xlink:to="lab_ofc_OfficePropertiesMember_4370ABA678F71A168BE09BE4B091AD8A" xlink:type="arc" />
    <link:label id="lab_ofc_PartiallyOperationalPropertiesMember_1660ADE903E8523534C69BE4B0914DDE_terseLabel_en-US" xlink:label="lab_ofc_PartiallyOperationalPropertiesMember_1660ADE903E8523534C69BE4B0914DDE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Partially operational properties [Member]</link:label>
    <link:label id="lab_ofc_PartiallyOperationalPropertiesMember_1660ADE903E8523534C69BE4B0914DDE_label_en-US" xlink:label="lab_ofc_PartiallyOperationalPropertiesMember_1660ADE903E8523534C69BE4B0914DDE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Partially Operational Properties [Member]</link:label>
    <link:label id="lab_ofc_PartiallyOperationalPropertiesMember_1660ADE903E8523534C69BE4B0914DDE_documentation_en-US" xlink:label="lab_ofc_PartiallyOperationalPropertiesMember_1660ADE903E8523534C69BE4B0914DDE" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents office properties under construction or redevelopment which are owned by the entity and which are partially operational.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PartiallyOperationalPropertiesMember" xlink:label="loc_ofc_PartiallyOperationalPropertiesMember_1660ADE903E8523534C69BE4B0914DDE" xlink:type="locator" />
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    <link:label id="lab_us-gaap_RealEstatePropertiesLineItems_5C153E136577347C24A69BE4B091F36B_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstatePropertiesLineItems_5C153E136577347C24A69BE4B091F36B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Investments in real estate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstatePropertiesLineItems" xlink:label="loc_us-gaap_RealEstatePropertiesLineItems_5C153E136577347C24A69BE4B091F36B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstatePropertiesLineItems_5C153E136577347C24A69BE4B091F36B" xlink:to="lab_us-gaap_RealEstatePropertiesLineItems_5C153E136577347C24A69BE4B091F36B" xlink:type="arc" />
    <link:label id="lab_us-gaap_AreaOfRealEstateProperty_92FE1348BC6E56F7472D9BE4B091BCC2_terseLabel_en-US" xlink:label="lab_us-gaap_AreaOfRealEstateProperty_92FE1348BC6E56F7472D9BE4B091BCC2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Area of real estate property (in sqft or acres)</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AreaOfRealEstateProperty" xlink:label="loc_us-gaap_AreaOfRealEstateProperty_92FE1348BC6E56F7472D9BE4B091BCC2" xlink:type="locator" />
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    <link:label id="lab_ofc_CriticalLoad_7200CE69BE310FA634EB9BE4B092AFE0_terseLabel_en-US" xlink:label="lab_ofc_CriticalLoad_7200CE69BE310FA634EB9BE4B092AFE0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Critical load (in megawatts)</link:label>
    <link:label id="lab_ofc_CriticalLoad_7200CE69BE310FA634EB9BE4B092AFE0_label_en-US" xlink:label="lab_ofc_CriticalLoad_7200CE69BE310FA634EB9BE4B092AFE0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Critical Load</link:label>
    <link:label id="lab_ofc_CriticalLoad_7200CE69BE310FA634EB9BE4B092AFE0_documentation_en-US" xlink:label="lab_ofc_CriticalLoad_7200CE69BE310FA634EB9BE4B092AFE0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the amount of the critical load of the property. Critical load is the amount of megawatts of power made available for the exclusive use tenants in the property.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_CriticalLoad" xlink:label="loc_ofc_CriticalLoad_7200CE69BE310FA634EB9BE4B092AFE0" xlink:type="locator" />
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    <link:label id="lab_us-gaap_EarningsPerShareAbstract_CB9AB52B0C6EA68209BD68EEA3A311F4_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareAbstract_CB9AB52B0C6EA68209BD68EEA3A311F4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Earnings Per Share [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract_CB9AB52B0C6EA68209BD68EEA3A311F4" xlink:type="locator" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3B2080BAE970B74868D99BE4B0400366" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3B2080BAE970B74868D99BE4B0400366" xlink:to="lab_us-gaap_ConcentrationRiskByBenchmarkAxis_3B2080BAE970B74868D99BE4B0400366" xlink:type="arc" />
    <link:label id="lab_us-gaap_ConcentrationRiskBenchmarkDomain_97BD1CD82490E896B6569BE4B0415E4A_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskBenchmarkDomain_97BD1CD82490E896B6569BE4B0415E4A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Concentration Risk Benchmark [Domain]</link:label>
    <link:label id="lab_us-gaap_ConcentrationRiskBenchmarkDomain_97BD1CD82490E896B6569BE4B0415E4A_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskBenchmarkDomain_97BD1CD82490E896B6569BE4B0415E4A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Concentration Risk Benchmark [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_97BD1CD82490E896B6569BE4B0415E4A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_97BD1CD82490E896B6569BE4B0415E4A" xlink:to="lab_us-gaap_ConcentrationRiskBenchmarkDomain_97BD1CD82490E896B6569BE4B0415E4A" xlink:type="arc" />
    <link:label id="lab_ofc_RentalRevenueMember_40EA0AB7635713CBF2C99BE4B041474B_terseLabel_en-US" xlink:label="lab_ofc_RentalRevenueMember_40EA0AB7635713CBF2C99BE4B041474B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Rental revenue [Member]</link:label>
    <link:label id="lab_ofc_RentalRevenueMember_40EA0AB7635713CBF2C99BE4B041474B_label_en-US" xlink:label="lab_ofc_RentalRevenueMember_40EA0AB7635713CBF2C99BE4B041474B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Rental Revenue [Member]</link:label>
    <link:label id="lab_ofc_RentalRevenueMember_40EA0AB7635713CBF2C99BE4B041474B_documentation_en-US" xlink:label="lab_ofc_RentalRevenueMember_40EA0AB7635713CBF2C99BE4B041474B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the rental revenue, excluding tenant recoveries and other real estate operations revenue, from various groups.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RentalRevenueMember" xlink:label="loc_ofc_RentalRevenueMember_40EA0AB7635713CBF2C99BE4B041474B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RentalRevenueMember_40EA0AB7635713CBF2C99BE4B041474B" xlink:to="lab_ofc_RentalRevenueMember_40EA0AB7635713CBF2C99BE4B041474B" xlink:type="arc" />
    <link:label id="lab_ofc_ConstructionContractRevenueMember_2BB982849213F0C9C20C9BE4B0411854_terseLabel_en-US" xlink:label="lab_ofc_ConstructionContractRevenueMember_2BB982849213F0C9C20C9BE4B0411854" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Construction contract revenue [Member]</link:label>
    <link:label id="lab_ofc_ConstructionContractRevenueMember_2BB982849213F0C9C20C9BE4B0411854_label_en-US" xlink:label="lab_ofc_ConstructionContractRevenueMember_2BB982849213F0C9C20C9BE4B0411854" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Construction Contract Revenue [Member]</link:label>
    <link:label id="lab_ofc_ConstructionContractRevenueMember_2BB982849213F0C9C20C9BE4B0411854_documentation_en-US" xlink:label="lab_ofc_ConstructionContractRevenueMember_2BB982849213F0C9C20C9BE4B0411854" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the construction contract revenue from various groups.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ConstructionContractRevenueMember" xlink:label="loc_ofc_ConstructionContractRevenueMember_2BB982849213F0C9C20C9BE4B0411854" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ConstructionContractRevenueMember_2BB982849213F0C9C20C9BE4B0411854" xlink:to="lab_ofc_ConstructionContractRevenueMember_2BB982849213F0C9C20C9BE4B0411854" xlink:type="arc" />
    <link:label id="lab_us-gaap_ConcentrationRiskByTypeAxis_D01BB74BBAFF551A04549BE4B0417847_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByTypeAxis_D01BB74BBAFF551A04549BE4B0417847" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Concentration Risk by Type [Axis]</link:label>
    <link:label id="lab_us-gaap_ConcentrationRiskByTypeAxis_D01BB74BBAFF551A04549BE4B0417847_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByTypeAxis_D01BB74BBAFF551A04549BE4B0417847" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Concentration Risk Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_D01BB74BBAFF551A04549BE4B0417847" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_D01BB74BBAFF551A04549BE4B0417847" xlink:to="lab_us-gaap_ConcentrationRiskByTypeAxis_D01BB74BBAFF551A04549BE4B0417847" xlink:type="arc" />
    <link:label id="lab_us-gaap_ConcentrationRiskTypeDomain_52F973A54EBC60D88A6B9BE4B0415E43_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskTypeDomain_52F973A54EBC60D88A6B9BE4B0415E43" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Concentration Risk Type [Domain]</link:label>
    <link:label id="lab_us-gaap_ConcentrationRiskTypeDomain_52F973A54EBC60D88A6B9BE4B0415E43_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskTypeDomain_52F973A54EBC60D88A6B9BE4B0415E43" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Concentration Risk Type [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_52F973A54EBC60D88A6B9BE4B0415E43" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_52F973A54EBC60D88A6B9BE4B0415E43" xlink:to="lab_us-gaap_ConcentrationRiskTypeDomain_52F973A54EBC60D88A6B9BE4B0415E43" xlink:type="arc" />
    <link:label id="lab_us-gaap_CustomerConcentrationRiskMember_2AF475D1CF42CF1F7F009BE4B041704E_terseLabel_en-US" xlink:label="lab_us-gaap_CustomerConcentrationRiskMember_2AF475D1CF42CF1F7F009BE4B041704E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Tenants [Member]</link:label>
    <link:label id="lab_us-gaap_CustomerConcentrationRiskMember_2AF475D1CF42CF1F7F009BE4B041704E_label_en-US" xlink:label="lab_us-gaap_CustomerConcentrationRiskMember_2AF475D1CF42CF1F7F009BE4B041704E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Customer Concentration Risk [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_2AF475D1CF42CF1F7F009BE4B041704E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CustomerConcentrationRiskMember_2AF475D1CF42CF1F7F009BE4B041704E" xlink:to="lab_us-gaap_CustomerConcentrationRiskMember_2AF475D1CF42CF1F7F009BE4B041704E" xlink:type="arc" />
    <link:label id="lab_us-gaap_MajorCustomersAxis_D535AA9BCD45B574662D9BE4B0418774_terseLabel_en-US" xlink:label="lab_us-gaap_MajorCustomersAxis_D535AA9BCD45B574662D9BE4B0418774" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Major Customers [Axis]</link:label>
    <link:label id="lab_us-gaap_MajorCustomersAxis_D535AA9BCD45B574662D9BE4B0418774_label_en-US" xlink:label="lab_us-gaap_MajorCustomersAxis_D535AA9BCD45B574662D9BE4B0418774" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Customer [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MajorCustomersAxis" xlink:label="loc_us-gaap_MajorCustomersAxis_D535AA9BCD45B574662D9BE4B0418774" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MajorCustomersAxis_D535AA9BCD45B574662D9BE4B0418774" xlink:to="lab_us-gaap_MajorCustomersAxis_D535AA9BCD45B574662D9BE4B0418774" xlink:type="arc" />
    <link:label id="lab_us-gaap_NameOfMajorCustomerDomain_6A040E33EDBD6B0784C29BE4B041B38E_terseLabel_en-US" xlink:label="lab_us-gaap_NameOfMajorCustomerDomain_6A040E33EDBD6B0784C29BE4B041B38E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Name of Major Customer [Domain]</link:label>
    <link:label id="lab_us-gaap_NameOfMajorCustomerDomain_6A040E33EDBD6B0784C29BE4B041B38E_label_en-US" xlink:label="lab_us-gaap_NameOfMajorCustomerDomain_6A040E33EDBD6B0784C29BE4B041B38E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Customer [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_6A040E33EDBD6B0784C29BE4B041B38E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_6A040E33EDBD6B0784C29BE4B041B38E" xlink:to="lab_us-gaap_NameOfMajorCustomerDomain_6A040E33EDBD6B0784C29BE4B041B38E" xlink:type="arc" />
    <link:label id="lab_ofc_UnitedStatesGovernmentMember_1345A536ABC166BE3A5A9BE4B041D653_terseLabel_en-US" xlink:label="lab_ofc_UnitedStatesGovernmentMember_1345A536ABC166BE3A5A9BE4B041D653" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">United States Government [Member]</link:label>
    <link:label id="lab_ofc_UnitedStatesGovernmentMember_1345A536ABC166BE3A5A9BE4B041D653_label_en-US" xlink:label="lab_ofc_UnitedStatesGovernmentMember_1345A536ABC166BE3A5A9BE4B041D653" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">United States Government [Member]</link:label>
    <link:label id="lab_ofc_UnitedStatesGovernmentMember_1345A536ABC166BE3A5A9BE4B041D653_documentation_en-US" xlink:label="lab_ofc_UnitedStatesGovernmentMember_1345A536ABC166BE3A5A9BE4B041D653" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the tenant, the United States Government.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_UnitedStatesGovernmentMember" xlink:label="loc_ofc_UnitedStatesGovernmentMember_1345A536ABC166BE3A5A9BE4B041D653" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_UnitedStatesGovernmentMember_1345A536ABC166BE3A5A9BE4B041D653" xlink:to="lab_ofc_UnitedStatesGovernmentMember_1345A536ABC166BE3A5A9BE4B041D653" xlink:type="arc" />
    <link:label id="lab_us-gaap_ConcentrationRiskLineItems_CFDDAFB881E4F91095279BE4B041A140_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskLineItems_CFDDAFB881E4F91095279BE4B041A140" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Concentration Risk</link:label>
    <link:label id="lab_us-gaap_ConcentrationRiskLineItems_CFDDAFB881E4F91095279BE4B041A140_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskLineItems_CFDDAFB881E4F91095279BE4B041A140" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Concentration Risk [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_CFDDAFB881E4F91095279BE4B041A140" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_CFDDAFB881E4F91095279BE4B041A140" xlink:to="lab_us-gaap_ConcentrationRiskLineItems_CFDDAFB881E4F91095279BE4B041A140" xlink:type="arc" />
    <link:label id="lab_us-gaap_ConcentrationRiskPercentage1_FD0398FF8E52230884829BE4B041C887_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskPercentage1_FD0398FF8E52230884829BE4B041C887" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Percentage of revenue</link:label>
    <link:label id="lab_us-gaap_ConcentrationRiskPercentage1_FD0398FF8E52230884829BE4B041C887_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskPercentage1_FD0398FF8E52230884829BE4B041C887" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Concentration Risk, Percentage</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_FD0398FF8E52230884829BE4B041C887" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskPercentage1_FD0398FF8E52230884829BE4B041C887" xlink:to="lab_us-gaap_ConcentrationRiskPercentage1_FD0398FF8E52230884829BE4B041C887" xlink:type="arc" />
    <link:label id="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_660DCF110F030BA968ED456A54612ECA_label_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_660DCF110F030BA968ED456A54612ECA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Commitments and Contingencies Disclosure [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_660DCF110F030BA968ED456A54612ECA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_660DCF110F030BA968ED456A54612ECA" xlink:to="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_660DCF110F030BA968ED456A54612ECA" xlink:type="arc" />
    <link:label id="lab_us-gaap_OperatingLeasesOfLesseeDisclosureTextBlock_664012CFC1900F18D749456A54625BC8_verboseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesOfLesseeDisclosureTextBlock_664012CFC1900F18D749456A54625BC8" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Schedule of future minimum rental payments</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesOfLesseeDisclosureTextBlock_664012CFC1900F18D749456A54625BC8_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesOfLesseeDisclosureTextBlock_664012CFC1900F18D749456A54625BC8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Disclosure [Table Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesOfLesseeDisclosureTextBlock" xlink:label="loc_us-gaap_OperatingLeasesOfLesseeDisclosureTextBlock_664012CFC1900F18D749456A54625BC8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesOfLesseeDisclosureTextBlock_664012CFC1900F18D749456A54625BC8" xlink:to="lab_us-gaap_OperatingLeasesOfLesseeDisclosureTextBlock_664012CFC1900F18D749456A54625BC8" xlink:type="arc" />
    <link:label id="lab_us-gaap_ScheduleOfFutureMinimumLeasePaymentsForCapitalLeasesTableTextBlock_E0F519878589E525B9C1456A546201F3_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfFutureMinimumLeasePaymentsForCapitalLeasesTableTextBlock_E0F519878589E525B9C1456A546201F3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Schedule of future minimum lease payments for capital leases</link:label>
    <link:label id="lab_us-gaap_ScheduleOfFutureMinimumLeasePaymentsForCapitalLeasesTableTextBlock_E0F519878589E525B9C1456A546201F3_label_en-US" xlink:label="lab_us-gaap_ScheduleOfFutureMinimumLeasePaymentsForCapitalLeasesTableTextBlock_E0F519878589E525B9C1456A546201F3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfFutureMinimumLeasePaymentsForCapitalLeasesTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfFutureMinimumLeasePaymentsForCapitalLeasesTableTextBlock_E0F519878589E525B9C1456A546201F3" xlink:type="locator" />
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredUnitsOutstanding_5564C53F08979BEDE2A39F27C4F00D5E" xlink:to="lab_us-gaap_PreferredUnitsOutstanding_5564C53F08979BEDE2A39F27C4F00D5E" xlink:type="arc" />
    <link:label id="lab_us-gaap_StockRedeemedOrCalledDuringPeriodShares_666AD2E4BCCB3C6E3F3D9F27C4F0FF7D_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_StockRedeemedOrCalledDuringPeriodShares_666AD2E4BCCB3C6E3F3D9F27C4F0FF7D" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Redemption of preferred shares/units</link:label>
    <link:label id="lab_us-gaap_StockRedeemedOrCalledDuringPeriodShares_666AD2E4BCCB3C6E3F3D9F27C4F0FF7D_label_en-US" xlink:label="lab_us-gaap_StockRedeemedOrCalledDuringPeriodShares_666AD2E4BCCB3C6E3F3D9F27C4F0FF7D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Redeemed or Called During Period, Shares</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodShares" xlink:label="loc_us-gaap_StockRedeemedOrCalledDuringPeriodShares_666AD2E4BCCB3C6E3F3D9F27C4F0FF7D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRedeemedOrCalledDuringPeriodShares_666AD2E4BCCB3C6E3F3D9F27C4F0FF7D" xlink:to="lab_us-gaap_StockRedeemedOrCalledDuringPeriodShares_666AD2E4BCCB3C6E3F3D9F27C4F0FF7D" xlink:type="arc" />
    <link:label id="lab_us-gaap_StockRedeemedOrCalledDuringPeriodValue_6FCFA0152640274584F69F27C4F03CE3_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_StockRedeemedOrCalledDuringPeriodValue_6FCFA0152640274584F69F27C4F03CE3" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Redemption of preferred shares/units (531,667 and 6,900,000 shares in 2016 and 2017, respectively)</link:label>
    <link:label id="lab_us-gaap_StockRedeemedOrCalledDuringPeriodValue_6FCFA0152640274584F69F27C4F03CE3_label_en-US" xlink:label="lab_us-gaap_StockRedeemedOrCalledDuringPeriodValue_6FCFA0152640274584F69F27C4F03CE3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Redeemed or Called During Period, Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockRedeemedOrCalledDuringPeriodValue" xlink:label="loc_us-gaap_StockRedeemedOrCalledDuringPeriodValue_6FCFA0152640274584F69F27C4F03CE3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRedeemedOrCalledDuringPeriodValue_6FCFA0152640274584F69F27C4F03CE3" xlink:to="lab_us-gaap_StockRedeemedOrCalledDuringPeriodValue_6FCFA0152640274584F69F27C4F03CE3" xlink:type="arc" />
    <link:label id="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_B11826D249EE4D665C209F27C4F0C892_verboseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_B11826D249EE4D665C209F27C4F0C892" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Conversion of common units to common shares (160,160, 87,000 and 339,513 shares in 2015, 2016 and 2017, respectively)</link:label>
    <link:label id="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_B11826D249EE4D665C209F27C4F0C892_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_B11826D249EE4D665C209F27C4F0C892" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Value, Conversion of Units</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfUnits" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_B11826D249EE4D665C209F27C4F0C892" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_B11826D249EE4D665C209F27C4F0C892" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueConversionOfUnits_B11826D249EE4D665C209F27C4F0C892" xlink:type="arc" />
    <link:label id="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement_60A6C1FC0BF649EECBD69F27C4F050B1_terseLabel_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement_60A6C1FC0BF649EECBD69F27C4F050B1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Common shares issued under forward equity sale agreements (1,678,913 shares)</link:label>
    <link:label id="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement_60A6C1FC0BF649EECBD69F27C4F050B1_label_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement_60A6C1FC0BF649EECBD69F27C4F050B1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Value, New Issues for Forward Equity Sale Agreement</link:label>
    <link:label id="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement_60A6C1FC0BF649EECBD69F27C4F050B1_documentation_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement_60A6C1FC0BF649EECBD69F27C4F050B1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Value, New Issues for Forward Equity Sale Agreement</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement" xlink:label="loc_ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement_60A6C1FC0BF649EECBD69F27C4F050B1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement_60A6C1FC0BF649EECBD69F27C4F050B1" xlink:to="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforForwardEquitySaleAgreement_60A6C1FC0BF649EECBD69F27C4F050B1" xlink:type="arc" />
    <link:label id="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement_0DFD4682A5FCF43CB0C29F27C4F0EC03_netLabel_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement_0DFD4682A5FCF43CB0C29F27C4F0EC03" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:type="resource" xml:lang="en-US">Issuance of common units resulting from COPT forward equity sale agreements (in shares)</link:label>
    <link:label id="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement_0DFD4682A5FCF43CB0C29F27C4F0EC03_label_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement_0DFD4682A5FCF43CB0C29F27C4F0EC03" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Shares, New Issues for Forward Equity Sale Agreement</link:label>
    <link:label id="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement_0DFD4682A5FCF43CB0C29F27C4F0EC03_documentation_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement_0DFD4682A5FCF43CB0C29F27C4F0EC03" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Shares, New Issues for Forward Equity Sale Agreement</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement" xlink:label="loc_ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement_0DFD4682A5FCF43CB0C29F27C4F0EC03" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement_0DFD4682A5FCF43CB0C29F27C4F0EC03" xlink:to="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforForwardEquitySaleAgreement_0DFD4682A5FCF43CB0C29F27C4F0EC03" xlink:type="arc" />
    <link:label id="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram_F4A59488BCD88E5525A59F27C4F095C7_terseLabel_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram_F4A59488BCD88E5525A59F27C4F095C7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Issuance of common units resulting from common shares issued under at-the-market program (in units)</link:label>
    <link:label id="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram_F4A59488BCD88E5525A59F27C4F095C7_label_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram_F4A59488BCD88E5525A59F27C4F095C7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Shares, New Issues for Other Program</link:label>
    <link:label id="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram_F4A59488BCD88E5525A59F27C4F095C7_documentation_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram_F4A59488BCD88E5525A59F27C4F095C7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Shares, New Issues for Other Program</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram" xlink:label="loc_ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram_F4A59488BCD88E5525A59F27C4F095C7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram_F4A59488BCD88E5525A59F27C4F095C7" xlink:to="lab_ofc_StockIssuedDuringPeriodSharesNewIssuesforOtherProgram_F4A59488BCD88E5525A59F27C4F095C7" xlink:type="arc" />
    <link:label id="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram_3B81A0756D17BACC8CAA9F27C4F05589_terseLabel_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram_3B81A0756D17BACC8CAA9F27C4F05589" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Issuance of common units resulting from common shares issued under at-the-market program (890,241, 3,721,227 and 591,042 shares in 2015, 2016 and 2017, respectively)</link:label>
    <link:label id="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram_3B81A0756D17BACC8CAA9F27C4F05589_label_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram_3B81A0756D17BACC8CAA9F27C4F05589" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Value, New Issues for Other Program</link:label>
    <link:label id="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram_3B81A0756D17BACC8CAA9F27C4F05589_documentation_en-US" xlink:label="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram_3B81A0756D17BACC8CAA9F27C4F05589" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Value, New Issues for Other Program</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram" xlink:label="loc_ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram_3B81A0756D17BACC8CAA9F27C4F05589" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram_3B81A0756D17BACC8CAA9F27C4F05589" xlink:to="lab_ofc_StockIssuedDuringPeriodValueNewIssuesforOtherProgram_3B81A0756D17BACC8CAA9F27C4F05589" xlink:type="arc" />
    <link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_69F9D4A1BAEE27E4D60F9F27C4F05808_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_69F9D4A1BAEE27E4D60F9F27C4F05808" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Exercise of share options (in units/shares)</link:label>
    <link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_69F9D4A1BAEE27E4D60F9F27C4F05808_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_69F9D4A1BAEE27E4D60F9F27C4F05808" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_69F9D4A1BAEE27E4D60F9F27C4F05808" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_69F9D4A1BAEE27E4D60F9F27C4F05808" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_69F9D4A1BAEE27E4D60F9F27C4F05808" xlink:type="arc" />
    <link:label id="lab_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_55BD16FD291A4B63B8DD9F27C4F02037_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_55BD16FD291A4B63B8DD9F27C4F02037" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Exercise of share options (76,474 and 5,000 shares in 2015 and 2017 respectively)</link:label>
    <link:label id="lab_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_55BD16FD291A4B63B8DD9F27C4F02037_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_55BD16FD291A4B63B8DD9F27C4F02037" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Value, Stock Options Exercised</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_55BD16FD291A4B63B8DD9F27C4F02037" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_55BD16FD291A4B63B8DD9F27C4F02037" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_55BD16FD291A4B63B8DD9F27C4F02037" xlink:type="arc" />
    <link:label id="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_84D521F9890F53DF51199F27C4F06C11_terseLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_84D521F9890F53DF51199F27C4F06C11" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Share-based compensation (149,353, 158,912 and 179,180 shares issued, net of redemptions in 2015, 2016 and 2017, respectively)</link:label>
    <link:label id="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_84D521F9890F53DF51199F27C4F06C11_label_en-US" xlink:label="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_84D521F9890F53DF51199F27C4F06C11" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_84D521F9890F53DF51199F27C4F06C11" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_84D521F9890F53DF51199F27C4F06C11" xlink:to="lab_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_84D521F9890F53DF51199F27C4F06C11" xlink:type="arc" />
    <link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_324A85492B19674C6CE19F27C4F09896_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_324A85492B19674C6CE19F27C4F09896" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Share-based compensation (in shares/units)</link:label>
    <link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_324A85492B19674C6CE19F27C4F09896_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_324A85492B19674C6CE19F27C4F09896" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_324A85492B19674C6CE19F27C4F09896" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_324A85492B19674C6CE19F27C4F09896" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_324A85492B19674C6CE19F27C4F09896" xlink:type="arc" />
    <link:label id="lab_us-gaap_StockRepurchasedDuringPeriodValue_1116060C11699C1378949F27C4F021F5_negatedLabel_en-US" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodValue_1116060C11699C1378949F27C4F021F5" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Redemption of vested equity awards</link:label>
    <link:label id="lab_us-gaap_StockRepurchasedDuringPeriodValue_1116060C11699C1378949F27C4F021F5_label_en-US" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodValue_1116060C11699C1378949F27C4F021F5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stock Repurchased During Period, Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_1116060C11699C1378949F27C4F021F5" xlink:type="locator" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_3B034468617CA9AB37C79B3DCD247866" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RepurchaseAgreementCounterpartyNameDomain_3B034468617CA9AB37C79B3DCD247866" xlink:to="lab_us-gaap_RepurchaseAgreementCounterpartyNameDomain_3B034468617CA9AB37C79B3DCD247866" xlink:type="arc" />
    <link:label id="lab_ofc_LwRedstoneCompanyLlcMember_42B73064F4395756F7AF9B3DCD292C0D_terseLabel_en-US" xlink:label="lab_ofc_LwRedstoneCompanyLlcMember_42B73064F4395756F7AF9B3DCD292C0D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">LW Redstone Company, LLC [Member]</link:label>
    <link:label id="lab_ofc_LwRedstoneCompanyLlcMember_42B73064F4395756F7AF9B3DCD292C0D_label_en-US" xlink:label="lab_ofc_LwRedstoneCompanyLlcMember_42B73064F4395756F7AF9B3DCD292C0D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">LW Redstone Company LLC [Member]</link:label>
    <link:label id="lab_ofc_LwRedstoneCompanyLlcMember_42B73064F4395756F7AF9B3DCD292C0D_documentation_en-US" xlink:label="lab_ofc_LwRedstoneCompanyLlcMember_42B73064F4395756F7AF9B3DCD292C0D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the investment in L W Redstone Company, LLC, a consolidated joint venture.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_LwRedstoneCompanyLlcMember" xlink:label="loc_ofc_LwRedstoneCompanyLlcMember_42B73064F4395756F7AF9B3DCD292C0D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_LwRedstoneCompanyLlcMember_42B73064F4395756F7AF9B3DCD292C0D" xlink:to="lab_ofc_LwRedstoneCompanyLlcMember_42B73064F4395756F7AF9B3DCD292C0D" xlink:type="arc" />
    <link:label id="lab_ofc_MSquareAssociatesLlcMember_9B74F72F986A043BC9369B3DCD29249A_terseLabel_en-US" xlink:label="lab_ofc_MSquareAssociatesLlcMember_9B74F72F986A043BC9369B3DCD29249A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">M Square Associates, LLC [Member]</link:label>
    <link:label id="lab_ofc_MSquareAssociatesLlcMember_9B74F72F986A043BC9369B3DCD29249A_label_en-US" xlink:label="lab_ofc_MSquareAssociatesLlcMember_9B74F72F986A043BC9369B3DCD29249A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">M Square Associates LLC [Member]</link:label>
    <link:label id="lab_ofc_MSquareAssociatesLlcMember_9B74F72F986A043BC9369B3DCD29249A_documentation_en-US" xlink:label="lab_ofc_MSquareAssociatesLlcMember_9B74F72F986A043BC9369B3DCD29249A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the investment in M Square Associates, LLC, a consolidated joint venture.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_MSquareAssociatesLlcMember" xlink:label="loc_ofc_MSquareAssociatesLlcMember_9B74F72F986A043BC9369B3DCD29249A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_MSquareAssociatesLlcMember_9B74F72F986A043BC9369B3DCD29249A" xlink:to="lab_ofc_MSquareAssociatesLlcMember_9B74F72F986A043BC9369B3DCD29249A" xlink:type="arc" />
    <link:label id="lab_ofc_StevensInvestorsLLCMember_D6C46F15329177F0C6449B3DCD291974_terseLabel_en-US" xlink:label="lab_ofc_StevensInvestorsLLCMember_D6C46F15329177F0C6449B3DCD291974" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Stevens Investors, LLC [Member]</link:label>
    <link:label id="lab_ofc_StevensInvestorsLLCMember_D6C46F15329177F0C6449B3DCD291974_label_en-US" xlink:label="lab_ofc_StevensInvestorsLLCMember_D6C46F15329177F0C6449B3DCD291974" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stevens Investors, LLC [Member]</link:label>
    <link:label id="lab_ofc_StevensInvestorsLLCMember_D6C46F15329177F0C6449B3DCD291974_documentation_en-US" xlink:label="lab_ofc_StevensInvestorsLLCMember_D6C46F15329177F0C6449B3DCD291974" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Stevens Investors, LLC [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_StevensInvestorsLLCMember" xlink:label="loc_ofc_StevensInvestorsLLCMember_D6C46F15329177F0C6449B3DCD291974" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_StevensInvestorsLLCMember_D6C46F15329177F0C6449B3DCD291974" xlink:to="lab_ofc_StevensInvestorsLLCMember_D6C46F15329177F0C6449B3DCD291974" xlink:type="arc" />
    <link:label id="lab_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_26FF8176C3205E0EEA419B3DCD2C3951_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_26FF8176C3205E0EEA419B3DCD2C3951" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Receivable Type [Axis]</link:label>
    <link:label id="lab_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_26FF8176C3205E0EEA419B3DCD2C3951_label_en-US" xlink:label="lab_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_26FF8176C3205E0EEA419B3DCD2C3951" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Receivable Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_26FF8176C3205E0EEA419B3DCD2C3951" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_26FF8176C3205E0EEA419B3DCD2C3951" xlink:to="lab_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_26FF8176C3205E0EEA419B3DCD2C3951" xlink:type="arc" />
    <link:label id="lab_us-gaap_ReceivableTypeDomain_C579C2964C8B6602C6E99B3DCD2C6A13_terseLabel_en-US" xlink:label="lab_us-gaap_ReceivableTypeDomain_C579C2964C8B6602C6E99B3DCD2C6A13" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Receivable Type [Domain]</link:label>
    <link:label id="lab_us-gaap_ReceivableTypeDomain_C579C2964C8B6602C6E99B3DCD2C6A13_label_en-US" xlink:label="lab_us-gaap_ReceivableTypeDomain_C579C2964C8B6602C6E99B3DCD2C6A13" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Receivable [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ReceivableTypeDomain" xlink:label="loc_us-gaap_ReceivableTypeDomain_C579C2964C8B6602C6E99B3DCD2C6A13" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ReceivableTypeDomain_C579C2964C8B6602C6E99B3DCD2C6A13" xlink:to="lab_us-gaap_ReceivableTypeDomain_C579C2964C8B6602C6E99B3DCD2C6A13" xlink:type="arc" />
    <link:label id="lab_ofc_NotesReceivableFromCityOfHuntsvilleMember_41460D0CCA4944B600CC9B3DCD2C3D7D_terseLabel_en-US" xlink:label="lab_ofc_NotesReceivableFromCityOfHuntsvilleMember_41460D0CCA4944B600CC9B3DCD2C3D7D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Notes receivable from City of Huntsville [Member]</link:label>
    <link:label id="lab_ofc_NotesReceivableFromCityOfHuntsvilleMember_41460D0CCA4944B600CC9B3DCD2C3D7D_label_en-US" xlink:label="lab_ofc_NotesReceivableFromCityOfHuntsvilleMember_41460D0CCA4944B600CC9B3DCD2C3D7D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Notes Receivable from City of Huntsville [Member]</link:label>
    <link:label id="lab_ofc_NotesReceivableFromCityOfHuntsvilleMember_41460D0CCA4944B600CC9B3DCD2C3D7D_documentation_en-US" xlink:label="lab_ofc_NotesReceivableFromCityOfHuntsvilleMember_41460D0CCA4944B600CC9B3DCD2C3D7D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents notes receivable from City of Huntsville.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NotesReceivableFromCityOfHuntsvilleMember" xlink:label="loc_ofc_NotesReceivableFromCityOfHuntsvilleMember_41460D0CCA4944B600CC9B3DCD2C3D7D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NotesReceivableFromCityOfHuntsvilleMember_41460D0CCA4944B600CC9B3DCD2C3D7D" xlink:to="lab_ofc_NotesReceivableFromCityOfHuntsvilleMember_41460D0CCA4944B600CC9B3DCD2C3D7D" xlink:type="arc" />
    <link:label id="lab_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis_FD42F029744FC08A93109B3DCD3241DE_terseLabel_en-US" xlink:label="lab_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis_FD42F029744FC08A93109B3DCD3241DE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Variable Interest Entities [Axis]</link:label>
    <link:label id="lab_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis_FD42F029744FC08A93109B3DCD3241DE_label_en-US" xlink:label="lab_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis_FD42F029744FC08A93109B3DCD3241DE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Interest Entities [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis" xlink:label="loc_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis_FD42F029744FC08A93109B3DCD3241DE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis_FD42F029744FC08A93109B3DCD3241DE" xlink:to="lab_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis_FD42F029744FC08A93109B3DCD3241DE" xlink:type="arc" />
    <link:label id="lab_us-gaap_ClassificationOfVariableInterestEntityDomain_32D8A65281840B4EDA6C9B3DCD3268B4_terseLabel_en-US" xlink:label="lab_us-gaap_ClassificationOfVariableInterestEntityDomain_32D8A65281840B4EDA6C9B3DCD3268B4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Variable Interest Entity, Classification [Domain]</link:label>
    <link:label id="lab_us-gaap_ClassificationOfVariableInterestEntityDomain_32D8A65281840B4EDA6C9B3DCD3268B4_label_en-US" xlink:label="lab_us-gaap_ClassificationOfVariableInterestEntityDomain_32D8A65281840B4EDA6C9B3DCD3268B4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Interest Entity, Classification [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ClassificationOfVariableInterestEntityDomain" xlink:label="loc_us-gaap_ClassificationOfVariableInterestEntityDomain_32D8A65281840B4EDA6C9B3DCD3268B4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ClassificationOfVariableInterestEntityDomain_32D8A65281840B4EDA6C9B3DCD3268B4" xlink:to="lab_us-gaap_ClassificationOfVariableInterestEntityDomain_32D8A65281840B4EDA6C9B3DCD3268B4" xlink:type="arc" />
    <link:label id="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember_B9A7B1A5014C4615718C9B3DCD32D970_terseLabel_en-US" xlink:label="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember_B9A7B1A5014C4615718C9B3DCD32D970" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Consolidated real estate joint ventures [Member]</link:label>
    <link:label id="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember_B9A7B1A5014C4615718C9B3DCD32D970_label_en-US" xlink:label="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember_B9A7B1A5014C4615718C9B3DCD32D970" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember_B9A7B1A5014C4615718C9B3DCD32D970" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember_B9A7B1A5014C4615718C9B3DCD32D970" xlink:to="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryAggregatedDisclosureMember_B9A7B1A5014C4615718C9B3DCD32D970" xlink:type="arc" />
    <link:label id="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_A3175AF23CAB618909119B3DCD33ACF3_terseLabel_en-US" xlink:label="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_A3175AF23CAB618909119B3DCD33ACF3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Primary Beneficiary [Member]</link:label>
    <link:label id="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_A3175AF23CAB618909119B3DCD33ACF3_label_en-US" xlink:label="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_A3175AF23CAB618909119B3DCD33ACF3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Interest Entity, Primary Beneficiary [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_A3175AF23CAB618909119B3DCD33ACF3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_A3175AF23CAB618909119B3DCD33ACF3" xlink:to="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_A3175AF23CAB618909119B3DCD33ACF3" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstateJointVentureLineItems_FF284A78822E7CB4BC269B3DCD339074_terseLabel_en-US" xlink:label="lab_ofc_RealEstateJointVentureLineItems_FF284A78822E7CB4BC269B3DCD339074" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Investments in real estate joint ventures</link:label>
    <link:label id="lab_ofc_RealEstateJointVentureLineItems_FF284A78822E7CB4BC269B3DCD339074_label_en-US" xlink:label="lab_ofc_RealEstateJointVentureLineItems_FF284A78822E7CB4BC269B3DCD339074" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Joint Venture [Line Items]</link:label>
    <link:label id="lab_ofc_RealEstateJointVentureLineItems_FF284A78822E7CB4BC269B3DCD339074_documentation_en-US" xlink:label="lab_ofc_RealEstateJointVentureLineItems_FF284A78822E7CB4BC269B3DCD339074" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US" />
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstateJointVentureLineItems" xlink:label="loc_ofc_RealEstateJointVentureLineItems_FF284A78822E7CB4BC269B3DCD339074" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstateJointVentureLineItems_FF284A78822E7CB4BC269B3DCD339074" xlink:to="lab_ofc_RealEstateJointVentureLineItems_FF284A78822E7CB4BC269B3DCD339074" xlink:type="arc" />
    <link:label id="lab_ofc_ConsolidatedJointVenturesDisclosureAbstract_5318AD983921DAA20EDC9B3DCD330A0E_terseLabel_en-US" xlink:label="lab_ofc_ConsolidatedJointVenturesDisclosureAbstract_5318AD983921DAA20EDC9B3DCD330A0E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Investments in consolidated real estate joint ventures</link:label>
    <link:label id="lab_ofc_ConsolidatedJointVenturesDisclosureAbstract_5318AD983921DAA20EDC9B3DCD330A0E_label_en-US" xlink:label="lab_ofc_ConsolidatedJointVenturesDisclosureAbstract_5318AD983921DAA20EDC9B3DCD330A0E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Consolidated Joint Ventures Disclosure [Abstract]</link:label>
    <link:label id="lab_ofc_ConsolidatedJointVenturesDisclosureAbstract_5318AD983921DAA20EDC9B3DCD330A0E_documentation_en-US" xlink:label="lab_ofc_ConsolidatedJointVenturesDisclosureAbstract_5318AD983921DAA20EDC9B3DCD330A0E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US" />
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ConsolidatedJointVenturesDisclosureAbstract" xlink:label="loc_ofc_ConsolidatedJointVenturesDisclosureAbstract_5318AD983921DAA20EDC9B3DCD330A0E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ConsolidatedJointVenturesDisclosureAbstract_5318AD983921DAA20EDC9B3DCD330A0E" xlink:to="lab_ofc_ConsolidatedJointVenturesDisclosureAbstract_5318AD983921DAA20EDC9B3DCD330A0E" xlink:type="arc" />
    <link:label id="lab_us-gaap_VariableInterestEntityOwnershipPercentage_38EB4CCE5CB79C8ABBEB9B3DCD33C123_terseLabel_en-US" xlink:label="lab_us-gaap_VariableInterestEntityOwnershipPercentage_38EB4CCE5CB79C8ABBEB9B3DCD33C123" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Ownership (as a percent)</link:label>
    <link:label id="lab_us-gaap_VariableInterestEntityOwnershipPercentage_38EB4CCE5CB79C8ABBEB9B3DCD33C123_label_en-US" xlink:label="lab_us-gaap_VariableInterestEntityOwnershipPercentage_38EB4CCE5CB79C8ABBEB9B3DCD33C123" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableInterestEntityOwnershipPercentage" xlink:label="loc_us-gaap_VariableInterestEntityOwnershipPercentage_38EB4CCE5CB79C8ABBEB9B3DCD33C123" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableInterestEntityOwnershipPercentage_38EB4CCE5CB79C8ABBEB9B3DCD33C123" xlink:to="lab_us-gaap_VariableInterestEntityOwnershipPercentage_38EB4CCE5CB79C8ABBEB9B3DCD33C123" xlink:type="arc" />
    <link:label id="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_AF78BEFDDF1ACF3B75889B3DCD33653A_terseLabel_en-US" xlink:label="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_AF78BEFDDF1ACF3B75889B3DCD33653A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Total Assets</link:label>
    <link:label id="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_AF78BEFDDF1ACF3B75889B3DCD33653A_label_en-US" xlink:label="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_AF78BEFDDF1ACF3B75889B3DCD33653A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Interest Entity, Consolidated, Carrying Amount, Assets</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets" xlink:label="loc_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_AF78BEFDDF1ACF3B75889B3DCD33653A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_AF78BEFDDF1ACF3B75889B3DCD33653A" xlink:to="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets_AF78BEFDDF1ACF3B75889B3DCD33653A" xlink:type="arc" />
    <link:label id="lab_us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate_167F8D68B7502523DD879B3DCD33BEAE_terseLabel_en-US" xlink:label="lab_us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate_167F8D68B7502523DD879B3DCD33BEAE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Encumbered Assets</link:label>
    <link:label id="lab_us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate_167F8D68B7502523DD879B3DCD33BEAE_label_en-US" xlink:label="lab_us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate_167F8D68B7502523DD879B3DCD33BEAE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Pledged Assets, Not Separately Reported, Real Estate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate" xlink:label="loc_us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate_167F8D68B7502523DD879B3DCD33BEAE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate_167F8D68B7502523DD879B3DCD33BEAE" xlink:to="lab_us-gaap_PledgedAssetsNotSeparatelyReportedRealEstate_167F8D68B7502523DD879B3DCD33BEAE" xlink:type="arc" />
    <link:label id="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities_84A1446560F0D8DC2B259B3DCD330F27_terseLabel_en-US" xlink:label="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities_84A1446560F0D8DC2B259B3DCD330F27" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Total Liabilities</link:label>
    <link:label id="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities_84A1446560F0D8DC2B259B3DCD330F27_label_en-US" xlink:label="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities_84A1446560F0D8DC2B259B3DCD330F27" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Interest Entity, Consolidated, Carrying Amount, Liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities" xlink:label="loc_us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities_84A1446560F0D8DC2B259B3DCD330F27" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities_84A1446560F0D8DC2B259B3DCD330F27" xlink:to="lab_us-gaap_VariableInterestEntityConsolidatedCarryingAmountLiabilities_84A1446560F0D8DC2B259B3DCD330F27" xlink:type="arc" />
    <link:label id="lab_ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest_EC0C3F6887A89F4FF77F9B3DCD34F814_verboseLabel_en-US" xlink:label="lab_ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest_EC0C3F6887A89F4FF77F9B3DCD34F814" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Distributions paid to redeemable noncontrolling interests</link:label>
    <link:label id="lab_ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest_EC0C3F6887A89F4FF77F9B3DCD34F814_label_en-US" xlink:label="lab_ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest_EC0C3F6887A89F4FF77F9B3DCD34F814" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Payments of Distributions, Redeemable Noncontrolling Interest</link:label>
    <link:label id="lab_ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest_EC0C3F6887A89F4FF77F9B3DCD34F814_documentation_en-US" xlink:label="lab_ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest_EC0C3F6887A89F4FF77F9B3DCD34F814" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Payments of Distributions, Redeemable Noncontrolling Interest</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest" xlink:label="loc_ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest_EC0C3F6887A89F4FF77F9B3DCD34F814" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest_EC0C3F6887A89F4FF77F9B3DCD34F814" xlink:to="lab_ofc_PaymentsofDistributionsRedeemableNoncontrollingInterest_EC0C3F6887A89F4FF77F9B3DCD34F814" xlink:type="arc" />
    <link:label id="lab_ofc_InfrastructureCostsAnticipatedToBeFunded_688303FCF677E202690A9B3DCD34AF24_terseLabel_en-US" xlink:label="lab_ofc_InfrastructureCostsAnticipatedToBeFunded_688303FCF677E202690A9B3DCD34AF24" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Infrastructure costs anticipated to be funded by entity for reimbursement by the City of Huntsville (in dollars)</link:label>
    <link:label id="lab_ofc_InfrastructureCostsAnticipatedToBeFunded_688303FCF677E202690A9B3DCD34AF24_label_en-US" xlink:label="lab_ofc_InfrastructureCostsAnticipatedToBeFunded_688303FCF677E202690A9B3DCD34AF24" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Infrastructure Costs Anticipated to be Funded</link:label>
    <link:label id="lab_ofc_InfrastructureCostsAnticipatedToBeFunded_688303FCF677E202690A9B3DCD34AF24_documentation_en-US" xlink:label="lab_ofc_InfrastructureCostsAnticipatedToBeFunded_688303FCF677E202690A9B3DCD34AF24" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents infrastructure costs anticipated to be funded by entity for reimbursement.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_InfrastructureCostsAnticipatedToBeFunded" xlink:label="loc_ofc_InfrastructureCostsAnticipatedToBeFunded_688303FCF677E202690A9B3DCD34AF24" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_InfrastructureCostsAnticipatedToBeFunded_688303FCF677E202690A9B3DCD34AF24" xlink:to="lab_ofc_InfrastructureCostsAnticipatedToBeFunded_688303FCF677E202690A9B3DCD34AF24" xlink:type="arc" />
    <link:label id="lab_us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount_F80EE5E931C76AD2CAFB9B3DCD3439B3_terseLabel_en-US" xlink:label="lab_us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount_F80EE5E931C76AD2CAFB9B3DCD3439B3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Amount of advanced</link:label>
    <link:label id="lab_us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount_F80EE5E931C76AD2CAFB9B3DCD3439B3_label_en-US" xlink:label="lab_us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount_F80EE5E931C76AD2CAFB9B3DCD3439B3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Variable Interest Entity, Financial or Other Support, Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount" xlink:label="loc_us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount_F80EE5E931C76AD2CAFB9B3DCD3439B3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount_F80EE5E931C76AD2CAFB9B3DCD3439B3" xlink:to="lab_us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount_F80EE5E931C76AD2CAFB9B3DCD3439B3" xlink:type="arc" />
    <link:label id="lab_ofc_PartnersCapitalAccountUponFormation_5CA2F02640A0851821C29B3DCD34A985_terseLabel_en-US" xlink:label="lab_ofc_PartnersCapitalAccountUponFormation_5CA2F02640A0851821C29B3DCD34A985" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Partner's capital account upon formation</link:label>
    <link:label id="lab_ofc_PartnersCapitalAccountUponFormation_5CA2F02640A0851821C29B3DCD34A985_label_en-US" xlink:label="lab_ofc_PartnersCapitalAccountUponFormation_5CA2F02640A0851821C29B3DCD34A985" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Partner's Capital Account Upon Formation</link:label>
    <link:label id="lab_ofc_PartnersCapitalAccountUponFormation_5CA2F02640A0851821C29B3DCD34A985_documentation_en-US" xlink:label="lab_ofc_PartnersCapitalAccountUponFormation_5CA2F02640A0851821C29B3DCD34A985" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the amount credited to the partner's capital upon formation.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PartnersCapitalAccountUponFormation" xlink:label="loc_ofc_PartnersCapitalAccountUponFormation_5CA2F02640A0851821C29B3DCD34A985" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PartnersCapitalAccountUponFormation_5CA2F02640A0851821C29B3DCD34A985" xlink:to="lab_ofc_PartnersCapitalAccountUponFormation_5CA2F02640A0851821C29B3DCD34A985" xlink:type="arc" />
    <link:label id="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital_AD50EA77268B0AF0BCA89B3DCD34B371_terseLabel_en-US" xlink:label="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital_AD50EA77268B0AF0BCA89B3DCD34B371" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital entitled to the company</link:label>
    <link:label id="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital_AD50EA77268B0AF0BCA89B3DCD34B371_label_en-US" xlink:label="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital_AD50EA77268B0AF0BCA89B3DCD34B371" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Percentage of Residual Distributable Cash Flows Entitled in Excess of Unpaid Cumulative Preferred Returns and Return of Invested Capital</link:label>
    <link:label id="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital_AD50EA77268B0AF0BCA89B3DCD34B371_documentation_en-US" xlink:label="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital_AD50EA77268B0AF0BCA89B3DCD34B371" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital in the joint venture to which the entity will be entitled.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital" xlink:label="loc_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital_AD50EA77268B0AF0BCA89B3DCD34B371" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital_AD50EA77268B0AF0BCA89B3DCD34B371" xlink:to="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCapital_AD50EA77268B0AF0BCA89B3DCD34B371" xlink:type="arc" />
    <link:label id="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner_DF1DD0AA8B444119256F9B3DCD34BF3D_terseLabel_en-US" xlink:label="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner_DF1DD0AA8B444119256F9B3DCD34BF3D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Percentage of residual distributable cash flows in excess of unpaid cumulative preferred returns and return of invested capital entitled to the entity's partners</link:label>
    <link:label id="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner_DF1DD0AA8B444119256F9B3DCD34BF3D_label_en-US" xlink:label="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner_DF1DD0AA8B444119256F9B3DCD34BF3D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Percentage Of Residual Distributable Cash Flows Entitled In Excess Of Unpaid Cumulative Preferred Returns and Return of Invested Cash Related To Real Estate Partner</link:label>
    <link:label id="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner_DF1DD0AA8B444119256F9B3DCD34BF3D_documentation_en-US" xlink:label="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner_DF1DD0AA8B444119256F9B3DCD34BF3D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the percentage of residual distributable cash flowsin excess of unpaid cumulative preferred turns and return of invested cash in the joint venture to which the entity's partners will be entitled.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner" xlink:label="loc_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner_DF1DD0AA8B444119256F9B3DCD34BF3D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner_DF1DD0AA8B444119256F9B3DCD34BF3D" xlink:to="lab_ofc_PercentageOfResidualDistributableCashFlowsEntitledInExcessOfUnpaidCumulativePreferredReturnsAndReturnOfInvestedCashRelatedToRealEstatePartner_DF1DD0AA8B444119256F9B3DCD34BF3D" xlink:type="arc" />
    <link:label id="lab_ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue_2DA093AB7DCAC47E10C69B3DCD34EF66_terseLabel_en-US" xlink:label="lab_ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue_2DA093AB7DCAC47E10C69B3DCD34EF66" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of years following construction commencement threshold achievement before partner's interest can be purchased at fair value</link:label>
    <link:label id="lab_ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue_2DA093AB7DCAC47E10C69B3DCD34EF66_label_en-US" xlink:label="lab_ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue_2DA093AB7DCAC47E10C69B3DCD34EF66" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number of Years Following Construction Commencement Threshold Achievement Before Partner's Interest Can Be Purchased At Fair Value</link:label>
    <link:label id="lab_ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue_2DA093AB7DCAC47E10C69B3DCD34EF66_documentation_en-US" xlink:label="lab_ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue_2DA093AB7DCAC47E10C69B3DCD34EF66" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number of years following construction commencement threshold achievement before partner's interest can be purchased at fair value</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue" xlink:label="loc_ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue_2DA093AB7DCAC47E10C69B3DCD34EF66" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue_2DA093AB7DCAC47E10C69B3DCD34EF66" xlink:to="lab_ofc_NumberOfYearsFollowingConstructionCommencementThresholdAchievementBeforePartnersInterestCanBePurchasedAtFairValue_2DA093AB7DCAC47E10C69B3DCD34EF66" xlink:type="arc" />
    <link:label id="lab_ofc_ConstructionCommencementThreshold_FA8D6801193BD30193B49B3DCD34B162_terseLabel_en-US" xlink:label="lab_ofc_ConstructionCommencementThreshold_FA8D6801193BD30193B49B3DCD34B162" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Construction commencement threshold (in square feet)</link:label>
    <link:label id="lab_ofc_ConstructionCommencementThreshold_FA8D6801193BD30193B49B3DCD34B162_label_en-US" xlink:label="lab_ofc_ConstructionCommencementThreshold_FA8D6801193BD30193B49B3DCD34B162" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Construction Commencement Threshold</link:label>
    <link:label id="lab_ofc_ConstructionCommencementThreshold_FA8D6801193BD30193B49B3DCD34B162_documentation_en-US" xlink:label="lab_ofc_ConstructionCommencementThreshold_FA8D6801193BD30193B49B3DCD34B162" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents a defined threshold for square footage of construction commencement for Company to be able to acquire partner's interest after five years.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ConstructionCommencementThreshold" xlink:label="loc_ofc_ConstructionCommencementThreshold_FA8D6801193BD30193B49B3DCD34B162" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ConstructionCommencementThreshold_FA8D6801193BD30193B49B3DCD34B162" xlink:to="lab_ofc_ConstructionCommencementThreshold_FA8D6801193BD30193B49B3DCD34B162" xlink:type="arc" />
    <link:label id="lab_ofc_ConstructionCommencementThresholdCompleted_2F891B3FB7CA2BF3603B9B3DCD34DE91_terseLabel_en-US" xlink:label="lab_ofc_ConstructionCommencementThresholdCompleted_2F891B3FB7CA2BF3603B9B3DCD34DE91" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Construction commencement completed (in sqft)</link:label>
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    <link:label id="lab_ofc_CapitalLeasesPurchaseOptionAmount_D129AD36D51925F8283D758C10F1EB45_documentation_en-US" xlink:label="lab_ofc_CapitalLeasesPurchaseOptionAmount_D129AD36D51925F8283D758C10F1EB45" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Capital Leases, Purchase Option Amount</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_CapitalLeasesPurchaseOptionAmount" xlink:label="loc_ofc_CapitalLeasesPurchaseOptionAmount_D129AD36D51925F8283D758C10F1EB45" xlink:type="locator" />
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    <link:label id="lab_us-gaap_CapitalLeaseObligations_5E16F2D44738DE6886EE758C10F1EA47_terseLabel_en-US" xlink:label="lab_us-gaap_CapitalLeaseObligations_5E16F2D44738DE6886EE758C10F1EA47" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Capital lease obligation</link:label>
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    <link:label id="lab_us-gaap_ContractualObligation_A7B8C2817DC0267AA357758C10F1C90D_terseLabel_en-US" xlink:label="lab_us-gaap_ContractualObligation_A7B8C2817DC0267AA357758C10F1C90D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Contractual obligation</link:label>
    <link:label id="lab_us-gaap_ContractualObligation_A7B8C2817DC0267AA357758C10F1C90D_label_en-US" xlink:label="lab_us-gaap_ContractualObligation_A7B8C2817DC0267AA357758C10F1C90D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Contractual Obligation</link:label>
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    <link:loc xlink:href="ofc-20171231.xsd#ofc_EnvironmentalIndemnityAgreementAbstract" xlink:label="loc_ofc_EnvironmentalIndemnityAgreementAbstract_EE32D6A2362F8D02FAFD758C10F1A101" xlink:type="locator" />
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    <link:label id="lab_ofc_PropertySubjecttoEnvironmentalIndemnityNumberofProperties_21DC2664076D2DF7F871758C10F1237C_documentation_en-US" xlink:label="lab_ofc_PropertySubjecttoEnvironmentalIndemnityNumberofProperties_21DC2664076D2DF7F871758C10F1237C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the number of properties in New Jersey which were provided environmental indemnifications by the entity.</link:label>
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    <link:loc xlink:href="ofc-20171231.xsd#ofc_MaximumAdditionalCostsAgreedToBePaidByTheEntityUnderEnvironmentalIndemnificationAgreement" xlink:label="loc_ofc_MaximumAdditionalCostsAgreedToBePaidByTheEntityUnderEnvironmentalIndemnificationAgreement_707FB6657D1A32B8971C758C10F1643C" xlink:type="locator" />
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    <link:label id="lab_ofc_IntangibleAssetsOnRealEstateAcquisitions_357DC1C57959F86F6F176ADFA1293E33_label_en-US" xlink:label="lab_ofc_IntangibleAssetsOnRealEstateAcquisitions_357DC1C57959F86F6F176ADFA1293E33" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Intangible Assets on Real Estate Acquisitions</link:label>
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    <link:loc xlink:href="ofc-20171231.xsd#ofc_IntangibleAssetsOnRealEstateAcquisitions" xlink:label="loc_ofc_IntangibleAssetsOnRealEstateAcquisitions_357DC1C57959F86F6F176ADFA1293E33" xlink:type="locator" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IntangibleAssetsDisclosureTextBlock" xlink:label="loc_us-gaap_IntangibleAssetsDisclosureTextBlock_1F364030A3E1609DB4A66ADFA129EF14" xlink:type="locator" />
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    <link:label id="lab_us-gaap_ScheduleOfDebtTableTextBlock_0AEB27C2991F05EA3F6067C5D52D9FCF_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfDebtTableTextBlock_0AEB27C2991F05EA3F6067C5D52D9FCF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Schedule of debt</link:label>
    <link:label id="lab_us-gaap_ScheduleOfDebtTableTextBlock_0AEB27C2991F05EA3F6067C5D52D9FCF_label_en-US" xlink:label="lab_us-gaap_ScheduleOfDebtTableTextBlock_0AEB27C2991F05EA3F6067C5D52D9FCF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Schedule of Debt [Table Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfDebtTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfDebtTableTextBlock_0AEB27C2991F05EA3F6067C5D52D9FCF" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfDebtTableTextBlock_0AEB27C2991F05EA3F6067C5D52D9FCF" xlink:to="lab_us-gaap_ScheduleOfDebtTableTextBlock_0AEB27C2991F05EA3F6067C5D52D9FCF" xlink:type="arc" />
    <link:label id="lab_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_95E753E5B146FF72262767C5D52DE1AF_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_95E753E5B146FF72262767C5D52DE1AF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Schedule of debt maturities</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_95E753E5B146FF72262767C5D52DE1AF" xlink:type="locator" />
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    <link:label id="lab_ofc_ScheduleOfFairValueOfDebtTableTextBlock_D1AA7629835BB705B1A167C5D52DD055_terseLabel_en-US" xlink:label="lab_ofc_ScheduleOfFairValueOfDebtTableTextBlock_D1AA7629835BB705B1A167C5D52DD055" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Schedule of the fair value of debt</link:label>
    <link:label id="lab_ofc_ScheduleOfFairValueOfDebtTableTextBlock_D1AA7629835BB705B1A167C5D52DD055_label_en-US" xlink:label="lab_ofc_ScheduleOfFairValueOfDebtTableTextBlock_D1AA7629835BB705B1A167C5D52DD055" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Schedule of Fair Value of Debt [Table Text Block]</link:label>
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    <link:label id="lab_us-gaap_ReconciliationOfCarryingAmountOfRealEstateInvestmentsRollForward_8F8F5EC327397284CA7D6ADFA24B6288_terseLabel_en-US" xlink:label="lab_us-gaap_ReconciliationOfCarryingAmountOfRealEstateInvestmentsRollForward_8F8F5EC327397284CA7D6ADFA24B6288" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Changes in cost of properties</link:label>
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    <link:label id="lab_us-gaap_RealEstateGrossAtCarryingValue_6867CF9212F2B34F49B36ADFA24BAD3C_periodStartLabel_en-US" xlink:label="lab_us-gaap_RealEstateGrossAtCarryingValue_6867CF9212F2B34F49B36ADFA24BAD3C" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xml:lang="en-US">Beginning balance</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateGrossAtCarryingValue_6867CF9212F2B34F49B36ADFA24BAD3C" xlink:to="lab_us-gaap_RealEstateGrossAtCarryingValue_6867CF9212F2B34F49B36ADFA24BAD3C" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateOtherAcquisitions_B2878CE06ED8D1F15A2D6ADFA24B235C_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateOtherAcquisitions_B2878CE06ED8D1F15A2D6ADFA24B235C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Acquisitions of operating properties</link:label>
    <link:label id="lab_us-gaap_RealEstateOtherAcquisitions_B2878CE06ED8D1F15A2D6ADFA24B235C_label_en-US" xlink:label="lab_us-gaap_RealEstateOtherAcquisitions_B2878CE06ED8D1F15A2D6ADFA24B235C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate, Other Acquisitions</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateOtherAcquisitions" xlink:label="loc_us-gaap_RealEstateOtherAcquisitions_B2878CE06ED8D1F15A2D6ADFA24B235C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateOtherAcquisitions_B2878CE06ED8D1F15A2D6ADFA24B235C" xlink:to="lab_us-gaap_RealEstateOtherAcquisitions_B2878CE06ED8D1F15A2D6ADFA24B235C" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateImprovements_0BDAC087B61565F2B2126ADFA24BEE5E_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateImprovements_0BDAC087B61565F2B2126ADFA24BEE5E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Improvements and other additions</link:label>
    <link:label id="lab_us-gaap_RealEstateImprovements_0BDAC087B61565F2B2126ADFA24BEE5E_label_en-US" xlink:label="lab_us-gaap_RealEstateImprovements_0BDAC087B61565F2B2126ADFA24BEE5E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate, Improvements</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateImprovements" xlink:label="loc_us-gaap_RealEstateImprovements_0BDAC087B61565F2B2126ADFA24BEE5E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateImprovements_0BDAC087B61565F2B2126ADFA24BEE5E" xlink:to="lab_us-gaap_RealEstateImprovements_0BDAC087B61565F2B2126ADFA24BEE5E" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateCostOfRealEstateSold_CB883EC49606EA5CC5F16ADFA24BD2D5_negatedLabel_en-US" xlink:label="lab_us-gaap_RealEstateCostOfRealEstateSold_CB883EC49606EA5CC5F16ADFA24BD2D5" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Sales</link:label>
    <link:label id="lab_us-gaap_RealEstateCostOfRealEstateSold_CB883EC49606EA5CC5F16ADFA24BD2D5_label_en-US" xlink:label="lab_us-gaap_RealEstateCostOfRealEstateSold_CB883EC49606EA5CC5F16ADFA24BD2D5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate, Cost of Real Estate Sold</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateCostOfRealEstateSold" xlink:label="loc_us-gaap_RealEstateCostOfRealEstateSold_CB883EC49606EA5CC5F16ADFA24BD2D5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateCostOfRealEstateSold_CB883EC49606EA5CC5F16ADFA24BD2D5" xlink:to="lab_us-gaap_RealEstateCostOfRealEstateSold_CB883EC49606EA5CC5F16ADFA24BD2D5" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstateImpairments_8DED85EDFBAF368A14B76ADFA24B100F_negatedLabel_en-US" xlink:label="lab_ofc_RealEstateImpairments_8DED85EDFBAF368A14B76ADFA24B100F" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Impairments</link:label>
    <link:label id="lab_ofc_RealEstateImpairments_8DED85EDFBAF368A14B76ADFA24B100F_label_en-US" xlink:label="lab_ofc_RealEstateImpairments_8DED85EDFBAF368A14B76ADFA24B100F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Impairments</link:label>
    <link:label id="lab_ofc_RealEstateImpairments_8DED85EDFBAF368A14B76ADFA24B100F_documentation_en-US" xlink:label="lab_ofc_RealEstateImpairments_8DED85EDFBAF368A14B76ADFA24B100F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the amount of impairment charged to real estate investments during the period.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstateImpairments" xlink:label="loc_ofc_RealEstateImpairments_8DED85EDFBAF368A14B76ADFA24B100F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstateImpairments_8DED85EDFBAF368A14B76ADFA24B100F" xlink:to="lab_ofc_RealEstateImpairments_8DED85EDFBAF368A14B76ADFA24B100F" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstateOtherDispositions_E6C4A4CB2173EE8556EC6ADFA24BC8BD_negatedTerseLabel_en-US" xlink:label="lab_ofc_RealEstateOtherDispositions_E6C4A4CB2173EE8556EC6ADFA24BC8BD" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Other dispositions</link:label>
    <link:label id="lab_ofc_RealEstateOtherDispositions_E6C4A4CB2173EE8556EC6ADFA24BC8BD_label_en-US" xlink:label="lab_ofc_RealEstateOtherDispositions_E6C4A4CB2173EE8556EC6ADFA24BC8BD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate, Other Dispositions</link:label>
    <link:label id="lab_ofc_RealEstateOtherDispositions_E6C4A4CB2173EE8556EC6ADFA24BC8BD_documentation_en-US" xlink:label="lab_ofc_RealEstateOtherDispositions_E6C4A4CB2173EE8556EC6ADFA24BC8BD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Real Estate, Other Dispositions</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstateOtherDispositions" xlink:label="loc_ofc_RealEstateOtherDispositions_E6C4A4CB2173EE8556EC6ADFA24BC8BD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstateOtherDispositions_E6C4A4CB2173EE8556EC6ADFA24BC8BD" xlink:to="lab_ofc_RealEstateOtherDispositions_E6C4A4CB2173EE8556EC6ADFA24BC8BD" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateGrossAtCarryingValue_24B6603B2D910EF08AD56ADFA24CF7F3_periodEndLabel_en-US" xlink:label="lab_us-gaap_RealEstateGrossAtCarryingValue_24B6603B2D910EF08AD56ADFA24CF7F3" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xml:lang="en-US">Ending balance</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateGrossAtCarryingValue" xlink:label="loc_us-gaap_RealEstateGrossAtCarryingValue_24B6603B2D910EF08AD56ADFA24CF7F3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateGrossAtCarryingValue_24B6603B2D910EF08AD56ADFA24CF7F3" xlink:to="lab_us-gaap_RealEstateGrossAtCarryingValue_24B6603B2D910EF08AD56ADFA24CF7F3" xlink:type="arc" />
    <link:label id="lab_us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward_17612AD34C8FD6ABE1056ADFA24C2CF7_terseLabel_en-US" xlink:label="lab_us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward_17612AD34C8FD6ABE1056ADFA24C2CF7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Changes in accumulated depreciation</link:label>
    <link:label id="lab_us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward_17612AD34C8FD6ABE1056ADFA24C2CF7_label_en-US" xlink:label="lab_us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward_17612AD34C8FD6ABE1056ADFA24C2CF7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward" xlink:label="loc_us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward_17612AD34C8FD6ABE1056ADFA24C2CF7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward_17612AD34C8FD6ABE1056ADFA24C2CF7" xlink:to="lab_us-gaap_ReconciliationOfRealEstateAccumulatedDepreciationRollForward_17612AD34C8FD6ABE1056ADFA24C2CF7" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAccumulatedDepreciation_1200B115408A43630FC76ADFA24CFEC4_periodStartLabel_en-US" xlink:label="lab_us-gaap_RealEstateAccumulatedDepreciation_1200B115408A43630FC76ADFA24CFEC4" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xml:lang="en-US">Beginning balance</link:label>
    <link:label id="lab_us-gaap_RealEstateAccumulatedDepreciation_1200B115408A43630FC76ADFA24CFEC4_label_en-US" xlink:label="lab_us-gaap_RealEstateAccumulatedDepreciation_1200B115408A43630FC76ADFA24CFEC4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate Accumulated Depreciation</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAccumulatedDepreciation" xlink:label="loc_us-gaap_RealEstateAccumulatedDepreciation_1200B115408A43630FC76ADFA24CFEC4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAccumulatedDepreciation_1200B115408A43630FC76ADFA24CFEC4" xlink:to="lab_us-gaap_RealEstateAccumulatedDepreciation_1200B115408A43630FC76ADFA24CFEC4" xlink:type="arc" />
    <link:label id="lab_us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense_4F06543EF405FA364DF26ADFA24C0F27_terseLabel_en-US" xlink:label="lab_us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense_4F06543EF405FA364DF26ADFA24C0F27" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Depreciation expense</link:label>
    <link:label id="lab_us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense_4F06543EF405FA364DF26ADFA24C0F27_label_en-US" xlink:label="lab_us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense_4F06543EF405FA364DF26ADFA24C0F27" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate Accumulated Depreciation, Depreciation Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense" xlink:label="loc_us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense_4F06543EF405FA364DF26ADFA24C0F27" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense_4F06543EF405FA364DF26ADFA24C0F27" xlink:to="lab_us-gaap_SECScheduleIIIRealEstateAccumulatedDepreciationDepreciationExpense_4F06543EF405FA364DF26ADFA24C0F27" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAccumulatedDepreciationRealEstateSold_E90DEEC7164DD77677EA6ADFA24CF1C2_negatedLabel_en-US" xlink:label="lab_us-gaap_RealEstateAccumulatedDepreciationRealEstateSold_E90DEEC7164DD77677EA6ADFA24CF1C2" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Sales</link:label>
    <link:label id="lab_us-gaap_RealEstateAccumulatedDepreciationRealEstateSold_E90DEEC7164DD77677EA6ADFA24CF1C2_label_en-US" xlink:label="lab_us-gaap_RealEstateAccumulatedDepreciationRealEstateSold_E90DEEC7164DD77677EA6ADFA24CF1C2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate Accumulated Depreciation, Real Estate Sold</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAccumulatedDepreciationRealEstateSold" xlink:label="loc_us-gaap_RealEstateAccumulatedDepreciationRealEstateSold_E90DEEC7164DD77677EA6ADFA24CF1C2" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAccumulatedDepreciationRealEstateSold_E90DEEC7164DD77677EA6ADFA24CF1C2" xlink:to="lab_us-gaap_RealEstateAccumulatedDepreciationRealEstateSold_E90DEEC7164DD77677EA6ADFA24CF1C2" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstateAccumulatedDepreciationImpairments_CB4BC054547BBCF7331A6ADFA24C9B59_negatedLabel_en-US" xlink:label="lab_ofc_RealEstateAccumulatedDepreciationImpairments_CB4BC054547BBCF7331A6ADFA24C9B59" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Impairments</link:label>
    <link:label id="lab_ofc_RealEstateAccumulatedDepreciationImpairments_CB4BC054547BBCF7331A6ADFA24C9B59_label_en-US" xlink:label="lab_ofc_RealEstateAccumulatedDepreciationImpairments_CB4BC054547BBCF7331A6ADFA24C9B59" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Accumulated Depreciation Impairments</link:label>
    <link:label id="lab_ofc_RealEstateAccumulatedDepreciationImpairments_CB4BC054547BBCF7331A6ADFA24C9B59_documentation_en-US" xlink:label="lab_ofc_RealEstateAccumulatedDepreciationImpairments_CB4BC054547BBCF7331A6ADFA24C9B59" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the amount that was removed from accumulated depreciation pertaining to impairment charged to real estate investments during the period.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstateAccumulatedDepreciationImpairments" xlink:label="loc_ofc_RealEstateAccumulatedDepreciationImpairments_CB4BC054547BBCF7331A6ADFA24C9B59" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstateAccumulatedDepreciationImpairments_CB4BC054547BBCF7331A6ADFA24C9B59" xlink:to="lab_ofc_RealEstateAccumulatedDepreciationImpairments_CB4BC054547BBCF7331A6ADFA24C9B59" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstateAccumulatedDepreciationOtherDispositions_69F1AC33F02D4202B33C6ADFA24CE5FF_negatedTerseLabel_en-US" xlink:label="lab_ofc_RealEstateAccumulatedDepreciationOtherDispositions_69F1AC33F02D4202B33C6ADFA24CE5FF" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Other dispositions</link:label>
    <link:label id="lab_ofc_RealEstateAccumulatedDepreciationOtherDispositions_69F1AC33F02D4202B33C6ADFA24CE5FF_label_en-US" xlink:label="lab_ofc_RealEstateAccumulatedDepreciationOtherDispositions_69F1AC33F02D4202B33C6ADFA24CE5FF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate, Accumulated Depreciation, Other Dispositions</link:label>
    <link:label id="lab_ofc_RealEstateAccumulatedDepreciationOtherDispositions_69F1AC33F02D4202B33C6ADFA24CE5FF_documentation_en-US" xlink:label="lab_ofc_RealEstateAccumulatedDepreciationOtherDispositions_69F1AC33F02D4202B33C6ADFA24CE5FF" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Real Estate, Accumulated Depreciation, Other Dispositions</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstateAccumulatedDepreciationOtherDispositions" xlink:label="loc_ofc_RealEstateAccumulatedDepreciationOtherDispositions_69F1AC33F02D4202B33C6ADFA24CE5FF" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstateAccumulatedDepreciationOtherDispositions_69F1AC33F02D4202B33C6ADFA24CE5FF" xlink:to="lab_ofc_RealEstateAccumulatedDepreciationOtherDispositions_69F1AC33F02D4202B33C6ADFA24CE5FF" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAccumulatedDepreciation_0DCA9A6778CE5A77B4EC6ADFA24C5696_periodEndLabel_en-US" xlink:label="lab_us-gaap_RealEstateAccumulatedDepreciation_0DCA9A6778CE5A77B4EC6ADFA24C5696" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xml:lang="en-US">Ending balance</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAccumulatedDepreciation" xlink:label="loc_us-gaap_RealEstateAccumulatedDepreciation_0DCA9A6778CE5A77B4EC6ADFA24C5696" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAccumulatedDepreciation_0DCA9A6778CE5A77B4EC6ADFA24C5696" xlink:to="lab_us-gaap_RealEstateAccumulatedDepreciation_0DCA9A6778CE5A77B4EC6ADFA24C5696" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationDisclosureTextBlock_445A67F8B489CEF2AC6C6ADFA162357D_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationDisclosureTextBlock_445A67F8B489CEF2AC6C6ADFA162357D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Schedule III-Real Estate and Accumulated Depreciation</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationDisclosureTextBlock_445A67F8B489CEF2AC6C6ADFA162357D_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationDisclosureTextBlock_445A67F8B489CEF2AC6C6ADFA162357D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationDisclosureTextBlock" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationDisclosureTextBlock_445A67F8B489CEF2AC6C6ADFA162357D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationDisclosureTextBlock_445A67F8B489CEF2AC6C6ADFA162357D" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationDisclosureTextBlock_445A67F8B489CEF2AC6C6ADFA162357D" xlink:type="arc" />
    <link:label id="lab_ofc_InPlaceLeaseValueMember_B0CD638303480633A60B6FFC35D8FEC4_terseLabel_en-US" xlink:label="lab_ofc_InPlaceLeaseValueMember_B0CD638303480633A60B6FFC35D8FEC4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">In-place lease value [Member]</link:label>
    <link:label id="lab_ofc_InPlaceLeaseValueMember_B0CD638303480633A60B6FFC35D8FEC4_label_en-US" xlink:label="lab_ofc_InPlaceLeaseValueMember_B0CD638303480633A60B6FFC35D8FEC4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">In Place Lease Value [Member]</link:label>
    <link:label id="lab_ofc_InPlaceLeaseValueMember_B0CD638303480633A60B6FFC35D8FEC4_documentation_en-US" xlink:label="lab_ofc_InPlaceLeaseValueMember_B0CD638303480633A60B6FFC35D8FEC4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents In-place lease value, which is based on the present value of additional income to be realized as a result of leases being in place on the acquired properties and costs to execute similar leases.</link:label>
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    <link:label id="lab_ofc_OtherMember_FE05F82C9751C95A07496FFC35D86E3D_terseLabel_en-US" xlink:label="lab_ofc_OtherMember_FE05F82C9751C95A07496FFC35D86E3D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other [Member]</link:label>
    <link:label id="lab_ofc_OtherMember_FE05F82C9751C95A07496FFC35D86E3D_label_en-US" xlink:label="lab_ofc_OtherMember_FE05F82C9751C95A07496FFC35D86E3D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other [Member]</link:label>
    <link:label id="lab_ofc_OtherMember_FE05F82C9751C95A07496FFC35D86E3D_documentation_en-US" xlink:label="lab_ofc_OtherMember_FE05F82C9751C95A07496FFC35D86E3D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Other</link:label>
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    <link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsGross_31993718C56ED6B326246FFC35D9C73D_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsGross_31993718C56ED6B326246FFC35D9C73D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Gross Carrying Amount</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_829EBB38622DEDF50E526FFC35D97726" xlink:type="locator" />
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    <link:label id="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_B87E7260FF3F079F3B086FFC35D9F858_totalLabel_en-US" xlink:label="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_B87E7260FF3F079F3B086FFC35D9F858" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Net Carrying Amount</link:label>
    <link:label id="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_B87E7260FF3F079F3B086FFC35D9F858_label_en-US" xlink:label="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_B87E7260FF3F079F3B086FFC35D9F858" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Intangible Assets, Net (Excluding Goodwill)</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_B87E7260FF3F079F3B086FFC35D9F858" xlink:type="locator" />
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    <link:label id="lab_us-gaap_AmortizationOfIntangibleAssets_F411C8957320463FAA936FFC35D95507_terseLabel_en-US" xlink:label="lab_us-gaap_AmortizationOfIntangibleAssets_F411C8957320463FAA936FFC35D95507" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Amortization of the intangible assets</link:label>
    <link:label id="lab_us-gaap_AmortizationOfIntangibleAssets_F411C8957320463FAA936FFC35D95507_label_en-US" xlink:label="lab_us-gaap_AmortizationOfIntangibleAssets_F411C8957320463FAA936FFC35D95507" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Amortization of Intangible Assets</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_F411C8957320463FAA936FFC35D95507" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AmortizationOfIntangibleAssets_F411C8957320463FAA936FFC35D95507" xlink:to="lab_us-gaap_AmortizationOfIntangibleAssets_F411C8957320463FAA936FFC35D95507" xlink:type="arc" />
    <link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_882D36E1BDB1CC3725616FFC35D94B6D_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_882D36E1BDB1CC3725616FFC35D94B6D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Estimated future amortization expense associated with the intangible asset categories for the next five years</link:label>
    <link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_882D36E1BDB1CC3725616FFC35D94B6D_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_882D36E1BDB1CC3725616FFC35D94B6D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_882D36E1BDB1CC3725616FFC35D94B6D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_882D36E1BDB1CC3725616FFC35D94B6D" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_882D36E1BDB1CC3725616FFC35D94B6D" xlink:type="arc" />
    <link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_98F1BDA53F9913B4B1AF6FFC35D97E5C_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_98F1BDA53F9913B4B1AF6FFC35D97E5C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2018</link:label>
    <link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_98F1BDA53F9913B4B1AF6FFC35D97E5C_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_98F1BDA53F9913B4B1AF6FFC35D97E5C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_98F1BDA53F9913B4B1AF6FFC35D97E5C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_98F1BDA53F9913B4B1AF6FFC35D97E5C" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_98F1BDA53F9913B4B1AF6FFC35D97E5C" xlink:type="arc" />
    <link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_CB178F6345BE29404C8D6FFC35DAB7B6_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_CB178F6345BE29404C8D6FFC35DAB7B6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2019</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_CB178F6345BE29404C8D6FFC35DAB7B6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_CB178F6345BE29404C8D6FFC35DAB7B6" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_CB178F6345BE29404C8D6FFC35DAB7B6" xlink:type="arc" />
    <link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_006482B4D6F264BA31636FFC35DA5B1F_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_006482B4D6F264BA31636FFC35DA5B1F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2020</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_006482B4D6F264BA31636FFC35DA5B1F" xlink:type="locator" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_F77B66B72E5349E316D16FFC35DAA06E" xlink:type="locator" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_FBA839125F314871C2246FFC35DA6E22" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_FBA839125F314871C2246FFC35DA6E22" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_FBA839125F314871C2246FFC35DA6E22" xlink:type="arc" />
    <link:label id="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_2F587F795AC6FCBC72349BE4B054597C_terseLabel_en-US" xlink:label="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_2F587F795AC6FCBC72349BE4B054597C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Impaired Long-Lived Assets Held and Used by Type [Axis]</link:label>
    <link:label id="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_2F587F795AC6FCBC72349BE4B054597C_label_en-US" xlink:label="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_2F587F795AC6FCBC72349BE4B054597C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Impaired Long-Lived Assets Held and Used by Type [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_2F587F795AC6FCBC72349BE4B054597C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_2F587F795AC6FCBC72349BE4B054597C" xlink:to="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_2F587F795AC6FCBC72349BE4B054597C" xlink:type="arc" />
    <link:label id="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_B580750176462B773D549BE4B0547AC8_terseLabel_en-US" xlink:label="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_B580750176462B773D549BE4B0547AC8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Impaired Long-Lived Assets Held and Used, Asset Name [Domain]</link:label>
    <link:label id="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_B580750176462B773D549BE4B0547AC8_label_en-US" xlink:label="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_B580750176462B773D549BE4B0547AC8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Impaired Long-Lived Assets Held and Used, Asset Name [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_B580750176462B773D549BE4B0547AC8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_B580750176462B773D549BE4B0547AC8" xlink:to="lab_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_B580750176462B773D549BE4B0547AC8" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstateInvestmentPropertiesNetMember_5ACDE924B0150300FC2A9BE4B0545028_terseLabel_en-US" xlink:label="lab_ofc_RealEstateInvestmentPropertiesNetMember_5ACDE924B0150300FC2A9BE4B0545028" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Operating properties, net [Member]</link:label>
    <link:label id="lab_ofc_RealEstateInvestmentPropertiesNetMember_5ACDE924B0150300FC2A9BE4B0545028_label_en-US" xlink:label="lab_ofc_RealEstateInvestmentPropertiesNetMember_5ACDE924B0150300FC2A9BE4B0545028" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Investment Properties, Net [Member]</link:label>
    <link:label id="lab_ofc_RealEstateInvestmentPropertiesNetMember_5ACDE924B0150300FC2A9BE4B0545028_documentation_en-US" xlink:label="lab_ofc_RealEstateInvestmentPropertiesNetMember_5ACDE924B0150300FC2A9BE4B0545028" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents details pertaining to real estate property held for investment purposes at time of measurement, excluding the effect of held for sale allocations.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstateInvestmentPropertiesNetMember" xlink:label="loc_ofc_RealEstateInvestmentPropertiesNetMember_5ACDE924B0150300FC2A9BE4B0545028" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstateInvestmentPropertiesNetMember_5ACDE924B0150300FC2A9BE4B0545028" xlink:to="lab_ofc_RealEstateInvestmentPropertiesNetMember_5ACDE924B0150300FC2A9BE4B0545028" xlink:type="arc" />
    <link:label id="lab_ofc_AberdeenMarylandMember_0774B40FDAA6FB998E0D9BE4B0559267_terseLabel_en-US" xlink:label="lab_ofc_AberdeenMarylandMember_0774B40FDAA6FB998E0D9BE4B0559267" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Aberdeen, Maryland [Member]</link:label>
    <link:label id="lab_ofc_AberdeenMarylandMember_0774B40FDAA6FB998E0D9BE4B0559267_label_en-US" xlink:label="lab_ofc_AberdeenMarylandMember_0774B40FDAA6FB998E0D9BE4B0559267" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Aberdeen, Maryland [Member]</link:label>
    <link:label id="lab_ofc_AberdeenMarylandMember_0774B40FDAA6FB998E0D9BE4B0559267_documentation_en-US" xlink:label="lab_ofc_AberdeenMarylandMember_0774B40FDAA6FB998E0D9BE4B0559267" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Aberdeen, Maryland [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_AberdeenMarylandMember" xlink:label="loc_ofc_AberdeenMarylandMember_0774B40FDAA6FB998E0D9BE4B0559267" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_AberdeenMarylandMember_0774B40FDAA6FB998E0D9BE4B0559267" xlink:to="lab_ofc_AberdeenMarylandMember_0774B40FDAA6FB998E0D9BE4B0559267" xlink:type="arc" />
    <link:label id="lab_ofc_FrederickMarylandMember_8D5C049657AE6FB49AE29BE4B056561E_terseLabel_en-US" xlink:label="lab_ofc_FrederickMarylandMember_8D5C049657AE6FB49AE29BE4B056561E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Frederick, Maryland [Member]</link:label>
    <link:label id="lab_ofc_FrederickMarylandMember_8D5C049657AE6FB49AE29BE4B056561E_label_en-US" xlink:label="lab_ofc_FrederickMarylandMember_8D5C049657AE6FB49AE29BE4B056561E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Frederick, Maryland [Member]</link:label>
    <link:label id="lab_ofc_FrederickMarylandMember_8D5C049657AE6FB49AE29BE4B056561E_documentation_en-US" xlink:label="lab_ofc_FrederickMarylandMember_8D5C049657AE6FB49AE29BE4B056561E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Frederick, Maryland [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_FrederickMarylandMember" xlink:label="loc_ofc_FrederickMarylandMember_8D5C049657AE6FB49AE29BE4B056561E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_FrederickMarylandMember_8D5C049657AE6FB49AE29BE4B056561E" xlink:to="lab_ofc_FrederickMarylandMember_8D5C049657AE6FB49AE29BE4B056561E" xlink:type="arc" />
    <link:label id="lab_ofc_GreaterPhiladelphiaPennsylvaniaMember_CBC69C4334471B7ADA2F9BE4B056B775_terseLabel_en-US" xlink:label="lab_ofc_GreaterPhiladelphiaPennsylvaniaMember_CBC69C4334471B7ADA2F9BE4B056B775" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Greater Philadelphia [Member]</link:label>
    <link:label id="lab_ofc_GreaterPhiladelphiaPennsylvaniaMember_CBC69C4334471B7ADA2F9BE4B056B775_label_en-US" xlink:label="lab_ofc_GreaterPhiladelphiaPennsylvaniaMember_CBC69C4334471B7ADA2F9BE4B056B775" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Greater Philadelphia, Pennsylvania [Member]</link:label>
    <link:label id="lab_ofc_GreaterPhiladelphiaPennsylvaniaMember_CBC69C4334471B7ADA2F9BE4B056B775_documentation_en-US" xlink:label="lab_ofc_GreaterPhiladelphiaPennsylvaniaMember_CBC69C4334471B7ADA2F9BE4B056B775" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents Greater Philadelphia, Pennsylvania office properties.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_GreaterPhiladelphiaPennsylvaniaMember" xlink:label="loc_ofc_GreaterPhiladelphiaPennsylvaniaMember_CBC69C4334471B7ADA2F9BE4B056B775" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_GreaterPhiladelphiaPennsylvaniaMember_CBC69C4334471B7ADA2F9BE4B056B775" xlink:to="lab_ofc_GreaterPhiladelphiaPennsylvaniaMember_CBC69C4334471B7ADA2F9BE4B056B775" xlink:type="arc" />
    <link:label id="lab_ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember_BDD62BBCDD76A43B9FAF9BE4B0560587_terseLabel_en-US" xlink:label="lab_ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember_BDD62BBCDD76A43B9FAF9BE4B0560587" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Colorado Springs, Colorado and White Marsh, Maryland [Member]</link:label>
    <link:label id="lab_ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember_BDD62BBCDD76A43B9FAF9BE4B0560587_label_en-US" xlink:label="lab_ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember_BDD62BBCDD76A43B9FAF9BE4B0560587" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Colorado Springs, Colorado and White Marsh, Maryland [Member]</link:label>
    <link:label id="lab_ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember_BDD62BBCDD76A43B9FAF9BE4B0560587_documentation_en-US" xlink:label="lab_ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember_BDD62BBCDD76A43B9FAF9BE4B0560587" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Colorado Springs, Colorado and White Marsh, Maryland [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember" xlink:label="loc_ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember_BDD62BBCDD76A43B9FAF9BE4B0560587" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember_BDD62BBCDD76A43B9FAF9BE4B0560587" xlink:to="lab_ofc_ColoradoSpringsColoradoandWhiteMarshMarylandMember_BDD62BBCDD76A43B9FAF9BE4B0560587" xlink:type="arc" />
    <link:label id="lab_ofc_ColoradoSpringsColoradoMember_B8236E1190007D9B36A59BE4B0565D7D_terseLabel_en-US" xlink:label="lab_ofc_ColoradoSpringsColoradoMember_B8236E1190007D9B36A59BE4B0565D7D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Colorado Springs [Member]</link:label>
    <link:label id="lab_ofc_ColoradoSpringsColoradoMember_B8236E1190007D9B36A59BE4B0565D7D_label_en-US" xlink:label="lab_ofc_ColoradoSpringsColoradoMember_B8236E1190007D9B36A59BE4B0565D7D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Colorado Springs, Colorado [Member]</link:label>
    <link:label id="lab_ofc_ColoradoSpringsColoradoMember_B8236E1190007D9B36A59BE4B0565D7D_documentation_en-US" xlink:label="lab_ofc_ColoradoSpringsColoradoMember_B8236E1190007D9B36A59BE4B0565D7D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents Colorado Springs, Colorado</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ColoradoSpringsColoradoMember" xlink:label="loc_ofc_ColoradoSpringsColoradoMember_B8236E1190007D9B36A59BE4B0565D7D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ColoradoSpringsColoradoMember_B8236E1190007D9B36A59BE4B0565D7D" xlink:to="lab_ofc_ColoradoSpringsColoradoMember_B8236E1190007D9B36A59BE4B0565D7D" xlink:type="arc" />
    <link:label id="lab_ofc_NorthernVirginiaVAMember_176AA5837C0B86C26F509BE4B05604FC_terseLabel_en-US" xlink:label="lab_ofc_NorthernVirginiaVAMember_176AA5837C0B86C26F509BE4B05604FC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Northern Virginia [Member]</link:label>
    <link:label id="lab_ofc_NorthernVirginiaVAMember_176AA5837C0B86C26F509BE4B05604FC_label_en-US" xlink:label="lab_ofc_NorthernVirginiaVAMember_176AA5837C0B86C26F509BE4B05604FC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Northern Virginia, VA [Member]</link:label>
    <link:label id="lab_ofc_NorthernVirginiaVAMember_176AA5837C0B86C26F509BE4B05604FC_documentation_en-US" xlink:label="lab_ofc_NorthernVirginiaVAMember_176AA5837C0B86C26F509BE4B05604FC" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Northern Virginia, VA [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NorthernVirginiaVAMember" xlink:label="loc_ofc_NorthernVirginiaVAMember_176AA5837C0B86C26F509BE4B05604FC" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NorthernVirginiaVAMember_176AA5837C0B86C26F509BE4B05604FC" xlink:to="lab_ofc_NorthernVirginiaVAMember_176AA5837C0B86C26F509BE4B05604FC" xlink:type="arc" />
    <link:label id="lab_ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember_A702A105F2FE9825DFFB9BE4B0578C0A_terseLabel_en-US" xlink:label="lab_ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember_A702A105F2FE9825DFFB9BE4B0578C0A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Northern Virginia Defense/IT and Fort Meade/Baltimore Washington Corridor [Member]</link:label>
    <link:label id="lab_ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember_A702A105F2FE9825DFFB9BE4B0578C0A_label_en-US" xlink:label="lab_ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember_A702A105F2FE9825DFFB9BE4B0578C0A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Northern Virginia Defense/IT and Fort Meade/Baltimore Washington Corridor [Member]</link:label>
    <link:label id="lab_ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember_A702A105F2FE9825DFFB9BE4B0578C0A_documentation_en-US" xlink:label="lab_ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember_A702A105F2FE9825DFFB9BE4B0578C0A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Northern Virginia Defense/IT and Fort Meade/Baltimore Washington Corridor[Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember" xlink:label="loc_ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember_A702A105F2FE9825DFFB9BE4B0578C0A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember_A702A105F2FE9825DFFB9BE4B0578C0A" xlink:to="lab_ofc_NorthernVirginiaDefenseITandFortMeadeBaltimoreWashingtonCorridorMember_A702A105F2FE9825DFFB9BE4B0578C0A" xlink:type="arc" />
    <link:label id="lab_us-gaap_BalanceSheetLocationAxis_21CED0F28C7531C64FF89BE4B0571844_terseLabel_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationAxis_21CED0F28C7531C64FF89BE4B0571844" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Balance Sheet Location [Axis]</link:label>
    <link:label id="lab_us-gaap_BalanceSheetLocationAxis_21CED0F28C7531C64FF89BE4B0571844_label_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationAxis_21CED0F28C7531C64FF89BE4B0571844" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Balance Sheet Location [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_21CED0F28C7531C64FF89BE4B0571844" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_21CED0F28C7531C64FF89BE4B0571844" xlink:to="lab_us-gaap_BalanceSheetLocationAxis_21CED0F28C7531C64FF89BE4B0571844" xlink:type="arc" />
    <link:label id="lab_us-gaap_BalanceSheetLocationDomain_C03D464E0DE945D49C8C9BE4B0570530_terseLabel_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationDomain_C03D464E0DE945D49C8C9BE4B0570530" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Balance Sheet Location [Domain]</link:label>
    <link:label id="lab_us-gaap_BalanceSheetLocationDomain_C03D464E0DE945D49C8C9BE4B0570530_label_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationDomain_C03D464E0DE945D49C8C9BE4B0570530" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Balance Sheet Location [Domain]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_C03D464E0DE945D49C8C9BE4B0570530" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_C03D464E0DE945D49C8C9BE4B0570530" xlink:to="lab_us-gaap_BalanceSheetLocationDomain_C03D464E0DE945D49C8C9BE4B0570530" xlink:type="arc" />
    <link:label id="lab_ofc_OperatingPropertiesNetMember_9D565C1FC70E31370B4C9C1E43435381_terseLabel_en-US" xlink:label="lab_ofc_OperatingPropertiesNetMember_9D565C1FC70E31370B4C9C1E43435381" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Operating properties, net [Member]</link:label>
    <link:label id="lab_ofc_OperatingPropertiesNetMember_9D565C1FC70E31370B4C9C1E43435381_label_en-US" xlink:label="lab_ofc_OperatingPropertiesNetMember_9D565C1FC70E31370B4C9C1E43435381" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Properties, Net [Member]</link:label>
    <link:label id="lab_ofc_OperatingPropertiesNetMember_9D565C1FC70E31370B4C9C1E43435381_documentation_en-US" xlink:label="lab_ofc_OperatingPropertiesNetMember_9D565C1FC70E31370B4C9C1E43435381" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Operating Properties, Net [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_OperatingPropertiesNetMember" xlink:label="loc_ofc_OperatingPropertiesNetMember_9D565C1FC70E31370B4C9C1E43435381" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_OperatingPropertiesNetMember_9D565C1FC70E31370B4C9C1E43435381" xlink:to="lab_ofc_OperatingPropertiesNetMember_9D565C1FC70E31370B4C9C1E43435381" xlink:type="arc" />
    <link:label id="lab_ofc_ProjectsInDevelopmentOrHeldForFutureDevelopmentMember_0CC758B5D3387CEC52499BE4B057ACB7_terseLabel_en-US" xlink:label="lab_ofc_ProjectsInDevelopmentOrHeldForFutureDevelopmentMember_0CC758B5D3387CEC52499BE4B057ACB7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Projects in development or held for future development [Member]</link:label>
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    <link:label id="lab_ofc_ProjectsInDevelopmentOrHeldForFutureDevelopmentMember_0CC758B5D3387CEC52499BE4B057ACB7_documentation_en-US" xlink:label="lab_ofc_ProjectsInDevelopmentOrHeldForFutureDevelopmentMember_0CC758B5D3387CEC52499BE4B057ACB7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents projects in development or held for future development.</link:label>
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    <link:label id="lab_ofc_NumberofPropertiesReclassifiedToHeldForSale_D25F0DC16285040F41D09BE4B0586544_terseLabel_en-US" xlink:label="lab_ofc_NumberofPropertiesReclassifiedToHeldForSale_D25F0DC16285040F41D09BE4B0586544" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of properties</link:label>
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    <link:label id="lab_ofc_DividendsDeclaredOrdinaryIncomePercentage_65C94032A860EFB00350955416A94432_documentation_en-US" xlink:label="lab_ofc_DividendsDeclaredOrdinaryIncomePercentage_65C94032A860EFB00350955416A94432" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the percentage of aggregate dividends declared during the period treated as ordinary income for federal tax purposes.</link:label>
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    <link:label id="lab_ofc_DividendsDeclaredLongTermCapitalGainPercentage_30DD3B82672C39C15D91955416A900A6_terseLabel_en-US" xlink:label="lab_ofc_DividendsDeclaredLongTermCapitalGainPercentage_30DD3B82672C39C15D91955416A900A6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Long-term capital gain (as a percent)</link:label>
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    <link:label id="lab_ofc_DividendsDeclaredLongTermCapitalGainPercentage_30DD3B82672C39C15D91955416A900A6_documentation_en-US" xlink:label="lab_ofc_DividendsDeclaredLongTermCapitalGainPercentage_30DD3B82672C39C15D91955416A900A6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the percentage of aggregate dividends declared during the period treated as a long-term capital gain for federal tax purposes.</link:label>
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    <link:label id="lab_ofc_DividendsDeclaredReturnOfCapitalPercentage_535876DBBCC8D01FB664955416A9082A_terseLabel_en-US" xlink:label="lab_ofc_DividendsDeclaredReturnOfCapitalPercentage_535876DBBCC8D01FB664955416A9082A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Return of capital (as a percent)</link:label>
    <link:label id="lab_ofc_DividendsDeclaredReturnOfCapitalPercentage_535876DBBCC8D01FB664955416A9082A_label_en-US" xlink:label="lab_ofc_DividendsDeclaredReturnOfCapitalPercentage_535876DBBCC8D01FB664955416A9082A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Dividends Declared, Return of Capital Percentage</link:label>
    <link:label id="lab_ofc_DividendsDeclaredReturnOfCapitalPercentage_535876DBBCC8D01FB664955416A9082A_documentation_en-US" xlink:label="lab_ofc_DividendsDeclaredReturnOfCapitalPercentage_535876DBBCC8D01FB664955416A9082A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the percentage of aggregate dividends declared during the period treated as return of capital for federal tax purposes.</link:label>
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    <link:label id="lab_ofc_ApproximateAmountbywhichNetBasisofAssetsandLiabilitiesforTaxReportingPurposesisHigherthanAmountReportedonConsolidatedBalanceSheet_9922357EE99CBF490E21955416A90773_documentation_en-US" xlink:label="lab_ofc_ApproximateAmountbywhichNetBasisofAssetsandLiabilitiesforTaxReportingPurposesisHigherthanAmountReportedonConsolidatedBalanceSheet_9922357EE99CBF490E21955416A90773" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the approximate amount by which basis of assets and liabilities for tax reporting purposes are higher than the amount reported on consolidated balance sheet.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ApproximateAmountbywhichNetBasisofAssetsandLiabilitiesforTaxReportingPurposesisHigherthanAmountReportedonConsolidatedBalanceSheet" xlink:label="loc_ofc_ApproximateAmountbywhichNetBasisofAssetsandLiabilitiesforTaxReportingPurposesisHigherthanAmountReportedonConsolidatedBalanceSheet_9922357EE99CBF490E21955416A90773" xlink:type="locator" />
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    <link:label id="lab_ofc_CompensationandIndirectCostsCapitalizedDeferredLeasingCosts_74D05383EE2B4E15ADBB955416A9B9EC_terseLabel_en-US" xlink:label="lab_ofc_CompensationandIndirectCostsCapitalizedDeferredLeasingCosts_74D05383EE2B4E15ADBB955416A9B9EC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Deferred lease related compensation costs</link:label>
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_4DB70FC5A5549EA0EA49955416A99084_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_4DB70FC5A5549EA0EA49955416A99084" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Future minimum payments due</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_4DB70FC5A5549EA0EA49955416A99084_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_4DB70FC5A5549EA0EA49955416A99084" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments Due</link:label>
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    <link:label id="lab_us-gaap_PrepaidExpenseCurrentAndNoncurrent_3660310635DBF96B6C4E955415B137EF_terseLabel_en-US" xlink:label="lab_us-gaap_PrepaidExpenseCurrentAndNoncurrent_3660310635DBF96B6C4E955415B137EF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Prepaid expenses</link:label>
    <link:label id="lab_us-gaap_PrepaidExpenseCurrentAndNoncurrent_3660310635DBF96B6C4E955415B137EF_label_en-US" xlink:label="lab_us-gaap_PrepaidExpenseCurrentAndNoncurrent_3660310635DBF96B6C4E955415B137EF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Prepaid Expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PrepaidExpenseCurrentAndNoncurrent" xlink:label="loc_us-gaap_PrepaidExpenseCurrentAndNoncurrent_3660310635DBF96B6C4E955415B137EF" xlink:type="locator" />
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    <link:label id="lab_us-gaap_IncentiveToLessee_7544A599C2BE1E75D438955415B1F36F_terseLabel_en-US" xlink:label="lab_us-gaap_IncentiveToLessee_7544A599C2BE1E75D438955415B1F36F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Lease incentives, net</link:label>
    <link:label id="lab_us-gaap_IncentiveToLessee_7544A599C2BE1E75D438955415B1F36F_label_en-US" xlink:label="lab_us-gaap_IncentiveToLessee_7544A599C2BE1E75D438955415B1F36F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Incentive to Lessee</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncentiveToLessee" xlink:label="loc_us-gaap_IncentiveToLessee_7544A599C2BE1E75D438955415B1F36F" xlink:type="locator" />
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    <link:label id="lab_us-gaap_PropertyPlantAndEquipmentNet_A7B0157D960F13B64881955415B1F430_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet_A7B0157D960F13B64881955415B1F430" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Furniture, fixtures and equipment, net</link:label>
    <link:label id="lab_us-gaap_PropertyPlantAndEquipmentNet_A7B0157D960F13B64881955415B1F430_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet_A7B0157D960F13B64881955415B1F430" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Property, Plant and Equipment, Net</link:label>
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    <link:label id="lab_us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrPrograms_8DE05AC164AF6B72139A955415B1CFE7_terseLabel_en-US" xlink:label="lab_us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrPrograms_8DE05AC164AF6B72139A955415B1CFE7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Construction contract costs incurred in excess of billings</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrPrograms" xlink:label="loc_us-gaap_CostsInExcessOfBillingsOnUncompletedContractsOrPrograms_8DE05AC164AF6B72139A955415B1CFE7" xlink:type="locator" />
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    <link:label id="lab_us-gaap_InterestRateCashFlowHedgeAssetAtFairValue_36EE047428DE1326538C955415B16A25_verboseLabel_en-US" xlink:label="lab_us-gaap_InterestRateCashFlowHedgeAssetAtFairValue_36EE047428DE1326538C955415B16A25" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Interest rate derivatives</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_InterestRateCashFlowHedgeAssetAtFairValue" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeAssetAtFairValue_36EE047428DE1326538C955415B16A25" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet_1A9A21ECC548FBEA080295B9D290EC78_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet_1A9A21ECC548FBEA080295B9D290EC78" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Deferred tax asset, net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_1A9A21ECC548FBEA080295B9D290EC78" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_1A9A21ECC548FBEA080295B9D290EC78" xlink:to="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet_1A9A21ECC548FBEA080295B9D290EC78" xlink:type="arc" />
    <link:label id="lab_us-gaap_OtherAssets_D4BDA83C311B52897E79955415B11589_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAssets_D4BDA83C311B52897E79955415B11589" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other assets</link:label>
    <link:label id="lab_us-gaap_OtherAssets_D4BDA83C311B52897E79955415B11589_label_en-US" xlink:label="lab_us-gaap_OtherAssets_D4BDA83C311B52897E79955415B11589" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Assets</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherAssets" xlink:label="loc_us-gaap_OtherAssets_D4BDA83C311B52897E79955415B11589" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssets_D4BDA83C311B52897E79955415B11589" xlink:to="lab_us-gaap_OtherAssets_D4BDA83C311B52897E79955415B11589" xlink:type="arc" />
    <link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssets_95A51AB21B1594710EAF955415B19B96_totalLabel_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssets_95A51AB21B1594710EAF955415B19B96" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Prepaid expenses and other assets, net</link:label>
    <link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssets_95A51AB21B1594710EAF955415B19B96_label_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssets_95A51AB21B1594710EAF955415B19B96" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Prepaid Expense and Other Assets</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssets" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssets_95A51AB21B1594710EAF955415B19B96" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PrepaidExpenseAndOtherAssets_95A51AB21B1594710EAF955415B19B96" xlink:to="lab_us-gaap_PrepaidExpenseAndOtherAssets_95A51AB21B1594710EAF955415B19B96" xlink:type="arc" />
    <link:label id="lab_us-gaap_StatementOfCashFlowsAbstract_494028FA9357D24A870C9B3DD0712350_label_en-US" xlink:label="lab_us-gaap_StatementOfCashFlowsAbstract_494028FA9357D24A870C9B3DD0712350" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Statement of Cash Flows [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementOfCashFlowsAbstract" xlink:label="loc_us-gaap_StatementOfCashFlowsAbstract_494028FA9357D24A870C9B3DD0712350" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_494028FA9357D24A870C9B3DD0712350" xlink:to="lab_us-gaap_StatementOfCashFlowsAbstract_494028FA9357D24A870C9B3DD0712350" xlink:type="arc" />
    <link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_965304DE365EFE73A2259B3DD0773686_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_965304DE365EFE73A2259B3DD0773686" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Cash flows from operating activities</link:label>
    <link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_965304DE365EFE73A2259B3DD0773686_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_965304DE365EFE73A2259B3DD0773686" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Net Cash Provided by (Used in) Operating Activities [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_965304DE365EFE73A2259B3DD0773686" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_965304DE365EFE73A2259B3DD0773686" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_965304DE365EFE73A2259B3DD0773686" xlink:type="arc" />
    <link:label id="lab_ofc_RevenuesFromRealEstateOperationsReceived_59B60CF701D7AC4095469B3DD078C3FA_terseLabel_en-US" xlink:label="lab_ofc_RevenuesFromRealEstateOperationsReceived_59B60CF701D7AC4095469B3DD078C3FA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Revenues from real estate operations received</link:label>
    <link:label id="lab_ofc_RevenuesFromRealEstateOperationsReceived_59B60CF701D7AC4095469B3DD078C3FA_label_en-US" xlink:label="lab_ofc_RevenuesFromRealEstateOperationsReceived_59B60CF701D7AC4095469B3DD078C3FA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Revenues from Real Estate Operations Received</link:label>
    <link:label id="lab_ofc_RevenuesFromRealEstateOperationsReceived_59B60CF701D7AC4095469B3DD078C3FA_documentation_en-US" xlink:label="lab_ofc_RevenuesFromRealEstateOperationsReceived_59B60CF701D7AC4095469B3DD078C3FA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Cash received for rents, tenant recoveries and other real estate operations during the current period.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RevenuesFromRealEstateOperationsReceived" xlink:label="loc_ofc_RevenuesFromRealEstateOperationsReceived_59B60CF701D7AC4095469B3DD078C3FA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RevenuesFromRealEstateOperationsReceived_59B60CF701D7AC4095469B3DD078C3FA" xlink:to="lab_ofc_RevenuesFromRealEstateOperationsReceived_59B60CF701D7AC4095469B3DD078C3FA" xlink:type="arc" />
    <link:label id="lab_ofc_ConstructionContractAndOtherServiceRevenuesReceived_8CAEB004D0F875DB3D079B3DD07866DA_terseLabel_en-US" xlink:label="lab_ofc_ConstructionContractAndOtherServiceRevenuesReceived_8CAEB004D0F875DB3D079B3DD07866DA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Construction contract and other service revenues received</link:label>
    <link:label id="lab_ofc_ConstructionContractAndOtherServiceRevenuesReceived_8CAEB004D0F875DB3D079B3DD07866DA_label_en-US" xlink:label="lab_ofc_ConstructionContractAndOtherServiceRevenuesReceived_8CAEB004D0F875DB3D079B3DD07866DA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Construction Contract and Other Service Revenues Received</link:label>
    <link:label id="lab_ofc_ConstructionContractAndOtherServiceRevenuesReceived_8CAEB004D0F875DB3D079B3DD07866DA_documentation_en-US" xlink:label="lab_ofc_ConstructionContractAndOtherServiceRevenuesReceived_8CAEB004D0F875DB3D079B3DD07866DA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Cash received for building and real estate development, which may include improvements (such as drainage, utilities, grading and subdividing) to a parcel of land, and general contracting services and from the sale of other goods or rendering of other services.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ConstructionContractAndOtherServiceRevenuesReceived" xlink:label="loc_ofc_ConstructionContractAndOtherServiceRevenuesReceived_8CAEB004D0F875DB3D079B3DD07866DA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ConstructionContractAndOtherServiceRevenuesReceived_8CAEB004D0F875DB3D079B3DD07866DA" xlink:to="lab_ofc_ConstructionContractAndOtherServiceRevenuesReceived_8CAEB004D0F875DB3D079B3DD07866DA" xlink:type="arc" />
    <link:label id="lab_ofc_PropertyOperatingExpensesPaid_EEC62C2E4D571EE384079B3DD078FB8E_negatedLabel_en-US" xlink:label="lab_ofc_PropertyOperatingExpensesPaid_EEC62C2E4D571EE384079B3DD078FB8E" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Property operating expenses paid</link:label>
    <link:label id="lab_ofc_PropertyOperatingExpensesPaid_EEC62C2E4D571EE384079B3DD078FB8E_label_en-US" xlink:label="lab_ofc_PropertyOperatingExpensesPaid_EEC62C2E4D571EE384079B3DD078FB8E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Property Operating Expenses Paid</link:label>
    <link:label id="lab_ofc_PropertyOperatingExpensesPaid_EEC62C2E4D571EE384079B3DD078FB8E_documentation_en-US" xlink:label="lab_ofc_PropertyOperatingExpensesPaid_EEC62C2E4D571EE384079B3DD078FB8E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element represents the amount of cash paid during the current period for costs that are directly related to generation of revenues from leased and rented properties or equipment.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PropertyOperatingExpensesPaid" xlink:label="loc_ofc_PropertyOperatingExpensesPaid_EEC62C2E4D571EE384079B3DD078FB8E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PropertyOperatingExpensesPaid_EEC62C2E4D571EE384079B3DD078FB8E" xlink:to="lab_ofc_PropertyOperatingExpensesPaid_EEC62C2E4D571EE384079B3DD078FB8E" xlink:type="arc" />
    <link:label id="lab_ofc_ConstructionContractAndOtherServiceExpensesPaid_AD63F799C3AAA849CFDA9B3DD078B870_negatedLabel_en-US" xlink:label="lab_ofc_ConstructionContractAndOtherServiceExpensesPaid_AD63F799C3AAA849CFDA9B3DD078B870" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Construction contract and other service expenses paid</link:label>
    <link:label id="lab_ofc_ConstructionContractAndOtherServiceExpensesPaid_AD63F799C3AAA849CFDA9B3DD078B870_label_en-US" xlink:label="lab_ofc_ConstructionContractAndOtherServiceExpensesPaid_AD63F799C3AAA849CFDA9B3DD078B870" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Construction Contract and Other Service Expenses Paid</link:label>
    <link:label id="lab_ofc_ConstructionContractAndOtherServiceExpensesPaid_AD63F799C3AAA849CFDA9B3DD078B870_documentation_en-US" xlink:label="lab_ofc_ConstructionContractAndOtherServiceExpensesPaid_AD63F799C3AAA849CFDA9B3DD078B870" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Cash payments for costs related to construction and development services and other service operations during the current period.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ConstructionContractAndOtherServiceExpensesPaid" xlink:label="loc_ofc_ConstructionContractAndOtherServiceExpensesPaid_AD63F799C3AAA849CFDA9B3DD078B870" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ConstructionContractAndOtherServiceExpensesPaid_AD63F799C3AAA849CFDA9B3DD078B870" xlink:to="lab_ofc_ConstructionContractAndOtherServiceExpensesPaid_AD63F799C3AAA849CFDA9B3DD078B870" xlink:type="arc" />
    <link:label id="lab_ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid_CAA4D7A52B0073680ACF9B3DD07809E8_negatedTerseLabel_en-US" xlink:label="lab_ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid_CAA4D7A52B0073680ACF9B3DD07809E8" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">General, administrative, leasing, business development and land carry costs paid</link:label>
    <link:label id="lab_ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid_CAA4D7A52B0073680ACF9B3DD07809E8_label_en-US" xlink:label="lab_ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid_CAA4D7A52B0073680ACF9B3DD07809E8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">General and Administrative, Leasing, Business Development and Land Carry Paid</link:label>
    <link:label id="lab_ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid_CAA4D7A52B0073680ACF9B3DD07809E8_documentation_en-US" xlink:label="lab_ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid_CAA4D7A52B0073680ACF9B3DD07809E8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Cash payments for aggregate total costs related to selling a firm's product and services, all other general and administrative expenses, business development and land carry costs in connection with properties not in operations.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid" xlink:label="loc_ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid_CAA4D7A52B0073680ACF9B3DD07809E8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid_CAA4D7A52B0073680ACF9B3DD07809E8" xlink:to="lab_ofc_GeneralandAdministrativeLeasingBusinessDevelopmentandLandCarryPaid_CAA4D7A52B0073680ACF9B3DD07809E8" xlink:type="arc" />
    <link:label id="lab_us-gaap_InterestPaidNet_D132CAA4BA4B4556B0EE9B3DD078E56E_negatedLabel_en-US" xlink:label="lab_us-gaap_InterestPaidNet_D132CAA4BA4B4556B0EE9B3DD078E56E" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Interest expense paid</link:label>
    <link:label id="lab_us-gaap_InterestPaidNet_D132CAA4BA4B4556B0EE9B3DD078E56E_label_en-US" xlink:label="lab_us-gaap_InterestPaidNet_D132CAA4BA4B4556B0EE9B3DD078E56E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Interest Paid, Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_InterestPaidNet" xlink:label="loc_us-gaap_InterestPaidNet_D132CAA4BA4B4556B0EE9B3DD078E56E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestPaidNet_D132CAA4BA4B4556B0EE9B3DD078E56E" xlink:to="lab_us-gaap_InterestPaidNet_D132CAA4BA4B4556B0EE9B3DD078E56E" xlink:type="arc" />
    <link:label id="lab_ofc_PaymentsofLeaseIncentives_C5BF4D48A53E1A248FBF9B3DD079DB9C_negatedTerseLabel_en-US" xlink:label="lab_ofc_PaymentsofLeaseIncentives_C5BF4D48A53E1A248FBF9B3DD079DB9C" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Lease incentives paid</link:label>
    <link:label id="lab_ofc_PaymentsofLeaseIncentives_C5BF4D48A53E1A248FBF9B3DD079DB9C_label_en-US" xlink:label="lab_ofc_PaymentsofLeaseIncentives_C5BF4D48A53E1A248FBF9B3DD079DB9C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Payments of Lease Incentives</link:label>
    <link:label id="lab_ofc_PaymentsofLeaseIncentives_C5BF4D48A53E1A248FBF9B3DD079DB9C_documentation_en-US" xlink:label="lab_ofc_PaymentsofLeaseIncentives_C5BF4D48A53E1A248FBF9B3DD079DB9C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Payments of Lease Incentives</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PaymentsofLeaseIncentives" xlink:label="loc_ofc_PaymentsofLeaseIncentives_C5BF4D48A53E1A248FBF9B3DD079DB9C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PaymentsofLeaseIncentives_C5BF4D48A53E1A248FBF9B3DD079DB9C" xlink:to="lab_ofc_PaymentsofLeaseIncentives_C5BF4D48A53E1A248FBF9B3DD079DB9C" xlink:type="arc" />
    <link:label id="lab_us-gaap_IncomeTaxesPaidNet_6F2E9820CBE34DD7E4419B3DD0797B3F_negatedLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaidNet_6F2E9820CBE34DD7E4419B3DD0797B3F" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Income taxes paid</link:label>
    <link:label id="lab_us-gaap_IncomeTaxesPaidNet_6F2E9820CBE34DD7E4419B3DD0797B3F_label_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaidNet_6F2E9820CBE34DD7E4419B3DD0797B3F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Income Taxes Paid, Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxesPaidNet" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_6F2E9820CBE34DD7E4419B3DD0797B3F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxesPaidNet_6F2E9820CBE34DD7E4419B3DD0797B3F" xlink:to="lab_us-gaap_IncomeTaxesPaidNet_6F2E9820CBE34DD7E4419B3DD0797B3F" xlink:type="arc" />
    <link:label id="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement_CBE80A732C23865928BC9B3DD079938E_terseLabel_en-US" xlink:label="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement_CBE80A732C23865928BC9B3DD079938E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other</link:label>
    <link:label id="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement_CBE80A732C23865928BC9B3DD079938E_label_en-US" xlink:label="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement_CBE80A732C23865928BC9B3DD079938E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Operating Activities, Cash Flow Statement</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_CBE80A732C23865928BC9B3DD079938E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_CBE80A732C23865928BC9B3DD079938E" xlink:to="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement_CBE80A732C23865928BC9B3DD079938E" xlink:type="arc" />
    <link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_7C80AAF7AB3BDC4C6BA69B3DD079889E_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_7C80AAF7AB3BDC4C6BA69B3DD079889E" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Net cash provided by operating activities</link:label>
    <link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_7C80AAF7AB3BDC4C6BA69B3DD079889E_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_7C80AAF7AB3BDC4C6BA69B3DD079889E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Net Cash Provided by (Used in) Operating Activities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7C80AAF7AB3BDC4C6BA69B3DD079889E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7C80AAF7AB3BDC4C6BA69B3DD079889E" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_7C80AAF7AB3BDC4C6BA69B3DD079889E" xlink:type="arc" />
    <link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8D46303A2090AD0F52269B3DD07996A0_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8D46303A2090AD0F52269B3DD07996A0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Cash flows from investing activities</link:label>
    <link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8D46303A2090AD0F52269B3DD07996A0_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8D46303A2090AD0F52269B3DD07996A0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Net Cash Provided by (Used in) Investing Activities [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8D46303A2090AD0F52269B3DD07996A0" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8D46303A2090AD0F52269B3DD07996A0" xlink:to="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8D46303A2090AD0F52269B3DD07996A0" xlink:type="arc" />
    <link:label id="lab_us-gaap_PaymentsToDevelopRealEstateAssets_E41F6097409F385ECAAC9B3DD07983D2_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsToDevelopRealEstateAssets_E41F6097409F385ECAAC9B3DD07983D2" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Construction, development and redevelopment</link:label>
    <link:label id="lab_us-gaap_PaymentsToDevelopRealEstateAssets_E41F6097409F385ECAAC9B3DD07983D2_label_en-US" xlink:label="lab_us-gaap_PaymentsToDevelopRealEstateAssets_E41F6097409F385ECAAC9B3DD07983D2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Payments to Develop Real Estate Assets</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PaymentsToDevelopRealEstateAssets" xlink:label="loc_us-gaap_PaymentsToDevelopRealEstateAssets_E41F6097409F385ECAAC9B3DD07983D2" xlink:type="locator" />
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    <link:label id="lab_us-gaap_PaymentsToAcquireCommercialRealEstate_3179AAD83994D906C5A59B3DD079920C_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireCommercialRealEstate_3179AAD83994D906C5A59B3DD079920C" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Acquisitions of operating properties and related intangible assets</link:label>
    <link:label id="lab_us-gaap_PaymentsToAcquireCommercialRealEstate_3179AAD83994D906C5A59B3DD079920C_label_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireCommercialRealEstate_3179AAD83994D906C5A59B3DD079920C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Payments to Acquire Commercial Real Estate</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PaymentsToAcquireCommercialRealEstate" xlink:label="loc_us-gaap_PaymentsToAcquireCommercialRealEstate_3179AAD83994D906C5A59B3DD079920C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireCommercialRealEstate_3179AAD83994D906C5A59B3DD079920C" xlink:to="lab_us-gaap_PaymentsToAcquireCommercialRealEstate_3179AAD83994D906C5A59B3DD079920C" xlink:type="arc" />
    <link:label id="lab_us-gaap_PaymentsForTenantImprovements_0C26EF3FF9ACC2C857B29B3DD07A7EB3_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsForTenantImprovements_0C26EF3FF9ACC2C857B29B3DD07A7EB3" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Tenant improvements on operating properties</link:label>
    <link:label id="lab_us-gaap_PaymentsForTenantImprovements_0C26EF3FF9ACC2C857B29B3DD07A7EB3_label_en-US" xlink:label="lab_us-gaap_PaymentsForTenantImprovements_0C26EF3FF9ACC2C857B29B3DD07A7EB3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Payments for Tenant Improvements</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PaymentsForTenantImprovements" xlink:label="loc_us-gaap_PaymentsForTenantImprovements_0C26EF3FF9ACC2C857B29B3DD07A7EB3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsForTenantImprovements_0C26EF3FF9ACC2C857B29B3DD07A7EB3" xlink:to="lab_us-gaap_PaymentsForTenantImprovements_0C26EF3FF9ACC2C857B29B3DD07A7EB3" xlink:type="arc" />
    <link:label id="lab_us-gaap_PaymentsForCapitalImprovements_1ADC9C0349338D5B4B9C9B3DD07AF38D_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsForCapitalImprovements_1ADC9C0349338D5B4B9C9B3DD07AF38D" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Other capital improvements on operating properties</link:label>
    <link:label id="lab_us-gaap_PaymentsForCapitalImprovements_1ADC9C0349338D5B4B9C9B3DD07AF38D_label_en-US" xlink:label="lab_us-gaap_PaymentsForCapitalImprovements_1ADC9C0349338D5B4B9C9B3DD07AF38D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Payments for Capital Improvements</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PaymentsForCapitalImprovements" xlink:label="loc_us-gaap_PaymentsForCapitalImprovements_1ADC9C0349338D5B4B9C9B3DD07AF38D" xlink:type="locator" />
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    <link:label id="lab_us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment_F14B07B6F1612D109DBB9B3DD07A1A21_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment_F14B07B6F1612D109DBB9B3DD07A1A21" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Proceeds from dispositions of properties</link:label>
    <link:label id="lab_us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment_F14B07B6F1612D109DBB9B3DD07A1A21_label_en-US" xlink:label="lab_us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment_F14B07B6F1612D109DBB9B3DD07A1A21" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Proceeds from Sale of Real Estate Held-for-investment</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment" xlink:label="loc_us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment_F14B07B6F1612D109DBB9B3DD07A1A21" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment_F14B07B6F1612D109DBB9B3DD07A1A21" xlink:to="lab_us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment_F14B07B6F1612D109DBB9B3DD07A1A21" xlink:type="arc" />
    <link:label id="lab_us-gaap_ProceedsFromDivestitureOfRealEstatePartnership_AA75BD0DC66EA7394CFA9B3DD07A6C86_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromDivestitureOfRealEstatePartnership_AA75BD0DC66EA7394CFA9B3DD07A6C86" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Proceeds from partial sales of properties, net of related debt</link:label>
    <link:label id="lab_us-gaap_ProceedsFromDivestitureOfRealEstatePartnership_AA75BD0DC66EA7394CFA9B3DD07A6C86_label_en-US" xlink:label="lab_us-gaap_ProceedsFromDivestitureOfRealEstatePartnership_AA75BD0DC66EA7394CFA9B3DD07A6C86" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Proceeds from Divestiture of Real Estate Partnership</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProceedsFromDivestitureOfRealEstatePartnership" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfRealEstatePartnership_AA75BD0DC66EA7394CFA9B3DD07A6C86" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromDivestitureOfRealEstatePartnership_AA75BD0DC66EA7394CFA9B3DD07A6C86" xlink:to="lab_us-gaap_ProceedsFromDivestitureOfRealEstatePartnership_AA75BD0DC66EA7394CFA9B3DD07A6C86" xlink:type="arc" />
    <link:label id="lab_us-gaap_PaymentsForLeasingCosts_C092D762DD8E2D3C7B379B3DD07AF15A_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsForLeasingCosts_C092D762DD8E2D3C7B379B3DD07AF15A" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Leasing costs paid</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PaymentsForLeasingCosts" xlink:label="loc_us-gaap_PaymentsForLeasingCosts_C092D762DD8E2D3C7B379B3DD07AF15A" xlink:type="locator" />
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    <link:label id="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_8DFD95FDA60B8256419E9B3DD07AAD63_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_8DFD95FDA60B8256419E9B3DD07AAD63" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Other</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_8DFD95FDA60B8256419E9B3DD07AAD63" xlink:type="locator" />
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    <link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_C41BEDBFF942612570BD9B3DD07A37EC_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_C41BEDBFF942612570BD9B3DD07A37EC" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Net cash (used in) provided by investing activities</link:label>
    <link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_C41BEDBFF942612570BD9B3DD07A37EC_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_C41BEDBFF942612570BD9B3DD07A37EC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Net Cash Provided by (Used in) Investing Activities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_C41BEDBFF942612570BD9B3DD07A37EC" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_C41BEDBFF942612570BD9B3DD07A37EC" xlink:to="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_C41BEDBFF942612570BD9B3DD07A37EC" xlink:type="arc" />
    <link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_5FBD0F1E328BBD1F32219B3DD07A9141_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_5FBD0F1E328BBD1F32219B3DD07A9141" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Cash flows from financing activities</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_5FBD0F1E328BBD1F32219B3DD07A9141" xlink:type="locator" />
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    <link:label id="lab_us-gaap_ProceedsFromIssuanceOfLongTermDebtAbstract_8982848150FC484FD0F19B3DD07A3EB8_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfLongTermDebtAbstract_8982848150FC484FD0F19B3DD07A3EB8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Proceeds from debt</link:label>
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    <link:label id="lab_us-gaap_ProceedsFromLongTermLinesOfCredit_7D50021C106BF0AA4B959B3DD07A9687_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromLongTermLinesOfCredit_7D50021C106BF0AA4B959B3DD07A9687" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Revolving Credit Facility</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProceedsFromLongTermLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_7D50021C106BF0AA4B959B3DD07A9687" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DepreciationDepletionAndAmortization_820AD505F1943BABBD009B3DD08270AA_terseLabel_en-US" xlink:label="lab_us-gaap_DepreciationDepletionAndAmortization_820AD505F1943BABBD009B3DD08270AA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Depreciation and other amortization</link:label>
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    <link:label id="lab_us-gaap_StraightLineRent_D77F1A4C7FC7407019609B3DD0822D59_negatedLabel_en-US" xlink:label="lab_us-gaap_StraightLineRent_D77F1A4C7FC7407019609B3DD0822D59" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Increase in deferred rent receivable</link:label>
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    <link:label id="lab_ofc_ExtinguishmentofDebtNoncashGainLoss_BDB14CB3C76FA9A51D5B9B3DD08338F5_terseLabel_en-US" xlink:label="lab_ofc_ExtinguishmentofDebtNoncashGainLoss_BDB14CB3C76FA9A51D5B9B3DD08338F5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Loss (gain) on early extinguishment of debt</link:label>
    <link:label id="lab_ofc_ExtinguishmentofDebtNoncashGainLoss_BDB14CB3C76FA9A51D5B9B3DD08338F5_label_en-US" xlink:label="lab_ofc_ExtinguishmentofDebtNoncashGainLoss_BDB14CB3C76FA9A51D5B9B3DD08338F5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Extinguishment of Debt, Non-cash (Gain) Loss</link:label>
    <link:label id="lab_ofc_ExtinguishmentofDebtNoncashGainLoss_BDB14CB3C76FA9A51D5B9B3DD08338F5_documentation_en-US" xlink:label="lab_ofc_ExtinguishmentofDebtNoncashGainLoss_BDB14CB3C76FA9A51D5B9B3DD08338F5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The aggregate non-cash (gain) loss on the early extinguishment of debt.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ExtinguishmentofDebtNoncashGainLoss" xlink:label="loc_ofc_ExtinguishmentofDebtNoncashGainLoss_BDB14CB3C76FA9A51D5B9B3DD08338F5" xlink:type="locator" />
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    <link:label id="lab_us-gaap_OtherNoncashIncomeExpense_41C095E6B53514C868E39B3DD0837304_negatedLabel_en-US" xlink:label="lab_us-gaap_OtherNoncashIncomeExpense_41C095E6B53514C868E39B3DD0837304" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Other</link:label>
    <link:label id="lab_us-gaap_OtherNoncashIncomeExpense_41C095E6B53514C868E39B3DD0837304_label_en-US" xlink:label="lab_us-gaap_OtherNoncashIncomeExpense_41C095E6B53514C868E39B3DD0837304" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Noncash Income (Expense)</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherNoncashIncomeExpense" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_41C095E6B53514C868E39B3DD0837304" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherNoncashIncomeExpense_41C095E6B53514C868E39B3DD0837304" xlink:to="lab_us-gaap_OtherNoncashIncomeExpense_41C095E6B53514C868E39B3DD0837304" xlink:type="arc" />
    <link:label id="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_5680719E18AE9321DB849B3DD083A18C_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_5680719E18AE9321DB849B3DD083A18C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Changes in operating assets and liabilities:</link:label>
    <link:label id="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_5680719E18AE9321DB849B3DD083A18C_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_5680719E18AE9321DB849B3DD083A18C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Increase (Decrease) in Operating Capital [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_5680719E18AE9321DB849B3DD083A18C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_5680719E18AE9321DB849B3DD083A18C" xlink:to="lab_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_5680719E18AE9321DB849B3DD083A18C" xlink:type="arc" />
    <link:label id="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_C707F7101252F1AB5EA09B3DD083A5DD_negatedLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_C707F7101252F1AB5EA09B3DD083A5DD" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Decrease (increase) in accounts receivable</link:label>
    <link:label id="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_C707F7101252F1AB5EA09B3DD083A5DD_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_C707F7101252F1AB5EA09B3DD083A5DD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Increase (Decrease) in Accounts Receivable</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_C707F7101252F1AB5EA09B3DD083A5DD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_C707F7101252F1AB5EA09B3DD083A5DD" xlink:to="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_C707F7101252F1AB5EA09B3DD083A5DD" xlink:type="arc" />
    <link:label id="lab_ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash_F81B3A6FE63489FD65599B3DD083DD83_negatedLabel_en-US" xlink:label="lab_ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash_F81B3A6FE63489FD65599B3DD083DD83" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Decrease (increase) in restricted cash and marketable securities</link:label>
    <link:label id="lab_ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash_F81B3A6FE63489FD65599B3DD083DD83_label_en-US" xlink:label="lab_ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash_F81B3A6FE63489FD65599B3DD083DD83" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Increase (Decrease) in Marketable Securities and Restricted Cash</link:label>
    <link:label id="lab_ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash_F81B3A6FE63489FD65599B3DD083DD83_documentation_en-US" xlink:label="lab_ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash_F81B3A6FE63489FD65599B3DD083DD83" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The net cash inflow (outflow) for the net change associated with funds that are not available for withdrawal or use (such as funds held in escrow) and are associated with underlying transactions that are classified as operating activities and marketable securities.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash" xlink:label="loc_ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash_F81B3A6FE63489FD65599B3DD083DD83" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash_F81B3A6FE63489FD65599B3DD083DD83" xlink:to="lab_ofc_IncreaseDecreaseInMarketableSecuritiesAndRestrictedCash_F81B3A6FE63489FD65599B3DD083DD83" xlink:type="arc" />
    <link:label id="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_BA6E1196F33B9958678F9B3DD083609C_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_BA6E1196F33B9958678F9B3DD083609C" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Decrease (increase) in prepaid expenses and other assets, net</link:label>
    <link:label id="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_BA6E1196F33B9958678F9B3DD083609C_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_BA6E1196F33B9958678F9B3DD083609C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Increase (Decrease) in Prepaid Expense and Other Assets</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_BA6E1196F33B9958678F9B3DD083609C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_BA6E1196F33B9958678F9B3DD083609C" xlink:to="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_BA6E1196F33B9958678F9B3DD083609C" xlink:type="arc" />
    <link:label id="lab_us-gaap_IncreaseDecreaseInOperatingLiabilities_EBC73D572B4DD954BA0A9B3DD0834E92_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOperatingLiabilities_EBC73D572B4DD954BA0A9B3DD0834E92" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Increase (decrease) in accounts payable, accrued expenses and other liabilities</link:label>
    <link:label id="lab_us-gaap_IncreaseDecreaseInOperatingLiabilities_EBC73D572B4DD954BA0A9B3DD0834E92_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOperatingLiabilities_EBC73D572B4DD954BA0A9B3DD0834E92" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Increase (Decrease) in Operating Liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingLiabilities_EBC73D572B4DD954BA0A9B3DD0834E92" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingLiabilities_EBC73D572B4DD954BA0A9B3DD0834E92" xlink:to="lab_us-gaap_IncreaseDecreaseInOperatingLiabilities_EBC73D572B4DD954BA0A9B3DD0834E92" xlink:type="arc" />
    <link:label id="lab_ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability_449F92DE2694F1AE34A39B3DD083851A_terseLabel_en-US" xlink:label="lab_ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability_449F92DE2694F1AE34A39B3DD083851A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">(Decrease) increase in rents received in advance and security deposits</link:label>
    <link:label id="lab_ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability_449F92DE2694F1AE34A39B3DD083851A_label_en-US" xlink:label="lab_ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability_449F92DE2694F1AE34A39B3DD083851A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Increase (Decrease) in Advance Rent and Security Deposit Liability</link:label>
    <link:label id="lab_ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability_449F92DE2694F1AE34A39B3DD083851A_documentation_en-US" xlink:label="lab_ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability_449F92DE2694F1AE34A39B3DD083851A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The net change in amount that has been received by the entity that represents collections of cash or other assets related to real estate operations revenue for which revenue has not yet been recognized and security deposits.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability" xlink:label="loc_ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability_449F92DE2694F1AE34A39B3DD083851A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability_449F92DE2694F1AE34A39B3DD083851A" xlink:to="lab_ofc_IncreaseDecreaseInAdvanceRentAndSecurityDepositLiability_449F92DE2694F1AE34A39B3DD083851A" xlink:type="arc" />
    <link:label id="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_109516459B6C2342F9909B3DD0833DFD_terseLabel_en-US" xlink:label="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_109516459B6C2342F9909B3DD0833DFD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Supplemental schedule of non-cash investing and financing activities:</link:label>
    <link:label id="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_109516459B6C2342F9909B3DD0833DFD_label_en-US" xlink:label="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_109516459B6C2342F9909B3DD0833DFD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_109516459B6C2342F9909B3DD0833DFD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_109516459B6C2342F9909B3DD0833DFD" xlink:to="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_109516459B6C2342F9909B3DD0833DFD" xlink:type="arc" />
    <link:label id="lab_ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts_F934B0855EB5775F9F8C9B3DD089A9E8_terseLabel_en-US" xlink:label="lab_ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts_F934B0855EB5775F9F8C9B3DD089A9E8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">(Decrease) increase in accrued capital improvements, leasing and other investing activity costs</link:label>
    <link:label id="lab_ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts_F934B0855EB5775F9F8C9B3DD089A9E8_label_en-US" xlink:label="lab_ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts_F934B0855EB5775F9F8C9B3DD089A9E8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Increase (Decrease) in Accrued Capital Improvements Leasing and Other Investing Activity Costs</link:label>
    <link:label id="lab_ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts_F934B0855EB5775F9F8C9B3DD089A9E8_documentation_en-US" xlink:label="lab_ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts_F934B0855EB5775F9F8C9B3DD089A9E8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The net change during the reporting period in future cash outflow to pay for purchases of fixed assets, construction in progress expenditures, deferred leasing costs and other investing activity costs that have occurred.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts" xlink:label="loc_ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts_F934B0855EB5775F9F8C9B3DD089A9E8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts_F934B0855EB5775F9F8C9B3DD089A9E8" xlink:to="lab_ofc_IncreaseDecreaseInAccruedCapitalImprovementsLeasingAndOtherInvestingActivityCosts_F934B0855EB5775F9F8C9B3DD089A9E8" xlink:type="arc" />
    <link:label id="lab_us-gaap_CapitalLeaseObligationsIncurred_B5879122DDAA0BA0D3799B3DD0898A53_terseLabel_en-US" xlink:label="lab_us-gaap_CapitalLeaseObligationsIncurred_B5879122DDAA0BA0D3799B3DD0898A53" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Increase in property in connection with capital lease obligation</link:label>
    <link:label id="lab_us-gaap_CapitalLeaseObligationsIncurred_B5879122DDAA0BA0D3799B3DD0898A53_label_en-US" xlink:label="lab_us-gaap_CapitalLeaseObligationsIncurred_B5879122DDAA0BA0D3799B3DD0898A53" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Capital Lease Obligations Incurred</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CapitalLeaseObligationsIncurred" xlink:label="loc_us-gaap_CapitalLeaseObligationsIncurred_B5879122DDAA0BA0D3799B3DD0898A53" xlink:type="locator" />
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    <link:label id="lab_ofc_DecreaseinRedeemableNoncontrollingInterestsinConnectionwithDistributionPayabletoRedeemableNoncontrollingInterest_D09B4902D3AB9738FF5E9B3DD08977A2_terseLabel_en-US" xlink:label="lab_ofc_DecreaseinRedeemableNoncontrollingInterestsinConnectionwithDistributionPayabletoRedeemableNoncontrollingInterest_D09B4902D3AB9738FF5E9B3DD08977A2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Decrease in redeemable noncontrolling interests and increase in other liabilities in connection with distribution payable to redeemable noncontrolling interests</link:label>
    <link:label id="lab_ofc_DecreaseinRedeemableNoncontrollingInterestsinConnectionwithDistributionPayabletoRedeemableNoncontrollingInterest_D09B4902D3AB9738FF5E9B3DD08977A2_label_en-US" xlink:label="lab_ofc_DecreaseinRedeemableNoncontrollingInterestsinConnectionwithDistributionPayabletoRedeemableNoncontrollingInterest_D09B4902D3AB9738FF5E9B3DD08977A2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Decrease in Redeemable Noncontrolling Interests in Connection with Distribution Payable to Redeemable Noncontrolling Interest</link:label>
    <link:label id="lab_ofc_DecreaseinRedeemableNoncontrollingInterestsinConnectionwithDistributionPayabletoRedeemableNoncontrollingInterest_D09B4902D3AB9738FF5E9B3DD08977A2_documentation_en-US" xlink:label="lab_ofc_DecreaseinRedeemableNoncontrollingInterestsinConnectionwithDistributionPayabletoRedeemableNoncontrollingInterest_D09B4902D3AB9738FF5E9B3DD08977A2" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Decrease in Redeemable Noncontrolling Interests in Connection with Distribution Payable to Redeemable Noncontrolling Interest</link:label>
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    <link:label id="lab_ofc_IncreaseinInvestmentinUnconsolidatedRealEstateJointVentureinConnectionWithPartialSaleofProperties_7122495F2588FAF89D4D9B3DD0896046_terseLabel_en-US" xlink:label="lab_ofc_IncreaseinInvestmentinUnconsolidatedRealEstateJointVentureinConnectionWithPartialSaleofProperties_7122495F2588FAF89D4D9B3DD0896046" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Increase in investment in unconsolidated real estate joint venture</link:label>
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    <link:label id="lab_ofc_NoncashorPartNoncashDispositionOtherNetDecreasesinAssetsandLiabilitiesinConnectionWithPartialSaleofProperties_1CECA8FA8B5AD976A27B9B3DD089515D_terseLabel_en-US" xlink:label="lab_ofc_NoncashorPartNoncashDispositionOtherNetDecreasesinAssetsandLiabilitiesinConnectionWithPartialSaleofProperties_1CECA8FA8B5AD976A27B9B3DD089515D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other net decreases in assets and liabilities</link:label>
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    <link:loc xlink:href="ofc-20171231.xsd#ofc_NoncashorPartNoncashDispositionOtherNetDecreasesinAssetsandLiabilitiesinConnectionWithPartialSaleofProperties" xlink:label="loc_ofc_NoncashorPartNoncashDispositionOtherNetDecreasesinAssetsandLiabilitiesinConnectionWithPartialSaleofProperties_1CECA8FA8B5AD976A27B9B3DD089515D" xlink:type="locator" />
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    <link:label id="lab_us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1_B463AD4A71A2D753784B9B3DD0897AFF_terseLabel_en-US" xlink:label="lab_us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1_B463AD4A71A2D753784B9B3DD0897AFF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Debt assumed on acquisition of operating property</link:label>
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    <link:label id="lab_us-gaap_NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1_B9CCD54E2BA328552E2F9B3DD0897AC2_terseLabel_en-US" xlink:label="lab_us-gaap_NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1_B9CCD54E2BA328552E2F9B3DD0897AC2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other liabilities assumed on acquisition of operating properties</link:label>
    <link:label id="lab_us-gaap_NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1_B9CCD54E2BA328552E2F9B3DD0897AC2_label_en-US" xlink:label="lab_us-gaap_NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1_B9CCD54E2BA328552E2F9B3DD0897AC2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Noncash or Part Noncash Acquisition, Value of Liabilities Assumed</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1_B9CCD54E2BA328552E2F9B3DD0897AC2" xlink:type="locator" />
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    <link:label id="lab_ofc_DecreaseinPropertyinConnectionwithSurrenderPropertyDebtSettlement_BF9DD67826A7414429319B3DD08AC986_negatedTerseLabel_en-US" xlink:label="lab_ofc_DecreaseinPropertyinConnectionwithSurrenderPropertyDebtSettlement_BF9DD67826A7414429319B3DD08AC986" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Decrease in property in connection with surrender of property in settlement of debt</link:label>
    <link:label id="lab_ofc_DecreaseinPropertyinConnectionwithSurrenderPropertyDebtSettlement_BF9DD67826A7414429319B3DD08AC986_label_en-US" xlink:label="lab_ofc_DecreaseinPropertyinConnectionwithSurrenderPropertyDebtSettlement_BF9DD67826A7414429319B3DD08AC986" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Decrease in Property in Connection with Surrender Property, Debt Settlement</link:label>
    <link:label id="lab_ofc_DecreaseinPropertyinConnectionwithSurrenderPropertyDebtSettlement_BF9DD67826A7414429319B3DD08AC986_documentation_en-US" xlink:label="lab_ofc_DecreaseinPropertyinConnectionwithSurrenderPropertyDebtSettlement_BF9DD67826A7414429319B3DD08AC986" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Decrease in Property in Connection with Surrender Property, Debt Settlement</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_DecreaseinPropertyinConnectionwithSurrenderPropertyDebtSettlement" xlink:label="loc_ofc_DecreaseinPropertyinConnectionwithSurrenderPropertyDebtSettlement_BF9DD67826A7414429319B3DD08AC986" xlink:type="locator" />
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    <link:label id="lab_ofc_DecreaseInDebtInConnectionWithSurrenderOfPropertyInSettlementOfDebt_5DAEDC2FEB66FDFFA8639B3DD08A488F_negatedTerseLabel_en-US" xlink:label="lab_ofc_DecreaseInDebtInConnectionWithSurrenderOfPropertyInSettlementOfDebt_5DAEDC2FEB66FDFFA8639B3DD08A488F" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Decrease in debt in connection with surrender of property in settlement of debt</link:label>
    <link:label id="lab_ofc_DecreaseInDebtInConnectionWithSurrenderOfPropertyInSettlementOfDebt_5DAEDC2FEB66FDFFA8639B3DD08A488F_label_en-US" xlink:label="lab_ofc_DecreaseInDebtInConnectionWithSurrenderOfPropertyInSettlementOfDebt_5DAEDC2FEB66FDFFA8639B3DD08A488F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Decrease In Debt In Connection With Surrender Of Property In Settlement Of Debt</link:label>
    <link:label id="lab_ofc_DecreaseInDebtInConnectionWithSurrenderOfPropertyInSettlementOfDebt_5DAEDC2FEB66FDFFA8639B3DD08A488F_documentation_en-US" xlink:label="lab_ofc_DecreaseInDebtInConnectionWithSurrenderOfPropertyInSettlementOfDebt_5DAEDC2FEB66FDFFA8639B3DD08A488F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Decrease In Debt In Connection With Surrender Of Property In Settlement Of Debt</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_DecreaseInDebtInConnectionWithSurrenderOfPropertyInSettlementOfDebt" xlink:label="loc_ofc_DecreaseInDebtInConnectionWithSurrenderOfPropertyInSettlementOfDebt_5DAEDC2FEB66FDFFA8639B3DD08A488F" xlink:type="locator" />
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    <link:label id="lab_ofc_ContributionofPropertyByNoncontrollingInterest_400DE5DAE9EA3E41DEF19B3DD08A7440_terseLabel_en-US" xlink:label="lab_ofc_ContributionofPropertyByNoncontrollingInterest_400DE5DAE9EA3E41DEF19B3DD08A7440" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Increase in property and redeemable noncontrolling interests in connection with property contribution by redeemable noncontrolling interests in a joint venture</link:label>
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_ADE16C3A00F870D0206170C1BE1800E8_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_ADE16C3A00F870D0206170C1BE1800E8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2018</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_ADE16C3A00F870D0206170C1BE1800E8_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_ADE16C3A00F870D0206170C1BE1800E8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments Due, Next Twelve Months</link:label>
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_4CB58E388463807081BD70BF8D11566F_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_4CB58E388463807081BD70BF8D11566F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2019</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_4CB58E388463807081BD70BF8D11566F" xlink:type="locator" />
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_DE91EFD85589EE93EA4070BF8D22F476_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_DE91EFD85589EE93EA4070BF8D22F476" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2020</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_DE91EFD85589EE93EA4070BF8D22F476_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_DE91EFD85589EE93EA4070BF8D22F476" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments, Due in Three Years</link:label>
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_53B72A05F5E008EC9EE170BF8D2C70DE_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_53B72A05F5E008EC9EE170BF8D2C70DE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2021</link:label>
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_6F82D2AD87D180660FBC70BF8D36FFEE_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_6F82D2AD87D180660FBC70BF8D36FFEE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2022</link:label>
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    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_D53A8D00C1FB7F1C411C758C1155C09E_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_D53A8D00C1FB7F1C411C758C1155C09E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Shares</link:label>
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    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_8A947A1B3F68A4D2D085758C11552136_periodStartLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_8A947A1B3F68A4D2D085758C11552136" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xml:lang="en-US">Unvested at the beginning of the period (in shares)</link:label>
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    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_298CC7807B9B47D6E034758C115514A4_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_298CC7807B9B47D6E034758C115514A4" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Vested (in shares)</link:label>
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    <link:label id="lab_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber_C935E2146ADCEBBC6ED4758C11555DAF_terseLabel_en-US" xlink:label="lab_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber_C935E2146ADCEBBC6ED4758C11555DAF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Restricted shares expected to vest (in shares)</link:label>
    <link:label id="lab_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber_C935E2146ADCEBBC6ED4758C11555DAF_label_en-US" xlink:label="lab_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber_C935E2146ADCEBBC6ED4758C11555DAF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award Equity Instruments Other than Options Expected to Vest Outstanding Number</link:label>
    <link:label id="lab_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber_C935E2146ADCEBBC6ED4758C11555DAF_documentation_en-US" xlink:label="lab_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber_C935E2146ADCEBBC6ED4758C11555DAF" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the number of expected to vest equity-based payment instruments, excluding stock (or unit) options, as of the balance sheet date.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber" xlink:label="loc_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber_C935E2146ADCEBBC6ED4758C11555DAF" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber_C935E2146ADCEBBC6ED4758C11555DAF" xlink:to="lab_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingNumber_C935E2146ADCEBBC6ED4758C11555DAF" xlink:type="arc" />
    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_70B0354F0A0CC25D8249758C1155C9F1_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_70B0354F0A0CC25D8249758C1155C9F1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Weighted Average Grant Date Fair Value</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_70B0354F0A0CC25D8249758C1155C9F1" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_70B0354F0A0CC25D8249758C1155C9F1" xlink:type="arc" />
    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_7DB1D9F4DA965BAAD3E2758C11553D35_periodStartLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_7DB1D9F4DA965BAAD3E2758C11553D35" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xml:lang="en-US">Unvested at the beginning of the period (in dollars per share)</link:label>
    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_7DB1D9F4DA965BAAD3E2758C11553D35_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_7DB1D9F4DA965BAAD3E2758C11553D35" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value</link:label>
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    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_2F0F36BC7E400840865B758C1155CAF7_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_2F0F36BC7E400840865B758C1155CAF7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Forfeited (in dollars per share)</link:label>
    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_2F0F36BC7E400840865B758C1155CAF7_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_2F0F36BC7E400840865B758C1155CAF7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value</link:label>
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    <link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_100AEAD8A9525542C2DB758C11550500_verboseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_100AEAD8A9525542C2DB758C11550500" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Vested (in dollars per share)</link:label>
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    <link:label id="lab_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingWeightedAverageGrantDateFairValue_2BDE2D5C2953835096CA758C115593AA_terseLabel_en-US" xlink:label="lab_ofc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestOutstandingWeightedAverageGrantDateFairValue_2BDE2D5C2953835096CA758C115593AA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Restricted shares expected to vest (in dollars per share)</link:label>
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    <link:label id="lab_us-gaap_AssetImpairmentCharges_5E098905FA69825EEFC69F845DCF32E4_negatedLabel_en-US" xlink:label="lab_us-gaap_AssetImpairmentCharges_5E098905FA69825EEFC69F845DCF32E4" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Impairment losses</link:label>
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    <link:label id="lab_us-gaap_InterestAndDebtExpense_A40DF937FE980FDE39399F845DCFA79D_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_InterestAndDebtExpense_A40DF937FE980FDE39399F845DCFA79D" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Interest expense</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_InterestAndDebtExpense" xlink:label="loc_us-gaap_InterestAndDebtExpense_A40DF937FE980FDE39399F845DCFA79D" xlink:type="locator" />
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    <link:label id="lab_ofc_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLossExcludingDepreciationAndAmortization_CA7825BE2D561C88E2ED9F845DCF4C57_terseLabel_en-US" xlink:label="lab_ofc_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLossExcludingDepreciationAndAmortization_CA7825BE2D561C88E2ED9F845DCF4C57" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">NOI from discontinued operations</link:label>
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    <link:loc xlink:href="ofc-20171231.xsd#ofc_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLossExcludingDepreciationAndAmortization" xlink:label="loc_ofc_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLossExcludingDepreciationAndAmortization_CA7825BE2D561C88E2ED9F845DCF4C57" xlink:type="locator" />
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    <link:label id="lab_ofc_UnconsolidatedJointVentureNetOperatingIncomeAllocabletoParent_28D040C9CD6ADF5A9DAF9F845DCFE533_terseLabel_en-US" xlink:label="lab_ofc_UnconsolidatedJointVentureNetOperatingIncomeAllocabletoParent_28D040C9CD6ADF5A9DAF9F845DCFE533" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">UJV NOI allocable to COPT</link:label>
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    <link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_5295D298C19494387EC69F845DCF2E54_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_5295D298C19494387EC69F845DCF2E54" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">COPT consolidated income (loss) from continuing operations</link:label>
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    <link:label id="lab_us-gaap_AssetsAbstract_E5E19220DC89C5F9586F955417C3F62B_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsAbstract_E5E19220DC89C5F9586F955417C3F62B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Assets</link:label>
    <link:label id="lab_us-gaap_AssetsAbstract_E5E19220DC89C5F9586F955417C3F62B_label_en-US" xlink:label="lab_us-gaap_AssetsAbstract_E5E19220DC89C5F9586F955417C3F62B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Assets [Abstract]</link:label>
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    <link:label id="lab_us-gaap_RealEstateInvestmentPropertyNetAbstract_CA3070DD8353986EF5A8955417C3E821_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateInvestmentPropertyNetAbstract_CA3070DD8353986EF5A8955417C3E821" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Properties, net:</link:label>
    <link:label id="lab_us-gaap_RealEstateInvestmentPropertyNetAbstract_CA3070DD8353986EF5A8955417C3E821_label_en-US" xlink:label="lab_us-gaap_RealEstateInvestmentPropertyNetAbstract_CA3070DD8353986EF5A8955417C3E821" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Investment Property, Net [Abstract]</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_796521170E45B92FA059955417C45163" xlink:type="locator" />
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    <link:label id="lab_ofc_RestrictedCashAndMarketableSecurities_F3C0750E86AFEF048E72955417C4C4EB_terseLabel_en-US" xlink:label="lab_ofc_RestrictedCashAndMarketableSecurities_F3C0750E86AFEF048E72955417C4C4EB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Restricted cash and marketable securities</link:label>
    <link:label id="lab_ofc_RestrictedCashAndMarketableSecurities_F3C0750E86AFEF048E72955417C4C4EB_label_en-US" xlink:label="lab_ofc_RestrictedCashAndMarketableSecurities_F3C0750E86AFEF048E72955417C4C4EB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Restricted Cash and Marketable Securities</link:label>
    <link:label id="lab_ofc_RestrictedCashAndMarketableSecurities_F3C0750E86AFEF048E72955417C4C4EB_documentation_en-US" xlink:label="lab_ofc_RestrictedCashAndMarketableSecurities_F3C0750E86AFEF048E72955417C4C4EB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. Also includes certain debt and equity financial instruments, including (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale, but excludes the carrying amount of equity interests in nonpublic companies accounted for using the cost or equity methods of accounting.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RestrictedCashAndMarketableSecurities" xlink:label="loc_ofc_RestrictedCashAndMarketableSecurities_F3C0750E86AFEF048E72955417C4C4EB" xlink:type="locator" />
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    <link:label id="lab_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_E987500C4C352AAAF24A955417C96A92_terseLabel_en-US" xlink:label="lab_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_E987500C4C352AAAF24A955417C96A92" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Investment in unconsolidated real estate joint venture</link:label>
    <link:label id="lab_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_E987500C4C352AAAF24A955417C96A92_label_en-US" xlink:label="lab_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_E987500C4C352AAAF24A955417C96A92" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_E987500C4C352AAAF24A955417C96A92" xlink:type="locator" />
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    <link:label id="lab_us-gaap_AccountsReceivableNet_E4C6E0C26A4531F2A1BC955417CA02F9_verboseLabel_en-US" xlink:label="lab_us-gaap_AccountsReceivableNet_E4C6E0C26A4531F2A1BC955417CA02F9" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Accounts receivable (net of allowance for doubtful accounts of $607 and $603, respectively)</link:label>
    <link:label id="lab_us-gaap_AccountsReceivableNet_E4C6E0C26A4531F2A1BC955417CA02F9_label_en-US" xlink:label="lab_us-gaap_AccountsReceivableNet_E4C6E0C26A4531F2A1BC955417CA02F9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Accounts Receivable, Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccountsReceivableNet" xlink:label="loc_us-gaap_AccountsReceivableNet_E4C6E0C26A4531F2A1BC955417CA02F9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableNet_E4C6E0C26A4531F2A1BC955417CA02F9" xlink:to="lab_us-gaap_AccountsReceivableNet_E4C6E0C26A4531F2A1BC955417CA02F9" xlink:type="arc" />
    <link:label id="lab_us-gaap_DeferredRentReceivablesNet_EFEF753884EBBE66C190955417CA283B_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredRentReceivablesNet_EFEF753884EBBE66C190955417CA283B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Deferred rent receivable (net of allowance of $364 and $373, respectively)</link:label>
    <link:label id="lab_us-gaap_DeferredRentReceivablesNet_EFEF753884EBBE66C190955417CA283B_label_en-US" xlink:label="lab_us-gaap_DeferredRentReceivablesNet_EFEF753884EBBE66C190955417CA283B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Deferred Rent Receivables, Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DeferredRentReceivablesNet" xlink:label="loc_us-gaap_DeferredRentReceivablesNet_EFEF753884EBBE66C190955417CA283B" xlink:type="locator" />
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    <link:label id="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_857B87CDCA1695A079AB955417CACEAB_terseLabel_en-US" xlink:label="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_857B87CDCA1695A079AB955417CACEAB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Intangible assets on real estate acquisitions, net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_857B87CDCA1695A079AB955417CACEAB" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DeferredCostsLeasingNet_96BF8FF369943DDF4E41955417CAFA81_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCostsLeasingNet_96BF8FF369943DDF4E41955417CAFA81" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Deferred leasing costs (net of accumulated amortization of $29,560 and $65,988, respectively)</link:label>
    <link:label id="lab_us-gaap_DeferredCostsLeasingNet_96BF8FF369943DDF4E41955417CAFA81_label_en-US" xlink:label="lab_us-gaap_DeferredCostsLeasingNet_96BF8FF369943DDF4E41955417CAFA81" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Deferred Costs, Leasing, Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DeferredCostsLeasingNet" xlink:label="loc_us-gaap_DeferredCostsLeasingNet_96BF8FF369943DDF4E41955417CAFA81" xlink:type="locator" />
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    <link:label id="lab_us-gaap_NotesReceivableNet_C4739BF52C7F4CF350F1955417CA8CB0_terseLabel_en-US" xlink:label="lab_us-gaap_NotesReceivableNet_C4739BF52C7F4CF350F1955417CA8CB0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Investing receivables</link:label>
    <link:label id="lab_us-gaap_NotesReceivableNet_C4739BF52C7F4CF350F1955417CA8CB0_label_en-US" xlink:label="lab_us-gaap_NotesReceivableNet_C4739BF52C7F4CF350F1955417CA8CB0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Financing Receivable, Net</link:label>
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    <link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssets_06C909D64BA0A9F2043D955417CABBB6_terseLabel_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssets_06C909D64BA0A9F2043D955417CABBB6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Prepaid expenses and other assets, net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssets" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssets_06C909D64BA0A9F2043D955417CABBB6" xlink:type="locator" />
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    <link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_A8D88C9E08E3EE5F9DAC955417CA20B0_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_A8D88C9E08E3EE5F9DAC955417CA20B0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Liabilities and equity</link:label>
    <link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_A8D88C9E08E3EE5F9DAC955417CA20B0_label_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_A8D88C9E08E3EE5F9DAC955417CA20B0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Liabilities and Equity [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_A8D88C9E08E3EE5F9DAC955417CA20B0" xlink:type="locator" />
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    <link:label id="lab_us-gaap_LiabilitiesAbstract_A8482E1170B7C11D3D35955417CAB751_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesAbstract_A8482E1170B7C11D3D35955417CAB751" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Liabilities:</link:label>
    <link:label id="lab_us-gaap_LiabilitiesAbstract_A8482E1170B7C11D3D35955417CAB751_label_en-US" xlink:label="lab_us-gaap_LiabilitiesAbstract_A8482E1170B7C11D3D35955417CAB751" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Liabilities [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesAbstract" xlink:label="loc_us-gaap_LiabilitiesAbstract_A8482E1170B7C11D3D35955417CAB751" xlink:type="locator" />
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    <link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_A02C2121327B0C33999A955417CA8B31_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_A02C2121327B0C33999A955417CA8B31" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Accounts payable and accrued expenses</link:label>
    <link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_A02C2121327B0C33999A955417CA8B31_label_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_A02C2121327B0C33999A955417CA8B31" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Accounts Payable and Accrued Liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_A02C2121327B0C33999A955417CA8B31" xlink:type="locator" />
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    <link:label id="lab_ofc_AdvanceRentAndSecurityDepositLiability_27DA80BFE65A46C09954955417CA8787_terseLabel_en-US" xlink:label="lab_ofc_AdvanceRentAndSecurityDepositLiability_27DA80BFE65A46C09954955417CA8787" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Rents received in advance and security deposits</link:label>
    <link:label id="lab_ofc_AdvanceRentAndSecurityDepositLiability_27DA80BFE65A46C09954955417CA8787_label_en-US" xlink:label="lab_ofc_AdvanceRentAndSecurityDepositLiability_27DA80BFE65A46C09954955417CA8787" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Advance Rent and Security Deposit Liability</link:label>
    <link:label id="lab_ofc_AdvanceRentAndSecurityDepositLiability_27DA80BFE65A46C09954955417CA8787_documentation_en-US" xlink:label="lab_ofc_AdvanceRentAndSecurityDepositLiability_27DA80BFE65A46C09954955417CA8787" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Amount at the balance sheet date that has been received by the entity that represents collections of cash or other assets related to real estate operations revenue for which revenue has not yet been recognized and money paid in advance to protect the provider of a product or service, such as a lessor, against damage or nonpayment by the buyer or tenant (lessee) during the term of the agreement. Such damages may include physical damage to the property, theft of property, and other contractual breaches. Security deposits held may be interest or noninterest bearing.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_AdvanceRentAndSecurityDepositLiability" xlink:label="loc_ofc_AdvanceRentAndSecurityDepositLiability_27DA80BFE65A46C09954955417CA8787" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DividendsPayableCurrentAndNoncurrent_E30D052F9EE574492A86955417CADBEA_terseLabel_en-US" xlink:label="lab_us-gaap_DividendsPayableCurrentAndNoncurrent_E30D052F9EE574492A86955417CADBEA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Dividends and distributions payable</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DividendsPayableCurrentAndNoncurrent" xlink:label="loc_us-gaap_DividendsPayableCurrentAndNoncurrent_E30D052F9EE574492A86955417CADBEA" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DeferredRevenueLeasesNet_85C8F074A3919FE00847955417CB5189_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredRevenueLeasesNet_85C8F074A3919FE00847955417CB5189" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Deferred revenue associated with operating leases</link:label>
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    <link:label id="lab_us-gaap_Liabilities_41768B9834AD03325B1E955417CB9F5C_label_en-US" xlink:label="lab_us-gaap_Liabilities_41768B9834AD03325B1E955417CB9F5C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_41768B9834AD03325B1E955417CB9F5C" xlink:type="locator" />
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    <link:label id="lab_us-gaap_CommitmentsAndContingencies_616B6BEEB9EF881914BA955417CB0DFB_label_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingencies_616B6BEEB9EF881914BA955417CB0DFB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Commitments and Contingencies</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaap_CommitmentsAndContingencies_616B6BEEB9EF881914BA955417CB0DFB" xlink:type="locator" />
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    <link:label id="lab_us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount_0736A12C21726DC4E918955417CB3AAF_label_en-US" xlink:label="lab_us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount_0736A12C21726DC4E918955417CB3AAF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Redeemable Noncontrolling Interest, Equity, Carrying Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" xlink:label="loc_us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount_0736A12C21726DC4E918955417CB3AAF" xlink:type="locator" />
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    <link:label id="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_0AD44A2324339C0CF11E955417CB932B_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_0AD44A2324339C0CF11E955417CB932B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_0AD44A2324339C0CF11E955417CB932B" xlink:type="locator" />
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    <link:label id="lab_us-gaap_StockholdersEquityAbstract_542C2A2ABEDD8C305814955417CB0430_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityAbstract_542C2A2ABEDD8C305814955417CB0430" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Corporate Office Properties Trust&#8217;s shareholders&#8217; equity:</link:label>
    <link:label id="lab_us-gaap_StockholdersEquityAbstract_542C2A2ABEDD8C305814955417CB0430_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityAbstract_542C2A2ABEDD8C305814955417CB0430" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Stockholders' Equity Attributable to Parent [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaap_StockholdersEquityAbstract_542C2A2ABEDD8C305814955417CB0430" xlink:type="locator" />
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    <link:label id="lab_us-gaap_PreferredStockLiquidationPreferenceValue_EAC604970ACDFFAABE7D955417CB96AD_label_en-US" xlink:label="lab_us-gaap_PreferredStockLiquidationPreferenceValue_EAC604970ACDFFAABE7D955417CB96AD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Preferred Stock, Liquidation Preference, Value</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PreferredStockLiquidationPreferenceValue" xlink:label="loc_us-gaap_PreferredStockLiquidationPreferenceValue_EAC604970ACDFFAABE7D955417CB96AD" xlink:type="locator" />
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    <link:label id="lab_us-gaap_PreferredUnitsPreferredPartnersCapitalAccounts_0CCCB4A5C88384D6D086955417CB14CE_label_en-US" xlink:label="lab_us-gaap_PreferredUnitsPreferredPartnersCapitalAccounts_0CCCB4A5C88384D6D086955417CB14CE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Preferred Units, Preferred Partners' Capital Accounts</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PreferredUnitsPreferredPartnersCapitalAccounts" xlink:label="loc_us-gaap_PreferredUnitsPreferredPartnersCapitalAccounts_0CCCB4A5C88384D6D086955417CB14CE" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DeferredCompensationPlanAssets_C20A17F967D7DAE1703247DC77FEDDFE_verboseLabel_en-US" xlink:label="lab_us-gaap_DeferredCompensationPlanAssets_C20A17F967D7DAE1703247DC77FEDDFE" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Balance of the plan which was fully funded</link:label>
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract_6C8FBFF4CD5CF978422570048CBACF6B_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract_6C8FBFF4CD5CF978422570048CBACF6B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Gross minimum future rentals</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract_6C8FBFF4CD5CF978422570048CBACF6B_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract_6C8FBFF4CD5CF978422570048CBACF6B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments Receivable [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract_6C8FBFF4CD5CF978422570048CBACF6B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract_6C8FBFF4CD5CF978422570048CBACF6B" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract_6C8FBFF4CD5CF978422570048CBACF6B" xlink:type="arc" />
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_D8A64EF59AAB35B8CE4670048CBBE973_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_D8A64EF59AAB35B8CE4670048CBBE973" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2018</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_D8A64EF59AAB35B8CE4670048CBBE973_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_D8A64EF59AAB35B8CE4670048CBBE973" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments Receivable, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_D8A64EF59AAB35B8CE4670048CBBE973" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_D8A64EF59AAB35B8CE4670048CBBE973" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent_D8A64EF59AAB35B8CE4670048CBBE973" xlink:type="arc" />
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_9004FB02BA8C521B18A770048CBB2FFA_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_9004FB02BA8C521B18A770048CBB2FFA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2019</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_9004FB02BA8C521B18A770048CBB2FFA_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_9004FB02BA8C521B18A770048CBB2FFA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments Receivable, in Two Years</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_9004FB02BA8C521B18A770048CBB2FFA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_9004FB02BA8C521B18A770048CBB2FFA" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears_9004FB02BA8C521B18A770048CBB2FFA" xlink:type="arc" />
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_12720D402CCA1B95A91770048CBBB1CD_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_12720D402CCA1B95A91770048CBBB1CD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2020</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_12720D402CCA1B95A91770048CBBB1CD_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_12720D402CCA1B95A91770048CBBB1CD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments Receivable, in Three Years</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_12720D402CCA1B95A91770048CBBB1CD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_12720D402CCA1B95A91770048CBBB1CD" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears_12720D402CCA1B95A91770048CBBB1CD" xlink:type="arc" />
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_77120FD53B263B825D9070048CBBE873_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_77120FD53B263B825D9070048CBBE873" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2021</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_77120FD53B263B825D9070048CBBE873_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_77120FD53B263B825D9070048CBBE873" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments Receivable, in Four Years</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_77120FD53B263B825D9070048CBBE873" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_77120FD53B263B825D9070048CBBE873" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears_77120FD53B263B825D9070048CBBE873" xlink:type="arc" />
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears_399E235FFD4FA405B34170048CBB9A45_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears_399E235FFD4FA405B34170048CBB9A45" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2022</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears_399E235FFD4FA405B34170048CBB9A45_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears_399E235FFD4FA405B34170048CBB9A45" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments Receivable, in Five Years</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears_399E235FFD4FA405B34170048CBB9A45" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears_399E235FFD4FA405B34170048CBB9A45" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears_399E235FFD4FA405B34170048CBB9A45" xlink:type="arc" />
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter_25B3D320586F41768BA170048CBB1DDB_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter_25B3D320586F41768BA170048CBB1DDB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Thereafter</link:label>
    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter_25B3D320586F41768BA170048CBB1DDB_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter_25B3D320586F41768BA170048CBB1DDB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Leases, Future Minimum Payments Receivable, Thereafter</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter_25B3D320586F41768BA170048CBB1DDB" xlink:type="locator" />
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    <link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable_48C0C848D6AEB3655AC870048CBBD012_totalLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable_48C0C848D6AEB3655AC870048CBBD012" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Total</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable_48C0C848D6AEB3655AC870048CBBD012" xlink:type="locator" />
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    <link:label id="lab_us-gaap_Revenues_58E7643A5E502814A5596BEB17713A58_terseLabel_en-US" xlink:label="lab_us-gaap_Revenues_58E7643A5E502814A5596BEB17713A58" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Revenues</link:label>
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    <link:label id="lab_ofc_Number1100RedstoneGatewayMember_FBC5E0188A4D76782DF69B3DC8540577_label_en-US" xlink:label="lab_ofc_Number1100RedstoneGatewayMember_FBC5E0188A4D76782DF69B3DC8540577" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1100 Redstone Gateway [Member]</link:label>
    <link:label id="lab_ofc_Number1100RedstoneGatewayMember_FBC5E0188A4D76782DF69B3DC8540577_documentation_en-US" xlink:label="lab_ofc_Number1100RedstoneGatewayMember_FBC5E0188A4D76782DF69B3DC8540577" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 1100 Redstone Gateway [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1100RedstoneGatewayMember" xlink:label="loc_ofc_Number1100RedstoneGatewayMember_FBC5E0188A4D76782DF69B3DC8540577" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1100RedstoneGatewayMember_FBC5E0188A4D76782DF69B3DC8540577" xlink:to="lab_ofc_Number1100RedstoneGatewayMember_FBC5E0188A4D76782DF69B3DC8540577" xlink:type="arc" />
    <link:label id="lab_ofc_Number114NationalBusinessParkwayMember_7CDB8139FE58CE0F43DF9B3DC8546CD6_terseLabel_en-US" xlink:label="lab_ofc_Number114NationalBusinessParkwayMember_7CDB8139FE58CE0F43DF9B3DC8546CD6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">114 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number114NationalBusinessParkwayMember_7CDB8139FE58CE0F43DF9B3DC8546CD6_label_en-US" xlink:label="lab_ofc_Number114NationalBusinessParkwayMember_7CDB8139FE58CE0F43DF9B3DC8546CD6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 114 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number114NationalBusinessParkwayMember_7CDB8139FE58CE0F43DF9B3DC8546CD6_documentation_en-US" xlink:label="lab_ofc_Number114NationalBusinessParkwayMember_7CDB8139FE58CE0F43DF9B3DC8546CD6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 114 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number114NationalBusinessParkwayMember" xlink:label="loc_ofc_Number114NationalBusinessParkwayMember_7CDB8139FE58CE0F43DF9B3DC8546CD6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number114NationalBusinessParkwayMember_7CDB8139FE58CE0F43DF9B3DC8546CD6" xlink:to="lab_ofc_Number114NationalBusinessParkwayMember_7CDB8139FE58CE0F43DF9B3DC8546CD6" xlink:type="arc" />
    <link:label id="lab_ofc_Number1200RedstoneGatewayMember_7ED41273F78F45B733AA9B3DC854FE81_terseLabel_en-US" xlink:label="lab_ofc_Number1200RedstoneGatewayMember_7ED41273F78F45B733AA9B3DC854FE81" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1200 Redstone Gateway [Member]</link:label>
    <link:label id="lab_ofc_Number1200RedstoneGatewayMember_7ED41273F78F45B733AA9B3DC854FE81_label_en-US" xlink:label="lab_ofc_Number1200RedstoneGatewayMember_7ED41273F78F45B733AA9B3DC854FE81" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1200 Redstone Gateway [Member]</link:label>
    <link:label id="lab_ofc_Number1200RedstoneGatewayMember_7ED41273F78F45B733AA9B3DC854FE81_documentation_en-US" xlink:label="lab_ofc_Number1200RedstoneGatewayMember_7ED41273F78F45B733AA9B3DC854FE81" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 1200 Redstone Gateway [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1200RedstoneGatewayMember" xlink:label="loc_ofc_Number1200RedstoneGatewayMember_7ED41273F78F45B733AA9B3DC854FE81" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1200RedstoneGatewayMember_7ED41273F78F45B733AA9B3DC854FE81" xlink:to="lab_ofc_Number1200RedstoneGatewayMember_7ED41273F78F45B733AA9B3DC854FE81" xlink:type="arc" />
    <link:label id="lab_ofc_Number1201MStreetMember_BFB987CC0EA6A56318D49B3DC85492BE_terseLabel_en-US" xlink:label="lab_ofc_Number1201MStreetMember_BFB987CC0EA6A56318D49B3DC85492BE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1201 M Street [Member]</link:label>
    <link:label id="lab_ofc_Number1201MStreetMember_BFB987CC0EA6A56318D49B3DC85492BE_label_en-US" xlink:label="lab_ofc_Number1201MStreetMember_BFB987CC0EA6A56318D49B3DC85492BE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1201 M Street [Member]</link:label>
    <link:label id="lab_ofc_Number1201MStreetMember_BFB987CC0EA6A56318D49B3DC85492BE_documentation_en-US" xlink:label="lab_ofc_Number1201MStreetMember_BFB987CC0EA6A56318D49B3DC85492BE" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1201 M Street, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1201MStreetMember" xlink:label="loc_ofc_Number1201MStreetMember_BFB987CC0EA6A56318D49B3DC85492BE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1201MStreetMember_BFB987CC0EA6A56318D49B3DC85492BE" xlink:to="lab_ofc_Number1201MStreetMember_BFB987CC0EA6A56318D49B3DC85492BE" xlink:type="arc" />
    <link:label id="lab_ofc_Number1201WintersonRoadMember_D3107665019A2C5E4A9B9B3DC8547507_terseLabel_en-US" xlink:label="lab_ofc_Number1201WintersonRoadMember_D3107665019A2C5E4A9B9B3DC8547507" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1201 Winterson Road [Member]</link:label>
    <link:label id="lab_ofc_Number1201WintersonRoadMember_D3107665019A2C5E4A9B9B3DC8547507_label_en-US" xlink:label="lab_ofc_Number1201WintersonRoadMember_D3107665019A2C5E4A9B9B3DC8547507" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1201 Winterson Road [Member]</link:label>
    <link:label id="lab_ofc_Number1201WintersonRoadMember_D3107665019A2C5E4A9B9B3DC8547507_documentation_en-US" xlink:label="lab_ofc_Number1201WintersonRoadMember_D3107665019A2C5E4A9B9B3DC8547507" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1201 Winterson Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1201WintersonRoadMember" xlink:label="loc_ofc_Number1201WintersonRoadMember_D3107665019A2C5E4A9B9B3DC8547507" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1201WintersonRoadMember_D3107665019A2C5E4A9B9B3DC8547507" xlink:to="lab_ofc_Number1201WintersonRoadMember_D3107665019A2C5E4A9B9B3DC8547507" xlink:type="arc" />
    <link:label id="lab_ofc_Number122012ThStreetSeMember_34C4ED6C62CB5B265BEE9B3DC854D377_terseLabel_en-US" xlink:label="lab_ofc_Number122012ThStreetSeMember_34C4ED6C62CB5B265BEE9B3DC854D377" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1220 12th Street, SE [Member]</link:label>
    <link:label id="lab_ofc_Number122012ThStreetSeMember_34C4ED6C62CB5B265BEE9B3DC854D377_label_en-US" xlink:label="lab_ofc_Number122012ThStreetSeMember_34C4ED6C62CB5B265BEE9B3DC854D377" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1220 12th Street Se [Member]</link:label>
    <link:label id="lab_ofc_Number122012ThStreetSeMember_34C4ED6C62CB5B265BEE9B3DC854D377_documentation_en-US" xlink:label="lab_ofc_Number122012ThStreetSeMember_34C4ED6C62CB5B265BEE9B3DC854D377" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1220 12th Street, SE, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number122012ThStreetSeMember" xlink:label="loc_ofc_Number122012ThStreetSeMember_34C4ED6C62CB5B265BEE9B3DC854D377" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number122012ThStreetSeMember_34C4ED6C62CB5B265BEE9B3DC854D377" xlink:to="lab_ofc_Number122012ThStreetSeMember_34C4ED6C62CB5B265BEE9B3DC854D377" xlink:type="arc" />
    <link:label id="lab_ofc_Number1243WintersonRoadMember_F0E5B1095E9B9A078AB59B3DC854013C_terseLabel_en-US" xlink:label="lab_ofc_Number1243WintersonRoadMember_F0E5B1095E9B9A078AB59B3DC854013C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1243 Winterson Road [Member]</link:label>
    <link:label id="lab_ofc_Number1243WintersonRoadMember_F0E5B1095E9B9A078AB59B3DC854013C_label_en-US" xlink:label="lab_ofc_Number1243WintersonRoadMember_F0E5B1095E9B9A078AB59B3DC854013C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1243 Winterson Road [Member]</link:label>
    <link:label id="lab_ofc_Number1243WintersonRoadMember_F0E5B1095E9B9A078AB59B3DC854013C_documentation_en-US" xlink:label="lab_ofc_Number1243WintersonRoadMember_F0E5B1095E9B9A078AB59B3DC854013C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1243 Winterson Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1243WintersonRoadMember" xlink:label="loc_ofc_Number1243WintersonRoadMember_F0E5B1095E9B9A078AB59B3DC854013C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1243WintersonRoadMember_F0E5B1095E9B9A078AB59B3DC854013C" xlink:to="lab_ofc_Number1243WintersonRoadMember_F0E5B1095E9B9A078AB59B3DC854013C" xlink:type="arc" />
    <link:label id="lab_ofc_Number131NationalBusinessParkwayMember_D9D5C229C22EB8931A1F9B3DC8546283_terseLabel_en-US" xlink:label="lab_ofc_Number131NationalBusinessParkwayMember_D9D5C229C22EB8931A1F9B3DC8546283" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">131 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number131NationalBusinessParkwayMember_D9D5C229C22EB8931A1F9B3DC8546283_label_en-US" xlink:label="lab_ofc_Number131NationalBusinessParkwayMember_D9D5C229C22EB8931A1F9B3DC8546283" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 131 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number131NationalBusinessParkwayMember_D9D5C229C22EB8931A1F9B3DC8546283_documentation_en-US" xlink:label="lab_ofc_Number131NationalBusinessParkwayMember_D9D5C229C22EB8931A1F9B3DC8546283" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 131 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number131NationalBusinessParkwayMember" xlink:label="loc_ofc_Number131NationalBusinessParkwayMember_D9D5C229C22EB8931A1F9B3DC8546283" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number131NationalBusinessParkwayMember_D9D5C229C22EB8931A1F9B3DC8546283" xlink:to="lab_ofc_Number131NationalBusinessParkwayMember_D9D5C229C22EB8931A1F9B3DC8546283" xlink:type="arc" />
    <link:label id="lab_ofc_Number132NationalBusinessParkwayMember_6BD4E65D8960263035299B3DC854616E_terseLabel_en-US" xlink:label="lab_ofc_Number132NationalBusinessParkwayMember_6BD4E65D8960263035299B3DC854616E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">132 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number132NationalBusinessParkwayMember_6BD4E65D8960263035299B3DC854616E_label_en-US" xlink:label="lab_ofc_Number132NationalBusinessParkwayMember_6BD4E65D8960263035299B3DC854616E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 132 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number132NationalBusinessParkwayMember_6BD4E65D8960263035299B3DC854616E_documentation_en-US" xlink:label="lab_ofc_Number132NationalBusinessParkwayMember_6BD4E65D8960263035299B3DC854616E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 132 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number132NationalBusinessParkwayMember" xlink:label="loc_ofc_Number132NationalBusinessParkwayMember_6BD4E65D8960263035299B3DC854616E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number132NationalBusinessParkwayMember_6BD4E65D8960263035299B3DC854616E" xlink:to="lab_ofc_Number132NationalBusinessParkwayMember_6BD4E65D8960263035299B3DC854616E" xlink:type="arc" />
    <link:label id="lab_ofc_Number133NationalBusinessParkwayMember_1B31D424E52CEAB77D859B3DC855B001_terseLabel_en-US" xlink:label="lab_ofc_Number133NationalBusinessParkwayMember_1B31D424E52CEAB77D859B3DC855B001" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">133 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number133NationalBusinessParkwayMember_1B31D424E52CEAB77D859B3DC855B001_label_en-US" xlink:label="lab_ofc_Number133NationalBusinessParkwayMember_1B31D424E52CEAB77D859B3DC855B001" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 133 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number133NationalBusinessParkwayMember_1B31D424E52CEAB77D859B3DC855B001_documentation_en-US" xlink:label="lab_ofc_Number133NationalBusinessParkwayMember_1B31D424E52CEAB77D859B3DC855B001" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 133 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number133NationalBusinessParkwayMember" xlink:label="loc_ofc_Number133NationalBusinessParkwayMember_1B31D424E52CEAB77D859B3DC855B001" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number133NationalBusinessParkwayMember_1B31D424E52CEAB77D859B3DC855B001" xlink:to="lab_ofc_Number133NationalBusinessParkwayMember_1B31D424E52CEAB77D859B3DC855B001" xlink:type="arc" />
    <link:label id="lab_ofc_Number134NationalBusinessParkwayMember_2520F9063C3B2A70AE839B3DC8551DBB_terseLabel_en-US" xlink:label="lab_ofc_Number134NationalBusinessParkwayMember_2520F9063C3B2A70AE839B3DC8551DBB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">134 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number134NationalBusinessParkwayMember_2520F9063C3B2A70AE839B3DC8551DBB_label_en-US" xlink:label="lab_ofc_Number134NationalBusinessParkwayMember_2520F9063C3B2A70AE839B3DC8551DBB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 134 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number134NationalBusinessParkwayMember_2520F9063C3B2A70AE839B3DC8551DBB_documentation_en-US" xlink:label="lab_ofc_Number134NationalBusinessParkwayMember_2520F9063C3B2A70AE839B3DC8551DBB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 134 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number134NationalBusinessParkwayMember" xlink:label="loc_ofc_Number134NationalBusinessParkwayMember_2520F9063C3B2A70AE839B3DC8551DBB" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number134NationalBusinessParkwayMember_2520F9063C3B2A70AE839B3DC8551DBB" xlink:to="lab_ofc_Number134NationalBusinessParkwayMember_2520F9063C3B2A70AE839B3DC8551DBB" xlink:type="arc" />
    <link:label id="lab_ofc_Number1340AshtonRoadMember_913AA95226647E129A329B3DC8558045_terseLabel_en-US" xlink:label="lab_ofc_Number1340AshtonRoadMember_913AA95226647E129A329B3DC8558045" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1340 Ashton Road [Member]</link:label>
    <link:label id="lab_ofc_Number1340AshtonRoadMember_913AA95226647E129A329B3DC8558045_label_en-US" xlink:label="lab_ofc_Number1340AshtonRoadMember_913AA95226647E129A329B3DC8558045" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1340 Ashton Road [Member]</link:label>
    <link:label id="lab_ofc_Number1340AshtonRoadMember_913AA95226647E129A329B3DC8558045_documentation_en-US" xlink:label="lab_ofc_Number1340AshtonRoadMember_913AA95226647E129A329B3DC8558045" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1340 Ashton Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1340AshtonRoadMember" xlink:label="loc_ofc_Number1340AshtonRoadMember_913AA95226647E129A329B3DC8558045" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1340AshtonRoadMember_913AA95226647E129A329B3DC8558045" xlink:to="lab_ofc_Number1340AshtonRoadMember_913AA95226647E129A329B3DC8558045" xlink:type="arc" />
    <link:label id="lab_ofc_Number13450SunriseValleyRoadMember_E4EE012F34702C6F35269B3DC8557BA0_terseLabel_en-US" xlink:label="lab_ofc_Number13450SunriseValleyRoadMember_E4EE012F34702C6F35269B3DC8557BA0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">13450 Sunrise Valley Road [Member]</link:label>
    <link:label id="lab_ofc_Number13450SunriseValleyRoadMember_E4EE012F34702C6F35269B3DC8557BA0_label_en-US" xlink:label="lab_ofc_Number13450SunriseValleyRoadMember_E4EE012F34702C6F35269B3DC8557BA0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 13450 Sunrise Valley Road [Member]</link:label>
    <link:label id="lab_ofc_Number13450SunriseValleyRoadMember_E4EE012F34702C6F35269B3DC8557BA0_documentation_en-US" xlink:label="lab_ofc_Number13450SunriseValleyRoadMember_E4EE012F34702C6F35269B3DC8557BA0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 13450 Sunrise Valley Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number13450SunriseValleyRoadMember" xlink:label="loc_ofc_Number13450SunriseValleyRoadMember_E4EE012F34702C6F35269B3DC8557BA0" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number13450SunriseValleyRoadMember_E4EE012F34702C6F35269B3DC8557BA0" xlink:to="lab_ofc_Number13450SunriseValleyRoadMember_E4EE012F34702C6F35269B3DC8557BA0" xlink:type="arc" />
    <link:label id="lab_ofc_Number13454SunriseValleyRoadMember_CEEE65BD22AD036182FA9B3DC8553232_terseLabel_en-US" xlink:label="lab_ofc_Number13454SunriseValleyRoadMember_CEEE65BD22AD036182FA9B3DC8553232" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">13454 Sunrise Valley Road [Member]</link:label>
    <link:label id="lab_ofc_Number13454SunriseValleyRoadMember_CEEE65BD22AD036182FA9B3DC8553232_label_en-US" xlink:label="lab_ofc_Number13454SunriseValleyRoadMember_CEEE65BD22AD036182FA9B3DC8553232" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 13454 Sunrise Valley Road [Member]</link:label>
    <link:label id="lab_ofc_Number13454SunriseValleyRoadMember_CEEE65BD22AD036182FA9B3DC8553232_documentation_en-US" xlink:label="lab_ofc_Number13454SunriseValleyRoadMember_CEEE65BD22AD036182FA9B3DC8553232" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 13454 Sunrise Valley Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number13454SunriseValleyRoadMember" xlink:label="loc_ofc_Number13454SunriseValleyRoadMember_CEEE65BD22AD036182FA9B3DC8553232" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number13454SunriseValleyRoadMember_CEEE65BD22AD036182FA9B3DC8553232" xlink:to="lab_ofc_Number13454SunriseValleyRoadMember_CEEE65BD22AD036182FA9B3DC8553232" xlink:type="arc" />
    <link:label id="lab_ofc_Number135NationalBusinessParkwayMember_B52D3EC3B53CFC91CA8B9B3DC8557FA6_terseLabel_en-US" xlink:label="lab_ofc_Number135NationalBusinessParkwayMember_B52D3EC3B53CFC91CA8B9B3DC8557FA6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">135 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number135NationalBusinessParkwayMember_B52D3EC3B53CFC91CA8B9B3DC8557FA6_label_en-US" xlink:label="lab_ofc_Number135NationalBusinessParkwayMember_B52D3EC3B53CFC91CA8B9B3DC8557FA6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 135 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number135NationalBusinessParkwayMember_B52D3EC3B53CFC91CA8B9B3DC8557FA6_documentation_en-US" xlink:label="lab_ofc_Number135NationalBusinessParkwayMember_B52D3EC3B53CFC91CA8B9B3DC8557FA6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 135 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number135NationalBusinessParkwayMember" xlink:label="loc_ofc_Number135NationalBusinessParkwayMember_B52D3EC3B53CFC91CA8B9B3DC8557FA6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number135NationalBusinessParkwayMember_B52D3EC3B53CFC91CA8B9B3DC8557FA6" xlink:to="lab_ofc_Number135NationalBusinessParkwayMember_B52D3EC3B53CFC91CA8B9B3DC8557FA6" xlink:type="arc" />
    <link:label id="lab_ofc_Number1362MellonRoadMember_15E5E6F0F4A90F6BA1B59B3DC8557166_terseLabel_en-US" xlink:label="lab_ofc_Number1362MellonRoadMember_15E5E6F0F4A90F6BA1B59B3DC8557166" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1362 Mellon Road [Member]</link:label>
    <link:label id="lab_ofc_Number1362MellonRoadMember_15E5E6F0F4A90F6BA1B59B3DC8557166_label_en-US" xlink:label="lab_ofc_Number1362MellonRoadMember_15E5E6F0F4A90F6BA1B59B3DC8557166" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1362 Mellon Road [Member]</link:label>
    <link:label id="lab_ofc_Number1362MellonRoadMember_15E5E6F0F4A90F6BA1B59B3DC8557166_documentation_en-US" xlink:label="lab_ofc_Number1362MellonRoadMember_15E5E6F0F4A90F6BA1B59B3DC8557166" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1362 Mellon Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1362MellonRoadMember" xlink:label="loc_ofc_Number1362MellonRoadMember_15E5E6F0F4A90F6BA1B59B3DC8557166" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1362MellonRoadMember_15E5E6F0F4A90F6BA1B59B3DC8557166" xlink:to="lab_ofc_Number1362MellonRoadMember_15E5E6F0F4A90F6BA1B59B3DC8557166" xlink:type="arc" />
    <link:label id="lab_ofc_Number13857MclearenRoadMember_111DDACA3156A5119E749B3DC8558AD8_terseLabel_en-US" xlink:label="lab_ofc_Number13857MclearenRoadMember_111DDACA3156A5119E749B3DC8558AD8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">13857 McLearen Road [Member]</link:label>
    <link:label id="lab_ofc_Number13857MclearenRoadMember_111DDACA3156A5119E749B3DC8558AD8_label_en-US" xlink:label="lab_ofc_Number13857MclearenRoadMember_111DDACA3156A5119E749B3DC8558AD8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 13857 McLearen Road [Member]</link:label>
    <link:label id="lab_ofc_Number13857MclearenRoadMember_111DDACA3156A5119E749B3DC8558AD8_documentation_en-US" xlink:label="lab_ofc_Number13857MclearenRoadMember_111DDACA3156A5119E749B3DC8558AD8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 13857 McLearen Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number13857MclearenRoadMember" xlink:label="loc_ofc_Number13857MclearenRoadMember_111DDACA3156A5119E749B3DC8558AD8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number13857MclearenRoadMember_111DDACA3156A5119E749B3DC8558AD8" xlink:to="lab_ofc_Number13857MclearenRoadMember_111DDACA3156A5119E749B3DC8558AD8" xlink:type="arc" />
    <link:label id="lab_ofc_Number140NationalBusinessParkwayMember_4FEDF963A722E6A5E2BA9B3DC855FFC3_terseLabel_en-US" xlink:label="lab_ofc_Number140NationalBusinessParkwayMember_4FEDF963A722E6A5E2BA9B3DC855FFC3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">140 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number140NationalBusinessParkwayMember_4FEDF963A722E6A5E2BA9B3DC855FFC3_label_en-US" xlink:label="lab_ofc_Number140NationalBusinessParkwayMember_4FEDF963A722E6A5E2BA9B3DC855FFC3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 140 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number140NationalBusinessParkwayMember_4FEDF963A722E6A5E2BA9B3DC855FFC3_documentation_en-US" xlink:label="lab_ofc_Number140NationalBusinessParkwayMember_4FEDF963A722E6A5E2BA9B3DC855FFC3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 140 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number140NationalBusinessParkwayMember" xlink:label="loc_ofc_Number140NationalBusinessParkwayMember_4FEDF963A722E6A5E2BA9B3DC855FFC3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number140NationalBusinessParkwayMember_4FEDF963A722E6A5E2BA9B3DC855FFC3" xlink:to="lab_ofc_Number140NationalBusinessParkwayMember_4FEDF963A722E6A5E2BA9B3DC855FFC3" xlink:type="arc" />
    <link:label id="lab_ofc_Number141NationalBusinessParkwayMember_27C4C3EC9C6FFA9303BA9B3DC855098C_terseLabel_en-US" xlink:label="lab_ofc_Number141NationalBusinessParkwayMember_27C4C3EC9C6FFA9303BA9B3DC855098C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">141 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number141NationalBusinessParkwayMember_27C4C3EC9C6FFA9303BA9B3DC855098C_label_en-US" xlink:label="lab_ofc_Number141NationalBusinessParkwayMember_27C4C3EC9C6FFA9303BA9B3DC855098C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 141 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number141NationalBusinessParkwayMember_27C4C3EC9C6FFA9303BA9B3DC855098C_documentation_en-US" xlink:label="lab_ofc_Number141NationalBusinessParkwayMember_27C4C3EC9C6FFA9303BA9B3DC855098C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 141 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number141NationalBusinessParkwayMember" xlink:label="loc_ofc_Number141NationalBusinessParkwayMember_27C4C3EC9C6FFA9303BA9B3DC855098C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number141NationalBusinessParkwayMember_27C4C3EC9C6FFA9303BA9B3DC855098C" xlink:to="lab_ofc_Number141NationalBusinessParkwayMember_27C4C3EC9C6FFA9303BA9B3DC855098C" xlink:type="arc" />
    <link:label id="lab_ofc_Number14280ParkMeadowDriveMember_7D4CB57475C2F1588D5C9B3DC855B6EA_terseLabel_en-US" xlink:label="lab_ofc_Number14280ParkMeadowDriveMember_7D4CB57475C2F1588D5C9B3DC855B6EA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">14280 Park Meadow Drive [Member]</link:label>
    <link:label id="lab_ofc_Number14280ParkMeadowDriveMember_7D4CB57475C2F1588D5C9B3DC855B6EA_label_en-US" xlink:label="lab_ofc_Number14280ParkMeadowDriveMember_7D4CB57475C2F1588D5C9B3DC855B6EA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 14280 Park Meadow Drive [Member]</link:label>
    <link:label id="lab_ofc_Number14280ParkMeadowDriveMember_7D4CB57475C2F1588D5C9B3DC855B6EA_documentation_en-US" xlink:label="lab_ofc_Number14280ParkMeadowDriveMember_7D4CB57475C2F1588D5C9B3DC855B6EA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 14280 Park Meadow Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number14280ParkMeadowDriveMember" xlink:label="loc_ofc_Number14280ParkMeadowDriveMember_7D4CB57475C2F1588D5C9B3DC855B6EA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number14280ParkMeadowDriveMember_7D4CB57475C2F1588D5C9B3DC855B6EA" xlink:to="lab_ofc_Number14280ParkMeadowDriveMember_7D4CB57475C2F1588D5C9B3DC855B6EA" xlink:type="arc" />
    <link:label id="lab_ofc_Number1460DorseyRoadMember_0183FC01BDDD12375F969B3DC855D0F3_terseLabel_en-US" xlink:label="lab_ofc_Number1460DorseyRoadMember_0183FC01BDDD12375F969B3DC855D0F3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1460 Dorsey Road [Member]</link:label>
    <link:label id="lab_ofc_Number1460DorseyRoadMember_0183FC01BDDD12375F969B3DC855D0F3_label_en-US" xlink:label="lab_ofc_Number1460DorseyRoadMember_0183FC01BDDD12375F969B3DC855D0F3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1460 Dorsey Road [Member]</link:label>
    <link:label id="lab_ofc_Number1460DorseyRoadMember_0183FC01BDDD12375F969B3DC855D0F3_documentation_en-US" xlink:label="lab_ofc_Number1460DorseyRoadMember_0183FC01BDDD12375F969B3DC855D0F3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1460 Dorsey Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1460DorseyRoadMember" xlink:label="loc_ofc_Number1460DorseyRoadMember_0183FC01BDDD12375F969B3DC855D0F3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1460DorseyRoadMember_0183FC01BDDD12375F969B3DC855D0F3" xlink:to="lab_ofc_Number1460DorseyRoadMember_0183FC01BDDD12375F969B3DC855D0F3" xlink:type="arc" />
    <link:label id="lab_ofc_Number14840ConferenceCenterDriveMember_602EAD43EAE3E743384C9B3DC8558110_terseLabel_en-US" xlink:label="lab_ofc_Number14840ConferenceCenterDriveMember_602EAD43EAE3E743384C9B3DC8558110" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">14840 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number14840ConferenceCenterDriveMember_602EAD43EAE3E743384C9B3DC8558110_label_en-US" xlink:label="lab_ofc_Number14840ConferenceCenterDriveMember_602EAD43EAE3E743384C9B3DC8558110" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 14840 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number14840ConferenceCenterDriveMember_602EAD43EAE3E743384C9B3DC8558110_documentation_en-US" xlink:label="lab_ofc_Number14840ConferenceCenterDriveMember_602EAD43EAE3E743384C9B3DC8558110" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 14840 Conference Center Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number14840ConferenceCenterDriveMember" xlink:label="loc_ofc_Number14840ConferenceCenterDriveMember_602EAD43EAE3E743384C9B3DC8558110" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number14840ConferenceCenterDriveMember_602EAD43EAE3E743384C9B3DC8558110" xlink:to="lab_ofc_Number14840ConferenceCenterDriveMember_602EAD43EAE3E743384C9B3DC8558110" xlink:type="arc" />
    <link:label id="lab_ofc_Number14850ConferenceCenterDriveMember_04400E1CE814D591ABD99B3DC8558B90_terseLabel_en-US" xlink:label="lab_ofc_Number14850ConferenceCenterDriveMember_04400E1CE814D591ABD99B3DC8558B90" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">14850 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number14850ConferenceCenterDriveMember_04400E1CE814D591ABD99B3DC8558B90_label_en-US" xlink:label="lab_ofc_Number14850ConferenceCenterDriveMember_04400E1CE814D591ABD99B3DC8558B90" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 14850 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number14850ConferenceCenterDriveMember_04400E1CE814D591ABD99B3DC8558B90_documentation_en-US" xlink:label="lab_ofc_Number14850ConferenceCenterDriveMember_04400E1CE814D591ABD99B3DC8558B90" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 14850 Conference Center Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number14850ConferenceCenterDriveMember" xlink:label="loc_ofc_Number14850ConferenceCenterDriveMember_04400E1CE814D591ABD99B3DC8558B90" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number14850ConferenceCenterDriveMember_04400E1CE814D591ABD99B3DC8558B90" xlink:to="lab_ofc_Number14850ConferenceCenterDriveMember_04400E1CE814D591ABD99B3DC8558B90" xlink:type="arc" />
    <link:label id="lab_ofc_Number14900ConferenceCenterDriveMember_7539DAA599833FD8A26B9B3DC855ACF3_terseLabel_en-US" xlink:label="lab_ofc_Number14900ConferenceCenterDriveMember_7539DAA599833FD8A26B9B3DC855ACF3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">14900 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number14900ConferenceCenterDriveMember_7539DAA599833FD8A26B9B3DC855ACF3_label_en-US" xlink:label="lab_ofc_Number14900ConferenceCenterDriveMember_7539DAA599833FD8A26B9B3DC855ACF3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 14900 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number14900ConferenceCenterDriveMember_7539DAA599833FD8A26B9B3DC855ACF3_documentation_en-US" xlink:label="lab_ofc_Number14900ConferenceCenterDriveMember_7539DAA599833FD8A26B9B3DC855ACF3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 14900 Conference Center Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number14900ConferenceCenterDriveMember" xlink:label="loc_ofc_Number14900ConferenceCenterDriveMember_7539DAA599833FD8A26B9B3DC855ACF3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number14900ConferenceCenterDriveMember_7539DAA599833FD8A26B9B3DC855ACF3" xlink:to="lab_ofc_Number14900ConferenceCenterDriveMember_7539DAA599833FD8A26B9B3DC855ACF3" xlink:type="arc" />
    <link:label id="lab_ofc_Number1501SouthClintonStreetMember_351AE10470D0B10DE0759B3DC855705D_terseLabel_en-US" xlink:label="lab_ofc_Number1501SouthClintonStreetMember_351AE10470D0B10DE0759B3DC855705D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1501 South Clinton Street [Member]</link:label>
    <link:label id="lab_ofc_Number1501SouthClintonStreetMember_351AE10470D0B10DE0759B3DC855705D_label_en-US" xlink:label="lab_ofc_Number1501SouthClintonStreetMember_351AE10470D0B10DE0759B3DC855705D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1501 South Clinton Street [Member]</link:label>
    <link:label id="lab_ofc_Number1501SouthClintonStreetMember_351AE10470D0B10DE0759B3DC855705D_documentation_en-US" xlink:label="lab_ofc_Number1501SouthClintonStreetMember_351AE10470D0B10DE0759B3DC855705D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1501 South Clinton Street, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1501SouthClintonStreetMember" xlink:label="loc_ofc_Number1501SouthClintonStreetMember_351AE10470D0B10DE0759B3DC855705D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1501SouthClintonStreetMember_351AE10470D0B10DE0759B3DC855705D" xlink:to="lab_ofc_Number1501SouthClintonStreetMember_351AE10470D0B10DE0759B3DC855705D" xlink:type="arc" />
    <link:label id="lab_ofc_Number15049ConferenceCenterDriveMember_6534C5CF126A957B6BD89B3DC856B4E8_terseLabel_en-US" xlink:label="lab_ofc_Number15049ConferenceCenterDriveMember_6534C5CF126A957B6BD89B3DC856B4E8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">15049 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number15049ConferenceCenterDriveMember_6534C5CF126A957B6BD89B3DC856B4E8_label_en-US" xlink:label="lab_ofc_Number15049ConferenceCenterDriveMember_6534C5CF126A957B6BD89B3DC856B4E8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 15049 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number15049ConferenceCenterDriveMember_6534C5CF126A957B6BD89B3DC856B4E8_documentation_en-US" xlink:label="lab_ofc_Number15049ConferenceCenterDriveMember_6534C5CF126A957B6BD89B3DC856B4E8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 15049 Conference Center Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number15049ConferenceCenterDriveMember" xlink:label="loc_ofc_Number15049ConferenceCenterDriveMember_6534C5CF126A957B6BD89B3DC856B4E8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number15049ConferenceCenterDriveMember_6534C5CF126A957B6BD89B3DC856B4E8" xlink:to="lab_ofc_Number15049ConferenceCenterDriveMember_6534C5CF126A957B6BD89B3DC856B4E8" xlink:type="arc" />
    <link:label id="lab_ofc_Number15059ConferenceCenterDriveMember_79613D47A5CE4619990B9B3DC856B2F9_terseLabel_en-US" xlink:label="lab_ofc_Number15059ConferenceCenterDriveMember_79613D47A5CE4619990B9B3DC856B2F9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">15059 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number15059ConferenceCenterDriveMember_79613D47A5CE4619990B9B3DC856B2F9_label_en-US" xlink:label="lab_ofc_Number15059ConferenceCenterDriveMember_79613D47A5CE4619990B9B3DC856B2F9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 15059 Conference Center Drive [Member]</link:label>
    <link:label id="lab_ofc_Number15059ConferenceCenterDriveMember_79613D47A5CE4619990B9B3DC856B2F9_documentation_en-US" xlink:label="lab_ofc_Number15059ConferenceCenterDriveMember_79613D47A5CE4619990B9B3DC856B2F9" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 15059 Conference Center Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number15059ConferenceCenterDriveMember" xlink:label="loc_ofc_Number15059ConferenceCenterDriveMember_79613D47A5CE4619990B9B3DC856B2F9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number15059ConferenceCenterDriveMember_79613D47A5CE4619990B9B3DC856B2F9" xlink:to="lab_ofc_Number15059ConferenceCenterDriveMember_79613D47A5CE4619990B9B3DC856B2F9" xlink:type="arc" />
    <link:label id="lab_ofc_Number1550WestNurseryRoadMember_0312D98612F0BFC46D0C9B3DC85698C9_terseLabel_en-US" xlink:label="lab_ofc_Number1550WestNurseryRoadMember_0312D98612F0BFC46D0C9B3DC85698C9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1550 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1550WestNurseryRoadMember_0312D98612F0BFC46D0C9B3DC85698C9_label_en-US" xlink:label="lab_ofc_Number1550WestNurseryRoadMember_0312D98612F0BFC46D0C9B3DC85698C9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1550 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1550WestNurseryRoadMember_0312D98612F0BFC46D0C9B3DC85698C9_documentation_en-US" xlink:label="lab_ofc_Number1550WestNurseryRoadMember_0312D98612F0BFC46D0C9B3DC85698C9" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1550 West Nursery Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1550WestNurseryRoadMember" xlink:label="loc_ofc_Number1550WestNurseryRoadMember_0312D98612F0BFC46D0C9B3DC85698C9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1550WestNurseryRoadMember_0312D98612F0BFC46D0C9B3DC85698C9" xlink:to="lab_ofc_Number1550WestNurseryRoadMember_0312D98612F0BFC46D0C9B3DC85698C9" xlink:type="arc" />
    <link:label id="lab_ofc_Number1560WestNurseryRoadMember_8478555472A7D1F355DA9B3DC856B6B7_terseLabel_en-US" xlink:label="lab_ofc_Number1560WestNurseryRoadMember_8478555472A7D1F355DA9B3DC856B6B7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1560 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1560WestNurseryRoadMember_8478555472A7D1F355DA9B3DC856B6B7_label_en-US" xlink:label="lab_ofc_Number1560WestNurseryRoadMember_8478555472A7D1F355DA9B3DC856B6B7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1560 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1560WestNurseryRoadMember_8478555472A7D1F355DA9B3DC856B6B7_documentation_en-US" xlink:label="lab_ofc_Number1560WestNurseryRoadMember_8478555472A7D1F355DA9B3DC856B6B7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 1560 West Nursery Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1560WestNurseryRoadMember" xlink:label="loc_ofc_Number1560WestNurseryRoadMember_8478555472A7D1F355DA9B3DC856B6B7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1560WestNurseryRoadMember_8478555472A7D1F355DA9B3DC856B6B7" xlink:to="lab_ofc_Number1560WestNurseryRoadMember_8478555472A7D1F355DA9B3DC856B6B7" xlink:type="arc" />
    <link:label id="lab_ofc_Number1610WestNurseryRoadMember_E850551504C4570C78849B3DC856896A_terseLabel_en-US" xlink:label="lab_ofc_Number1610WestNurseryRoadMember_E850551504C4570C78849B3DC856896A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1610 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1610WestNurseryRoadMember_E850551504C4570C78849B3DC856896A_label_en-US" xlink:label="lab_ofc_Number1610WestNurseryRoadMember_E850551504C4570C78849B3DC856896A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1610 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1610WestNurseryRoadMember_E850551504C4570C78849B3DC856896A_documentation_en-US" xlink:label="lab_ofc_Number1610WestNurseryRoadMember_E850551504C4570C78849B3DC856896A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 1610 West Nursery Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1610WestNurseryRoadMember" xlink:label="loc_ofc_Number1610WestNurseryRoadMember_E850551504C4570C78849B3DC856896A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1610WestNurseryRoadMember_E850551504C4570C78849B3DC856896A" xlink:to="lab_ofc_Number1610WestNurseryRoadMember_E850551504C4570C78849B3DC856896A" xlink:type="arc" />
    <link:label id="lab_ofc_Number1616WestNurseryRoadMember_B2F31C77B3A83BD75FE49B3DC8566584_terseLabel_en-US" xlink:label="lab_ofc_Number1616WestNurseryRoadMember_B2F31C77B3A83BD75FE49B3DC8566584" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1616 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1616WestNurseryRoadMember_B2F31C77B3A83BD75FE49B3DC8566584_label_en-US" xlink:label="lab_ofc_Number1616WestNurseryRoadMember_B2F31C77B3A83BD75FE49B3DC8566584" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1616 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1616WestNurseryRoadMember_B2F31C77B3A83BD75FE49B3DC8566584_documentation_en-US" xlink:label="lab_ofc_Number1616WestNurseryRoadMember_B2F31C77B3A83BD75FE49B3DC8566584" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 1616 West Nursery Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1616WestNurseryRoadMember" xlink:label="loc_ofc_Number1616WestNurseryRoadMember_B2F31C77B3A83BD75FE49B3DC8566584" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1616WestNurseryRoadMember_B2F31C77B3A83BD75FE49B3DC8566584" xlink:to="lab_ofc_Number1616WestNurseryRoadMember_B2F31C77B3A83BD75FE49B3DC8566584" xlink:type="arc" />
    <link:label id="lab_ofc_Number1622WestNurseryRoadMember_CB5A8493D8FD4A349E819B3DC856273D_terseLabel_en-US" xlink:label="lab_ofc_Number1622WestNurseryRoadMember_CB5A8493D8FD4A349E819B3DC856273D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1622 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1622WestNurseryRoadMember_CB5A8493D8FD4A349E819B3DC856273D_label_en-US" xlink:label="lab_ofc_Number1622WestNurseryRoadMember_CB5A8493D8FD4A349E819B3DC856273D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1622 West Nursery Road [Member]</link:label>
    <link:label id="lab_ofc_Number1622WestNurseryRoadMember_CB5A8493D8FD4A349E819B3DC856273D_documentation_en-US" xlink:label="lab_ofc_Number1622WestNurseryRoadMember_CB5A8493D8FD4A349E819B3DC856273D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 1622 West Nursery Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1622WestNurseryRoadMember" xlink:label="loc_ofc_Number1622WestNurseryRoadMember_CB5A8493D8FD4A349E819B3DC856273D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1622WestNurseryRoadMember_CB5A8493D8FD4A349E819B3DC856273D" xlink:to="lab_ofc_Number1622WestNurseryRoadMember_CB5A8493D8FD4A349E819B3DC856273D" xlink:type="arc" />
    <link:label id="lab_ofc_Number16442CommerceDriveMember_9B5E3CF7D9AD089188A19B3DC856D98B_terseLabel_en-US" xlink:label="lab_ofc_Number16442CommerceDriveMember_9B5E3CF7D9AD089188A19B3DC856D98B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">16442 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16442CommerceDriveMember_9B5E3CF7D9AD089188A19B3DC856D98B_label_en-US" xlink:label="lab_ofc_Number16442CommerceDriveMember_9B5E3CF7D9AD089188A19B3DC856D98B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 16442 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16442CommerceDriveMember_9B5E3CF7D9AD089188A19B3DC856D98B_documentation_en-US" xlink:label="lab_ofc_Number16442CommerceDriveMember_9B5E3CF7D9AD089188A19B3DC856D98B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 16442 Commerce Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number16442CommerceDriveMember" xlink:label="loc_ofc_Number16442CommerceDriveMember_9B5E3CF7D9AD089188A19B3DC856D98B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number16442CommerceDriveMember_9B5E3CF7D9AD089188A19B3DC856D98B" xlink:to="lab_ofc_Number16442CommerceDriveMember_9B5E3CF7D9AD089188A19B3DC856D98B" xlink:type="arc" />
    <link:label id="lab_ofc_Number16480CommerceDriveMember_44B809A3EDFA7C27B8529B3DC856527A_terseLabel_en-US" xlink:label="lab_ofc_Number16480CommerceDriveMember_44B809A3EDFA7C27B8529B3DC856527A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">16480 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16480CommerceDriveMember_44B809A3EDFA7C27B8529B3DC856527A_label_en-US" xlink:label="lab_ofc_Number16480CommerceDriveMember_44B809A3EDFA7C27B8529B3DC856527A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 16480 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16480CommerceDriveMember_44B809A3EDFA7C27B8529B3DC856527A_documentation_en-US" xlink:label="lab_ofc_Number16480CommerceDriveMember_44B809A3EDFA7C27B8529B3DC856527A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 16480 Commerce Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number16480CommerceDriveMember" xlink:label="loc_ofc_Number16480CommerceDriveMember_44B809A3EDFA7C27B8529B3DC856527A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number16480CommerceDriveMember_44B809A3EDFA7C27B8529B3DC856527A" xlink:to="lab_ofc_Number16480CommerceDriveMember_44B809A3EDFA7C27B8529B3DC856527A" xlink:type="arc" />
    <link:label id="lab_ofc_Number16501CommerceDriveMember_FBB66034CD6FB6D5DF0D9B3DC8563AC4_terseLabel_en-US" xlink:label="lab_ofc_Number16501CommerceDriveMember_FBB66034CD6FB6D5DF0D9B3DC8563AC4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">16501 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16501CommerceDriveMember_FBB66034CD6FB6D5DF0D9B3DC8563AC4_label_en-US" xlink:label="lab_ofc_Number16501CommerceDriveMember_FBB66034CD6FB6D5DF0D9B3DC8563AC4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 16501 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16501CommerceDriveMember_FBB66034CD6FB6D5DF0D9B3DC8563AC4_documentation_en-US" xlink:label="lab_ofc_Number16501CommerceDriveMember_FBB66034CD6FB6D5DF0D9B3DC8563AC4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 16501 Commerce Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number16501CommerceDriveMember" xlink:label="loc_ofc_Number16501CommerceDriveMember_FBB66034CD6FB6D5DF0D9B3DC8563AC4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number16501CommerceDriveMember_FBB66034CD6FB6D5DF0D9B3DC8563AC4" xlink:to="lab_ofc_Number16501CommerceDriveMember_FBB66034CD6FB6D5DF0D9B3DC8563AC4" xlink:type="arc" />
    <link:label id="lab_ofc_Number16539CommerceDriveMember_9E5F7E2BA7CB8847E1809B3DC8560F3E_terseLabel_en-US" xlink:label="lab_ofc_Number16539CommerceDriveMember_9E5F7E2BA7CB8847E1809B3DC8560F3E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">16539 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16539CommerceDriveMember_9E5F7E2BA7CB8847E1809B3DC8560F3E_label_en-US" xlink:label="lab_ofc_Number16539CommerceDriveMember_9E5F7E2BA7CB8847E1809B3DC8560F3E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 16539 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16539CommerceDriveMember_9E5F7E2BA7CB8847E1809B3DC8560F3E_documentation_en-US" xlink:label="lab_ofc_Number16539CommerceDriveMember_9E5F7E2BA7CB8847E1809B3DC8560F3E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 16539 Commerce Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number16539CommerceDriveMember" xlink:label="loc_ofc_Number16539CommerceDriveMember_9E5F7E2BA7CB8847E1809B3DC8560F3E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number16539CommerceDriveMember_9E5F7E2BA7CB8847E1809B3DC8560F3E" xlink:to="lab_ofc_Number16539CommerceDriveMember_9E5F7E2BA7CB8847E1809B3DC8560F3E" xlink:type="arc" />
    <link:label id="lab_ofc_Number16541CommerceDriveMember_9B62E6D421B14E1BECE99B3DC856CA6C_terseLabel_en-US" xlink:label="lab_ofc_Number16541CommerceDriveMember_9B62E6D421B14E1BECE99B3DC856CA6C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">16541 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16541CommerceDriveMember_9B62E6D421B14E1BECE99B3DC856CA6C_label_en-US" xlink:label="lab_ofc_Number16541CommerceDriveMember_9B62E6D421B14E1BECE99B3DC856CA6C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 16541 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16541CommerceDriveMember_9B62E6D421B14E1BECE99B3DC856CA6C_documentation_en-US" xlink:label="lab_ofc_Number16541CommerceDriveMember_9B62E6D421B14E1BECE99B3DC856CA6C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 16541 Commerce Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number16541CommerceDriveMember" xlink:label="loc_ofc_Number16541CommerceDriveMember_9B62E6D421B14E1BECE99B3DC856CA6C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number16541CommerceDriveMember_9B62E6D421B14E1BECE99B3DC856CA6C" xlink:to="lab_ofc_Number16541CommerceDriveMember_9B62E6D421B14E1BECE99B3DC856CA6C" xlink:type="arc" />
    <link:label id="lab_ofc_Number16543CommerceDriveMember_FD91EE4003024CD2BA779B3DC856A65C_terseLabel_en-US" xlink:label="lab_ofc_Number16543CommerceDriveMember_FD91EE4003024CD2BA779B3DC856A65C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">16543 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16543CommerceDriveMember_FD91EE4003024CD2BA779B3DC856A65C_label_en-US" xlink:label="lab_ofc_Number16543CommerceDriveMember_FD91EE4003024CD2BA779B3DC856A65C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 16543 Commerce Drive [Member]</link:label>
    <link:label id="lab_ofc_Number16543CommerceDriveMember_FD91EE4003024CD2BA779B3DC856A65C_documentation_en-US" xlink:label="lab_ofc_Number16543CommerceDriveMember_FD91EE4003024CD2BA779B3DC856A65C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 16543 Commerce Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number16543CommerceDriveMember" xlink:label="loc_ofc_Number16543CommerceDriveMember_FD91EE4003024CD2BA779B3DC856A65C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number16543CommerceDriveMember_FD91EE4003024CD2BA779B3DC856A65C" xlink:to="lab_ofc_Number16543CommerceDriveMember_FD91EE4003024CD2BA779B3DC856A65C" xlink:type="arc" />
    <link:label id="lab_ofc_Number1751PinnacleDriveMember_13606D7B83E5DE81FC2E9B3DC8566DAB_terseLabel_en-US" xlink:label="lab_ofc_Number1751PinnacleDriveMember_13606D7B83E5DE81FC2E9B3DC8566DAB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1751 Pinnacle Drive [Member]</link:label>
    <link:label id="lab_ofc_Number1751PinnacleDriveMember_13606D7B83E5DE81FC2E9B3DC8566DAB_label_en-US" xlink:label="lab_ofc_Number1751PinnacleDriveMember_13606D7B83E5DE81FC2E9B3DC8566DAB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1751 Pinnacle Drive [Member]</link:label>
    <link:label id="lab_ofc_Number1751PinnacleDriveMember_13606D7B83E5DE81FC2E9B3DC8566DAB_documentation_en-US" xlink:label="lab_ofc_Number1751PinnacleDriveMember_13606D7B83E5DE81FC2E9B3DC8566DAB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1751 Pinnacle Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1751PinnacleDriveMember" xlink:label="loc_ofc_Number1751PinnacleDriveMember_13606D7B83E5DE81FC2E9B3DC8566DAB" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1751PinnacleDriveMember_13606D7B83E5DE81FC2E9B3DC8566DAB" xlink:to="lab_ofc_Number1751PinnacleDriveMember_13606D7B83E5DE81FC2E9B3DC8566DAB" xlink:type="arc" />
    <link:label id="lab_ofc_Number1753PinnacleDriveMember_B95E64D64D7E3E6D385E9B3DC856A702_terseLabel_en-US" xlink:label="lab_ofc_Number1753PinnacleDriveMember_B95E64D64D7E3E6D385E9B3DC856A702" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">1753 Pinnacle Drive [Member]</link:label>
    <link:label id="lab_ofc_Number1753PinnacleDriveMember_B95E64D64D7E3E6D385E9B3DC856A702_label_en-US" xlink:label="lab_ofc_Number1753PinnacleDriveMember_B95E64D64D7E3E6D385E9B3DC856A702" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 1753 Pinnacle Drive [Member]</link:label>
    <link:label id="lab_ofc_Number1753PinnacleDriveMember_B95E64D64D7E3E6D385E9B3DC856A702_documentation_en-US" xlink:label="lab_ofc_Number1753PinnacleDriveMember_B95E64D64D7E3E6D385E9B3DC856A702" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 1753 Pinnacle Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number1753PinnacleDriveMember" xlink:label="loc_ofc_Number1753PinnacleDriveMember_B95E64D64D7E3E6D385E9B3DC856A702" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number1753PinnacleDriveMember_B95E64D64D7E3E6D385E9B3DC856A702" xlink:to="lab_ofc_Number1753PinnacleDriveMember_B95E64D64D7E3E6D385E9B3DC856A702" xlink:type="arc" />
    <link:label id="lab_ofc_Number206ResearchBoulevardMember_4FA27F4EE1DD07439B649B3DC85638A7_terseLabel_en-US" xlink:label="lab_ofc_Number206ResearchBoulevardMember_4FA27F4EE1DD07439B649B3DC85638A7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">206 Research Boulevard [Member]</link:label>
    <link:label id="lab_ofc_Number206ResearchBoulevardMember_4FA27F4EE1DD07439B649B3DC85638A7_label_en-US" xlink:label="lab_ofc_Number206ResearchBoulevardMember_4FA27F4EE1DD07439B649B3DC85638A7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 206 Research Boulevard [Member]</link:label>
    <link:label id="lab_ofc_Number206ResearchBoulevardMember_4FA27F4EE1DD07439B649B3DC85638A7_documentation_en-US" xlink:label="lab_ofc_Number206ResearchBoulevardMember_4FA27F4EE1DD07439B649B3DC85638A7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 206 Research Boulevard, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number206ResearchBoulevardMember" xlink:label="loc_ofc_Number206ResearchBoulevardMember_4FA27F4EE1DD07439B649B3DC85638A7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number206ResearchBoulevardMember_4FA27F4EE1DD07439B649B3DC85638A7" xlink:to="lab_ofc_Number206ResearchBoulevardMember_4FA27F4EE1DD07439B649B3DC85638A7" xlink:type="arc" />
    <link:label id="lab_ofc_Number209ResearchBoulevardMember_E00D0B98416D946CDACA9B3DC857AD91_terseLabel_en-US" xlink:label="lab_ofc_Number209ResearchBoulevardMember_E00D0B98416D946CDACA9B3DC857AD91" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">209 Research Boulevard [Member]</link:label>
    <link:label id="lab_ofc_Number209ResearchBoulevardMember_E00D0B98416D946CDACA9B3DC857AD91_label_en-US" xlink:label="lab_ofc_Number209ResearchBoulevardMember_E00D0B98416D946CDACA9B3DC857AD91" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 209 Research Boulevard [Member]</link:label>
    <link:label id="lab_ofc_Number209ResearchBoulevardMember_E00D0B98416D946CDACA9B3DC857AD91_documentation_en-US" xlink:label="lab_ofc_Number209ResearchBoulevardMember_E00D0B98416D946CDACA9B3DC857AD91" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 209 Research Boulevard, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number209ResearchBoulevardMember" xlink:label="loc_ofc_Number209ResearchBoulevardMember_E00D0B98416D946CDACA9B3DC857AD91" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number209ResearchBoulevardMember_E00D0B98416D946CDACA9B3DC857AD91" xlink:to="lab_ofc_Number209ResearchBoulevardMember_E00D0B98416D946CDACA9B3DC857AD91" xlink:type="arc" />
    <link:label id="lab_ofc_Number210ResearchBoulevardMember_3CF8CA5735F28C5F55D79B3DC857EDCC_terseLabel_en-US" xlink:label="lab_ofc_Number210ResearchBoulevardMember_3CF8CA5735F28C5F55D79B3DC857EDCC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">210 Research Boulevard [Member]</link:label>
    <link:label id="lab_ofc_Number210ResearchBoulevardMember_3CF8CA5735F28C5F55D79B3DC857EDCC_label_en-US" xlink:label="lab_ofc_Number210ResearchBoulevardMember_3CF8CA5735F28C5F55D79B3DC857EDCC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 210 Research Boulevard [Member]</link:label>
    <link:label id="lab_ofc_Number210ResearchBoulevardMember_3CF8CA5735F28C5F55D79B3DC857EDCC_documentation_en-US" xlink:label="lab_ofc_Number210ResearchBoulevardMember_3CF8CA5735F28C5F55D79B3DC857EDCC" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 210 Research Boulevard, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number210ResearchBoulevardMember" xlink:label="loc_ofc_Number210ResearchBoulevardMember_3CF8CA5735F28C5F55D79B3DC857EDCC" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number210ResearchBoulevardMember_3CF8CA5735F28C5F55D79B3DC857EDCC" xlink:to="lab_ofc_Number210ResearchBoulevardMember_3CF8CA5735F28C5F55D79B3DC857EDCC" xlink:type="arc" />
    <link:label id="lab_ofc_Number2100LStreetMember_FEC0FBC65E0E60E692E69B3DC85766D4_terseLabel_en-US" xlink:label="lab_ofc_Number2100LStreetMember_FEC0FBC65E0E60E692E69B3DC85766D4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2100 L Street [Member]</link:label>
    <link:label id="lab_ofc_Number2100LStreetMember_FEC0FBC65E0E60E692E69B3DC85766D4_label_en-US" xlink:label="lab_ofc_Number2100LStreetMember_FEC0FBC65E0E60E692E69B3DC85766D4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2100 L Street [Member]</link:label>
    <link:label id="lab_ofc_Number2100LStreetMember_FEC0FBC65E0E60E692E69B3DC85766D4_documentation_en-US" xlink:label="lab_ofc_Number2100LStreetMember_FEC0FBC65E0E60E692E69B3DC85766D4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 2100 L Street [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2100LStreetMember" xlink:label="loc_ofc_Number2100LStreetMember_FEC0FBC65E0E60E692E69B3DC85766D4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2100LStreetMember_FEC0FBC65E0E60E692E69B3DC85766D4" xlink:to="lab_ofc_Number2100LStreetMember_FEC0FBC65E0E60E692E69B3DC85766D4" xlink:type="arc" />
    <link:label id="lab_ofc_Number2100RideoutRoadMember_523C4864CF7E9B72A2449B3DC8570655_terseLabel_en-US" xlink:label="lab_ofc_Number2100RideoutRoadMember_523C4864CF7E9B72A2449B3DC8570655" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2100 Rideout Road [Member]</link:label>
    <link:label id="lab_ofc_Number2100RideoutRoadMember_523C4864CF7E9B72A2449B3DC8570655_label_en-US" xlink:label="lab_ofc_Number2100RideoutRoadMember_523C4864CF7E9B72A2449B3DC8570655" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2100 Rideout Road [Member]</link:label>
    <link:label id="lab_ofc_Number2100RideoutRoadMember_523C4864CF7E9B72A2449B3DC8570655_documentation_en-US" xlink:label="lab_ofc_Number2100RideoutRoadMember_523C4864CF7E9B72A2449B3DC8570655" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 2100 Rideout Road [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2100RideoutRoadMember" xlink:label="loc_ofc_Number2100RideoutRoadMember_523C4864CF7E9B72A2449B3DC8570655" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2100RideoutRoadMember_523C4864CF7E9B72A2449B3DC8570655" xlink:to="lab_ofc_Number2100RideoutRoadMember_523C4864CF7E9B72A2449B3DC8570655" xlink:type="arc" />
    <link:label id="lab_ofc_Number22289ExplorationDriveMember_0D5E081848A0F2A744159B3DC8570AF4_terseLabel_en-US" xlink:label="lab_ofc_Number22289ExplorationDriveMember_0D5E081848A0F2A744159B3DC8570AF4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">22289 Exploration Drive [Member]</link:label>
    <link:label id="lab_ofc_Number22289ExplorationDriveMember_0D5E081848A0F2A744159B3DC8570AF4_label_en-US" xlink:label="lab_ofc_Number22289ExplorationDriveMember_0D5E081848A0F2A744159B3DC8570AF4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 22289 Exploration Drive [Member]</link:label>
    <link:label id="lab_ofc_Number22289ExplorationDriveMember_0D5E081848A0F2A744159B3DC8570AF4_documentation_en-US" xlink:label="lab_ofc_Number22289ExplorationDriveMember_0D5E081848A0F2A744159B3DC8570AF4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 22289 Exploration Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number22289ExplorationDriveMember" xlink:label="loc_ofc_Number22289ExplorationDriveMember_0D5E081848A0F2A744159B3DC8570AF4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number22289ExplorationDriveMember_0D5E081848A0F2A744159B3DC8570AF4" xlink:to="lab_ofc_Number22289ExplorationDriveMember_0D5E081848A0F2A744159B3DC8570AF4" xlink:type="arc" />
    <link:label id="lab_ofc_Number22299ExplorationDriveMember_8017AB968DA856E424D09B3DC8572427_terseLabel_en-US" xlink:label="lab_ofc_Number22299ExplorationDriveMember_8017AB968DA856E424D09B3DC8572427" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">22299 Exploration Drive [Member]</link:label>
    <link:label id="lab_ofc_Number22299ExplorationDriveMember_8017AB968DA856E424D09B3DC8572427_label_en-US" xlink:label="lab_ofc_Number22299ExplorationDriveMember_8017AB968DA856E424D09B3DC8572427" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 22299 Exploration Drive [Member]</link:label>
    <link:label id="lab_ofc_Number22299ExplorationDriveMember_8017AB968DA856E424D09B3DC8572427_documentation_en-US" xlink:label="lab_ofc_Number22299ExplorationDriveMember_8017AB968DA856E424D09B3DC8572427" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 22299 Exploration Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number22299ExplorationDriveMember" xlink:label="loc_ofc_Number22299ExplorationDriveMember_8017AB968DA856E424D09B3DC8572427" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number22299ExplorationDriveMember_8017AB968DA856E424D09B3DC8572427" xlink:to="lab_ofc_Number22299ExplorationDriveMember_8017AB968DA856E424D09B3DC8572427" xlink:type="arc" />
    <link:label id="lab_ofc_Number22300ExplorationDriveMember_68CB3D458B8E1D8641669B3DC8571D29_terseLabel_en-US" xlink:label="lab_ofc_Number22300ExplorationDriveMember_68CB3D458B8E1D8641669B3DC8571D29" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">22300 Exploration Drive [Member]</link:label>
    <link:label id="lab_ofc_Number22300ExplorationDriveMember_68CB3D458B8E1D8641669B3DC8571D29_label_en-US" xlink:label="lab_ofc_Number22300ExplorationDriveMember_68CB3D458B8E1D8641669B3DC8571D29" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 22300 Exploration Drive [Member]</link:label>
    <link:label id="lab_ofc_Number22300ExplorationDriveMember_68CB3D458B8E1D8641669B3DC8571D29_documentation_en-US" xlink:label="lab_ofc_Number22300ExplorationDriveMember_68CB3D458B8E1D8641669B3DC8571D29" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 22230 Exploration Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number22300ExplorationDriveMember" xlink:label="loc_ofc_Number22300ExplorationDriveMember_68CB3D458B8E1D8641669B3DC8571D29" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number22300ExplorationDriveMember_68CB3D458B8E1D8641669B3DC8571D29" xlink:to="lab_ofc_Number22300ExplorationDriveMember_68CB3D458B8E1D8641669B3DC8571D29" xlink:type="arc" />
    <link:label id="lab_ofc_Number22309ExplorationDriveMember_268467707036D61AABE29B3DC857C139_terseLabel_en-US" xlink:label="lab_ofc_Number22309ExplorationDriveMember_268467707036D61AABE29B3DC857C139" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">22309 Exploration Drive [Member]</link:label>
    <link:label id="lab_ofc_Number22309ExplorationDriveMember_268467707036D61AABE29B3DC857C139_label_en-US" xlink:label="lab_ofc_Number22309ExplorationDriveMember_268467707036D61AABE29B3DC857C139" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 22309 Exploration Drive [Member]</link:label>
    <link:label id="lab_ofc_Number22309ExplorationDriveMember_268467707036D61AABE29B3DC857C139_documentation_en-US" xlink:label="lab_ofc_Number22309ExplorationDriveMember_268467707036D61AABE29B3DC857C139" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 22309 Exploration Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number22309ExplorationDriveMember" xlink:label="loc_ofc_Number22309ExplorationDriveMember_268467707036D61AABE29B3DC857C139" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number22309ExplorationDriveMember_268467707036D61AABE29B3DC857C139" xlink:to="lab_ofc_Number22309ExplorationDriveMember_268467707036D61AABE29B3DC857C139" xlink:type="arc" />
    <link:label id="lab_ofc_Number23535CottonwoodParkwayMember_D3A554EBA928BE8504739B3DC8578B6B_terseLabel_en-US" xlink:label="lab_ofc_Number23535CottonwoodParkwayMember_D3A554EBA928BE8504739B3DC8578B6B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">23535 Cottonwood Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number23535CottonwoodParkwayMember_D3A554EBA928BE8504739B3DC8578B6B_label_en-US" xlink:label="lab_ofc_Number23535CottonwoodParkwayMember_D3A554EBA928BE8504739B3DC8578B6B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 23535 Cottonwood Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number23535CottonwoodParkwayMember_D3A554EBA928BE8504739B3DC8578B6B_documentation_en-US" xlink:label="lab_ofc_Number23535CottonwoodParkwayMember_D3A554EBA928BE8504739B3DC8578B6B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 23535 Cottonwood Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number23535CottonwoodParkwayMember" xlink:label="loc_ofc_Number23535CottonwoodParkwayMember_D3A554EBA928BE8504739B3DC8578B6B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number23535CottonwoodParkwayMember_D3A554EBA928BE8504739B3DC8578B6B" xlink:to="lab_ofc_Number23535CottonwoodParkwayMember_D3A554EBA928BE8504739B3DC8578B6B" xlink:type="arc" />
    <link:label id="lab_ofc_Number250WPrattStMember_69A68BA9D5EAFC107EDC9B3DC858E1F6_terseLabel_en-US" xlink:label="lab_ofc_Number250WPrattStMember_69A68BA9D5EAFC107EDC9B3DC858E1F6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">250 W Pratt St [Member]</link:label>
    <link:label id="lab_ofc_Number250WPrattStMember_69A68BA9D5EAFC107EDC9B3DC858E1F6_label_en-US" xlink:label="lab_ofc_Number250WPrattStMember_69A68BA9D5EAFC107EDC9B3DC858E1F6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 250 W Pratt St [Member]</link:label>
    <link:label id="lab_ofc_Number250WPrattStMember_69A68BA9D5EAFC107EDC9B3DC858E1F6_documentation_en-US" xlink:label="lab_ofc_Number250WPrattStMember_69A68BA9D5EAFC107EDC9B3DC858E1F6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 250 W Pratt St [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number250WPrattStMember" xlink:label="loc_ofc_Number250WPrattStMember_69A68BA9D5EAFC107EDC9B3DC858E1F6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number250WPrattStMember_69A68BA9D5EAFC107EDC9B3DC858E1F6" xlink:to="lab_ofc_Number250WPrattStMember_69A68BA9D5EAFC107EDC9B3DC858E1F6" xlink:type="arc" />
    <link:label id="lab_ofc_Number2500RivaRoadMember_FAAAAD747AD95ACF294B9B3DC8586B3A_terseLabel_en-US" xlink:label="lab_ofc_Number2500RivaRoadMember_FAAAAD747AD95ACF294B9B3DC8586B3A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2500 Riva Road [Member]</link:label>
    <link:label id="lab_ofc_Number2500RivaRoadMember_FAAAAD747AD95ACF294B9B3DC8586B3A_label_en-US" xlink:label="lab_ofc_Number2500RivaRoadMember_FAAAAD747AD95ACF294B9B3DC8586B3A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2500 Riva Road [Member]</link:label>
    <link:label id="lab_ofc_Number2500RivaRoadMember_FAAAAD747AD95ACF294B9B3DC8586B3A_documentation_en-US" xlink:label="lab_ofc_Number2500RivaRoadMember_FAAAAD747AD95ACF294B9B3DC8586B3A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 2500 Riva Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2500RivaRoadMember" xlink:label="loc_ofc_Number2500RivaRoadMember_FAAAAD747AD95ACF294B9B3DC8586B3A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2500RivaRoadMember_FAAAAD747AD95ACF294B9B3DC8586B3A" xlink:to="lab_ofc_Number2500RivaRoadMember_FAAAAD747AD95ACF294B9B3DC8586B3A" xlink:type="arc" />
    <link:label id="lab_ofc_Number2600ParkTowerDriveMember_41E3BD50B2076550EBE39B3DC8584376_terseLabel_en-US" xlink:label="lab_ofc_Number2600ParkTowerDriveMember_41E3BD50B2076550EBE39B3DC8584376" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2600 Park Tower Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2600ParkTowerDriveMember_41E3BD50B2076550EBE39B3DC8584376_label_en-US" xlink:label="lab_ofc_Number2600ParkTowerDriveMember_41E3BD50B2076550EBE39B3DC8584376" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2600 Park Tower Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2600ParkTowerDriveMember_41E3BD50B2076550EBE39B3DC8584376_documentation_en-US" xlink:label="lab_ofc_Number2600ParkTowerDriveMember_41E3BD50B2076550EBE39B3DC8584376" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 2600 Park Tower Drive [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2600ParkTowerDriveMember" xlink:label="loc_ofc_Number2600ParkTowerDriveMember_41E3BD50B2076550EBE39B3DC8584376" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2600ParkTowerDriveMember_41E3BD50B2076550EBE39B3DC8584376" xlink:to="lab_ofc_Number2600ParkTowerDriveMember_41E3BD50B2076550EBE39B3DC8584376" xlink:type="arc" />
    <link:label id="lab_ofc_Number2691TechnologyDriveMember_7D193E28DA3ECFE47AD29B3DC8589D9D_terseLabel_en-US" xlink:label="lab_ofc_Number2691TechnologyDriveMember_7D193E28DA3ECFE47AD29B3DC8589D9D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2691 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2691TechnologyDriveMember_7D193E28DA3ECFE47AD29B3DC8589D9D_label_en-US" xlink:label="lab_ofc_Number2691TechnologyDriveMember_7D193E28DA3ECFE47AD29B3DC8589D9D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2691 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2691TechnologyDriveMember_7D193E28DA3ECFE47AD29B3DC8589D9D_documentation_en-US" xlink:label="lab_ofc_Number2691TechnologyDriveMember_7D193E28DA3ECFE47AD29B3DC8589D9D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 2691 Technology Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2691TechnologyDriveMember" xlink:label="loc_ofc_Number2691TechnologyDriveMember_7D193E28DA3ECFE47AD29B3DC8589D9D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2691TechnologyDriveMember_7D193E28DA3ECFE47AD29B3DC8589D9D" xlink:to="lab_ofc_Number2691TechnologyDriveMember_7D193E28DA3ECFE47AD29B3DC8589D9D" xlink:type="arc" />
    <link:label id="lab_ofc_Number2701TechnologyDriveMember_E04CFDAF8EE19D83B6519B3DC8585E2D_terseLabel_en-US" xlink:label="lab_ofc_Number2701TechnologyDriveMember_E04CFDAF8EE19D83B6519B3DC8585E2D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2701 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2701TechnologyDriveMember_E04CFDAF8EE19D83B6519B3DC8585E2D_label_en-US" xlink:label="lab_ofc_Number2701TechnologyDriveMember_E04CFDAF8EE19D83B6519B3DC8585E2D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2701 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2701TechnologyDriveMember_E04CFDAF8EE19D83B6519B3DC8585E2D_documentation_en-US" xlink:label="lab_ofc_Number2701TechnologyDriveMember_E04CFDAF8EE19D83B6519B3DC8585E2D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 2701 Technology Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2701TechnologyDriveMember" xlink:label="loc_ofc_Number2701TechnologyDriveMember_E04CFDAF8EE19D83B6519B3DC8585E2D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2701TechnologyDriveMember_E04CFDAF8EE19D83B6519B3DC8585E2D" xlink:to="lab_ofc_Number2701TechnologyDriveMember_E04CFDAF8EE19D83B6519B3DC8585E2D" xlink:type="arc" />
    <link:label id="lab_ofc_Number2711TechnologyDriveMember_5F74172417AA081AF4439B3DC858CD0A_terseLabel_en-US" xlink:label="lab_ofc_Number2711TechnologyDriveMember_5F74172417AA081AF4439B3DC858CD0A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2711 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2711TechnologyDriveMember_5F74172417AA081AF4439B3DC858CD0A_label_en-US" xlink:label="lab_ofc_Number2711TechnologyDriveMember_5F74172417AA081AF4439B3DC858CD0A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2711 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2711TechnologyDriveMember_5F74172417AA081AF4439B3DC858CD0A_documentation_en-US" xlink:label="lab_ofc_Number2711TechnologyDriveMember_5F74172417AA081AF4439B3DC858CD0A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 2711 Technology Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2711TechnologyDriveMember" xlink:label="loc_ofc_Number2711TechnologyDriveMember_5F74172417AA081AF4439B3DC858CD0A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2711TechnologyDriveMember_5F74172417AA081AF4439B3DC858CD0A" xlink:to="lab_ofc_Number2711TechnologyDriveMember_5F74172417AA081AF4439B3DC858CD0A" xlink:type="arc" />
    <link:label id="lab_ofc_Number2720TechnologyDriveMember_D404C3947277DE6B36F39B3DC8589BF6_terseLabel_en-US" xlink:label="lab_ofc_Number2720TechnologyDriveMember_D404C3947277DE6B36F39B3DC8589BF6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2720 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2720TechnologyDriveMember_D404C3947277DE6B36F39B3DC8589BF6_label_en-US" xlink:label="lab_ofc_Number2720TechnologyDriveMember_D404C3947277DE6B36F39B3DC8589BF6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2720 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2720TechnologyDriveMember_D404C3947277DE6B36F39B3DC8589BF6_documentation_en-US" xlink:label="lab_ofc_Number2720TechnologyDriveMember_D404C3947277DE6B36F39B3DC8589BF6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 2720 Technology Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2720TechnologyDriveMember" xlink:label="loc_ofc_Number2720TechnologyDriveMember_D404C3947277DE6B36F39B3DC8589BF6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2720TechnologyDriveMember_D404C3947277DE6B36F39B3DC8589BF6" xlink:to="lab_ofc_Number2720TechnologyDriveMember_D404C3947277DE6B36F39B3DC8589BF6" xlink:type="arc" />
    <link:label id="lab_ofc_Number2721TechnologyDriveMember_00B67D57F1A3377103279B3DC858D64A_terseLabel_en-US" xlink:label="lab_ofc_Number2721TechnologyDriveMember_00B67D57F1A3377103279B3DC858D64A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2721 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2721TechnologyDriveMember_00B67D57F1A3377103279B3DC858D64A_label_en-US" xlink:label="lab_ofc_Number2721TechnologyDriveMember_00B67D57F1A3377103279B3DC858D64A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2721 Technology Drive [Member]</link:label>
    <link:label id="lab_ofc_Number2721TechnologyDriveMember_00B67D57F1A3377103279B3DC858D64A_documentation_en-US" xlink:label="lab_ofc_Number2721TechnologyDriveMember_00B67D57F1A3377103279B3DC858D64A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 2721 Technology Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2721TechnologyDriveMember" xlink:label="loc_ofc_Number2721TechnologyDriveMember_00B67D57F1A3377103279B3DC858D64A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2721TechnologyDriveMember_00B67D57F1A3377103279B3DC858D64A" xlink:to="lab_ofc_Number2721TechnologyDriveMember_00B67D57F1A3377103279B3DC858D64A" xlink:type="arc" />
    <link:label id="lab_ofc_Number2730HerculesRoadMember_A056B9F4ED132E4332439B3DC8591A4E_terseLabel_en-US" xlink:label="lab_ofc_Number2730HerculesRoadMember_A056B9F4ED132E4332439B3DC8591A4E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2730 Hercules Road [Member]</link:label>
    <link:label id="lab_ofc_Number2730HerculesRoadMember_A056B9F4ED132E4332439B3DC8591A4E_label_en-US" xlink:label="lab_ofc_Number2730HerculesRoadMember_A056B9F4ED132E4332439B3DC8591A4E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 2730 Hercules Road [Member]</link:label>
    <link:label id="lab_ofc_Number2730HerculesRoadMember_A056B9F4ED132E4332439B3DC8591A4E_documentation_en-US" xlink:label="lab_ofc_Number2730HerculesRoadMember_A056B9F4ED132E4332439B3DC8591A4E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 2730 Hercules Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number2730HerculesRoadMember" xlink:label="loc_ofc_Number2730HerculesRoadMember_A056B9F4ED132E4332439B3DC8591A4E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number2730HerculesRoadMember_A056B9F4ED132E4332439B3DC8591A4E" xlink:to="lab_ofc_Number2730HerculesRoadMember_A056B9F4ED132E4332439B3DC8591A4E" xlink:type="arc" />
    <link:label id="lab_ofc_Number30LightStreetMember_78E5D072BC1295CC7E4B9B3DC859A8E9_terseLabel_en-US" xlink:label="lab_ofc_Number30LightStreetMember_78E5D072BC1295CC7E4B9B3DC859A8E9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">30 Light Street [Member]</link:label>
    <link:label id="lab_ofc_Number30LightStreetMember_78E5D072BC1295CC7E4B9B3DC859A8E9_label_en-US" xlink:label="lab_ofc_Number30LightStreetMember_78E5D072BC1295CC7E4B9B3DC859A8E9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 30 Light Street [Member]</link:label>
    <link:label id="lab_ofc_Number30LightStreetMember_78E5D072BC1295CC7E4B9B3DC859A8E9_documentation_en-US" xlink:label="lab_ofc_Number30LightStreetMember_78E5D072BC1295CC7E4B9B3DC859A8E9" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 30 Light Street [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number30LightStreetMember" xlink:label="loc_ofc_Number30LightStreetMember_78E5D072BC1295CC7E4B9B3DC859A8E9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number30LightStreetMember_78E5D072BC1295CC7E4B9B3DC859A8E9" xlink:to="lab_ofc_Number30LightStreetMember_78E5D072BC1295CC7E4B9B3DC859A8E9" xlink:type="arc" />
    <link:label id="lab_ofc_Number300SentinelDriveMember_4213FD97AB73A369B03C9B3DC8597530_terseLabel_en-US" xlink:label="lab_ofc_Number300SentinelDriveMember_4213FD97AB73A369B03C9B3DC8597530" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">300 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number300SentinelDriveMember_4213FD97AB73A369B03C9B3DC8597530_label_en-US" xlink:label="lab_ofc_Number300SentinelDriveMember_4213FD97AB73A369B03C9B3DC8597530" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 300 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number300SentinelDriveMember_4213FD97AB73A369B03C9B3DC8597530_documentation_en-US" xlink:label="lab_ofc_Number300SentinelDriveMember_4213FD97AB73A369B03C9B3DC8597530" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 300 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number300SentinelDriveMember" xlink:label="loc_ofc_Number300SentinelDriveMember_4213FD97AB73A369B03C9B3DC8597530" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number300SentinelDriveMember_4213FD97AB73A369B03C9B3DC8597530" xlink:to="lab_ofc_Number300SentinelDriveMember_4213FD97AB73A369B03C9B3DC8597530" xlink:type="arc" />
    <link:label id="lab_ofc_Number302SentinelDriveMember_9A29014EE80EA426920A9B3DC8591A60_terseLabel_en-US" xlink:label="lab_ofc_Number302SentinelDriveMember_9A29014EE80EA426920A9B3DC8591A60" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">302 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number302SentinelDriveMember_9A29014EE80EA426920A9B3DC8591A60_label_en-US" xlink:label="lab_ofc_Number302SentinelDriveMember_9A29014EE80EA426920A9B3DC8591A60" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 302 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number302SentinelDriveMember_9A29014EE80EA426920A9B3DC8591A60_documentation_en-US" xlink:label="lab_ofc_Number302SentinelDriveMember_9A29014EE80EA426920A9B3DC8591A60" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 302 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number302SentinelDriveMember" xlink:label="loc_ofc_Number302SentinelDriveMember_9A29014EE80EA426920A9B3DC8591A60" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number302SentinelDriveMember_9A29014EE80EA426920A9B3DC8591A60" xlink:to="lab_ofc_Number302SentinelDriveMember_9A29014EE80EA426920A9B3DC8591A60" xlink:type="arc" />
    <link:label id="lab_ofc_Number304SentinelDriveMember_9C39DF22B06CB129221D9B3DC859ECE0_terseLabel_en-US" xlink:label="lab_ofc_Number304SentinelDriveMember_9C39DF22B06CB129221D9B3DC859ECE0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">304 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number304SentinelDriveMember_9C39DF22B06CB129221D9B3DC859ECE0_label_en-US" xlink:label="lab_ofc_Number304SentinelDriveMember_9C39DF22B06CB129221D9B3DC859ECE0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 304 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number304SentinelDriveMember_9C39DF22B06CB129221D9B3DC859ECE0_documentation_en-US" xlink:label="lab_ofc_Number304SentinelDriveMember_9C39DF22B06CB129221D9B3DC859ECE0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 304 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number304SentinelDriveMember" xlink:label="loc_ofc_Number304SentinelDriveMember_9C39DF22B06CB129221D9B3DC859ECE0" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number304SentinelDriveMember_9C39DF22B06CB129221D9B3DC859ECE0" xlink:to="lab_ofc_Number304SentinelDriveMember_9C39DF22B06CB129221D9B3DC859ECE0" xlink:type="arc" />
    <link:label id="lab_ofc_Number306SentinelDriveMember_9F99563847B8EF6950B79B3DC859734D_terseLabel_en-US" xlink:label="lab_ofc_Number306SentinelDriveMember_9F99563847B8EF6950B79B3DC859734D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">306 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number306SentinelDriveMember_9F99563847B8EF6950B79B3DC859734D_label_en-US" xlink:label="lab_ofc_Number306SentinelDriveMember_9F99563847B8EF6950B79B3DC859734D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 306 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number306SentinelDriveMember_9F99563847B8EF6950B79B3DC859734D_documentation_en-US" xlink:label="lab_ofc_Number306SentinelDriveMember_9F99563847B8EF6950B79B3DC859734D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 306 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number306SentinelDriveMember" xlink:label="loc_ofc_Number306SentinelDriveMember_9F99563847B8EF6950B79B3DC859734D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number306SentinelDriveMember_9F99563847B8EF6950B79B3DC859734D" xlink:to="lab_ofc_Number306SentinelDriveMember_9F99563847B8EF6950B79B3DC859734D" xlink:type="arc" />
    <link:label id="lab_ofc_Number308SentinelDriveMember_AC6A95CC6BA8CC0F076C9B3DC85931C0_terseLabel_en-US" xlink:label="lab_ofc_Number308SentinelDriveMember_AC6A95CC6BA8CC0F076C9B3DC85931C0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">308 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number308SentinelDriveMember_AC6A95CC6BA8CC0F076C9B3DC85931C0_label_en-US" xlink:label="lab_ofc_Number308SentinelDriveMember_AC6A95CC6BA8CC0F076C9B3DC85931C0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 308 Sentinel Drive [Member]</link:label>
    <link:label id="lab_ofc_Number308SentinelDriveMember_AC6A95CC6BA8CC0F076C9B3DC85931C0_documentation_en-US" xlink:label="lab_ofc_Number308SentinelDriveMember_AC6A95CC6BA8CC0F076C9B3DC85931C0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 308 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number308SentinelDriveMember" xlink:label="loc_ofc_Number308SentinelDriveMember_AC6A95CC6BA8CC0F076C9B3DC85931C0" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number308SentinelDriveMember_AC6A95CC6BA8CC0F076C9B3DC85931C0" xlink:to="lab_ofc_Number308SentinelDriveMember_AC6A95CC6BA8CC0F076C9B3DC85931C0" xlink:type="arc" />
    <link:label id="lab_ofc_Number310SentinelWayMember_8E4DF712A37E33011A099B3DC85A5984_terseLabel_en-US" xlink:label="lab_ofc_Number310SentinelWayMember_8E4DF712A37E33011A099B3DC85A5984" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">310 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number310SentinelWayMember_8E4DF712A37E33011A099B3DC85A5984_label_en-US" xlink:label="lab_ofc_Number310SentinelWayMember_8E4DF712A37E33011A099B3DC85A5984" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 310 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number310SentinelWayMember_8E4DF712A37E33011A099B3DC85A5984_documentation_en-US" xlink:label="lab_ofc_Number310SentinelWayMember_8E4DF712A37E33011A099B3DC85A5984" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 310 Sentinel Way [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number310SentinelWayMember" xlink:label="loc_ofc_Number310SentinelWayMember_8E4DF712A37E33011A099B3DC85A5984" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number310SentinelWayMember_8E4DF712A37E33011A099B3DC85A5984" xlink:to="lab_ofc_Number310SentinelWayMember_8E4DF712A37E33011A099B3DC85A5984" xlink:type="arc" />
    <link:label id="lab_ofc_Number310BridgeStreetMember_827F0D959FFF579FCE929B3DC85A8664_terseLabel_en-US" xlink:label="lab_ofc_Number310BridgeStreetMember_827F0D959FFF579FCE929B3DC85A8664" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">310 The Bridge Street [Member]</link:label>
    <link:label id="lab_ofc_Number310BridgeStreetMember_827F0D959FFF579FCE929B3DC85A8664_label_en-US" xlink:label="lab_ofc_Number310BridgeStreetMember_827F0D959FFF579FCE929B3DC85A8664" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 310 the Bridge Street [Member]</link:label>
    <link:label id="lab_ofc_Number310BridgeStreetMember_827F0D959FFF579FCE929B3DC85A8664_documentation_en-US" xlink:label="lab_ofc_Number310BridgeStreetMember_827F0D959FFF579FCE929B3DC85A8664" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 310 The Bridge Street, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number310BridgeStreetMember" xlink:label="loc_ofc_Number310BridgeStreetMember_827F0D959FFF579FCE929B3DC85A8664" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number310BridgeStreetMember_827F0D959FFF579FCE929B3DC85A8664" xlink:to="lab_ofc_Number310BridgeStreetMember_827F0D959FFF579FCE929B3DC85A8664" xlink:type="arc" />
    <link:label id="lab_ofc_Number312SentinelWayMember_01C01AEDA2A48E5AA6079B3DC85A35DD_terseLabel_en-US" xlink:label="lab_ofc_Number312SentinelWayMember_01C01AEDA2A48E5AA6079B3DC85A35DD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">312 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number312SentinelWayMember_01C01AEDA2A48E5AA6079B3DC85A35DD_label_en-US" xlink:label="lab_ofc_Number312SentinelWayMember_01C01AEDA2A48E5AA6079B3DC85A35DD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 312 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number312SentinelWayMember_01C01AEDA2A48E5AA6079B3DC85A35DD_documentation_en-US" xlink:label="lab_ofc_Number312SentinelWayMember_01C01AEDA2A48E5AA6079B3DC85A35DD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 312 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number312SentinelWayMember" xlink:label="loc_ofc_Number312SentinelWayMember_01C01AEDA2A48E5AA6079B3DC85A35DD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number312SentinelWayMember_01C01AEDA2A48E5AA6079B3DC85A35DD" xlink:to="lab_ofc_Number312SentinelWayMember_01C01AEDA2A48E5AA6079B3DC85A35DD" xlink:type="arc" />
    <link:label id="lab_ofc_Number314SentinelWayMember_0E27BF30F02D80BC8A969B3DC85A34D4_terseLabel_en-US" xlink:label="lab_ofc_Number314SentinelWayMember_0E27BF30F02D80BC8A969B3DC85A34D4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">314 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number314SentinelWayMember_0E27BF30F02D80BC8A969B3DC85A34D4_label_en-US" xlink:label="lab_ofc_Number314SentinelWayMember_0E27BF30F02D80BC8A969B3DC85A34D4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 314 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number314SentinelWayMember_0E27BF30F02D80BC8A969B3DC85A34D4_documentation_en-US" xlink:label="lab_ofc_Number314SentinelWayMember_0E27BF30F02D80BC8A969B3DC85A34D4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 314 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number314SentinelWayMember" xlink:label="loc_ofc_Number314SentinelWayMember_0E27BF30F02D80BC8A969B3DC85A34D4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number314SentinelWayMember_0E27BF30F02D80BC8A969B3DC85A34D4" xlink:to="lab_ofc_Number314SentinelWayMember_0E27BF30F02D80BC8A969B3DC85A34D4" xlink:type="arc" />
    <link:label id="lab_ofc_Number316SentinelWayMember_552CCE94A1ED1613D8CE9B3DC85AD244_terseLabel_en-US" xlink:label="lab_ofc_Number316SentinelWayMember_552CCE94A1ED1613D8CE9B3DC85AD244" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">316 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number316SentinelWayMember_552CCE94A1ED1613D8CE9B3DC85AD244_label_en-US" xlink:label="lab_ofc_Number316SentinelWayMember_552CCE94A1ED1613D8CE9B3DC85AD244" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 316 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number316SentinelWayMember_552CCE94A1ED1613D8CE9B3DC85AD244_documentation_en-US" xlink:label="lab_ofc_Number316SentinelWayMember_552CCE94A1ED1613D8CE9B3DC85AD244" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 316 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number316SentinelWayMember" xlink:label="loc_ofc_Number316SentinelWayMember_552CCE94A1ED1613D8CE9B3DC85AD244" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number316SentinelWayMember_552CCE94A1ED1613D8CE9B3DC85AD244" xlink:to="lab_ofc_Number316SentinelWayMember_552CCE94A1ED1613D8CE9B3DC85AD244" xlink:type="arc" />
    <link:label id="lab_ofc_Number318SentinelWayMember_B50AFC72128B753B91899B3DC85AF063_terseLabel_en-US" xlink:label="lab_ofc_Number318SentinelWayMember_B50AFC72128B753B91899B3DC85AF063" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">318 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number318SentinelWayMember_B50AFC72128B753B91899B3DC85AF063_label_en-US" xlink:label="lab_ofc_Number318SentinelWayMember_B50AFC72128B753B91899B3DC85AF063" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 318 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number318SentinelWayMember_B50AFC72128B753B91899B3DC85AF063_documentation_en-US" xlink:label="lab_ofc_Number318SentinelWayMember_B50AFC72128B753B91899B3DC85AF063" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 318 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number318SentinelWayMember" xlink:label="loc_ofc_Number318SentinelWayMember_B50AFC72128B753B91899B3DC85AF063" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number318SentinelWayMember_B50AFC72128B753B91899B3DC85AF063" xlink:to="lab_ofc_Number318SentinelWayMember_B50AFC72128B753B91899B3DC85AF063" xlink:type="arc" />
    <link:label id="lab_ofc_Number320SentinelWayMember_B98EE7FFC4F1EA6190E89B3DC85ACF48_terseLabel_en-US" xlink:label="lab_ofc_Number320SentinelWayMember_B98EE7FFC4F1EA6190E89B3DC85ACF48" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">320 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number320SentinelWayMember_B98EE7FFC4F1EA6190E89B3DC85ACF48_label_en-US" xlink:label="lab_ofc_Number320SentinelWayMember_B98EE7FFC4F1EA6190E89B3DC85ACF48" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 320 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number320SentinelWayMember_B98EE7FFC4F1EA6190E89B3DC85ACF48_documentation_en-US" xlink:label="lab_ofc_Number320SentinelWayMember_B98EE7FFC4F1EA6190E89B3DC85ACF48" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 320 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number320SentinelWayMember" xlink:label="loc_ofc_Number320SentinelWayMember_B98EE7FFC4F1EA6190E89B3DC85ACF48" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number320SentinelWayMember_B98EE7FFC4F1EA6190E89B3DC85ACF48" xlink:to="lab_ofc_Number320SentinelWayMember_B98EE7FFC4F1EA6190E89B3DC85ACF48" xlink:type="arc" />
    <link:label id="lab_ofc_Number322SentinelWayMember_C70A05946A2EB3E2FECE9B3DC85A06A7_terseLabel_en-US" xlink:label="lab_ofc_Number322SentinelWayMember_C70A05946A2EB3E2FECE9B3DC85A06A7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">322 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number322SentinelWayMember_C70A05946A2EB3E2FECE9B3DC85A06A7_label_en-US" xlink:label="lab_ofc_Number322SentinelWayMember_C70A05946A2EB3E2FECE9B3DC85A06A7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 322 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number322SentinelWayMember_C70A05946A2EB3E2FECE9B3DC85A06A7_documentation_en-US" xlink:label="lab_ofc_Number322SentinelWayMember_C70A05946A2EB3E2FECE9B3DC85A06A7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 322 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number322SentinelWayMember" xlink:label="loc_ofc_Number322SentinelWayMember_C70A05946A2EB3E2FECE9B3DC85A06A7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number322SentinelWayMember_C70A05946A2EB3E2FECE9B3DC85A06A7" xlink:to="lab_ofc_Number322SentinelWayMember_C70A05946A2EB3E2FECE9B3DC85A06A7" xlink:type="arc" />
    <link:label id="lab_ofc_Number324SentinelWayMember_FF195D52D5B12CD1B2F69B3DC85AAA7F_terseLabel_en-US" xlink:label="lab_ofc_Number324SentinelWayMember_FF195D52D5B12CD1B2F69B3DC85AAA7F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">324 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number324SentinelWayMember_FF195D52D5B12CD1B2F69B3DC85AAA7F_label_en-US" xlink:label="lab_ofc_Number324SentinelWayMember_FF195D52D5B12CD1B2F69B3DC85AAA7F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 324 Sentinel Way [Member]</link:label>
    <link:label id="lab_ofc_Number324SentinelWayMember_FF195D52D5B12CD1B2F69B3DC85AAA7F_documentation_en-US" xlink:label="lab_ofc_Number324SentinelWayMember_FF195D52D5B12CD1B2F69B3DC85AAA7F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 324 Sentinel Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number324SentinelWayMember" xlink:label="loc_ofc_Number324SentinelWayMember_FF195D52D5B12CD1B2F69B3DC85AAA7F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number324SentinelWayMember_FF195D52D5B12CD1B2F69B3DC85AAA7F" xlink:to="lab_ofc_Number324SentinelWayMember_FF195D52D5B12CD1B2F69B3DC85AAA7F" xlink:type="arc" />
    <link:label id="lab_ofc_Number4000MarketStreetMember_D04CF78637BCC2BB6C759B3DC85A0518_terseLabel_en-US" xlink:label="lab_ofc_Number4000MarketStreetMember_D04CF78637BCC2BB6C759B3DC85A0518" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">4000 Market Street [Member]</link:label>
    <link:label id="lab_ofc_Number4000MarketStreetMember_D04CF78637BCC2BB6C759B3DC85A0518_label_en-US" xlink:label="lab_ofc_Number4000MarketStreetMember_D04CF78637BCC2BB6C759B3DC85A0518" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 4000 Market Street [Member]</link:label>
    <link:label id="lab_ofc_Number4000MarketStreetMember_D04CF78637BCC2BB6C759B3DC85A0518_documentation_en-US" xlink:label="lab_ofc_Number4000MarketStreetMember_D04CF78637BCC2BB6C759B3DC85A0518" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 4000 Market Street [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number4000MarketStreetMember" xlink:label="loc_ofc_Number4000MarketStreetMember_D04CF78637BCC2BB6C759B3DC85A0518" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number4000MarketStreetMember_D04CF78637BCC2BB6C759B3DC85A0518" xlink:to="lab_ofc_Number4000MarketStreetMember_D04CF78637BCC2BB6C759B3DC85A0518" xlink:type="arc" />
    <link:label id="lab_ofc_Number4100MarketStreetMember_CDBE6F070A4705F3236D9B3DC85B43C4_terseLabel_en-US" xlink:label="lab_ofc_Number4100MarketStreetMember_CDBE6F070A4705F3236D9B3DC85B43C4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">4100 Market Street [Member]</link:label>
    <link:label id="lab_ofc_Number4100MarketStreetMember_CDBE6F070A4705F3236D9B3DC85B43C4_label_en-US" xlink:label="lab_ofc_Number4100MarketStreetMember_CDBE6F070A4705F3236D9B3DC85B43C4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 4100 Market Street [Member]</link:label>
    <link:label id="lab_ofc_Number4100MarketStreetMember_CDBE6F070A4705F3236D9B3DC85B43C4_documentation_en-US" xlink:label="lab_ofc_Number4100MarketStreetMember_CDBE6F070A4705F3236D9B3DC85B43C4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 4100 Market Street [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number4100MarketStreetMember" xlink:label="loc_ofc_Number4100MarketStreetMember_CDBE6F070A4705F3236D9B3DC85B43C4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number4100MarketStreetMember_CDBE6F070A4705F3236D9B3DC85B43C4" xlink:to="lab_ofc_Number4100MarketStreetMember_CDBE6F070A4705F3236D9B3DC85B43C4" xlink:type="arc" />
    <link:label id="lab_ofc_Number410NationalBusinessParkwayMember_B5896FEA10C03F8F25C49B3DC85B95A2_terseLabel_en-US" xlink:label="lab_ofc_Number410NationalBusinessParkwayMember_B5896FEA10C03F8F25C49B3DC85B95A2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">410 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number410NationalBusinessParkwayMember_B5896FEA10C03F8F25C49B3DC85B95A2_label_en-US" xlink:label="lab_ofc_Number410NationalBusinessParkwayMember_B5896FEA10C03F8F25C49B3DC85B95A2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 410 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number410NationalBusinessParkwayMember_B5896FEA10C03F8F25C49B3DC85B95A2_documentation_en-US" xlink:label="lab_ofc_Number410NationalBusinessParkwayMember_B5896FEA10C03F8F25C49B3DC85B95A2" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 410 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number410NationalBusinessParkwayMember" xlink:label="loc_ofc_Number410NationalBusinessParkwayMember_B5896FEA10C03F8F25C49B3DC85B95A2" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number410NationalBusinessParkwayMember_B5896FEA10C03F8F25C49B3DC85B95A2" xlink:to="lab_ofc_Number410NationalBusinessParkwayMember_B5896FEA10C03F8F25C49B3DC85B95A2" xlink:type="arc" />
    <link:label id="lab_ofc_Number420NationalBusinessParkwayMember_B7BD1674DBF6F30FEC129B3DC85BFF74_terseLabel_en-US" xlink:label="lab_ofc_Number420NationalBusinessParkwayMember_B7BD1674DBF6F30FEC129B3DC85BFF74" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">420 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number420NationalBusinessParkwayMember_B7BD1674DBF6F30FEC129B3DC85BFF74_label_en-US" xlink:label="lab_ofc_Number420NationalBusinessParkwayMember_B7BD1674DBF6F30FEC129B3DC85BFF74" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 420 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number420NationalBusinessParkwayMember_B7BD1674DBF6F30FEC129B3DC85BFF74_documentation_en-US" xlink:label="lab_ofc_Number420NationalBusinessParkwayMember_B7BD1674DBF6F30FEC129B3DC85BFF74" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 420 National Business Parkway [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number420NationalBusinessParkwayMember" xlink:label="loc_ofc_Number420NationalBusinessParkwayMember_B7BD1674DBF6F30FEC129B3DC85BFF74" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number420NationalBusinessParkwayMember_B7BD1674DBF6F30FEC129B3DC85BFF74" xlink:to="lab_ofc_Number420NationalBusinessParkwayMember_B7BD1674DBF6F30FEC129B3DC85BFF74" xlink:type="arc" />
    <link:label id="lab_ofc_Number430NationalBusinessParkwayMember_037D509C4C021A9A88D79B3DC85BF3DF_terseLabel_en-US" xlink:label="lab_ofc_Number430NationalBusinessParkwayMember_037D509C4C021A9A88D79B3DC85BF3DF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">430 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number430NationalBusinessParkwayMember_037D509C4C021A9A88D79B3DC85BF3DF_label_en-US" xlink:label="lab_ofc_Number430NationalBusinessParkwayMember_037D509C4C021A9A88D79B3DC85BF3DF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 430 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number430NationalBusinessParkwayMember_037D509C4C021A9A88D79B3DC85BF3DF_documentation_en-US" xlink:label="lab_ofc_Number430NationalBusinessParkwayMember_037D509C4C021A9A88D79B3DC85BF3DF" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 430 National Business Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number430NationalBusinessParkwayMember" xlink:label="loc_ofc_Number430NationalBusinessParkwayMember_037D509C4C021A9A88D79B3DC85BF3DF" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number430NationalBusinessParkwayMember_037D509C4C021A9A88D79B3DC85BF3DF" xlink:to="lab_ofc_Number430NationalBusinessParkwayMember_037D509C4C021A9A88D79B3DC85BF3DF" xlink:type="arc" />
    <link:label id="lab_ofc_Number44408PecanCourtMember_76B130BBA14CF90821799B3DC85B85A7_terseLabel_en-US" xlink:label="lab_ofc_Number44408PecanCourtMember_76B130BBA14CF90821799B3DC85B85A7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">44408 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44408PecanCourtMember_76B130BBA14CF90821799B3DC85B85A7_label_en-US" xlink:label="lab_ofc_Number44408PecanCourtMember_76B130BBA14CF90821799B3DC85B85A7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 44408 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44408PecanCourtMember_76B130BBA14CF90821799B3DC85B85A7_documentation_en-US" xlink:label="lab_ofc_Number44408PecanCourtMember_76B130BBA14CF90821799B3DC85B85A7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 44408 Pecan Court, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number44408PecanCourtMember" xlink:label="loc_ofc_Number44408PecanCourtMember_76B130BBA14CF90821799B3DC85B85A7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number44408PecanCourtMember_76B130BBA14CF90821799B3DC85B85A7" xlink:to="lab_ofc_Number44408PecanCourtMember_76B130BBA14CF90821799B3DC85B85A7" xlink:type="arc" />
    <link:label id="lab_ofc_Number44414PecanCourtMember_E2CB1FC5432B2EF579D39B3DC85B9755_terseLabel_en-US" xlink:label="lab_ofc_Number44414PecanCourtMember_E2CB1FC5432B2EF579D39B3DC85B9755" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">44414 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44414PecanCourtMember_E2CB1FC5432B2EF579D39B3DC85B9755_label_en-US" xlink:label="lab_ofc_Number44414PecanCourtMember_E2CB1FC5432B2EF579D39B3DC85B9755" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 44414 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44414PecanCourtMember_E2CB1FC5432B2EF579D39B3DC85B9755_documentation_en-US" xlink:label="lab_ofc_Number44414PecanCourtMember_E2CB1FC5432B2EF579D39B3DC85B9755" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 44414 Pecan Court, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number44414PecanCourtMember" xlink:label="loc_ofc_Number44414PecanCourtMember_E2CB1FC5432B2EF579D39B3DC85B9755" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number44414PecanCourtMember_E2CB1FC5432B2EF579D39B3DC85B9755" xlink:to="lab_ofc_Number44414PecanCourtMember_E2CB1FC5432B2EF579D39B3DC85B9755" xlink:type="arc" />
    <link:label id="lab_ofc_Number44417PecanCourtMember_FC7C68CFE86B858312B59B3DC85B8D2E_terseLabel_en-US" xlink:label="lab_ofc_Number44417PecanCourtMember_FC7C68CFE86B858312B59B3DC85B8D2E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">44417 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44417PecanCourtMember_FC7C68CFE86B858312B59B3DC85B8D2E_label_en-US" xlink:label="lab_ofc_Number44417PecanCourtMember_FC7C68CFE86B858312B59B3DC85B8D2E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 44417 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44417PecanCourtMember_FC7C68CFE86B858312B59B3DC85B8D2E_documentation_en-US" xlink:label="lab_ofc_Number44417PecanCourtMember_FC7C68CFE86B858312B59B3DC85B8D2E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 44417 Pecan Court, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number44417PecanCourtMember" xlink:label="loc_ofc_Number44417PecanCourtMember_FC7C68CFE86B858312B59B3DC85B8D2E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number44417PecanCourtMember_FC7C68CFE86B858312B59B3DC85B8D2E" xlink:to="lab_ofc_Number44417PecanCourtMember_FC7C68CFE86B858312B59B3DC85B8D2E" xlink:type="arc" />
    <link:label id="lab_ofc_Number44420PecanCourtMember_5EF559076DA57E4C22E19B3DC85B4CF3_terseLabel_en-US" xlink:label="lab_ofc_Number44420PecanCourtMember_5EF559076DA57E4C22E19B3DC85B4CF3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">44420 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44420PecanCourtMember_5EF559076DA57E4C22E19B3DC85B4CF3_label_en-US" xlink:label="lab_ofc_Number44420PecanCourtMember_5EF559076DA57E4C22E19B3DC85B4CF3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 44420 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44420PecanCourtMember_5EF559076DA57E4C22E19B3DC85B4CF3_documentation_en-US" xlink:label="lab_ofc_Number44420PecanCourtMember_5EF559076DA57E4C22E19B3DC85B4CF3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 44420 Pecan Court, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number44420PecanCourtMember" xlink:label="loc_ofc_Number44420PecanCourtMember_5EF559076DA57E4C22E19B3DC85B4CF3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number44420PecanCourtMember_5EF559076DA57E4C22E19B3DC85B4CF3" xlink:to="lab_ofc_Number44420PecanCourtMember_5EF559076DA57E4C22E19B3DC85B4CF3" xlink:type="arc" />
    <link:label id="lab_ofc_Number44425PecanCourtMember_9565FB19294598C36F849B3DC85C98D5_terseLabel_en-US" xlink:label="lab_ofc_Number44425PecanCourtMember_9565FB19294598C36F849B3DC85C98D5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">44425 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44425PecanCourtMember_9565FB19294598C36F849B3DC85C98D5_label_en-US" xlink:label="lab_ofc_Number44425PecanCourtMember_9565FB19294598C36F849B3DC85C98D5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 44425 Pecan Court [Member]</link:label>
    <link:label id="lab_ofc_Number44425PecanCourtMember_9565FB19294598C36F849B3DC85C98D5_documentation_en-US" xlink:label="lab_ofc_Number44425PecanCourtMember_9565FB19294598C36F849B3DC85C98D5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 44425 Pecan Court, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number44425PecanCourtMember" xlink:label="loc_ofc_Number44425PecanCourtMember_9565FB19294598C36F849B3DC85C98D5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number44425PecanCourtMember_9565FB19294598C36F849B3DC85C98D5" xlink:to="lab_ofc_Number44425PecanCourtMember_9565FB19294598C36F849B3DC85C98D5" xlink:type="arc" />
    <link:label id="lab_ofc_Number45310AbellHouseLaneMember_3AF2DD896894087B43A99B3DC85CAE5C_terseLabel_en-US" xlink:label="lab_ofc_Number45310AbellHouseLaneMember_3AF2DD896894087B43A99B3DC85CAE5C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">45310 Abell House Lane [Member]</link:label>
    <link:label id="lab_ofc_Number45310AbellHouseLaneMember_3AF2DD896894087B43A99B3DC85CAE5C_label_en-US" xlink:label="lab_ofc_Number45310AbellHouseLaneMember_3AF2DD896894087B43A99B3DC85CAE5C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 45310 Abell House Lane [Member]</link:label>
    <link:label id="lab_ofc_Number45310AbellHouseLaneMember_3AF2DD896894087B43A99B3DC85CAE5C_documentation_en-US" xlink:label="lab_ofc_Number45310AbellHouseLaneMember_3AF2DD896894087B43A99B3DC85CAE5C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 45310 Abell House Lane, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number45310AbellHouseLaneMember" xlink:label="loc_ofc_Number45310AbellHouseLaneMember_3AF2DD896894087B43A99B3DC85CAE5C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number45310AbellHouseLaneMember_3AF2DD896894087B43A99B3DC85CAE5C" xlink:to="lab_ofc_Number45310AbellHouseLaneMember_3AF2DD896894087B43A99B3DC85CAE5C" xlink:type="arc" />
    <link:label id="lab_ofc_Number46579ExpeditionDriveMember_CC4B23D59CF4A02DECE19B3DC85C94F6_terseLabel_en-US" xlink:label="lab_ofc_Number46579ExpeditionDriveMember_CC4B23D59CF4A02DECE19B3DC85C94F6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">46579 Expedition Drive [Member]</link:label>
    <link:label id="lab_ofc_Number46579ExpeditionDriveMember_CC4B23D59CF4A02DECE19B3DC85C94F6_label_en-US" xlink:label="lab_ofc_Number46579ExpeditionDriveMember_CC4B23D59CF4A02DECE19B3DC85C94F6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 46579 Expedition Drive [Member]</link:label>
    <link:label id="lab_ofc_Number46579ExpeditionDriveMember_CC4B23D59CF4A02DECE19B3DC85C94F6_documentation_en-US" xlink:label="lab_ofc_Number46579ExpeditionDriveMember_CC4B23D59CF4A02DECE19B3DC85C94F6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 46579 Expedition Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number46579ExpeditionDriveMember" xlink:label="loc_ofc_Number46579ExpeditionDriveMember_CC4B23D59CF4A02DECE19B3DC85C94F6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number46579ExpeditionDriveMember_CC4B23D59CF4A02DECE19B3DC85C94F6" xlink:to="lab_ofc_Number46579ExpeditionDriveMember_CC4B23D59CF4A02DECE19B3DC85C94F6" xlink:type="arc" />
    <link:label id="lab_ofc_Number46591ExpeditionDriveMember_832FB9CFB9135FDB39089B3DC85C6867_terseLabel_en-US" xlink:label="lab_ofc_Number46591ExpeditionDriveMember_832FB9CFB9135FDB39089B3DC85C6867" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">46591 Expedition Drive [Member]</link:label>
    <link:label id="lab_ofc_Number46591ExpeditionDriveMember_832FB9CFB9135FDB39089B3DC85C6867_label_en-US" xlink:label="lab_ofc_Number46591ExpeditionDriveMember_832FB9CFB9135FDB39089B3DC85C6867" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 46591 Expedition Drive [Member]</link:label>
    <link:label id="lab_ofc_Number46591ExpeditionDriveMember_832FB9CFB9135FDB39089B3DC85C6867_documentation_en-US" xlink:label="lab_ofc_Number46591ExpeditionDriveMember_832FB9CFB9135FDB39089B3DC85C6867" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 46591 Expedition Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number46591ExpeditionDriveMember" xlink:label="loc_ofc_Number46591ExpeditionDriveMember_832FB9CFB9135FDB39089B3DC85C6867" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number46591ExpeditionDriveMember_832FB9CFB9135FDB39089B3DC85C6867" xlink:to="lab_ofc_Number46591ExpeditionDriveMember_832FB9CFB9135FDB39089B3DC85C6867" xlink:type="arc" />
    <link:label id="lab_ofc_Number4851StonecroftBoulevardMember_0F06EA47DE4B6A4CE5AA9B3DC85C87CA_terseLabel_en-US" xlink:label="lab_ofc_Number4851StonecroftBoulevardMember_0F06EA47DE4B6A4CE5AA9B3DC85C87CA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">4851 Stonecroft Boulevard [Member]</link:label>
    <link:label id="lab_ofc_Number4851StonecroftBoulevardMember_0F06EA47DE4B6A4CE5AA9B3DC85C87CA_label_en-US" xlink:label="lab_ofc_Number4851StonecroftBoulevardMember_0F06EA47DE4B6A4CE5AA9B3DC85C87CA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 4851 Stonecroft Boulevard [Member]</link:label>
    <link:label id="lab_ofc_Number4851StonecroftBoulevardMember_0F06EA47DE4B6A4CE5AA9B3DC85C87CA_documentation_en-US" xlink:label="lab_ofc_Number4851StonecroftBoulevardMember_0F06EA47DE4B6A4CE5AA9B3DC85C87CA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 4851 Stonecroft Boulevard, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number4851StonecroftBoulevardMember" xlink:label="loc_ofc_Number4851StonecroftBoulevardMember_0F06EA47DE4B6A4CE5AA9B3DC85C87CA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number4851StonecroftBoulevardMember_0F06EA47DE4B6A4CE5AA9B3DC85C87CA" xlink:to="lab_ofc_Number4851StonecroftBoulevardMember_0F06EA47DE4B6A4CE5AA9B3DC85C87CA" xlink:type="arc" />
    <link:label id="lab_ofc_Number540NationalBusinessParkwayMember_4BD201835AD3CFE3916F9B3DC85CD055_terseLabel_en-US" xlink:label="lab_ofc_Number540NationalBusinessParkwayMember_4BD201835AD3CFE3916F9B3DC85CD055" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">540 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number540NationalBusinessParkwayMember_4BD201835AD3CFE3916F9B3DC85CD055_label_en-US" xlink:label="lab_ofc_Number540NationalBusinessParkwayMember_4BD201835AD3CFE3916F9B3DC85CD055" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 540 National Business Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number540NationalBusinessParkwayMember_4BD201835AD3CFE3916F9B3DC85CD055_documentation_en-US" xlink:label="lab_ofc_Number540NationalBusinessParkwayMember_4BD201835AD3CFE3916F9B3DC85CD055" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 540 National Business Parkway [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number540NationalBusinessParkwayMember" xlink:label="loc_ofc_Number540NationalBusinessParkwayMember_4BD201835AD3CFE3916F9B3DC85CD055" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number540NationalBusinessParkwayMember_4BD201835AD3CFE3916F9B3DC85CD055" xlink:to="lab_ofc_Number540NationalBusinessParkwayMember_4BD201835AD3CFE3916F9B3DC85CD055" xlink:type="arc" />
    <link:label id="lab_ofc_Number5520ResearchParkDriveMember_AFF0F5D3D6DD156356049B3DC85C6CD6_terseLabel_en-US" xlink:label="lab_ofc_Number5520ResearchParkDriveMember_AFF0F5D3D6DD156356049B3DC85C6CD6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">5520 Research Park Drive [Member]</link:label>
    <link:label id="lab_ofc_Number5520ResearchParkDriveMember_AFF0F5D3D6DD156356049B3DC85C6CD6_label_en-US" xlink:label="lab_ofc_Number5520ResearchParkDriveMember_AFF0F5D3D6DD156356049B3DC85C6CD6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 5520 Research Park Drive [Member]</link:label>
    <link:label id="lab_ofc_Number5520ResearchParkDriveMember_AFF0F5D3D6DD156356049B3DC85C6CD6_documentation_en-US" xlink:label="lab_ofc_Number5520ResearchParkDriveMember_AFF0F5D3D6DD156356049B3DC85C6CD6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 5520 Research Park Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number5520ResearchParkDriveMember" xlink:label="loc_ofc_Number5520ResearchParkDriveMember_AFF0F5D3D6DD156356049B3DC85C6CD6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number5520ResearchParkDriveMember_AFF0F5D3D6DD156356049B3DC85C6CD6" xlink:to="lab_ofc_Number5520ResearchParkDriveMember_AFF0F5D3D6DD156356049B3DC85C6CD6" xlink:type="arc" />
    <link:label id="lab_ofc_Number5522ResearchParkDriveMember_D25B836A910BA863209D9B3DC85C41B5_terseLabel_en-US" xlink:label="lab_ofc_Number5522ResearchParkDriveMember_D25B836A910BA863209D9B3DC85C41B5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">5522 Research Park Drive [Member]</link:label>
    <link:label id="lab_ofc_Number5522ResearchParkDriveMember_D25B836A910BA863209D9B3DC85C41B5_label_en-US" xlink:label="lab_ofc_Number5522ResearchParkDriveMember_D25B836A910BA863209D9B3DC85C41B5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 5522 Research Park Drive [Member]</link:label>
    <link:label id="lab_ofc_Number5522ResearchParkDriveMember_D25B836A910BA863209D9B3DC85C41B5_documentation_en-US" xlink:label="lab_ofc_Number5522ResearchParkDriveMember_D25B836A910BA863209D9B3DC85C41B5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 5522 Research Park Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number5522ResearchParkDriveMember" xlink:label="loc_ofc_Number5522ResearchParkDriveMember_D25B836A910BA863209D9B3DC85C41B5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number5522ResearchParkDriveMember_D25B836A910BA863209D9B3DC85C41B5" xlink:to="lab_ofc_Number5522ResearchParkDriveMember_D25B836A910BA863209D9B3DC85C41B5" xlink:type="arc" />
    <link:label id="lab_ofc_Number5801UniversityResearchCourtMember_984D885A23B169CF70ED9B3DC85C724E_terseLabel_en-US" xlink:label="lab_ofc_Number5801UniversityResearchCourtMember_984D885A23B169CF70ED9B3DC85C724E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">5801 University Research Court [Member]</link:label>
    <link:label id="lab_ofc_Number5801UniversityResearchCourtMember_984D885A23B169CF70ED9B3DC85C724E_label_en-US" xlink:label="lab_ofc_Number5801UniversityResearchCourtMember_984D885A23B169CF70ED9B3DC85C724E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 5801 University Research Court [Member]</link:label>
    <link:label id="lab_ofc_Number5801UniversityResearchCourtMember_984D885A23B169CF70ED9B3DC85C724E_documentation_en-US" xlink:label="lab_ofc_Number5801UniversityResearchCourtMember_984D885A23B169CF70ED9B3DC85C724E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 5801 University Research Court [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number5801UniversityResearchCourtMember" xlink:label="loc_ofc_Number5801UniversityResearchCourtMember_984D885A23B169CF70ED9B3DC85C724E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number5801UniversityResearchCourtMember_984D885A23B169CF70ED9B3DC85C724E" xlink:to="lab_ofc_Number5801UniversityResearchCourtMember_984D885A23B169CF70ED9B3DC85C724E" xlink:type="arc" />
    <link:label id="lab_ofc_Number5825UniversityResearchCourtMember_BA2AA4DCC7B33E88B24F9B3DC85D4AC7_terseLabel_en-US" xlink:label="lab_ofc_Number5825UniversityResearchCourtMember_BA2AA4DCC7B33E88B24F9B3DC85D4AC7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">5825 University Research Court [Member]</link:label>
    <link:label id="lab_ofc_Number5825UniversityResearchCourtMember_BA2AA4DCC7B33E88B24F9B3DC85D4AC7_label_en-US" xlink:label="lab_ofc_Number5825UniversityResearchCourtMember_BA2AA4DCC7B33E88B24F9B3DC85D4AC7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 5825 University Research Court [Member]</link:label>
    <link:label id="lab_ofc_Number5825UniversityResearchCourtMember_BA2AA4DCC7B33E88B24F9B3DC85D4AC7_documentation_en-US" xlink:label="lab_ofc_Number5825UniversityResearchCourtMember_BA2AA4DCC7B33E88B24F9B3DC85D4AC7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 5825 University Research Court, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number5825UniversityResearchCourtMember" xlink:label="loc_ofc_Number5825UniversityResearchCourtMember_BA2AA4DCC7B33E88B24F9B3DC85D4AC7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number5825UniversityResearchCourtMember_BA2AA4DCC7B33E88B24F9B3DC85D4AC7" xlink:to="lab_ofc_Number5825UniversityResearchCourtMember_BA2AA4DCC7B33E88B24F9B3DC85D4AC7" xlink:type="arc" />
    <link:label id="lab_ofc_Number5850UniversityResearchCourtMember_B191C6F0F4DF37D327889B3DC85DF7A5_terseLabel_en-US" xlink:label="lab_ofc_Number5850UniversityResearchCourtMember_B191C6F0F4DF37D327889B3DC85DF7A5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">5850 University Research Court [Member]</link:label>
    <link:label id="lab_ofc_Number5850UniversityResearchCourtMember_B191C6F0F4DF37D327889B3DC85DF7A5_label_en-US" xlink:label="lab_ofc_Number5850UniversityResearchCourtMember_B191C6F0F4DF37D327889B3DC85DF7A5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 5850 University Research Court [Member]</link:label>
    <link:label id="lab_ofc_Number5850UniversityResearchCourtMember_B191C6F0F4DF37D327889B3DC85DF7A5_documentation_en-US" xlink:label="lab_ofc_Number5850UniversityResearchCourtMember_B191C6F0F4DF37D327889B3DC85DF7A5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 5850 University Research Court, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number5850UniversityResearchCourtMember" xlink:label="loc_ofc_Number5850UniversityResearchCourtMember_B191C6F0F4DF37D327889B3DC85DF7A5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number5850UniversityResearchCourtMember_B191C6F0F4DF37D327889B3DC85DF7A5" xlink:to="lab_ofc_Number5850UniversityResearchCourtMember_B191C6F0F4DF37D327889B3DC85DF7A5" xlink:type="arc" />
    <link:label id="lab_ofc_Number6700AlexanderBellDriveMember_085D165E500578D40BF59B3DC85D9DDB_terseLabel_en-US" xlink:label="lab_ofc_Number6700AlexanderBellDriveMember_085D165E500578D40BF59B3DC85D9DDB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6700 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6700AlexanderBellDriveMember_085D165E500578D40BF59B3DC85D9DDB_label_en-US" xlink:label="lab_ofc_Number6700AlexanderBellDriveMember_085D165E500578D40BF59B3DC85D9DDB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6700 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6700AlexanderBellDriveMember_085D165E500578D40BF59B3DC85D9DDB_documentation_en-US" xlink:label="lab_ofc_Number6700AlexanderBellDriveMember_085D165E500578D40BF59B3DC85D9DDB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6700 Alexander Bell Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6700AlexanderBellDriveMember" xlink:label="loc_ofc_Number6700AlexanderBellDriveMember_085D165E500578D40BF59B3DC85D9DDB" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6700AlexanderBellDriveMember_085D165E500578D40BF59B3DC85D9DDB" xlink:to="lab_ofc_Number6700AlexanderBellDriveMember_085D165E500578D40BF59B3DC85D9DDB" xlink:type="arc" />
    <link:label id="lab_ofc_Number6708AlexanderBellDriveMember_E8DD4E65F51BF801E8D89B3DC85DD543_terseLabel_en-US" xlink:label="lab_ofc_Number6708AlexanderBellDriveMember_E8DD4E65F51BF801E8D89B3DC85DD543" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6708 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6708AlexanderBellDriveMember_E8DD4E65F51BF801E8D89B3DC85DD543_label_en-US" xlink:label="lab_ofc_Number6708AlexanderBellDriveMember_E8DD4E65F51BF801E8D89B3DC85DD543" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6708 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6708AlexanderBellDriveMember_E8DD4E65F51BF801E8D89B3DC85DD543_documentation_en-US" xlink:label="lab_ofc_Number6708AlexanderBellDriveMember_E8DD4E65F51BF801E8D89B3DC85DD543" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6708 Alexander Bell Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6708AlexanderBellDriveMember" xlink:label="loc_ofc_Number6708AlexanderBellDriveMember_E8DD4E65F51BF801E8D89B3DC85DD543" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6708AlexanderBellDriveMember_E8DD4E65F51BF801E8D89B3DC85DD543" xlink:to="lab_ofc_Number6708AlexanderBellDriveMember_E8DD4E65F51BF801E8D89B3DC85DD543" xlink:type="arc" />
    <link:label id="lab_ofc_Number6711ColumbiaGatewayDriveMember_314E956AEACA899F0FC99B3DC85D82D5_terseLabel_en-US" xlink:label="lab_ofc_Number6711ColumbiaGatewayDriveMember_314E956AEACA899F0FC99B3DC85D82D5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6711 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6711ColumbiaGatewayDriveMember_314E956AEACA899F0FC99B3DC85D82D5_label_en-US" xlink:label="lab_ofc_Number6711ColumbiaGatewayDriveMember_314E956AEACA899F0FC99B3DC85D82D5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6711 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6711ColumbiaGatewayDriveMember_314E956AEACA899F0FC99B3DC85D82D5_documentation_en-US" xlink:label="lab_ofc_Number6711ColumbiaGatewayDriveMember_314E956AEACA899F0FC99B3DC85D82D5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6711 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6711ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number6711ColumbiaGatewayDriveMember_314E956AEACA899F0FC99B3DC85D82D5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6711ColumbiaGatewayDriveMember_314E956AEACA899F0FC99B3DC85D82D5" xlink:to="lab_ofc_Number6711ColumbiaGatewayDriveMember_314E956AEACA899F0FC99B3DC85D82D5" xlink:type="arc" />
    <link:label id="lab_ofc_Number6716AlexanderBellDriveMember_5D6FCE1D64CC77BA29AE9B3DC85DEF27_terseLabel_en-US" xlink:label="lab_ofc_Number6716AlexanderBellDriveMember_5D6FCE1D64CC77BA29AE9B3DC85DEF27" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6716 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6716AlexanderBellDriveMember_5D6FCE1D64CC77BA29AE9B3DC85DEF27_label_en-US" xlink:label="lab_ofc_Number6716AlexanderBellDriveMember_5D6FCE1D64CC77BA29AE9B3DC85DEF27" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6716 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6716AlexanderBellDriveMember_5D6FCE1D64CC77BA29AE9B3DC85DEF27_documentation_en-US" xlink:label="lab_ofc_Number6716AlexanderBellDriveMember_5D6FCE1D64CC77BA29AE9B3DC85DEF27" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6716 Alexander Bell Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6716AlexanderBellDriveMember" xlink:label="loc_ofc_Number6716AlexanderBellDriveMember_5D6FCE1D64CC77BA29AE9B3DC85DEF27" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6716AlexanderBellDriveMember_5D6FCE1D64CC77BA29AE9B3DC85DEF27" xlink:to="lab_ofc_Number6716AlexanderBellDriveMember_5D6FCE1D64CC77BA29AE9B3DC85DEF27" xlink:type="arc" />
    <link:label id="lab_ofc_Number6721ColumbiaGatewayDriveMember_E8F0691FCD07D0AA1E639B3DC85D9AB3_terseLabel_en-US" xlink:label="lab_ofc_Number6721ColumbiaGatewayDriveMember_E8F0691FCD07D0AA1E639B3DC85D9AB3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6721 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6721ColumbiaGatewayDriveMember_E8F0691FCD07D0AA1E639B3DC85D9AB3_label_en-US" xlink:label="lab_ofc_Number6721ColumbiaGatewayDriveMember_E8F0691FCD07D0AA1E639B3DC85D9AB3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6721 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6721ColumbiaGatewayDriveMember_E8F0691FCD07D0AA1E639B3DC85D9AB3_documentation_en-US" xlink:label="lab_ofc_Number6721ColumbiaGatewayDriveMember_E8F0691FCD07D0AA1E639B3DC85D9AB3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6721 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6721ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number6721ColumbiaGatewayDriveMember_E8F0691FCD07D0AA1E639B3DC85D9AB3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6721ColumbiaGatewayDriveMember_E8F0691FCD07D0AA1E639B3DC85D9AB3" xlink:to="lab_ofc_Number6721ColumbiaGatewayDriveMember_E8F0691FCD07D0AA1E639B3DC85D9AB3" xlink:type="arc" />
    <link:label id="lab_ofc_Number6724AlexanderBellDriveMember_94B8E67A3C3D4F0A646A9B3DC85D9021_terseLabel_en-US" xlink:label="lab_ofc_Number6724AlexanderBellDriveMember_94B8E67A3C3D4F0A646A9B3DC85D9021" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6724 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6724AlexanderBellDriveMember_94B8E67A3C3D4F0A646A9B3DC85D9021_label_en-US" xlink:label="lab_ofc_Number6724AlexanderBellDriveMember_94B8E67A3C3D4F0A646A9B3DC85D9021" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6724 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6724AlexanderBellDriveMember_94B8E67A3C3D4F0A646A9B3DC85D9021_documentation_en-US" xlink:label="lab_ofc_Number6724AlexanderBellDriveMember_94B8E67A3C3D4F0A646A9B3DC85D9021" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6724 Alexander Bell Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6724AlexanderBellDriveMember" xlink:label="loc_ofc_Number6724AlexanderBellDriveMember_94B8E67A3C3D4F0A646A9B3DC85D9021" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6724AlexanderBellDriveMember_94B8E67A3C3D4F0A646A9B3DC85D9021" xlink:to="lab_ofc_Number6724AlexanderBellDriveMember_94B8E67A3C3D4F0A646A9B3DC85D9021" xlink:type="arc" />
    <link:label id="lab_ofc_Number6731ColumbiaGatewayDriveMember_CFC570A111B5B92B72449B3DC85D76B4_terseLabel_en-US" xlink:label="lab_ofc_Number6731ColumbiaGatewayDriveMember_CFC570A111B5B92B72449B3DC85D76B4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6731 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6731ColumbiaGatewayDriveMember_CFC570A111B5B92B72449B3DC85D76B4_label_en-US" xlink:label="lab_ofc_Number6731ColumbiaGatewayDriveMember_CFC570A111B5B92B72449B3DC85D76B4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6731 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6731ColumbiaGatewayDriveMember_CFC570A111B5B92B72449B3DC85D76B4_documentation_en-US" xlink:label="lab_ofc_Number6731ColumbiaGatewayDriveMember_CFC570A111B5B92B72449B3DC85D76B4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6731 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6731ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number6731ColumbiaGatewayDriveMember_CFC570A111B5B92B72449B3DC85D76B4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6731ColumbiaGatewayDriveMember_CFC570A111B5B92B72449B3DC85D76B4" xlink:to="lab_ofc_Number6731ColumbiaGatewayDriveMember_CFC570A111B5B92B72449B3DC85D76B4" xlink:type="arc" />
    <link:label id="lab_ofc_Number6740AlexanderBellDriveMember_098BE36BE2DEDC663F519B3DC85EB6E6_terseLabel_en-US" xlink:label="lab_ofc_Number6740AlexanderBellDriveMember_098BE36BE2DEDC663F519B3DC85EB6E6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6740 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6740AlexanderBellDriveMember_098BE36BE2DEDC663F519B3DC85EB6E6_label_en-US" xlink:label="lab_ofc_Number6740AlexanderBellDriveMember_098BE36BE2DEDC663F519B3DC85EB6E6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6740 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6740AlexanderBellDriveMember_098BE36BE2DEDC663F519B3DC85EB6E6_documentation_en-US" xlink:label="lab_ofc_Number6740AlexanderBellDriveMember_098BE36BE2DEDC663F519B3DC85EB6E6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6740 Alexander Bell Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6740AlexanderBellDriveMember" xlink:label="loc_ofc_Number6740AlexanderBellDriveMember_098BE36BE2DEDC663F519B3DC85EB6E6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6740AlexanderBellDriveMember_098BE36BE2DEDC663F519B3DC85EB6E6" xlink:to="lab_ofc_Number6740AlexanderBellDriveMember_098BE36BE2DEDC663F519B3DC85EB6E6" xlink:type="arc" />
    <link:label id="lab_ofc_Number6741ColumbiaGatewayDriveMember_780AC7E1AD600089464E9B3DC85E4D4B_terseLabel_en-US" xlink:label="lab_ofc_Number6741ColumbiaGatewayDriveMember_780AC7E1AD600089464E9B3DC85E4D4B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6741 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6741ColumbiaGatewayDriveMember_780AC7E1AD600089464E9B3DC85E4D4B_label_en-US" xlink:label="lab_ofc_Number6741ColumbiaGatewayDriveMember_780AC7E1AD600089464E9B3DC85E4D4B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6741 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6741ColumbiaGatewayDriveMember_780AC7E1AD600089464E9B3DC85E4D4B_documentation_en-US" xlink:label="lab_ofc_Number6741ColumbiaGatewayDriveMember_780AC7E1AD600089464E9B3DC85E4D4B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6741 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6741ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number6741ColumbiaGatewayDriveMember_780AC7E1AD600089464E9B3DC85E4D4B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6741ColumbiaGatewayDriveMember_780AC7E1AD600089464E9B3DC85E4D4B" xlink:to="lab_ofc_Number6741ColumbiaGatewayDriveMember_780AC7E1AD600089464E9B3DC85E4D4B" xlink:type="arc" />
    <link:label id="lab_ofc_Number6750AlexanderBellDriveMember_B21EC1778CD0A33083619B3DC85E197C_terseLabel_en-US" xlink:label="lab_ofc_Number6750AlexanderBellDriveMember_B21EC1778CD0A33083619B3DC85E197C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6750 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6750AlexanderBellDriveMember_B21EC1778CD0A33083619B3DC85E197C_label_en-US" xlink:label="lab_ofc_Number6750AlexanderBellDriveMember_B21EC1778CD0A33083619B3DC85E197C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6750 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6750AlexanderBellDriveMember_B21EC1778CD0A33083619B3DC85E197C_documentation_en-US" xlink:label="lab_ofc_Number6750AlexanderBellDriveMember_B21EC1778CD0A33083619B3DC85E197C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6750 Alexander Bell Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6750AlexanderBellDriveMember" xlink:label="loc_ofc_Number6750AlexanderBellDriveMember_B21EC1778CD0A33083619B3DC85E197C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6750AlexanderBellDriveMember_B21EC1778CD0A33083619B3DC85E197C" xlink:to="lab_ofc_Number6750AlexanderBellDriveMember_B21EC1778CD0A33083619B3DC85E197C" xlink:type="arc" />
    <link:label id="lab_ofc_Number6760AlexanderBellDriveMember_0B958B9CDF90B86FE0039B3DC85EBC89_terseLabel_en-US" xlink:label="lab_ofc_Number6760AlexanderBellDriveMember_0B958B9CDF90B86FE0039B3DC85EBC89" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6760 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6760AlexanderBellDriveMember_0B958B9CDF90B86FE0039B3DC85EBC89_label_en-US" xlink:label="lab_ofc_Number6760AlexanderBellDriveMember_0B958B9CDF90B86FE0039B3DC85EBC89" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6760 Alexander Bell Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6760AlexanderBellDriveMember_0B958B9CDF90B86FE0039B3DC85EBC89_documentation_en-US" xlink:label="lab_ofc_Number6760AlexanderBellDriveMember_0B958B9CDF90B86FE0039B3DC85EBC89" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6760 Alexander Bell Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6760AlexanderBellDriveMember" xlink:label="loc_ofc_Number6760AlexanderBellDriveMember_0B958B9CDF90B86FE0039B3DC85EBC89" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6760AlexanderBellDriveMember_0B958B9CDF90B86FE0039B3DC85EBC89" xlink:to="lab_ofc_Number6760AlexanderBellDriveMember_0B958B9CDF90B86FE0039B3DC85EBC89" xlink:type="arc" />
    <link:label id="lab_ofc_Number6940ColumbiaGatewayDriveMember_AA2CBFC2C31C6A4CBE389B3DC85EE048_terseLabel_en-US" xlink:label="lab_ofc_Number6940ColumbiaGatewayDriveMember_AA2CBFC2C31C6A4CBE389B3DC85EE048" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6940 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6940ColumbiaGatewayDriveMember_AA2CBFC2C31C6A4CBE389B3DC85EE048_label_en-US" xlink:label="lab_ofc_Number6940ColumbiaGatewayDriveMember_AA2CBFC2C31C6A4CBE389B3DC85EE048" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6940 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6940ColumbiaGatewayDriveMember_AA2CBFC2C31C6A4CBE389B3DC85EE048_documentation_en-US" xlink:label="lab_ofc_Number6940ColumbiaGatewayDriveMember_AA2CBFC2C31C6A4CBE389B3DC85EE048" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6940 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6940ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number6940ColumbiaGatewayDriveMember_AA2CBFC2C31C6A4CBE389B3DC85EE048" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6940ColumbiaGatewayDriveMember_AA2CBFC2C31C6A4CBE389B3DC85EE048" xlink:to="lab_ofc_Number6940ColumbiaGatewayDriveMember_AA2CBFC2C31C6A4CBE389B3DC85EE048" xlink:type="arc" />
    <link:label id="lab_ofc_Number6950ColumbiaGatewayDriveMember_A7A1D82230343C1DEDF79B3DC85EA774_terseLabel_en-US" xlink:label="lab_ofc_Number6950ColumbiaGatewayDriveMember_A7A1D82230343C1DEDF79B3DC85EA774" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">6950 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6950ColumbiaGatewayDriveMember_A7A1D82230343C1DEDF79B3DC85EA774_label_en-US" xlink:label="lab_ofc_Number6950ColumbiaGatewayDriveMember_A7A1D82230343C1DEDF79B3DC85EA774" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 6950 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number6950ColumbiaGatewayDriveMember_A7A1D82230343C1DEDF79B3DC85EA774_documentation_en-US" xlink:label="lab_ofc_Number6950ColumbiaGatewayDriveMember_A7A1D82230343C1DEDF79B3DC85EA774" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 6950 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number6950ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number6950ColumbiaGatewayDriveMember_A7A1D82230343C1DEDF79B3DC85EA774" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number6950ColumbiaGatewayDriveMember_A7A1D82230343C1DEDF79B3DC85EA774" xlink:to="lab_ofc_Number6950ColumbiaGatewayDriveMember_A7A1D82230343C1DEDF79B3DC85EA774" xlink:type="arc" />
    <link:label id="lab_ofc_Number7000ColumbiaGatewayDriveMember_2CDD0A59BADDC4358EEA9B3DC85E38C2_terseLabel_en-US" xlink:label="lab_ofc_Number7000ColumbiaGatewayDriveMember_2CDD0A59BADDC4358EEA9B3DC85E38C2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7000 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7000ColumbiaGatewayDriveMember_2CDD0A59BADDC4358EEA9B3DC85E38C2_label_en-US" xlink:label="lab_ofc_Number7000ColumbiaGatewayDriveMember_2CDD0A59BADDC4358EEA9B3DC85E38C2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7000 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7000ColumbiaGatewayDriveMember_2CDD0A59BADDC4358EEA9B3DC85E38C2_documentation_en-US" xlink:label="lab_ofc_Number7000ColumbiaGatewayDriveMember_2CDD0A59BADDC4358EEA9B3DC85E38C2" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7000 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7000ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7000ColumbiaGatewayDriveMember_2CDD0A59BADDC4358EEA9B3DC85E38C2" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7000ColumbiaGatewayDriveMember_2CDD0A59BADDC4358EEA9B3DC85E38C2" xlink:to="lab_ofc_Number7000ColumbiaGatewayDriveMember_2CDD0A59BADDC4358EEA9B3DC85E38C2" xlink:type="arc" />
    <link:label id="lab_ofc_Number7005ColumbiaGatewayDriveMember_D4D08516EDD33D98BDD89B3DC85EF104_terseLabel_en-US" xlink:label="lab_ofc_Number7005ColumbiaGatewayDriveMember_D4D08516EDD33D98BDD89B3DC85EF104" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7005 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7005ColumbiaGatewayDriveMember_D4D08516EDD33D98BDD89B3DC85EF104_label_en-US" xlink:label="lab_ofc_Number7005ColumbiaGatewayDriveMember_D4D08516EDD33D98BDD89B3DC85EF104" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7005 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7005ColumbiaGatewayDriveMember_D4D08516EDD33D98BDD89B3DC85EF104_documentation_en-US" xlink:label="lab_ofc_Number7005ColumbiaGatewayDriveMember_D4D08516EDD33D98BDD89B3DC85EF104" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 7005 Columbia Gateway Drive [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7005ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7005ColumbiaGatewayDriveMember_D4D08516EDD33D98BDD89B3DC85EF104" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7005ColumbiaGatewayDriveMember_D4D08516EDD33D98BDD89B3DC85EF104" xlink:to="lab_ofc_Number7005ColumbiaGatewayDriveMember_D4D08516EDD33D98BDD89B3DC85EF104" xlink:type="arc" />
    <link:label id="lab_ofc_Number7015AlbertEinsteinDriveMember_504E04C1CDB0BE3818869B3DC85EFBC7_terseLabel_en-US" xlink:label="lab_ofc_Number7015AlbertEinsteinDriveMember_504E04C1CDB0BE3818869B3DC85EFBC7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7015 Albert Einstein Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7015AlbertEinsteinDriveMember_504E04C1CDB0BE3818869B3DC85EFBC7_label_en-US" xlink:label="lab_ofc_Number7015AlbertEinsteinDriveMember_504E04C1CDB0BE3818869B3DC85EFBC7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7015 Albert Einstein Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7015AlbertEinsteinDriveMember_504E04C1CDB0BE3818869B3DC85EFBC7_documentation_en-US" xlink:label="lab_ofc_Number7015AlbertEinsteinDriveMember_504E04C1CDB0BE3818869B3DC85EFBC7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7015 Albert Einstein Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7015AlbertEinsteinDriveMember" xlink:label="loc_ofc_Number7015AlbertEinsteinDriveMember_504E04C1CDB0BE3818869B3DC85EFBC7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7015AlbertEinsteinDriveMember_504E04C1CDB0BE3818869B3DC85EFBC7" xlink:to="lab_ofc_Number7015AlbertEinsteinDriveMember_504E04C1CDB0BE3818869B3DC85EFBC7" xlink:type="arc" />
    <link:label id="lab_ofc_Number7061ColumbiaGatewayDriveMember_2011B456FB17BBF010589B3DC85F688E_terseLabel_en-US" xlink:label="lab_ofc_Number7061ColumbiaGatewayDriveMember_2011B456FB17BBF010589B3DC85F688E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7061 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7061ColumbiaGatewayDriveMember_2011B456FB17BBF010589B3DC85F688E_label_en-US" xlink:label="lab_ofc_Number7061ColumbiaGatewayDriveMember_2011B456FB17BBF010589B3DC85F688E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7061 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7061ColumbiaGatewayDriveMember_2011B456FB17BBF010589B3DC85F688E_documentation_en-US" xlink:label="lab_ofc_Number7061ColumbiaGatewayDriveMember_2011B456FB17BBF010589B3DC85F688E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7061 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7061ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7061ColumbiaGatewayDriveMember_2011B456FB17BBF010589B3DC85F688E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7061ColumbiaGatewayDriveMember_2011B456FB17BBF010589B3DC85F688E" xlink:to="lab_ofc_Number7061ColumbiaGatewayDriveMember_2011B456FB17BBF010589B3DC85F688E" xlink:type="arc" />
    <link:label id="lab_ofc_Number7063ColumbiaGatewayDriveMember_DFF13B97FCE6A9E42B989B3DC85F2478_terseLabel_en-US" xlink:label="lab_ofc_Number7063ColumbiaGatewayDriveMember_DFF13B97FCE6A9E42B989B3DC85F2478" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7063 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7063ColumbiaGatewayDriveMember_DFF13B97FCE6A9E42B989B3DC85F2478_label_en-US" xlink:label="lab_ofc_Number7063ColumbiaGatewayDriveMember_DFF13B97FCE6A9E42B989B3DC85F2478" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7063 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7063ColumbiaGatewayDriveMember_DFF13B97FCE6A9E42B989B3DC85F2478_documentation_en-US" xlink:label="lab_ofc_Number7063ColumbiaGatewayDriveMember_DFF13B97FCE6A9E42B989B3DC85F2478" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7063 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7063ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7063ColumbiaGatewayDriveMember_DFF13B97FCE6A9E42B989B3DC85F2478" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7063ColumbiaGatewayDriveMember_DFF13B97FCE6A9E42B989B3DC85F2478" xlink:to="lab_ofc_Number7063ColumbiaGatewayDriveMember_DFF13B97FCE6A9E42B989B3DC85F2478" xlink:type="arc" />
    <link:label id="lab_ofc_Number7065ColumbiaGatewayDriveMember_332CE445FFC7676B463D9B3DC85FC32B_terseLabel_en-US" xlink:label="lab_ofc_Number7065ColumbiaGatewayDriveMember_332CE445FFC7676B463D9B3DC85FC32B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7065 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7065ColumbiaGatewayDriveMember_332CE445FFC7676B463D9B3DC85FC32B_label_en-US" xlink:label="lab_ofc_Number7065ColumbiaGatewayDriveMember_332CE445FFC7676B463D9B3DC85FC32B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7065 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7065ColumbiaGatewayDriveMember_332CE445FFC7676B463D9B3DC85FC32B_documentation_en-US" xlink:label="lab_ofc_Number7065ColumbiaGatewayDriveMember_332CE445FFC7676B463D9B3DC85FC32B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7065 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7065ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7065ColumbiaGatewayDriveMember_332CE445FFC7676B463D9B3DC85FC32B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7065ColumbiaGatewayDriveMember_332CE445FFC7676B463D9B3DC85FC32B" xlink:to="lab_ofc_Number7065ColumbiaGatewayDriveMember_332CE445FFC7676B463D9B3DC85FC32B" xlink:type="arc" />
    <link:label id="lab_ofc_Number7067ColumbiaGatewayDriveMember_9333F981A0C68150C89C9B3DC85FEAD4_terseLabel_en-US" xlink:label="lab_ofc_Number7067ColumbiaGatewayDriveMember_9333F981A0C68150C89C9B3DC85FEAD4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7067 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7067ColumbiaGatewayDriveMember_9333F981A0C68150C89C9B3DC85FEAD4_label_en-US" xlink:label="lab_ofc_Number7067ColumbiaGatewayDriveMember_9333F981A0C68150C89C9B3DC85FEAD4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7067 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7067ColumbiaGatewayDriveMember_9333F981A0C68150C89C9B3DC85FEAD4_documentation_en-US" xlink:label="lab_ofc_Number7067ColumbiaGatewayDriveMember_9333F981A0C68150C89C9B3DC85FEAD4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7067 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7067ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7067ColumbiaGatewayDriveMember_9333F981A0C68150C89C9B3DC85FEAD4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7067ColumbiaGatewayDriveMember_9333F981A0C68150C89C9B3DC85FEAD4" xlink:to="lab_ofc_Number7067ColumbiaGatewayDriveMember_9333F981A0C68150C89C9B3DC85FEAD4" xlink:type="arc" />
    <link:label id="lab_ofc_Number7125ColumbiaGatewayDriveLandMember_1545329622492DC61B7E9B3DC85F85B4_terseLabel_en-US" xlink:label="lab_ofc_Number7125ColumbiaGatewayDriveLandMember_1545329622492DC61B7E9B3DC85F85B4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7125 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7125ColumbiaGatewayDriveLandMember_1545329622492DC61B7E9B3DC85F85B4_label_en-US" xlink:label="lab_ofc_Number7125ColumbiaGatewayDriveLandMember_1545329622492DC61B7E9B3DC85F85B4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7125 Columbia Gateway Drive Land [Member]</link:label>
    <link:label id="lab_ofc_Number7125ColumbiaGatewayDriveLandMember_1545329622492DC61B7E9B3DC85F85B4_documentation_en-US" xlink:label="lab_ofc_Number7125ColumbiaGatewayDriveLandMember_1545329622492DC61B7E9B3DC85F85B4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7125 Columbia Gateway Drive Land, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7125ColumbiaGatewayDriveLandMember" xlink:label="loc_ofc_Number7125ColumbiaGatewayDriveLandMember_1545329622492DC61B7E9B3DC85F85B4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7125ColumbiaGatewayDriveLandMember_1545329622492DC61B7E9B3DC85F85B4" xlink:to="lab_ofc_Number7125ColumbiaGatewayDriveLandMember_1545329622492DC61B7E9B3DC85F85B4" xlink:type="arc" />
    <link:label id="lab_ofc_Number7125ColumbiaGatewayDriveMember_4830F49B57DE6C9EBA4A9B3DC85FB15B_terseLabel_en-US" xlink:label="lab_ofc_Number7125ColumbiaGatewayDriveMember_4830F49B57DE6C9EBA4A9B3DC85FB15B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7125 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7125ColumbiaGatewayDriveMember_4830F49B57DE6C9EBA4A9B3DC85FB15B_label_en-US" xlink:label="lab_ofc_Number7125ColumbiaGatewayDriveMember_4830F49B57DE6C9EBA4A9B3DC85FB15B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7125 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7125ColumbiaGatewayDriveMember_4830F49B57DE6C9EBA4A9B3DC85FB15B_documentation_en-US" xlink:label="lab_ofc_Number7125ColumbiaGatewayDriveMember_4830F49B57DE6C9EBA4A9B3DC85FB15B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7125 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7125ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7125ColumbiaGatewayDriveMember_4830F49B57DE6C9EBA4A9B3DC85FB15B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7125ColumbiaGatewayDriveMember_4830F49B57DE6C9EBA4A9B3DC85FB15B" xlink:to="lab_ofc_Number7125ColumbiaGatewayDriveMember_4830F49B57DE6C9EBA4A9B3DC85FB15B" xlink:type="arc" />
    <link:label id="lab_ofc_Number7130ColumbiaGatewayDriveMember_54674502098F80AEE55E9B3DC85F365A_terseLabel_en-US" xlink:label="lab_ofc_Number7130ColumbiaGatewayDriveMember_54674502098F80AEE55E9B3DC85F365A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7130 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7130ColumbiaGatewayDriveMember_54674502098F80AEE55E9B3DC85F365A_label_en-US" xlink:label="lab_ofc_Number7130ColumbiaGatewayDriveMember_54674502098F80AEE55E9B3DC85F365A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7130 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7130ColumbiaGatewayDriveMember_54674502098F80AEE55E9B3DC85F365A_documentation_en-US" xlink:label="lab_ofc_Number7130ColumbiaGatewayDriveMember_54674502098F80AEE55E9B3DC85F365A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7130 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7130ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7130ColumbiaGatewayDriveMember_54674502098F80AEE55E9B3DC85F365A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7130ColumbiaGatewayDriveMember_54674502098F80AEE55E9B3DC85F365A" xlink:to="lab_ofc_Number7130ColumbiaGatewayDriveMember_54674502098F80AEE55E9B3DC85F365A" xlink:type="arc" />
    <link:label id="lab_ofc_Number7134ColumbiaGatewayDriveMember_571C5BED0134DE8BC2A79B3DC85FB4B1_terseLabel_en-US" xlink:label="lab_ofc_Number7134ColumbiaGatewayDriveMember_571C5BED0134DE8BC2A79B3DC85FB4B1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7134 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7134ColumbiaGatewayDriveMember_571C5BED0134DE8BC2A79B3DC85FB4B1_label_en-US" xlink:label="lab_ofc_Number7134ColumbiaGatewayDriveMember_571C5BED0134DE8BC2A79B3DC85FB4B1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7134 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7134ColumbiaGatewayDriveMember_571C5BED0134DE8BC2A79B3DC85FB4B1_documentation_en-US" xlink:label="lab_ofc_Number7134ColumbiaGatewayDriveMember_571C5BED0134DE8BC2A79B3DC85FB4B1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7134 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7134ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7134ColumbiaGatewayDriveMember_571C5BED0134DE8BC2A79B3DC85FB4B1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7134ColumbiaGatewayDriveMember_571C5BED0134DE8BC2A79B3DC85FB4B1" xlink:to="lab_ofc_Number7134ColumbiaGatewayDriveMember_571C5BED0134DE8BC2A79B3DC85FB4B1" xlink:type="arc" />
    <link:label id="lab_ofc_Number7138ColumbiaGatewayDriveMember_EA5ECF22F92F962688459B3DC85F160C_terseLabel_en-US" xlink:label="lab_ofc_Number7138ColumbiaGatewayDriveMember_EA5ECF22F92F962688459B3DC85F160C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7138 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7138ColumbiaGatewayDriveMember_EA5ECF22F92F962688459B3DC85F160C_label_en-US" xlink:label="lab_ofc_Number7138ColumbiaGatewayDriveMember_EA5ECF22F92F962688459B3DC85F160C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7138 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7138ColumbiaGatewayDriveMember_EA5ECF22F92F962688459B3DC85F160C_documentation_en-US" xlink:label="lab_ofc_Number7138ColumbiaGatewayDriveMember_EA5ECF22F92F962688459B3DC85F160C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7138 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7138ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7138ColumbiaGatewayDriveMember_EA5ECF22F92F962688459B3DC85F160C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7138ColumbiaGatewayDriveMember_EA5ECF22F92F962688459B3DC85F160C" xlink:to="lab_ofc_Number7138ColumbiaGatewayDriveMember_EA5ECF22F92F962688459B3DC85F160C" xlink:type="arc" />
    <link:label id="lab_ofc_Number7142ColumbiaGatewayDriveMember_6F3EE0F6F29D4CE6D41A9B3DC8603079_terseLabel_en-US" xlink:label="lab_ofc_Number7142ColumbiaGatewayDriveMember_6F3EE0F6F29D4CE6D41A9B3DC8603079" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7142 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7142ColumbiaGatewayDriveMember_6F3EE0F6F29D4CE6D41A9B3DC8603079_label_en-US" xlink:label="lab_ofc_Number7142ColumbiaGatewayDriveMember_6F3EE0F6F29D4CE6D41A9B3DC8603079" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7142 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7142ColumbiaGatewayDriveMember_6F3EE0F6F29D4CE6D41A9B3DC8603079_documentation_en-US" xlink:label="lab_ofc_Number7142ColumbiaGatewayDriveMember_6F3EE0F6F29D4CE6D41A9B3DC8603079" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7142 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7142ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7142ColumbiaGatewayDriveMember_6F3EE0F6F29D4CE6D41A9B3DC8603079" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7142ColumbiaGatewayDriveMember_6F3EE0F6F29D4CE6D41A9B3DC8603079" xlink:to="lab_ofc_Number7142ColumbiaGatewayDriveMember_6F3EE0F6F29D4CE6D41A9B3DC8603079" xlink:type="arc" />
    <link:label id="lab_ofc_Number7150ColumbiaGatewayDriveMember_03877FC5EEAB7C30EC7B9B3DC860EFCD_terseLabel_en-US" xlink:label="lab_ofc_Number7150ColumbiaGatewayDriveMember_03877FC5EEAB7C30EC7B9B3DC860EFCD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7150 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7150ColumbiaGatewayDriveMember_03877FC5EEAB7C30EC7B9B3DC860EFCD_label_en-US" xlink:label="lab_ofc_Number7150ColumbiaGatewayDriveMember_03877FC5EEAB7C30EC7B9B3DC860EFCD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7150 Columbia Gateway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7150ColumbiaGatewayDriveMember_03877FC5EEAB7C30EC7B9B3DC860EFCD_documentation_en-US" xlink:label="lab_ofc_Number7150ColumbiaGatewayDriveMember_03877FC5EEAB7C30EC7B9B3DC860EFCD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7150 Columbia Gateway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7150ColumbiaGatewayDriveMember" xlink:label="loc_ofc_Number7150ColumbiaGatewayDriveMember_03877FC5EEAB7C30EC7B9B3DC860EFCD" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7150ColumbiaGatewayDriveMember_03877FC5EEAB7C30EC7B9B3DC860EFCD" xlink:to="lab_ofc_Number7150ColumbiaGatewayDriveMember_03877FC5EEAB7C30EC7B9B3DC860EFCD" xlink:type="arc" />
    <link:label id="lab_ofc_Number7150RiverwoodDriveMember_83F16530208AC95AC8C79B3DC860ADB0_terseLabel_en-US" xlink:label="lab_ofc_Number7150RiverwoodDriveMember_83F16530208AC95AC8C79B3DC860ADB0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7150 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7150RiverwoodDriveMember_83F16530208AC95AC8C79B3DC860ADB0_label_en-US" xlink:label="lab_ofc_Number7150RiverwoodDriveMember_83F16530208AC95AC8C79B3DC860ADB0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7150 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7150RiverwoodDriveMember_83F16530208AC95AC8C79B3DC860ADB0_documentation_en-US" xlink:label="lab_ofc_Number7150RiverwoodDriveMember_83F16530208AC95AC8C79B3DC860ADB0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7150 Riverwood Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7150RiverwoodDriveMember" xlink:label="loc_ofc_Number7150RiverwoodDriveMember_83F16530208AC95AC8C79B3DC860ADB0" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7150RiverwoodDriveMember_83F16530208AC95AC8C79B3DC860ADB0" xlink:to="lab_ofc_Number7150RiverwoodDriveMember_83F16530208AC95AC8C79B3DC860ADB0" xlink:type="arc" />
    <link:label id="lab_ofc_Number7160RiverwoodDriveMember_93EE48B3F2F1842C92DD9B3DC860E273_terseLabel_en-US" xlink:label="lab_ofc_Number7160RiverwoodDriveMember_93EE48B3F2F1842C92DD9B3DC860E273" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7160 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7160RiverwoodDriveMember_93EE48B3F2F1842C92DD9B3DC860E273_label_en-US" xlink:label="lab_ofc_Number7160RiverwoodDriveMember_93EE48B3F2F1842C92DD9B3DC860E273" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7160 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7160RiverwoodDriveMember_93EE48B3F2F1842C92DD9B3DC860E273_documentation_en-US" xlink:label="lab_ofc_Number7160RiverwoodDriveMember_93EE48B3F2F1842C92DD9B3DC860E273" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7160 Riverwood Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7160RiverwoodDriveMember" xlink:label="loc_ofc_Number7160RiverwoodDriveMember_93EE48B3F2F1842C92DD9B3DC860E273" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7160RiverwoodDriveMember_93EE48B3F2F1842C92DD9B3DC860E273" xlink:to="lab_ofc_Number7160RiverwoodDriveMember_93EE48B3F2F1842C92DD9B3DC860E273" xlink:type="arc" />
    <link:label id="lab_ofc_Number7170RiverwoodDriveMember_933ED21D2C3C0B9EC69C9B3DC86054C1_terseLabel_en-US" xlink:label="lab_ofc_Number7170RiverwoodDriveMember_933ED21D2C3C0B9EC69C9B3DC86054C1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7170 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7170RiverwoodDriveMember_933ED21D2C3C0B9EC69C9B3DC86054C1_label_en-US" xlink:label="lab_ofc_Number7170RiverwoodDriveMember_933ED21D2C3C0B9EC69C9B3DC86054C1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7170 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7170RiverwoodDriveMember_933ED21D2C3C0B9EC69C9B3DC86054C1_documentation_en-US" xlink:label="lab_ofc_Number7170RiverwoodDriveMember_933ED21D2C3C0B9EC69C9B3DC86054C1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7170 Riverwood Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7170RiverwoodDriveMember" xlink:label="loc_ofc_Number7170RiverwoodDriveMember_933ED21D2C3C0B9EC69C9B3DC86054C1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7170RiverwoodDriveMember_933ED21D2C3C0B9EC69C9B3DC86054C1" xlink:to="lab_ofc_Number7170RiverwoodDriveMember_933ED21D2C3C0B9EC69C9B3DC86054C1" xlink:type="arc" />
    <link:label id="lab_ofc_Number7175RiverwoodDriveMember_1969E8FD531D6D449F859B3DC8603F02_terseLabel_en-US" xlink:label="lab_ofc_Number7175RiverwoodDriveMember_1969E8FD531D6D449F859B3DC8603F02" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7175 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7175RiverwoodDriveMember_1969E8FD531D6D449F859B3DC8603F02_label_en-US" xlink:label="lab_ofc_Number7175RiverwoodDriveMember_1969E8FD531D6D449F859B3DC8603F02" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7175 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7175RiverwoodDriveMember_1969E8FD531D6D449F859B3DC8603F02_documentation_en-US" xlink:label="lab_ofc_Number7175RiverwoodDriveMember_1969E8FD531D6D449F859B3DC8603F02" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7175 Riverwood Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7175RiverwoodDriveMember" xlink:label="loc_ofc_Number7175RiverwoodDriveMember_1969E8FD531D6D449F859B3DC8603F02" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7175RiverwoodDriveMember_1969E8FD531D6D449F859B3DC8603F02" xlink:to="lab_ofc_Number7175RiverwoodDriveMember_1969E8FD531D6D449F859B3DC8603F02" xlink:type="arc" />
    <link:label id="lab_ofc_Number7200RedstoneGatewayMember_10B3830EC5F526661A8F9B3DC860FD39_terseLabel_en-US" xlink:label="lab_ofc_Number7200RedstoneGatewayMember_10B3830EC5F526661A8F9B3DC860FD39" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7200 Redstone Gateway [Member]</link:label>
    <link:label id="lab_ofc_Number7200RedstoneGatewayMember_10B3830EC5F526661A8F9B3DC860FD39_label_en-US" xlink:label="lab_ofc_Number7200RedstoneGatewayMember_10B3830EC5F526661A8F9B3DC860FD39" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7200 Redstone Gateway [Member]</link:label>
    <link:label id="lab_ofc_Number7200RedstoneGatewayMember_10B3830EC5F526661A8F9B3DC860FD39_documentation_en-US" xlink:label="lab_ofc_Number7200RedstoneGatewayMember_10B3830EC5F526661A8F9B3DC860FD39" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 7200 Redstone Gateway [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7200RedstoneGatewayMember" xlink:label="loc_ofc_Number7200RedstoneGatewayMember_10B3830EC5F526661A8F9B3DC860FD39" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7200RedstoneGatewayMember_10B3830EC5F526661A8F9B3DC860FD39" xlink:to="lab_ofc_Number7200RedstoneGatewayMember_10B3830EC5F526661A8F9B3DC860FD39" xlink:type="arc" />
    <link:label id="lab_ofc_Number7200RiverwoodRoadMember_75F04EF4A947E4866A3B9B3DC860B3AB_terseLabel_en-US" xlink:label="lab_ofc_Number7200RiverwoodRoadMember_75F04EF4A947E4866A3B9B3DC860B3AB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7200 Riverwood Road [Member]</link:label>
    <link:label id="lab_ofc_Number7200RiverwoodRoadMember_75F04EF4A947E4866A3B9B3DC860B3AB_label_en-US" xlink:label="lab_ofc_Number7200RiverwoodRoadMember_75F04EF4A947E4866A3B9B3DC860B3AB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7200 Riverwood Road [Member]</link:label>
    <link:label id="lab_ofc_Number7200RiverwoodRoadMember_75F04EF4A947E4866A3B9B3DC860B3AB_documentation_en-US" xlink:label="lab_ofc_Number7200RiverwoodRoadMember_75F04EF4A947E4866A3B9B3DC860B3AB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7200 Riverwood Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7200RiverwoodRoadMember" xlink:label="loc_ofc_Number7200RiverwoodRoadMember_75F04EF4A947E4866A3B9B3DC860B3AB" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7200RiverwoodRoadMember_75F04EF4A947E4866A3B9B3DC860B3AB" xlink:to="lab_ofc_Number7200RiverwoodRoadMember_75F04EF4A947E4866A3B9B3DC860B3AB" xlink:type="arc" />
    <link:label id="lab_ofc_Number7205RiverwoodDriveMember_F6FDE3C4DA0B24C2ECEE9B3DC861C4C9_terseLabel_en-US" xlink:label="lab_ofc_Number7205RiverwoodDriveMember_F6FDE3C4DA0B24C2ECEE9B3DC861C4C9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7205 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7205RiverwoodDriveMember_F6FDE3C4DA0B24C2ECEE9B3DC861C4C9_label_en-US" xlink:label="lab_ofc_Number7205RiverwoodDriveMember_F6FDE3C4DA0B24C2ECEE9B3DC861C4C9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7205 Riverwood Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7205RiverwoodDriveMember_F6FDE3C4DA0B24C2ECEE9B3DC861C4C9_documentation_en-US" xlink:label="lab_ofc_Number7205RiverwoodDriveMember_F6FDE3C4DA0B24C2ECEE9B3DC861C4C9" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7160 Riverwood Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7205RiverwoodDriveMember" xlink:label="loc_ofc_Number7205RiverwoodDriveMember_F6FDE3C4DA0B24C2ECEE9B3DC861C4C9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7205RiverwoodDriveMember_F6FDE3C4DA0B24C2ECEE9B3DC861C4C9" xlink:to="lab_ofc_Number7205RiverwoodDriveMember_F6FDE3C4DA0B24C2ECEE9B3DC861C4C9" xlink:type="arc" />
    <link:label id="lab_ofc_Number7272ParkCircleDriveMember_846EA0BB71006A6243BA9B3DC861B4D3_terseLabel_en-US" xlink:label="lab_ofc_Number7272ParkCircleDriveMember_846EA0BB71006A6243BA9B3DC861B4D3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7272 Park Circle Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7272ParkCircleDriveMember_846EA0BB71006A6243BA9B3DC861B4D3_label_en-US" xlink:label="lab_ofc_Number7272ParkCircleDriveMember_846EA0BB71006A6243BA9B3DC861B4D3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7272 Park Circle Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7272ParkCircleDriveMember_846EA0BB71006A6243BA9B3DC861B4D3_documentation_en-US" xlink:label="lab_ofc_Number7272ParkCircleDriveMember_846EA0BB71006A6243BA9B3DC861B4D3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7272 Park Circle Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7272ParkCircleDriveMember" xlink:label="loc_ofc_Number7272ParkCircleDriveMember_846EA0BB71006A6243BA9B3DC861B4D3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7272ParkCircleDriveMember_846EA0BB71006A6243BA9B3DC861B4D3" xlink:to="lab_ofc_Number7272ParkCircleDriveMember_846EA0BB71006A6243BA9B3DC861B4D3" xlink:type="arc" />
    <link:label id="lab_ofc_Number7318ParkwayDriveMember_5A50D38F3A39855041C69B3DC861EE60_terseLabel_en-US" xlink:label="lab_ofc_Number7318ParkwayDriveMember_5A50D38F3A39855041C69B3DC861EE60" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7318 Parkway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7318ParkwayDriveMember_5A50D38F3A39855041C69B3DC861EE60_label_en-US" xlink:label="lab_ofc_Number7318ParkwayDriveMember_5A50D38F3A39855041C69B3DC861EE60" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7318 Parkway Drive [Member]</link:label>
    <link:label id="lab_ofc_Number7318ParkwayDriveMember_5A50D38F3A39855041C69B3DC861EE60_documentation_en-US" xlink:label="lab_ofc_Number7318ParkwayDriveMember_5A50D38F3A39855041C69B3DC861EE60" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7318 Parkway Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7318ParkwayDriveMember" xlink:label="loc_ofc_Number7318ParkwayDriveMember_5A50D38F3A39855041C69B3DC861EE60" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7318ParkwayDriveMember_5A50D38F3A39855041C69B3DC861EE60" xlink:to="lab_ofc_Number7318ParkwayDriveMember_5A50D38F3A39855041C69B3DC861EE60" xlink:type="arc" />
    <link:label id="lab_ofc_Number7400RedstoneGatewayMember_03A00A0905D5D3E39AB99B3DC861472B_terseLabel_en-US" xlink:label="lab_ofc_Number7400RedstoneGatewayMember_03A00A0905D5D3E39AB99B3DC861472B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7400 Redstone Gateway [Member]</link:label>
    <link:label id="lab_ofc_Number7400RedstoneGatewayMember_03A00A0905D5D3E39AB99B3DC861472B_label_en-US" xlink:label="lab_ofc_Number7400RedstoneGatewayMember_03A00A0905D5D3E39AB99B3DC861472B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7400 Redstone Gateway [Member]</link:label>
    <link:label id="lab_ofc_Number7400RedstoneGatewayMember_03A00A0905D5D3E39AB99B3DC861472B_documentation_en-US" xlink:label="lab_ofc_Number7400RedstoneGatewayMember_03A00A0905D5D3E39AB99B3DC861472B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 7400 Redstone Gateway [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7400RedstoneGatewayMember" xlink:label="loc_ofc_Number7400RedstoneGatewayMember_03A00A0905D5D3E39AB99B3DC861472B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7400RedstoneGatewayMember_03A00A0905D5D3E39AB99B3DC861472B" xlink:to="lab_ofc_Number7400RedstoneGatewayMember_03A00A0905D5D3E39AB99B3DC861472B" xlink:type="arc" />
    <link:label id="lab_ofc_Number7467RidgeRoadMember_63DC560038207F43B4E39B3DC8614E45_terseLabel_en-US" xlink:label="lab_ofc_Number7467RidgeRoadMember_63DC560038207F43B4E39B3DC8614E45" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7467 Ridge Road [Member]</link:label>
    <link:label id="lab_ofc_Number7467RidgeRoadMember_63DC560038207F43B4E39B3DC8614E45_label_en-US" xlink:label="lab_ofc_Number7467RidgeRoadMember_63DC560038207F43B4E39B3DC8614E45" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7467 Ridge Road [Member]</link:label>
    <link:label id="lab_ofc_Number7467RidgeRoadMember_63DC560038207F43B4E39B3DC8614E45_documentation_en-US" xlink:label="lab_ofc_Number7467RidgeRoadMember_63DC560038207F43B4E39B3DC8614E45" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7467 Ridge Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7467RidgeRoadMember" xlink:label="loc_ofc_Number7467RidgeRoadMember_63DC560038207F43B4E39B3DC8614E45" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7467RidgeRoadMember_63DC560038207F43B4E39B3DC8614E45" xlink:to="lab_ofc_Number7467RidgeRoadMember_63DC560038207F43B4E39B3DC8614E45" xlink:type="arc" />
    <link:label id="lab_ofc_Number7740MilestoneParkwayMember_5A91A78C3B663EDD0A289B3DC86105B4_terseLabel_en-US" xlink:label="lab_ofc_Number7740MilestoneParkwayMember_5A91A78C3B663EDD0A289B3DC86105B4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7740 Milestone Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number7740MilestoneParkwayMember_5A91A78C3B663EDD0A289B3DC86105B4_label_en-US" xlink:label="lab_ofc_Number7740MilestoneParkwayMember_5A91A78C3B663EDD0A289B3DC86105B4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7740 Milestone Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number7740MilestoneParkwayMember_5A91A78C3B663EDD0A289B3DC86105B4_documentation_en-US" xlink:label="lab_ofc_Number7740MilestoneParkwayMember_5A91A78C3B663EDD0A289B3DC86105B4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to7740 Milestone Parkway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7740MilestoneParkwayMember" xlink:label="loc_ofc_Number7740MilestoneParkwayMember_5A91A78C3B663EDD0A289B3DC86105B4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7740MilestoneParkwayMember_5A91A78C3B663EDD0A289B3DC86105B4" xlink:to="lab_ofc_Number7740MilestoneParkwayMember_5A91A78C3B663EDD0A289B3DC86105B4" xlink:type="arc" />
    <link:label id="lab_ofc_Number7770BacklickRoadMember_39CD2E063AFF0953E8419B3DC8616355_terseLabel_en-US" xlink:label="lab_ofc_Number7770BacklickRoadMember_39CD2E063AFF0953E8419B3DC8616355" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7770 Backlick Road [Member]</link:label>
    <link:label id="lab_ofc_Number7770BacklickRoadMember_39CD2E063AFF0953E8419B3DC8616355_label_en-US" xlink:label="lab_ofc_Number7770BacklickRoadMember_39CD2E063AFF0953E8419B3DC8616355" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7770 Backlick Road [Member]</link:label>
    <link:label id="lab_ofc_Number7770BacklickRoadMember_39CD2E063AFF0953E8419B3DC8616355_documentation_en-US" xlink:label="lab_ofc_Number7770BacklickRoadMember_39CD2E063AFF0953E8419B3DC8616355" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7770 Backlick Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7770BacklickRoadMember" xlink:label="loc_ofc_Number7770BacklickRoadMember_39CD2E063AFF0953E8419B3DC8616355" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7770BacklickRoadMember_39CD2E063AFF0953E8419B3DC8616355" xlink:to="lab_ofc_Number7770BacklickRoadMember_39CD2E063AFF0953E8419B3DC8616355" xlink:type="arc" />
    <link:label id="lab_ofc_Number7880MilestoneParkwayMember_12CC7B54FC8B008F4CC19B3DC8613A70_terseLabel_en-US" xlink:label="lab_ofc_Number7880MilestoneParkwayMember_12CC7B54FC8B008F4CC19B3DC8613A70" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">7880 Milestone Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number7880MilestoneParkwayMember_12CC7B54FC8B008F4CC19B3DC8613A70_label_en-US" xlink:label="lab_ofc_Number7880MilestoneParkwayMember_12CC7B54FC8B008F4CC19B3DC8613A70" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 7880 Milestone Parkway [Member]</link:label>
    <link:label id="lab_ofc_Number7880MilestoneParkwayMember_12CC7B54FC8B008F4CC19B3DC8613A70_documentation_en-US" xlink:label="lab_ofc_Number7880MilestoneParkwayMember_12CC7B54FC8B008F4CC19B3DC8613A70" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number 7880 Milestone Parkway [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number7880MilestoneParkwayMember" xlink:label="loc_ofc_Number7880MilestoneParkwayMember_12CC7B54FC8B008F4CC19B3DC8613A70" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number7880MilestoneParkwayMember_12CC7B54FC8B008F4CC19B3DC8613A70" xlink:to="lab_ofc_Number7880MilestoneParkwayMember_12CC7B54FC8B008F4CC19B3DC8613A70" xlink:type="arc" />
    <link:label id="lab_ofc_Number8621RobertFultonDriveMember_30F9AAF717DFCAABA8789B3DC862525A_terseLabel_en-US" xlink:label="lab_ofc_Number8621RobertFultonDriveMember_30F9AAF717DFCAABA8789B3DC862525A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">8621 Robert Fulton Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8621RobertFultonDriveMember_30F9AAF717DFCAABA8789B3DC862525A_label_en-US" xlink:label="lab_ofc_Number8621RobertFultonDriveMember_30F9AAF717DFCAABA8789B3DC862525A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 8621 Robert Fulton Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8621RobertFultonDriveMember_30F9AAF717DFCAABA8789B3DC862525A_documentation_en-US" xlink:label="lab_ofc_Number8621RobertFultonDriveMember_30F9AAF717DFCAABA8789B3DC862525A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 8621 Robert Fulton Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number8621RobertFultonDriveMember" xlink:label="loc_ofc_Number8621RobertFultonDriveMember_30F9AAF717DFCAABA8789B3DC862525A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number8621RobertFultonDriveMember_30F9AAF717DFCAABA8789B3DC862525A" xlink:to="lab_ofc_Number8621RobertFultonDriveMember_30F9AAF717DFCAABA8789B3DC862525A" xlink:type="arc" />
    <link:label id="lab_ofc_Number8661RobertFultonDriveMember_36CA6D64785185E8E2389B3DC8628817_terseLabel_en-US" xlink:label="lab_ofc_Number8661RobertFultonDriveMember_36CA6D64785185E8E2389B3DC8628817" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">8661 Robert Fulton Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8661RobertFultonDriveMember_36CA6D64785185E8E2389B3DC8628817_label_en-US" xlink:label="lab_ofc_Number8661RobertFultonDriveMember_36CA6D64785185E8E2389B3DC8628817" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 8661 Robert Fulton Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8661RobertFultonDriveMember_36CA6D64785185E8E2389B3DC8628817_documentation_en-US" xlink:label="lab_ofc_Number8661RobertFultonDriveMember_36CA6D64785185E8E2389B3DC8628817" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 8661 Robert Fulton Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number8661RobertFultonDriveMember" xlink:label="loc_ofc_Number8661RobertFultonDriveMember_36CA6D64785185E8E2389B3DC8628817" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number8661RobertFultonDriveMember_36CA6D64785185E8E2389B3DC8628817" xlink:to="lab_ofc_Number8661RobertFultonDriveMember_36CA6D64785185E8E2389B3DC8628817" xlink:type="arc" />
    <link:label id="lab_ofc_Number8671RobertFultonDriveMember_AD3647C6B4CD39B62DC39B3DC8625AD1_terseLabel_en-US" xlink:label="lab_ofc_Number8671RobertFultonDriveMember_AD3647C6B4CD39B62DC39B3DC8625AD1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">8671 Robert Fulton Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8671RobertFultonDriveMember_AD3647C6B4CD39B62DC39B3DC8625AD1_label_en-US" xlink:label="lab_ofc_Number8671RobertFultonDriveMember_AD3647C6B4CD39B62DC39B3DC8625AD1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 8671 Robert Fulton Drive [Member]</link:label>
    <link:label id="lab_ofc_Number8671RobertFultonDriveMember_AD3647C6B4CD39B62DC39B3DC8625AD1_documentation_en-US" xlink:label="lab_ofc_Number8671RobertFultonDriveMember_AD3647C6B4CD39B62DC39B3DC8625AD1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 8671 Robert Fulton Drive, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number8671RobertFultonDriveMember" xlink:label="loc_ofc_Number8671RobertFultonDriveMember_AD3647C6B4CD39B62DC39B3DC8625AD1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number8671RobertFultonDriveMember_AD3647C6B4CD39B62DC39B3DC8625AD1" xlink:to="lab_ofc_Number8671RobertFultonDriveMember_AD3647C6B4CD39B62DC39B3DC8625AD1" xlink:type="arc" />
    <link:label id="lab_ofc_Number870ElkridgeLandingRoadMember_DF76559BC6FBDE21F18D9B3DC862ECB5_terseLabel_en-US" xlink:label="lab_ofc_Number870ElkridgeLandingRoadMember_DF76559BC6FBDE21F18D9B3DC862ECB5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">870 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number870ElkridgeLandingRoadMember_DF76559BC6FBDE21F18D9B3DC862ECB5_label_en-US" xlink:label="lab_ofc_Number870ElkridgeLandingRoadMember_DF76559BC6FBDE21F18D9B3DC862ECB5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 870 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number870ElkridgeLandingRoadMember_DF76559BC6FBDE21F18D9B3DC862ECB5_documentation_en-US" xlink:label="lab_ofc_Number870ElkridgeLandingRoadMember_DF76559BC6FBDE21F18D9B3DC862ECB5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 870 Elkridge Landing Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number870ElkridgeLandingRoadMember" xlink:label="loc_ofc_Number870ElkridgeLandingRoadMember_DF76559BC6FBDE21F18D9B3DC862ECB5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number870ElkridgeLandingRoadMember_DF76559BC6FBDE21F18D9B3DC862ECB5" xlink:to="lab_ofc_Number870ElkridgeLandingRoadMember_DF76559BC6FBDE21F18D9B3DC862ECB5" xlink:type="arc" />
    <link:label id="lab_ofc_Number891ElkridgeLandingRoadMember_D5966B2DE983C4032E089B3DC862DB90_terseLabel_en-US" xlink:label="lab_ofc_Number891ElkridgeLandingRoadMember_D5966B2DE983C4032E089B3DC862DB90" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">891 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number891ElkridgeLandingRoadMember_D5966B2DE983C4032E089B3DC862DB90_label_en-US" xlink:label="lab_ofc_Number891ElkridgeLandingRoadMember_D5966B2DE983C4032E089B3DC862DB90" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 891 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number891ElkridgeLandingRoadMember_D5966B2DE983C4032E089B3DC862DB90_documentation_en-US" xlink:label="lab_ofc_Number891ElkridgeLandingRoadMember_D5966B2DE983C4032E089B3DC862DB90" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 891 Elkridge Landing Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number891ElkridgeLandingRoadMember" xlink:label="loc_ofc_Number891ElkridgeLandingRoadMember_D5966B2DE983C4032E089B3DC862DB90" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number891ElkridgeLandingRoadMember_D5966B2DE983C4032E089B3DC862DB90" xlink:to="lab_ofc_Number891ElkridgeLandingRoadMember_D5966B2DE983C4032E089B3DC862DB90" xlink:type="arc" />
    <link:label id="lab_ofc_Number901ElkridgeLandingRoadMember_961364F7FC6B5B75A0D09B3DC86205D5_terseLabel_en-US" xlink:label="lab_ofc_Number901ElkridgeLandingRoadMember_961364F7FC6B5B75A0D09B3DC86205D5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">901 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number901ElkridgeLandingRoadMember_961364F7FC6B5B75A0D09B3DC86205D5_label_en-US" xlink:label="lab_ofc_Number901ElkridgeLandingRoadMember_961364F7FC6B5B75A0D09B3DC86205D5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 901 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number901ElkridgeLandingRoadMember_961364F7FC6B5B75A0D09B3DC86205D5_documentation_en-US" xlink:label="lab_ofc_Number901ElkridgeLandingRoadMember_961364F7FC6B5B75A0D09B3DC86205D5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 901 Elkridge Landing Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number901ElkridgeLandingRoadMember" xlink:label="loc_ofc_Number901ElkridgeLandingRoadMember_961364F7FC6B5B75A0D09B3DC86205D5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number901ElkridgeLandingRoadMember_961364F7FC6B5B75A0D09B3DC86205D5" xlink:to="lab_ofc_Number901ElkridgeLandingRoadMember_961364F7FC6B5B75A0D09B3DC86205D5" xlink:type="arc" />
    <link:label id="lab_ofc_Number911ElkridgeLandingRoadMember_366DD7AE90953416B65F9B3DC8623C75_terseLabel_en-US" xlink:label="lab_ofc_Number911ElkridgeLandingRoadMember_366DD7AE90953416B65F9B3DC8623C75" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">911 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number911ElkridgeLandingRoadMember_366DD7AE90953416B65F9B3DC8623C75_label_en-US" xlink:label="lab_ofc_Number911ElkridgeLandingRoadMember_366DD7AE90953416B65F9B3DC8623C75" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 911 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number911ElkridgeLandingRoadMember_366DD7AE90953416B65F9B3DC8623C75_documentation_en-US" xlink:label="lab_ofc_Number911ElkridgeLandingRoadMember_366DD7AE90953416B65F9B3DC8623C75" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 911 Elkridge Landing Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number911ElkridgeLandingRoadMember" xlink:label="loc_ofc_Number911ElkridgeLandingRoadMember_366DD7AE90953416B65F9B3DC8623C75" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number911ElkridgeLandingRoadMember_366DD7AE90953416B65F9B3DC8623C75" xlink:to="lab_ofc_Number911ElkridgeLandingRoadMember_366DD7AE90953416B65F9B3DC8623C75" xlink:type="arc" />
    <link:label id="lab_ofc_Number938ElkridgeLandingRoadMember_211464B932261C784F6B9B3DC8636C33_terseLabel_en-US" xlink:label="lab_ofc_Number938ElkridgeLandingRoadMember_211464B932261C784F6B9B3DC8636C33" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">938 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number938ElkridgeLandingRoadMember_211464B932261C784F6B9B3DC8636C33_label_en-US" xlink:label="lab_ofc_Number938ElkridgeLandingRoadMember_211464B932261C784F6B9B3DC8636C33" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 938 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number938ElkridgeLandingRoadMember_211464B932261C784F6B9B3DC8636C33_documentation_en-US" xlink:label="lab_ofc_Number938ElkridgeLandingRoadMember_211464B932261C784F6B9B3DC8636C33" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 938 Elkridge Landing Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number938ElkridgeLandingRoadMember" xlink:label="loc_ofc_Number938ElkridgeLandingRoadMember_211464B932261C784F6B9B3DC8636C33" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number938ElkridgeLandingRoadMember_211464B932261C784F6B9B3DC8636C33" xlink:to="lab_ofc_Number938ElkridgeLandingRoadMember_211464B932261C784F6B9B3DC8636C33" xlink:type="arc" />
    <link:label id="lab_ofc_Number939ElkridgeLandingRoadMember_E31114844962388F802B9B3DC8639359_terseLabel_en-US" xlink:label="lab_ofc_Number939ElkridgeLandingRoadMember_E31114844962388F802B9B3DC8639359" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">939 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number939ElkridgeLandingRoadMember_E31114844962388F802B9B3DC8639359_label_en-US" xlink:label="lab_ofc_Number939ElkridgeLandingRoadMember_E31114844962388F802B9B3DC8639359" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 939 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number939ElkridgeLandingRoadMember_E31114844962388F802B9B3DC8639359_documentation_en-US" xlink:label="lab_ofc_Number939ElkridgeLandingRoadMember_E31114844962388F802B9B3DC8639359" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 939 Elkridge Landing Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number939ElkridgeLandingRoadMember" xlink:label="loc_ofc_Number939ElkridgeLandingRoadMember_E31114844962388F802B9B3DC8639359" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number939ElkridgeLandingRoadMember_E31114844962388F802B9B3DC8639359" xlink:to="lab_ofc_Number939ElkridgeLandingRoadMember_E31114844962388F802B9B3DC8639359" xlink:type="arc" />
    <link:label id="lab_ofc_Number940ElkridgeLandingRoadMember_B9CE5B935A9100CE329F9B3DC86380E8_terseLabel_en-US" xlink:label="lab_ofc_Number940ElkridgeLandingRoadMember_B9CE5B935A9100CE329F9B3DC86380E8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">940 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number940ElkridgeLandingRoadMember_B9CE5B935A9100CE329F9B3DC86380E8_label_en-US" xlink:label="lab_ofc_Number940ElkridgeLandingRoadMember_B9CE5B935A9100CE329F9B3DC86380E8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 940 Elkridge Landing Road [Member]</link:label>
    <link:label id="lab_ofc_Number940ElkridgeLandingRoadMember_B9CE5B935A9100CE329F9B3DC86380E8_documentation_en-US" xlink:label="lab_ofc_Number940ElkridgeLandingRoadMember_B9CE5B935A9100CE329F9B3DC86380E8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 940 Elkridge Landing Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number940ElkridgeLandingRoadMember" xlink:label="loc_ofc_Number940ElkridgeLandingRoadMember_B9CE5B935A9100CE329F9B3DC86380E8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number940ElkridgeLandingRoadMember_B9CE5B935A9100CE329F9B3DC86380E8" xlink:to="lab_ofc_Number940ElkridgeLandingRoadMember_B9CE5B935A9100CE329F9B3DC86380E8" xlink:type="arc" />
    <link:label id="lab_ofc_Number9651HornbakerRoadMember_C0B3A3921794F46A4F3E9B3DC8635D7A_terseLabel_en-US" xlink:label="lab_ofc_Number9651HornbakerRoadMember_C0B3A3921794F46A4F3E9B3DC8635D7A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">9651 Hornbaker Road [Member]</link:label>
    <link:label id="lab_ofc_Number9651HornbakerRoadMember_C0B3A3921794F46A4F3E9B3DC8635D7A_label_en-US" xlink:label="lab_ofc_Number9651HornbakerRoadMember_C0B3A3921794F46A4F3E9B3DC8635D7A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number 9651 Hornbaker Road [Member]</link:label>
    <link:label id="lab_ofc_Number9651HornbakerRoadMember_C0B3A3921794F46A4F3E9B3DC8635D7A_documentation_en-US" xlink:label="lab_ofc_Number9651HornbakerRoadMember_C0B3A3921794F46A4F3E9B3DC8635D7A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 9651 Hornbaker Road, a data center owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Number9651HornbakerRoadMember" xlink:label="loc_ofc_Number9651HornbakerRoadMember_C0B3A3921794F46A4F3E9B3DC8635D7A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Number9651HornbakerRoadMember_C0B3A3921794F46A4F3E9B3DC8635D7A" xlink:to="lab_ofc_Number9651HornbakerRoadMember_C0B3A3921794F46A4F3E9B3DC8635D7A" xlink:type="arc" />
    <link:label id="lab_ofc_ArundelPreserveMember_3B60AB1C42195F71C2349B3DC863E3E0_terseLabel_en-US" xlink:label="lab_ofc_ArundelPreserveMember_3B60AB1C42195F71C2349B3DC863E3E0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Arundel Preserve [Member]</link:label>
    <link:label id="lab_ofc_ArundelPreserveMember_3B60AB1C42195F71C2349B3DC863E3E0_label_en-US" xlink:label="lab_ofc_ArundelPreserveMember_3B60AB1C42195F71C2349B3DC863E3E0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Arundel Preserve [Member]</link:label>
    <link:label id="lab_ofc_ArundelPreserveMember_3B60AB1C42195F71C2349B3DC863E3E0_documentation_en-US" xlink:label="lab_ofc_ArundelPreserveMember_3B60AB1C42195F71C2349B3DC863E3E0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Arundel Preserve, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ArundelPreserveMember" xlink:label="loc_ofc_ArundelPreserveMember_3B60AB1C42195F71C2349B3DC863E3E0" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ArundelPreserveMember_3B60AB1C42195F71C2349B3DC863E3E0" xlink:to="lab_ofc_ArundelPreserveMember_3B60AB1C42195F71C2349B3DC863E3E0" xlink:type="arc" />
    <link:label id="lab_ofc_BethlehemTechnologyParkDC18Member_D097ED94F4179C24C7659B3DC8635338_terseLabel_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC18Member_D097ED94F4179C24C7659B3DC8635338" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Bethlehem Tech Park-DC18 [Member]</link:label>
    <link:label id="lab_ofc_BethlehemTechnologyParkDC18Member_D097ED94F4179C24C7659B3DC8635338_label_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC18Member_D097ED94F4179C24C7659B3DC8635338" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Bethlehem Technology Park-DC18 [Member]</link:label>
    <link:label id="lab_ofc_BethlehemTechnologyParkDC18Member_D097ED94F4179C24C7659B3DC8635338_documentation_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC18Member_D097ED94F4179C24C7659B3DC8635338" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Bethlehem Technology Park-DC18 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_BethlehemTechnologyParkDC18Member" xlink:label="loc_ofc_BethlehemTechnologyParkDC18Member_D097ED94F4179C24C7659B3DC8635338" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_BethlehemTechnologyParkDC18Member_D097ED94F4179C24C7659B3DC8635338" xlink:to="lab_ofc_BethlehemTechnologyParkDC18Member_D097ED94F4179C24C7659B3DC8635338" xlink:type="arc" />
    <link:label id="lab_ofc_BethlehemTechnologyParkDC19Member_07340F71B0DFD1E474F69B3DC8648BB8_terseLabel_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC19Member_07340F71B0DFD1E474F69B3DC8648BB8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Bethlehem Tech Park-DC19 [Member]</link:label>
    <link:label id="lab_ofc_BethlehemTechnologyParkDC19Member_07340F71B0DFD1E474F69B3DC8648BB8_label_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC19Member_07340F71B0DFD1E474F69B3DC8648BB8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Bethlehem Technology Park-DC19 [Member]</link:label>
    <link:label id="lab_ofc_BethlehemTechnologyParkDC19Member_07340F71B0DFD1E474F69B3DC8648BB8_documentation_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC19Member_07340F71B0DFD1E474F69B3DC8648BB8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Bethlehem Technology Park-DC19 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_BethlehemTechnologyParkDC19Member" xlink:label="loc_ofc_BethlehemTechnologyParkDC19Member_07340F71B0DFD1E474F69B3DC8648BB8" xlink:type="locator" />
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    <link:label id="lab_ofc_BethlehemTechnologyParkDC20Member_445A7FAFC68B5DDBCB569B3DC864AA47_terseLabel_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC20Member_445A7FAFC68B5DDBCB569B3DC864AA47" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Bethlehem Tech Park-DC20 [Member]</link:label>
    <link:label id="lab_ofc_BethlehemTechnologyParkDC20Member_445A7FAFC68B5DDBCB569B3DC864AA47_label_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC20Member_445A7FAFC68B5DDBCB569B3DC864AA47" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Bethlehem Technology Park-DC20 [Member]</link:label>
    <link:label id="lab_ofc_BethlehemTechnologyParkDC20Member_445A7FAFC68B5DDBCB569B3DC864AA47_documentation_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC20Member_445A7FAFC68B5DDBCB569B3DC864AA47" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Bethlehem Technology Park-DC20 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_BethlehemTechnologyParkDC20Member" xlink:label="loc_ofc_BethlehemTechnologyParkDC20Member_445A7FAFC68B5DDBCB569B3DC864AA47" xlink:type="locator" />
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    <link:label id="lab_ofc_BethlehemTechnologyParkDC23Member_84A81B83EAC678C7CFE09B3DC8644FFD_label_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC23Member_84A81B83EAC678C7CFE09B3DC8644FFD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Bethlehem Technology Park - DC 23 [Member]</link:label>
    <link:label id="lab_ofc_BethlehemTechnologyParkDC23Member_84A81B83EAC678C7CFE09B3DC8644FFD_documentation_en-US" xlink:label="lab_ofc_BethlehemTechnologyParkDC23Member_84A81B83EAC678C7CFE09B3DC8644FFD" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Bethlehem Technology Park - DC 23 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_BethlehemTechnologyParkDC23Member" xlink:label="loc_ofc_BethlehemTechnologyParkDC23Member_84A81B83EAC678C7CFE09B3DC8644FFD" xlink:type="locator" />
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    <link:label id="lab_ofc_BLC1Member_3847FBAF0A85944343B19B3DC8647D7D_documentation_en-US" xlink:label="lab_ofc_BLC1Member_3847FBAF0A85944343B19B3DC8647D7D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">BLC 1 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_BLC1Member" xlink:label="loc_ofc_BLC1Member_3847FBAF0A85944343B19B3DC8647D7D" xlink:type="locator" />
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    <link:label id="lab_ofc_BLC2Member_39858C437B377D68A7C19B3DC86440AA_label_en-US" xlink:label="lab_ofc_BLC2Member_39858C437B377D68A7C19B3DC86440AA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">BLC 2 [Member]</link:label>
    <link:label id="lab_ofc_BLC2Member_39858C437B377D68A7C19B3DC86440AA_documentation_en-US" xlink:label="lab_ofc_BLC2Member_39858C437B377D68A7C19B3DC86440AA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">BLC 2 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_BLC2Member" xlink:label="loc_ofc_BLC2Member_39858C437B377D68A7C19B3DC86440AA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_BLC2Member_39858C437B377D68A7C19B3DC86440AA" xlink:to="lab_ofc_BLC2Member_39858C437B377D68A7C19B3DC86440AA" xlink:type="arc" />
    <link:label id="lab_ofc_CantonCrossingLandMember_37ED8B519C7156B8E3499B3DC864B428_terseLabel_en-US" xlink:label="lab_ofc_CantonCrossingLandMember_37ED8B519C7156B8E3499B3DC864B428" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Canton Crossing Land [Member]</link:label>
    <link:label id="lab_ofc_CantonCrossingLandMember_37ED8B519C7156B8E3499B3DC864B428_label_en-US" xlink:label="lab_ofc_CantonCrossingLandMember_37ED8B519C7156B8E3499B3DC864B428" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Canton Crossing Land [Member]</link:label>
    <link:label id="lab_ofc_CantonCrossingLandMember_37ED8B519C7156B8E3499B3DC864B428_documentation_en-US" xlink:label="lab_ofc_CantonCrossingLandMember_37ED8B519C7156B8E3499B3DC864B428" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Canton Crossing Land, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_CantonCrossingLandMember" xlink:label="loc_ofc_CantonCrossingLandMember_37ED8B519C7156B8E3499B3DC864B428" xlink:type="locator" />
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    <link:label id="lab_ofc_CantonCrossingUtilDistrCtrMember_A23997584631A659C7709B3DC864D806_terseLabel_en-US" xlink:label="lab_ofc_CantonCrossingUtilDistrCtrMember_A23997584631A659C7709B3DC864D806" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Canton Crossing Util Distr Ctr [Member]</link:label>
    <link:label id="lab_ofc_CantonCrossingUtilDistrCtrMember_A23997584631A659C7709B3DC864D806_label_en-US" xlink:label="lab_ofc_CantonCrossingUtilDistrCtrMember_A23997584631A659C7709B3DC864D806" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Canton Crossing Util Distr Ctr [Member]</link:label>
    <link:label id="lab_ofc_CantonCrossingUtilDistrCtrMember_A23997584631A659C7709B3DC864D806_documentation_en-US" xlink:label="lab_ofc_CantonCrossingUtilDistrCtrMember_A23997584631A659C7709B3DC864D806" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Canton Crossing Util Distr Ctr, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_CantonCrossingUtilDistrCtrMember" xlink:label="loc_ofc_CantonCrossingUtilDistrCtrMember_A23997584631A659C7709B3DC864D806" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_CantonCrossingUtilDistrCtrMember_A23997584631A659C7709B3DC864D806" xlink:to="lab_ofc_CantonCrossingUtilDistrCtrMember_A23997584631A659C7709B3DC864D806" xlink:type="arc" />
    <link:label id="lab_ofc_ColumbiaGatewaySouthridgeMember_642B7A3A301817D8D6B19B3DC864B7BA_terseLabel_en-US" xlink:label="lab_ofc_ColumbiaGatewaySouthridgeMember_642B7A3A301817D8D6B19B3DC864B7BA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Columbia Gateway - Southridge [Member]</link:label>
    <link:label id="lab_ofc_ColumbiaGatewaySouthridgeMember_642B7A3A301817D8D6B19B3DC864B7BA_label_en-US" xlink:label="lab_ofc_ColumbiaGatewaySouthridgeMember_642B7A3A301817D8D6B19B3DC864B7BA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Columbia Gateway - Southridge [Member]</link:label>
    <link:label id="lab_ofc_ColumbiaGatewaySouthridgeMember_642B7A3A301817D8D6B19B3DC864B7BA_documentation_en-US" xlink:label="lab_ofc_ColumbiaGatewaySouthridgeMember_642B7A3A301817D8D6B19B3DC864B7BA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Columbia Gateway - Southridge, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ColumbiaGatewaySouthridgeMember" xlink:label="loc_ofc_ColumbiaGatewaySouthridgeMember_642B7A3A301817D8D6B19B3DC864B7BA" xlink:type="locator" />
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    <link:label id="lab_ofc_DahlgrenTechnologyCenterMember_F1434BBDA8536325A5459B3DC8643D44_terseLabel_en-US" xlink:label="lab_ofc_DahlgrenTechnologyCenterMember_F1434BBDA8536325A5459B3DC8643D44" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Dahlgren Technology Center [Member]</link:label>
    <link:label id="lab_ofc_DahlgrenTechnologyCenterMember_F1434BBDA8536325A5459B3DC8643D44_label_en-US" xlink:label="lab_ofc_DahlgrenTechnologyCenterMember_F1434BBDA8536325A5459B3DC8643D44" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Dahlgren Technology Center [Member]</link:label>
    <link:label id="lab_ofc_DahlgrenTechnologyCenterMember_F1434BBDA8536325A5459B3DC8643D44_documentation_en-US" xlink:label="lab_ofc_DahlgrenTechnologyCenterMember_F1434BBDA8536325A5459B3DC8643D44" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Dahlgren Technology Center, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_DahlgrenTechnologyCenterMember" xlink:label="loc_ofc_DahlgrenTechnologyCenterMember_F1434BBDA8536325A5459B3DC8643D44" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_DahlgrenTechnologyCenterMember_F1434BBDA8536325A5459B3DC8643D44" xlink:to="lab_ofc_DahlgrenTechnologyCenterMember_F1434BBDA8536325A5459B3DC8643D44" xlink:type="arc" />
    <link:label id="lab_ofc_ExpeditionViiMember_B84E5541B78F8AE4702F9B3DC8653A92_terseLabel_en-US" xlink:label="lab_ofc_ExpeditionViiMember_B84E5541B78F8AE4702F9B3DC8653A92" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Expedition VII [Member]</link:label>
    <link:label id="lab_ofc_ExpeditionViiMember_B84E5541B78F8AE4702F9B3DC8653A92_label_en-US" xlink:label="lab_ofc_ExpeditionViiMember_B84E5541B78F8AE4702F9B3DC8653A92" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Expedition VII [Member]</link:label>
    <link:label id="lab_ofc_ExpeditionViiMember_B84E5541B78F8AE4702F9B3DC8653A92_documentation_en-US" xlink:label="lab_ofc_ExpeditionViiMember_B84E5541B78F8AE4702F9B3DC8653A92" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Expedition VII, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ExpeditionViiMember" xlink:label="loc_ofc_ExpeditionViiMember_B84E5541B78F8AE4702F9B3DC8653A92" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ExpeditionViiMember_B84E5541B78F8AE4702F9B3DC8653A92" xlink:to="lab_ofc_ExpeditionViiMember_B84E5541B78F8AE4702F9B3DC8653A92" xlink:type="arc" />
    <link:label id="lab_ofc_InnovationParkMember_12708D1E2F11B9EF56439B3DC86507E5_terseLabel_en-US" xlink:label="lab_ofc_InnovationParkMember_12708D1E2F11B9EF56439B3DC86507E5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Innovation Park [Member]</link:label>
    <link:label id="lab_ofc_InnovationParkMember_12708D1E2F11B9EF56439B3DC86507E5_label_en-US" xlink:label="lab_ofc_InnovationParkMember_12708D1E2F11B9EF56439B3DC86507E5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Innovation Park [Member]</link:label>
    <link:label id="lab_ofc_InnovationParkMember_12708D1E2F11B9EF56439B3DC86507E5_documentation_en-US" xlink:label="lab_ofc_InnovationParkMember_12708D1E2F11B9EF56439B3DC86507E5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Innovation Park [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_InnovationParkMember" xlink:label="loc_ofc_InnovationParkMember_12708D1E2F11B9EF56439B3DC86507E5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_InnovationParkMember_12708D1E2F11B9EF56439B3DC86507E5" xlink:to="lab_ofc_InnovationParkMember_12708D1E2F11B9EF56439B3DC86507E5" xlink:type="arc" />
    <link:label id="lab_ofc_MSquareResearchParkMember_4A7B1CA2A730F7C425099B3DC8657FD9_terseLabel_en-US" xlink:label="lab_ofc_MSquareResearchParkMember_4A7B1CA2A730F7C425099B3DC8657FD9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">M Square Research Park [Member]</link:label>
    <link:label id="lab_ofc_MSquareResearchParkMember_4A7B1CA2A730F7C425099B3DC8657FD9_label_en-US" xlink:label="lab_ofc_MSquareResearchParkMember_4A7B1CA2A730F7C425099B3DC8657FD9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">M Square Research Park [Member]</link:label>
    <link:label id="lab_ofc_MSquareResearchParkMember_4A7B1CA2A730F7C425099B3DC8657FD9_documentation_en-US" xlink:label="lab_ofc_MSquareResearchParkMember_4A7B1CA2A730F7C425099B3DC8657FD9" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to M Square Research Park, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_MSquareResearchParkMember" xlink:label="loc_ofc_MSquareResearchParkMember_4A7B1CA2A730F7C425099B3DC8657FD9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_MSquareResearchParkMember_4A7B1CA2A730F7C425099B3DC8657FD9" xlink:to="lab_ofc_MSquareResearchParkMember_4A7B1CA2A730F7C425099B3DC8657FD9" xlink:type="arc" />
    <link:label id="lab_ofc_MRLandMember_CB1094D27AC805C75FB99B3DC8654629_terseLabel_en-US" xlink:label="lab_ofc_MRLandMember_CB1094D27AC805C75FB99B3DC8654629" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">MR Land [Member]</link:label>
    <link:label id="lab_ofc_MRLandMember_CB1094D27AC805C75FB99B3DC8654629_label_en-US" xlink:label="lab_ofc_MRLandMember_CB1094D27AC805C75FB99B3DC8654629" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">MR Land [Member]</link:label>
    <link:label id="lab_ofc_MRLandMember_CB1094D27AC805C75FB99B3DC8654629_documentation_en-US" xlink:label="lab_ofc_MRLandMember_CB1094D27AC805C75FB99B3DC8654629" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">MR Land [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_MRLandMember" xlink:label="loc_ofc_MRLandMember_CB1094D27AC805C75FB99B3DC8654629" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_MRLandMember_CB1094D27AC805C75FB99B3DC8654629" xlink:to="lab_ofc_MRLandMember_CB1094D27AC805C75FB99B3DC8654629" xlink:type="arc" />
    <link:label id="lab_ofc_NationalBusinessParkNorthMember_3C2CC903E71773B280679B3DC866AC66_terseLabel_en-US" xlink:label="lab_ofc_NationalBusinessParkNorthMember_3C2CC903E71773B280679B3DC866AC66" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">National Business Park North [Member]</link:label>
    <link:label id="lab_ofc_NationalBusinessParkNorthMember_3C2CC903E71773B280679B3DC866AC66_label_en-US" xlink:label="lab_ofc_NationalBusinessParkNorthMember_3C2CC903E71773B280679B3DC866AC66" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">National Business Park North [Member]</link:label>
    <link:label id="lab_ofc_NationalBusinessParkNorthMember_3C2CC903E71773B280679B3DC866AC66_documentation_en-US" xlink:label="lab_ofc_NationalBusinessParkNorthMember_3C2CC903E71773B280679B3DC866AC66" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to National Business Park North, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NationalBusinessParkNorthMember" xlink:label="loc_ofc_NationalBusinessParkNorthMember_3C2CC903E71773B280679B3DC866AC66" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NationalBusinessParkNorthMember_3C2CC903E71773B280679B3DC866AC66" xlink:to="lab_ofc_NationalBusinessParkNorthMember_3C2CC903E71773B280679B3DC866AC66" xlink:type="arc" />
    <link:label id="lab_ofc_NorthGateBusinessParkMember_DAAB6219C12DD969ECAA9B3DC8664E51_terseLabel_en-US" xlink:label="lab_ofc_NorthGateBusinessParkMember_DAAB6219C12DD969ECAA9B3DC8664E51" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">North Gate Business Park [Member]</link:label>
    <link:label id="lab_ofc_NorthGateBusinessParkMember_DAAB6219C12DD969ECAA9B3DC8664E51_label_en-US" xlink:label="lab_ofc_NorthGateBusinessParkMember_DAAB6219C12DD969ECAA9B3DC8664E51" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">North Gate Business Park [Member]</link:label>
    <link:label id="lab_ofc_NorthGateBusinessParkMember_DAAB6219C12DD969ECAA9B3DC8664E51_documentation_en-US" xlink:label="lab_ofc_NorthGateBusinessParkMember_DAAB6219C12DD969ECAA9B3DC8664E51" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to North Gate Business Park, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NorthGateBusinessParkMember" xlink:label="loc_ofc_NorthGateBusinessParkMember_DAAB6219C12DD969ECAA9B3DC8664E51" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NorthGateBusinessParkMember_DAAB6219C12DD969ECAA9B3DC8664E51" xlink:to="lab_ofc_NorthGateBusinessParkMember_DAAB6219C12DD969ECAA9B3DC8664E51" xlink:type="arc" />
    <link:label id="lab_ofc_NorthwestCrossroadsMember_4A9E6C5E42D351FAA6289B3DC8661B90_terseLabel_en-US" xlink:label="lab_ofc_NorthwestCrossroadsMember_4A9E6C5E42D351FAA6289B3DC8661B90" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Northwest Crossroads [Member]</link:label>
    <link:label id="lab_ofc_NorthwestCrossroadsMember_4A9E6C5E42D351FAA6289B3DC8661B90_label_en-US" xlink:label="lab_ofc_NorthwestCrossroadsMember_4A9E6C5E42D351FAA6289B3DC8661B90" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Northwest Crossroads [Member]</link:label>
    <link:label id="lab_ofc_NorthwestCrossroadsMember_4A9E6C5E42D351FAA6289B3DC8661B90_documentation_en-US" xlink:label="lab_ofc_NorthwestCrossroadsMember_4A9E6C5E42D351FAA6289B3DC8661B90" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Northwest Crossroads, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NorthwestCrossroadsMember" xlink:label="loc_ofc_NorthwestCrossroadsMember_4A9E6C5E42D351FAA6289B3DC8661B90" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NorthwestCrossroadsMember_4A9E6C5E42D351FAA6289B3DC8661B90" xlink:to="lab_ofc_NorthwestCrossroadsMember_4A9E6C5E42D351FAA6289B3DC8661B90" xlink:type="arc" />
    <link:label id="lab_ofc_NOVAOfficeAMember_428F665CDBF2F19384509B3DC866E3EA_terseLabel_en-US" xlink:label="lab_ofc_NOVAOfficeAMember_428F665CDBF2F19384509B3DC866E3EA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">NOVA Office A [Member]</link:label>
    <link:label id="lab_ofc_NOVAOfficeAMember_428F665CDBF2F19384509B3DC866E3EA_label_en-US" xlink:label="lab_ofc_NOVAOfficeAMember_428F665CDBF2F19384509B3DC866E3EA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">NOVA Office A [Member]</link:label>
    <link:label id="lab_ofc_NOVAOfficeAMember_428F665CDBF2F19384509B3DC866E3EA_documentation_en-US" xlink:label="lab_ofc_NOVAOfficeAMember_428F665CDBF2F19384509B3DC866E3EA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">NOVA Office A [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NOVAOfficeAMember" xlink:label="loc_ofc_NOVAOfficeAMember_428F665CDBF2F19384509B3DC866E3EA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NOVAOfficeAMember_428F665CDBF2F19384509B3DC866E3EA" xlink:to="lab_ofc_NOVAOfficeAMember_428F665CDBF2F19384509B3DC866E3EA" xlink:type="arc" />
    <link:label id="lab_ofc_NOVAOfficeBMember_2E4471C23E7B5EE981C79B3DC86643DA_terseLabel_en-US" xlink:label="lab_ofc_NOVAOfficeBMember_2E4471C23E7B5EE981C79B3DC86643DA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">NOVA Office B [Member]</link:label>
    <link:label id="lab_ofc_NOVAOfficeBMember_2E4471C23E7B5EE981C79B3DC86643DA_label_en-US" xlink:label="lab_ofc_NOVAOfficeBMember_2E4471C23E7B5EE981C79B3DC86643DA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">NOVA Office B [Member]</link:label>
    <link:label id="lab_ofc_NOVAOfficeBMember_2E4471C23E7B5EE981C79B3DC86643DA_documentation_en-US" xlink:label="lab_ofc_NOVAOfficeBMember_2E4471C23E7B5EE981C79B3DC86643DA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">NOVA Office B [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NOVAOfficeBMember" xlink:label="loc_ofc_NOVAOfficeBMember_2E4471C23E7B5EE981C79B3DC86643DA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NOVAOfficeBMember_2E4471C23E7B5EE981C79B3DC86643DA" xlink:to="lab_ofc_NOVAOfficeBMember_2E4471C23E7B5EE981C79B3DC86643DA" xlink:type="arc" />
    <link:label id="lab_ofc_NOVAOfficeDMember_B4367A558692C431F0C39B3DC866B274_terseLabel_en-US" xlink:label="lab_ofc_NOVAOfficeDMember_B4367A558692C431F0C39B3DC866B274" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">NOVA Office D [Member]</link:label>
    <link:label id="lab_ofc_NOVAOfficeDMember_B4367A558692C431F0C39B3DC866B274_label_en-US" xlink:label="lab_ofc_NOVAOfficeDMember_B4367A558692C431F0C39B3DC866B274" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">NOVA Office D [Member]</link:label>
    <link:label id="lab_ofc_NOVAOfficeDMember_B4367A558692C431F0C39B3DC866B274_documentation_en-US" xlink:label="lab_ofc_NOVAOfficeDMember_B4367A558692C431F0C39B3DC866B274" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">NOVA Office D [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NOVAOfficeDMember" xlink:label="loc_ofc_NOVAOfficeDMember_B4367A558692C431F0C39B3DC866B274" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NOVAOfficeDMember_B4367A558692C431F0C39B3DC866B274" xlink:to="lab_ofc_NOVAOfficeDMember_B4367A558692C431F0C39B3DC866B274" xlink:type="arc" />
    <link:label id="lab_ofc_OldAnnapolisRoadMember_34B35F574B77F710BF619B3DC867A5A3_terseLabel_en-US" xlink:label="lab_ofc_OldAnnapolisRoadMember_34B35F574B77F710BF619B3DC867A5A3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Old Annapolis Road [Member]</link:label>
    <link:label id="lab_ofc_OldAnnapolisRoadMember_34B35F574B77F710BF619B3DC867A5A3_label_en-US" xlink:label="lab_ofc_OldAnnapolisRoadMember_34B35F574B77F710BF619B3DC867A5A3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Old Annapolis Road [Member]</link:label>
    <link:label id="lab_ofc_OldAnnapolisRoadMember_34B35F574B77F710BF619B3DC867A5A3_documentation_en-US" xlink:label="lab_ofc_OldAnnapolisRoadMember_34B35F574B77F710BF619B3DC867A5A3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Old Annapolis Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_OldAnnapolisRoadMember" xlink:label="loc_ofc_OldAnnapolisRoadMember_34B35F574B77F710BF619B3DC867A5A3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_OldAnnapolisRoadMember_34B35F574B77F710BF619B3DC867A5A3" xlink:to="lab_ofc_OldAnnapolisRoadMember_34B35F574B77F710BF619B3DC867A5A3" xlink:type="arc" />
    <link:label id="lab_ofc_ParagonParkDC21Member_731238C21683AE4C72089B3DC8673AFA_terseLabel_en-US" xlink:label="lab_ofc_ParagonParkDC21Member_731238C21683AE4C72089B3DC8673AFA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Paragon Park - DC 21 [Member]</link:label>
    <link:label id="lab_ofc_ParagonParkDC21Member_731238C21683AE4C72089B3DC8673AFA_label_en-US" xlink:label="lab_ofc_ParagonParkDC21Member_731238C21683AE4C72089B3DC8673AFA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Paragon Park - DC 21 [Member]</link:label>
    <link:label id="lab_ofc_ParagonParkDC21Member_731238C21683AE4C72089B3DC8673AFA_documentation_en-US" xlink:label="lab_ofc_ParagonParkDC21Member_731238C21683AE4C72089B3DC8673AFA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Paragon Park - DC 21 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ParagonParkDC21Member" xlink:label="loc_ofc_ParagonParkDC21Member_731238C21683AE4C72089B3DC8673AFA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ParagonParkDC21Member_731238C21683AE4C72089B3DC8673AFA" xlink:to="lab_ofc_ParagonParkDC21Member_731238C21683AE4C72089B3DC8673AFA" xlink:type="arc" />
    <link:label id="lab_ofc_ParagonParkDC22Member_AE80DC9FC824F5A0F6869B3DC867AA90_terseLabel_en-US" xlink:label="lab_ofc_ParagonParkDC22Member_AE80DC9FC824F5A0F6869B3DC867AA90" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Paragon Park - DC 22 [Member]</link:label>
    <link:label id="lab_ofc_ParagonParkDC22Member_AE80DC9FC824F5A0F6869B3DC867AA90_label_en-US" xlink:label="lab_ofc_ParagonParkDC22Member_AE80DC9FC824F5A0F6869B3DC867AA90" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Paragon Park - DC22 [Member]</link:label>
    <link:label id="lab_ofc_ParagonParkDC22Member_AE80DC9FC824F5A0F6869B3DC867AA90_documentation_en-US" xlink:label="lab_ofc_ParagonParkDC22Member_AE80DC9FC824F5A0F6869B3DC867AA90" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Paragon Park - DC22 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ParagonParkDC22Member" xlink:label="loc_ofc_ParagonParkDC22Member_AE80DC9FC824F5A0F6869B3DC867AA90" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_ParagonParkDC22Member_AE80DC9FC824F5A0F6869B3DC867AA90" xlink:to="lab_ofc_ParagonParkDC22Member_AE80DC9FC824F5A0F6869B3DC867AA90" xlink:type="arc" />
    <link:label id="lab_ofc_PatriotPointDC15Member_7456E50D5A68028A260F9B3DC8674CA9_terseLabel_en-US" xlink:label="lab_ofc_PatriotPointDC15Member_7456E50D5A68028A260F9B3DC8674CA9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Patriot Point - DC15 [Member]</link:label>
    <link:label id="lab_ofc_PatriotPointDC15Member_7456E50D5A68028A260F9B3DC8674CA9_label_en-US" xlink:label="lab_ofc_PatriotPointDC15Member_7456E50D5A68028A260F9B3DC8674CA9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Patriot Point - DC15 [Member]</link:label>
    <link:label id="lab_ofc_PatriotPointDC15Member_7456E50D5A68028A260F9B3DC8674CA9_documentation_en-US" xlink:label="lab_ofc_PatriotPointDC15Member_7456E50D5A68028A260F9B3DC8674CA9" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Patriot Point - DC15 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PatriotPointDC15Member" xlink:label="loc_ofc_PatriotPointDC15Member_7456E50D5A68028A260F9B3DC8674CA9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PatriotPointDC15Member_7456E50D5A68028A260F9B3DC8674CA9" xlink:to="lab_ofc_PatriotPointDC15Member_7456E50D5A68028A260F9B3DC8674CA9" xlink:type="arc" />
    <link:label id="lab_ofc_PatriotPointDC16Member_F9229AF10EF5657D6B649B3DC867F97C_terseLabel_en-US" xlink:label="lab_ofc_PatriotPointDC16Member_F9229AF10EF5657D6B649B3DC867F97C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Patriot Point - DC16 [Member]</link:label>
    <link:label id="lab_ofc_PatriotPointDC16Member_F9229AF10EF5657D6B649B3DC867F97C_label_en-US" xlink:label="lab_ofc_PatriotPointDC16Member_F9229AF10EF5657D6B649B3DC867F97C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Patriot Point - DC16 [Member]</link:label>
    <link:label id="lab_ofc_PatriotPointDC16Member_F9229AF10EF5657D6B649B3DC867F97C_documentation_en-US" xlink:label="lab_ofc_PatriotPointDC16Member_F9229AF10EF5657D6B649B3DC867F97C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Patriot Point - DC16 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PatriotPointDC16Member" xlink:label="loc_ofc_PatriotPointDC16Member_F9229AF10EF5657D6B649B3DC867F97C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PatriotPointDC16Member_F9229AF10EF5657D6B649B3DC867F97C" xlink:to="lab_ofc_PatriotPointDC16Member_F9229AF10EF5657D6B649B3DC867F97C" xlink:type="arc" />
    <link:label id="lab_ofc_PatriotPointDC17Member_CEFBA0EB36D0F1CC869E9B3DC86796BC_terseLabel_en-US" xlink:label="lab_ofc_PatriotPointDC17Member_CEFBA0EB36D0F1CC869E9B3DC86796BC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Patriot Point - DC17 [Member]</link:label>
    <link:label id="lab_ofc_PatriotPointDC17Member_CEFBA0EB36D0F1CC869E9B3DC86796BC_label_en-US" xlink:label="lab_ofc_PatriotPointDC17Member_CEFBA0EB36D0F1CC869E9B3DC86796BC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Patriot Point - DC17 [Member]</link:label>
    <link:label id="lab_ofc_PatriotPointDC17Member_CEFBA0EB36D0F1CC869E9B3DC86796BC_documentation_en-US" xlink:label="lab_ofc_PatriotPointDC17Member_CEFBA0EB36D0F1CC869E9B3DC86796BC" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Patriot Point - DC17 [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PatriotPointDC17Member" xlink:label="loc_ofc_PatriotPointDC17Member_CEFBA0EB36D0F1CC869E9B3DC86796BC" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PatriotPointDC17Member_CEFBA0EB36D0F1CC869E9B3DC86796BC" xlink:to="lab_ofc_PatriotPointDC17Member_CEFBA0EB36D0F1CC869E9B3DC86796BC" xlink:type="arc" />
    <link:label id="lab_ofc_PatriotRidgeMember_54FF9CD5DB272A6C89EE9B3DC8675AE0_terseLabel_en-US" xlink:label="lab_ofc_PatriotRidgeMember_54FF9CD5DB272A6C89EE9B3DC8675AE0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Patriot Ridge [Member]</link:label>
    <link:label id="lab_ofc_PatriotRidgeMember_54FF9CD5DB272A6C89EE9B3DC8675AE0_label_en-US" xlink:label="lab_ofc_PatriotRidgeMember_54FF9CD5DB272A6C89EE9B3DC8675AE0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Patriot Ridge [Member]</link:label>
    <link:label id="lab_ofc_PatriotRidgeMember_54FF9CD5DB272A6C89EE9B3DC8675AE0_documentation_en-US" xlink:label="lab_ofc_PatriotRidgeMember_54FF9CD5DB272A6C89EE9B3DC8675AE0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Patriot Ridge, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PatriotRidgeMember" xlink:label="loc_ofc_PatriotRidgeMember_54FF9CD5DB272A6C89EE9B3DC8675AE0" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_PatriotRidgeMember_54FF9CD5DB272A6C89EE9B3DC8675AE0" xlink:to="lab_ofc_PatriotRidgeMember_54FF9CD5DB272A6C89EE9B3DC8675AE0" xlink:type="arc" />
    <link:label id="lab_ofc_RedstoneGatewayMember_AD9B37F54EF0D7F854689B3DC8672592_terseLabel_en-US" xlink:label="lab_ofc_RedstoneGatewayMember_AD9B37F54EF0D7F854689B3DC8672592" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Redstone Gateway [Member]</link:label>
    <link:label id="lab_ofc_RedstoneGatewayMember_AD9B37F54EF0D7F854689B3DC8672592_label_en-US" xlink:label="lab_ofc_RedstoneGatewayMember_AD9B37F54EF0D7F854689B3DC8672592" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Redstone Gateway [Member]</link:label>
    <link:label id="lab_ofc_RedstoneGatewayMember_AD9B37F54EF0D7F854689B3DC8672592_documentation_en-US" xlink:label="lab_ofc_RedstoneGatewayMember_AD9B37F54EF0D7F854689B3DC8672592" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Redstone Gateway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RedstoneGatewayMember" xlink:label="loc_ofc_RedstoneGatewayMember_AD9B37F54EF0D7F854689B3DC8672592" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RedstoneGatewayMember_AD9B37F54EF0D7F854689B3DC8672592" xlink:to="lab_ofc_RedstoneGatewayMember_AD9B37F54EF0D7F854689B3DC8672592" xlink:type="arc" />
    <link:label id="lab_ofc_Route15BiggsFordRoadMember_0A65B0B5CE6AC81A16539B3DC868C447_terseLabel_en-US" xlink:label="lab_ofc_Route15BiggsFordRoadMember_0A65B0B5CE6AC81A16539B3DC868C447" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Route 15/Biggs Ford Road [Member]</link:label>
    <link:label id="lab_ofc_Route15BiggsFordRoadMember_0A65B0B5CE6AC81A16539B3DC868C447_label_en-US" xlink:label="lab_ofc_Route15BiggsFordRoadMember_0A65B0B5CE6AC81A16539B3DC868C447" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Route 15 Biggs Ford Road [Member]</link:label>
    <link:label id="lab_ofc_Route15BiggsFordRoadMember_0A65B0B5CE6AC81A16539B3DC868C447_documentation_en-US" xlink:label="lab_ofc_Route15BiggsFordRoadMember_0A65B0B5CE6AC81A16539B3DC868C447" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Route 15/Biggs Ford Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_Route15BiggsFordRoadMember" xlink:label="loc_ofc_Route15BiggsFordRoadMember_0A65B0B5CE6AC81A16539B3DC868C447" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_Route15BiggsFordRoadMember_0A65B0B5CE6AC81A16539B3DC868C447" xlink:to="lab_ofc_Route15BiggsFordRoadMember_0A65B0B5CE6AC81A16539B3DC868C447" xlink:type="arc" />
    <link:label id="lab_ofc_SentryGatewayMember_9ADC0A4B548F7578CAEC9B3DC868BD05_terseLabel_en-US" xlink:label="lab_ofc_SentryGatewayMember_9ADC0A4B548F7578CAEC9B3DC868BD05" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Sentry Gateway [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayMember_9ADC0A4B548F7578CAEC9B3DC868BD05_label_en-US" xlink:label="lab_ofc_SentryGatewayMember_9ADC0A4B548F7578CAEC9B3DC868BD05" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Sentry Gateway [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayMember_9ADC0A4B548F7578CAEC9B3DC868BD05_documentation_en-US" xlink:label="lab_ofc_SentryGatewayMember_9ADC0A4B548F7578CAEC9B3DC868BD05" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Sentry Gateway, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SentryGatewayMember" xlink:label="loc_ofc_SentryGatewayMember_9ADC0A4B548F7578CAEC9B3DC868BD05" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_SentryGatewayMember_9ADC0A4B548F7578CAEC9B3DC868BD05" xlink:to="lab_ofc_SentryGatewayMember_9ADC0A4B548F7578CAEC9B3DC868BD05" xlink:type="arc" />
    <link:label id="lab_ofc_SentryGatewayTMember_E6217170863E31FB73FC9B3DC86859C6_terseLabel_en-US" xlink:label="lab_ofc_SentryGatewayTMember_E6217170863E31FB73FC9B3DC86859C6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Sentry Gateway - T [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayTMember_E6217170863E31FB73FC9B3DC86859C6_label_en-US" xlink:label="lab_ofc_SentryGatewayTMember_E6217170863E31FB73FC9B3DC86859C6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Sentry Gateway - T [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayTMember_E6217170863E31FB73FC9B3DC86859C6_documentation_en-US" xlink:label="lab_ofc_SentryGatewayTMember_E6217170863E31FB73FC9B3DC86859C6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to 7700 Potranco Road, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SentryGatewayTMember" xlink:label="loc_ofc_SentryGatewayTMember_E6217170863E31FB73FC9B3DC86859C6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_SentryGatewayTMember_E6217170863E31FB73FC9B3DC86859C6" xlink:to="lab_ofc_SentryGatewayTMember_E6217170863E31FB73FC9B3DC86859C6" xlink:type="arc" />
    <link:label id="lab_ofc_SentryGatewayVMember_EB5AAA8AE9D8EEA386CA9B3DC868C148_terseLabel_en-US" xlink:label="lab_ofc_SentryGatewayVMember_EB5AAA8AE9D8EEA386CA9B3DC868C148" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Sentry Gateway - V [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayVMember_EB5AAA8AE9D8EEA386CA9B3DC868C148_label_en-US" xlink:label="lab_ofc_SentryGatewayVMember_EB5AAA8AE9D8EEA386CA9B3DC868C148" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Sentry Gateway -V [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayVMember_EB5AAA8AE9D8EEA386CA9B3DC868C148_documentation_en-US" xlink:label="lab_ofc_SentryGatewayVMember_EB5AAA8AE9D8EEA386CA9B3DC868C148" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Sentry Gateway -V, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SentryGatewayVMember" xlink:label="loc_ofc_SentryGatewayVMember_EB5AAA8AE9D8EEA386CA9B3DC868C148" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_SentryGatewayVMember_EB5AAA8AE9D8EEA386CA9B3DC868C148" xlink:to="lab_ofc_SentryGatewayVMember_EB5AAA8AE9D8EEA386CA9B3DC868C148" xlink:type="arc" />
    <link:label id="lab_ofc_SentryGatewayWMember_1D340ECF4DB036096B389B3DC868204E_terseLabel_en-US" xlink:label="lab_ofc_SentryGatewayWMember_1D340ECF4DB036096B389B3DC868204E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Sentry Gateway - W [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayWMember_1D340ECF4DB036096B389B3DC868204E_label_en-US" xlink:label="lab_ofc_SentryGatewayWMember_1D340ECF4DB036096B389B3DC868204E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Sentry Gateway - W [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayWMember_1D340ECF4DB036096B389B3DC868204E_documentation_en-US" xlink:label="lab_ofc_SentryGatewayWMember_1D340ECF4DB036096B389B3DC868204E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Sentry Gateway - W, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SentryGatewayWMember" xlink:label="loc_ofc_SentryGatewayWMember_1D340ECF4DB036096B389B3DC868204E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_SentryGatewayWMember_1D340ECF4DB036096B389B3DC868204E" xlink:to="lab_ofc_SentryGatewayWMember_1D340ECF4DB036096B389B3DC868204E" xlink:type="arc" />
    <link:label id="lab_ofc_SentryGatewayXMember_3C10215EA50A12EABE019B3DC8682B43_terseLabel_en-US" xlink:label="lab_ofc_SentryGatewayXMember_3C10215EA50A12EABE019B3DC8682B43" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Sentry Gateway - X [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayXMember_3C10215EA50A12EABE019B3DC8682B43_label_en-US" xlink:label="lab_ofc_SentryGatewayXMember_3C10215EA50A12EABE019B3DC8682B43" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Sentry Gateway - X [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayXMember_3C10215EA50A12EABE019B3DC8682B43_documentation_en-US" xlink:label="lab_ofc_SentryGatewayXMember_3C10215EA50A12EABE019B3DC8682B43" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Sentry Gateway - X, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SentryGatewayXMember" xlink:label="loc_ofc_SentryGatewayXMember_3C10215EA50A12EABE019B3DC8682B43" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_SentryGatewayXMember_3C10215EA50A12EABE019B3DC8682B43" xlink:to="lab_ofc_SentryGatewayXMember_3C10215EA50A12EABE019B3DC8682B43" xlink:type="arc" />
    <link:label id="lab_ofc_SentryGatewayYMember_24FEE515B64E11E2A2DA9B3DC868D070_terseLabel_en-US" xlink:label="lab_ofc_SentryGatewayYMember_24FEE515B64E11E2A2DA9B3DC868D070" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Sentry Gateway - Y [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayYMember_24FEE515B64E11E2A2DA9B3DC868D070_label_en-US" xlink:label="lab_ofc_SentryGatewayYMember_24FEE515B64E11E2A2DA9B3DC868D070" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Sentry Gateway - Y [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayYMember_24FEE515B64E11E2A2DA9B3DC868D070_documentation_en-US" xlink:label="lab_ofc_SentryGatewayYMember_24FEE515B64E11E2A2DA9B3DC868D070" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Sentry Gateway - Y, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SentryGatewayYMember" xlink:label="loc_ofc_SentryGatewayYMember_24FEE515B64E11E2A2DA9B3DC868D070" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_SentryGatewayYMember_24FEE515B64E11E2A2DA9B3DC868D070" xlink:to="lab_ofc_SentryGatewayYMember_24FEE515B64E11E2A2DA9B3DC868D070" xlink:type="arc" />
    <link:label id="lab_ofc_SentryGatewayZMember_3707E97F7A5957F743BE9B3DC8681288_terseLabel_en-US" xlink:label="lab_ofc_SentryGatewayZMember_3707E97F7A5957F743BE9B3DC8681288" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Sentry Gateway - Z [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayZMember_3707E97F7A5957F743BE9B3DC8681288_label_en-US" xlink:label="lab_ofc_SentryGatewayZMember_3707E97F7A5957F743BE9B3DC8681288" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Sentry Gateway - Z [Member]</link:label>
    <link:label id="lab_ofc_SentryGatewayZMember_3707E97F7A5957F743BE9B3DC8681288_documentation_en-US" xlink:label="lab_ofc_SentryGatewayZMember_3707E97F7A5957F743BE9B3DC8681288" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Sentry Gateway - Z, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SentryGatewayZMember" xlink:label="loc_ofc_SentryGatewayZMember_3707E97F7A5957F743BE9B3DC8681288" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_SentryGatewayZMember_3707E97F7A5957F743BE9B3DC8681288" xlink:to="lab_ofc_SentryGatewayZMember_3707E97F7A5957F743BE9B3DC8681288" xlink:type="arc" />
    <link:label id="lab_ofc_WestfieldsParkCenterMember_B4EC526AA75328BAAAC19B3DC868EE0C_terseLabel_en-US" xlink:label="lab_ofc_WestfieldsParkCenterMember_B4EC526AA75328BAAAC19B3DC868EE0C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Westfields - Park Center [Member]</link:label>
    <link:label id="lab_ofc_WestfieldsParkCenterMember_B4EC526AA75328BAAAC19B3DC868EE0C_label_en-US" xlink:label="lab_ofc_WestfieldsParkCenterMember_B4EC526AA75328BAAAC19B3DC868EE0C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Westfields Park Center [Member]</link:label>
    <link:label id="lab_ofc_WestfieldsParkCenterMember_B4EC526AA75328BAAAC19B3DC868EE0C_documentation_en-US" xlink:label="lab_ofc_WestfieldsParkCenterMember_B4EC526AA75328BAAAC19B3DC868EE0C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Westfields - Park Center, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_WestfieldsParkCenterMember" xlink:label="loc_ofc_WestfieldsParkCenterMember_B4EC526AA75328BAAAC19B3DC868EE0C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_WestfieldsParkCenterMember_B4EC526AA75328BAAAC19B3DC868EE0C" xlink:to="lab_ofc_WestfieldsParkCenterMember_B4EC526AA75328BAAAC19B3DC868EE0C" xlink:type="arc" />
    <link:label id="lab_ofc_WestfieldsCorporateCenterMember_FC1E1ABB59BC3C609ADC9B3DC8686356_terseLabel_en-US" xlink:label="lab_ofc_WestfieldsCorporateCenterMember_FC1E1ABB59BC3C609ADC9B3DC8686356" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Westfields Corporate Center [Member]</link:label>
    <link:label id="lab_ofc_WestfieldsCorporateCenterMember_FC1E1ABB59BC3C609ADC9B3DC8686356_label_en-US" xlink:label="lab_ofc_WestfieldsCorporateCenterMember_FC1E1ABB59BC3C609ADC9B3DC8686356" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Westfields Corporate Center [Member]</link:label>
    <link:label id="lab_ofc_WestfieldsCorporateCenterMember_FC1E1ABB59BC3C609ADC9B3DC8686356_documentation_en-US" xlink:label="lab_ofc_WestfieldsCorporateCenterMember_FC1E1ABB59BC3C609ADC9B3DC8686356" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to Westfields Corporate Center, an office property owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_WestfieldsCorporateCenterMember" xlink:label="loc_ofc_WestfieldsCorporateCenterMember_FC1E1ABB59BC3C609ADC9B3DC8686356" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_WestfieldsCorporateCenterMember_FC1E1ABB59BC3C609ADC9B3DC8686356" xlink:to="lab_ofc_WestfieldsCorporateCenterMember_FC1E1ABB59BC3C609ADC9B3DC8686356" xlink:type="arc" />
    <link:label id="lab_ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember_A1B0686989AFA9248F8B9B3DC869DF0E_terseLabel_en-US" xlink:label="lab_ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember_A1B0686989AFA9248F8B9B3DC869DF0E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other Developments, including intercompany eliminations [Member]</link:label>
    <link:label id="lab_ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember_A1B0686989AFA9248F8B9B3DC869DF0E_label_en-US" xlink:label="lab_ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember_A1B0686989AFA9248F8B9B3DC869DF0E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Developments Including Intercompany Eliminations [Member]</link:label>
    <link:label id="lab_ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember_A1B0686989AFA9248F8B9B3DC869DF0E_documentation_en-US" xlink:label="lab_ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember_A1B0686989AFA9248F8B9B3DC869DF0E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the information pertaining to other developments including intercompany eliminations, various types of properties owned by the entity.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember" xlink:label="loc_ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember_A1B0686989AFA9248F8B9B3DC869DF0E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember_A1B0686989AFA9248F8B9B3DC869DF0E" xlink:to="lab_ofc_OtherDevelopmentsIncludingIntercompanyEliminationsMember_A1B0686989AFA9248F8B9B3DC869DF0E" xlink:type="arc" />
    <link:label id="lab_us-gaap_UnsecuredDebtMember_E3F621318118C3750D829B3DC869A3AA_terseLabel_en-US" xlink:label="lab_us-gaap_UnsecuredDebtMember_E3F621318118C3750D829B3DC869A3AA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Unsecured notes payable [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_UnsecuredDebtMember" xlink:label="loc_us-gaap_UnsecuredDebtMember_E3F621318118C3750D829B3DC869A3AA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnsecuredDebtMember_E3F621318118C3750D829B3DC869A3AA" xlink:to="lab_us-gaap_UnsecuredDebtMember_E3F621318118C3750D829B3DC869A3AA" xlink:type="arc" />
    <link:label id="lab_ofc_AssetsbyTypeAxis_B2821A1B618812BDA1D99B3DC869F198_terseLabel_en-US" xlink:label="lab_ofc_AssetsbyTypeAxis_B2821A1B618812BDA1D99B3DC869F198" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Assets by Type [Axis]</link:label>
    <link:label id="lab_ofc_AssetsbyTypeAxis_B2821A1B618812BDA1D99B3DC869F198_label_en-US" xlink:label="lab_ofc_AssetsbyTypeAxis_B2821A1B618812BDA1D99B3DC869F198" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Assets by Type [Axis]</link:label>
    <link:label id="lab_ofc_AssetsbyTypeAxis_B2821A1B618812BDA1D99B3DC869F198_documentation_en-US" xlink:label="lab_ofc_AssetsbyTypeAxis_B2821A1B618812BDA1D99B3DC869F198" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the type of assets.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_AssetsbyTypeAxis" xlink:label="loc_ofc_AssetsbyTypeAxis_B2821A1B618812BDA1D99B3DC869F198" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_AssetsbyTypeAxis_B2821A1B618812BDA1D99B3DC869F198" xlink:to="lab_ofc_AssetsbyTypeAxis_B2821A1B618812BDA1D99B3DC869F198" xlink:type="arc" />
    <link:label id="lab_ofc_AssetsbyTypeDomain_D2FF6A2C7EA1603BB32D9B3DC8696619_terseLabel_en-US" xlink:label="lab_ofc_AssetsbyTypeDomain_D2FF6A2C7EA1603BB32D9B3DC8696619" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Assets by Type [Domain]</link:label>
    <link:label id="lab_ofc_AssetsbyTypeDomain_D2FF6A2C7EA1603BB32D9B3DC8696619_label_en-US" xlink:label="lab_ofc_AssetsbyTypeDomain_D2FF6A2C7EA1603BB32D9B3DC8696619" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Assets by Type [Domain]</link:label>
    <link:label id="lab_ofc_AssetsbyTypeDomain_D2FF6A2C7EA1603BB32D9B3DC8696619_documentation_en-US" xlink:label="lab_ofc_AssetsbyTypeDomain_D2FF6A2C7EA1603BB32D9B3DC8696619" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the type of assets.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_AssetsbyTypeDomain" xlink:label="loc_ofc_AssetsbyTypeDomain_D2FF6A2C7EA1603BB32D9B3DC8696619" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_AssetsbyTypeDomain_D2FF6A2C7EA1603BB32D9B3DC8696619" xlink:to="lab_ofc_AssetsbyTypeDomain_D2FF6A2C7EA1603BB32D9B3DC8696619" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstateInvestmentPropertiesNetMember_C35F8F2DE9CBDC1B80A89B3DC8695F87_verboseLabel_en-US" xlink:label="lab_ofc_RealEstateInvestmentPropertiesNetMember_C35F8F2DE9CBDC1B80A89B3DC8695F87" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Real Estate Investment Properties, Net [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstateInvestmentPropertiesNetMember" xlink:label="loc_ofc_RealEstateInvestmentPropertiesNetMember_C35F8F2DE9CBDC1B80A89B3DC8695F87" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstateInvestmentPropertiesNetMember_C35F8F2DE9CBDC1B80A89B3DC8695F87" xlink:to="lab_ofc_RealEstateInvestmentPropertiesNetMember_C35F8F2DE9CBDC1B80A89B3DC8695F87" xlink:type="arc" />
    <link:label id="lab_ofc_RealEstateHeldMember_55A8BBBA6E769A762B219B3DC86978EB_terseLabel_en-US" xlink:label="lab_ofc_RealEstateHeldMember_55A8BBBA6E769A762B219B3DC86978EB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Real Estate Held [Member]</link:label>
    <link:label id="lab_ofc_RealEstateHeldMember_55A8BBBA6E769A762B219B3DC86978EB_label_en-US" xlink:label="lab_ofc_RealEstateHeldMember_55A8BBBA6E769A762B219B3DC86978EB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Held [Member]</link:label>
    <link:label id="lab_ofc_RealEstateHeldMember_55A8BBBA6E769A762B219B3DC86978EB_documentation_en-US" xlink:label="lab_ofc_RealEstateHeldMember_55A8BBBA6E769A762B219B3DC86978EB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Real estate held at period end [Member]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_RealEstateHeldMember" xlink:label="loc_ofc_RealEstateHeldMember_55A8BBBA6E769A762B219B3DC86978EB" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_RealEstateHeldMember_55A8BBBA6E769A762B219B3DC86978EB" xlink:to="lab_ofc_RealEstateHeldMember_55A8BBBA6E769A762B219B3DC86978EB" xlink:type="arc" />
    <link:label id="lab_us-gaap_BuildingImprovementsMember_C3EE96205D7E2C2696F19B3DC86ADB14_terseLabel_en-US" xlink:label="lab_us-gaap_BuildingImprovementsMember_C3EE96205D7E2C2696F19B3DC86ADB14" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Buildings improvements [Member]</link:label>
    <link:label id="lab_us-gaap_BuildingImprovementsMember_C3EE96205D7E2C2696F19B3DC86ADB14_label_en-US" xlink:label="lab_us-gaap_BuildingImprovementsMember_C3EE96205D7E2C2696F19B3DC86ADB14" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Building Improvements [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BuildingImprovementsMember" xlink:label="loc_us-gaap_BuildingImprovementsMember_C3EE96205D7E2C2696F19B3DC86ADB14" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BuildingImprovementsMember_C3EE96205D7E2C2696F19B3DC86ADB14" xlink:to="lab_us-gaap_BuildingImprovementsMember_C3EE96205D7E2C2696F19B3DC86ADB14" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationLineItems_454F96F838D0F6D64ED59B3DC86BB328_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationLineItems_454F96F838D0F6D64ED59B3DC86BB328" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Real Estate and Accumulated Depreciation</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationLineItems_454F96F838D0F6D64ED59B3DC86BB328_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationLineItems_454F96F838D0F6D64ED59B3DC86BB328" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationLineItems" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationLineItems_454F96F838D0F6D64ED59B3DC86BB328" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationLineItems_454F96F838D0F6D64ED59B3DC86BB328" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationLineItems_454F96F838D0F6D64ED59B3DC86BB328" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances_B1B2A36D34B4CFD9F6E69B3DC86B74D1_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances_B1B2A36D34B4CFD9F6E69B3DC86B74D1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Encumbrances</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances_B1B2A36D34B4CFD9F6E69B3DC86B74D1_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances_B1B2A36D34B4CFD9F6E69B3DC86B74D1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances_B1B2A36D34B4CFD9F6E69B3DC86B74D1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances_B1B2A36D34B4CFD9F6E69B3DC86B74D1" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances_B1B2A36D34B4CFD9F6E69B3DC86B74D1" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostAbstract_8BD0E44AE4AFD491F2FA9B3DC86BFF4D_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostAbstract_8BD0E44AE4AFD491F2FA9B3DC86BFF4D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Initial Cost</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostAbstract_8BD0E44AE4AFD491F2FA9B3DC86BFF4D_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostAbstract_8BD0E44AE4AFD491F2FA9B3DC86BFF4D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationInitialCostAbstract" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostAbstract_8BD0E44AE4AFD491F2FA9B3DC86BFF4D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostAbstract_8BD0E44AE4AFD491F2FA9B3DC86BFF4D" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostAbstract_8BD0E44AE4AFD491F2FA9B3DC86BFF4D" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand_8E21D1D3D9AF0B5AEABD9B3DC86BDEFE_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand_8E21D1D3D9AF0B5AEABD9B3DC86BDEFE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Land</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand_8E21D1D3D9AF0B5AEABD9B3DC86BDEFE_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand_8E21D1D3D9AF0B5AEABD9B3DC86BDEFE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand_8E21D1D3D9AF0B5AEABD9B3DC86BDEFE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand_8E21D1D3D9AF0B5AEABD9B3DC86BDEFE" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand_8E21D1D3D9AF0B5AEABD9B3DC86BDEFE" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements_89FEFBA34F44F385F69B9B3DC86C2ADE_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements_89FEFBA34F44F385F69B9B3DC86C2ADE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Building and Land Improvements</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements_89FEFBA34F44F385F69B9B3DC86C2ADE_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements_89FEFBA34F44F385F69B9B3DC86C2ADE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements_89FEFBA34F44F385F69B9B3DC86C2ADE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements_89FEFBA34F44F385F69B9B3DC86C2ADE" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements_89FEFBA34F44F385F69B9B3DC86C2ADE" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionCarryingCosts_F3AF803BD9EE69CFDC6D9B3DC86DE1D1_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionCarryingCosts_F3AF803BD9EE69CFDC6D9B3DC86DE1D1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Costs Capitalized Subsequent to Acquisition</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionCarryingCosts_F3AF803BD9EE69CFDC6D9B3DC86DE1D1_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionCarryingCosts_F3AF803BD9EE69CFDC6D9B3DC86DE1D1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionCarryingCosts" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionCarryingCosts_F3AF803BD9EE69CFDC6D9B3DC86DE1D1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionCarryingCosts_F3AF803BD9EE69CFDC6D9B3DC86DE1D1" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionCarryingCosts_F3AF803BD9EE69CFDC6D9B3DC86DE1D1" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAbstract_EA9A44B0FBBE5943712E9B3DC86DB91C_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAbstract_EA9A44B0FBBE5943712E9B3DC86DB91C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Gross Amounts Carried At Close of Period</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAbstract_EA9A44B0FBBE5943712E9B3DC86DB91C_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAbstract_EA9A44B0FBBE5943712E9B3DC86DB91C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate, Gross [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAbstract" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAbstract_EA9A44B0FBBE5943712E9B3DC86DB91C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAbstract_EA9A44B0FBBE5943712E9B3DC86DB91C" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAbstract_EA9A44B0FBBE5943712E9B3DC86DB91C" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand_0094C66EB3B9A6481F409B3DC86D73E7_terseLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand_0094C66EB3B9A6481F409B3DC86D73E7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Land</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand_0094C66EB3B9A6481F409B3DC86D73E7_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand_0094C66EB3B9A6481F409B3DC86D73E7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand_0094C66EB3B9A6481F409B3DC86D73E7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand_0094C66EB3B9A6481F409B3DC86D73E7" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand_0094C66EB3B9A6481F409B3DC86D73E7" xlink:type="arc" />
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements_37FF5AE19F10FE9C4A1E9B3DC86EDDA8_totalLabel_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements_37FF5AE19F10FE9C4A1E9B3DC86EDDA8" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Building and Land Improvements</link:label>
    <link:label id="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements_37FF5AE19F10FE9C4A1E9B3DC86EDDA8_label_en-US" xlink:label="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements_37FF5AE19F10FE9C4A1E9B3DC86EDDA8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements" xlink:label="loc_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements_37FF5AE19F10FE9C4A1E9B3DC86EDDA8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements_37FF5AE19F10FE9C4A1E9B3DC86EDDA8" xlink:to="lab_us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovements_37FF5AE19F10FE9C4A1E9B3DC86EDDA8" xlink:type="arc" />
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    <link:label id="lab_us-gaap_BuildingAndBuildingImprovementsMember_FF40EAAF52FDFF6B61486ADFA3267A93_verboseLabel_en-US" xlink:label="lab_us-gaap_BuildingAndBuildingImprovementsMember_FF40EAAF52FDFF6B61486ADFA3267A93" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Buildings and building improvements [Member]</link:label>
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    <link:label id="lab_us-gaap_LandImprovementsMember_1C438DA1B975912ED66A6ADFA32676FF_terseLabel_en-US" xlink:label="lab_us-gaap_LandImprovementsMember_1C438DA1B975912ED66A6ADFA32676FF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Land improvements [Member]</link:label>
    <link:label id="lab_us-gaap_LandImprovementsMember_1C438DA1B975912ED66A6ADFA32676FF_label_en-US" xlink:label="lab_us-gaap_LandImprovementsMember_1C438DA1B975912ED66A6ADFA32676FF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Land Improvements [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LandImprovementsMember" xlink:label="loc_us-gaap_LandImprovementsMember_1C438DA1B975912ED66A6ADFA32676FF" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LandImprovementsMember_1C438DA1B975912ED66A6ADFA32676FF" xlink:to="lab_us-gaap_LandImprovementsMember_1C438DA1B975912ED66A6ADFA32676FF" xlink:type="arc" />
    <link:label id="lab_ofc_EquipmentAndPersonalPropertyMember_A7CA50CEC230A27A1D346ADFA3262632_terseLabel_en-US" xlink:label="lab_ofc_EquipmentAndPersonalPropertyMember_A7CA50CEC230A27A1D346ADFA3262632" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Equipment and personal property [Member]</link:label>
    <link:label id="lab_ofc_EquipmentAndPersonalPropertyMember_A7CA50CEC230A27A1D346ADFA3262632_label_en-US" xlink:label="lab_ofc_EquipmentAndPersonalPropertyMember_A7CA50CEC230A27A1D346ADFA3262632" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Equipment and Personal Property [Member]</link:label>
    <link:label id="lab_ofc_EquipmentAndPersonalPropertyMember_A7CA50CEC230A27A1D346ADFA3262632_documentation_en-US" xlink:label="lab_ofc_EquipmentAndPersonalPropertyMember_A7CA50CEC230A27A1D346ADFA3262632" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the equipment and personal property, depreciable assets of the entity.</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_EquipmentAndPersonalPropertyMember_A7CA50CEC230A27A1D346ADFA3262632" xlink:to="lab_ofc_EquipmentAndPersonalPropertyMember_A7CA50CEC230A27A1D346ADFA3262632" xlink:type="arc" />
    <link:label id="lab_us-gaap_PropertyPlantAndEquipmentLineItems_26BF38D42AE4639FDE136ADFA32681EA_verboseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentLineItems_26BF38D42AE4639FDE136ADFA32681EA" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Property, Plant and Equipment [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_26BF38D42AE4639FDE136ADFA32681EA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_26BF38D42AE4639FDE136ADFA32681EA" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentLineItems_26BF38D42AE4639FDE136ADFA32681EA" xlink:type="arc" />
    <link:label id="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C69F455BBDBF5CF7E6B36ADFA3266E0F_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C69F455BBDBF5CF7E6B36ADFA3266E0F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Estimated useful life</link:label>
    <link:label id="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C69F455BBDBF5CF7E6B36ADFA3266E0F_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C69F455BBDBF5CF7E6B36ADFA3266E0F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Property, Plant and Equipment, Useful Life</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_C69F455BBDBF5CF7E6B36ADFA3266E0F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_C69F455BBDBF5CF7E6B36ADFA3266E0F" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C69F455BBDBF5CF7E6B36ADFA3266E0F" xlink:type="arc" />
    <link:label id="lab_ofc_PeriodusedrecoveryanalysisforPotentiallyImpairedLongLivedAssetHeldandUsed_B9598CB8F048E3E4CB386ADFA326DB4D_verboseLabel_en-US" xlink:label="lab_ofc_PeriodusedrecoveryanalysisforPotentiallyImpairedLongLivedAssetHeldandUsed_B9598CB8F048E3E4CB386ADFA326DB4D" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Period used recovery analysis for long-lived assets to be held and used that may be impaired (in years)</link:label>
    <link:label id="lab_ofc_PeriodusedrecoveryanalysisforPotentiallyImpairedLongLivedAssetHeldandUsed_B9598CB8F048E3E4CB386ADFA326DB4D_label_en-US" xlink:label="lab_ofc_PeriodusedrecoveryanalysisforPotentiallyImpairedLongLivedAssetHeldandUsed_B9598CB8F048E3E4CB386ADFA326DB4D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Period used recovery analysis for Potentially Impaired Long Lived Asset Held and Used</link:label>
    <link:label id="lab_ofc_PeriodusedrecoveryanalysisforPotentiallyImpairedLongLivedAssetHeldandUsed_B9598CB8F048E3E4CB386ADFA326DB4D_documentation_en-US" xlink:label="lab_ofc_PeriodusedrecoveryanalysisforPotentiallyImpairedLongLivedAssetHeldandUsed_B9598CB8F048E3E4CB386ADFA326DB4D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Period used for recovery analysis of long lived assets to be held and used that may be impaired.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_PeriodusedrecoveryanalysisforPotentiallyImpairedLongLivedAssetHeldandUsed" xlink:label="loc_ofc_PeriodusedrecoveryanalysisforPotentiallyImpairedLongLivedAssetHeldandUsed_B9598CB8F048E3E4CB386ADFA326DB4D" xlink:type="locator" />
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    <link:label id="lab_us-gaap_FinancingReceivablesTextBlock_19E93A96BDA110A7A8486ADFA3584C37_terseLabel_en-US" xlink:label="lab_us-gaap_FinancingReceivablesTextBlock_19E93A96BDA110A7A8486ADFA3584C37" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Investing Receivables</link:label>
    <link:label id="lab_us-gaap_FinancingReceivablesTextBlock_19E93A96BDA110A7A8486ADFA3584C37_label_en-US" xlink:label="lab_us-gaap_FinancingReceivablesTextBlock_19E93A96BDA110A7A8486ADFA3584C37" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Financing Receivables [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FinancingReceivablesTextBlock" xlink:label="loc_us-gaap_FinancingReceivablesTextBlock_19E93A96BDA110A7A8486ADFA3584C37" xlink:type="locator" />
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    <link:label id="lab_ofc_SegmentReportingRevenueReconcilingItemAbstract_9A65B746248C338552D668E9DAC6753F_terseLabel_en-US" xlink:label="lab_ofc_SegmentReportingRevenueReconcilingItemAbstract_9A65B746248C338552D668E9DAC6753F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Reconciliation of segment revenues to total revenues</link:label>
    <link:label id="lab_ofc_SegmentReportingRevenueReconcilingItemAbstract_9A65B746248C338552D668E9DAC6753F_label_en-US" xlink:label="lab_ofc_SegmentReportingRevenueReconcilingItemAbstract_9A65B746248C338552D668E9DAC6753F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Segment Reporting Revenue Reconciling Item [Abstract]</link:label>
    <link:label id="lab_ofc_SegmentReportingRevenueReconcilingItemAbstract_9A65B746248C338552D668E9DAC6753F_documentation_en-US" xlink:label="lab_ofc_SegmentReportingRevenueReconcilingItemAbstract_9A65B746248C338552D668E9DAC6753F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US" />
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SegmentReportingRevenueReconcilingItemAbstract" xlink:label="loc_ofc_SegmentReportingRevenueReconcilingItemAbstract_9A65B746248C338552D668E9DAC6753F" xlink:type="locator" />
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    <link:label id="lab_us-gaap_RealEstateRevenueNet_7BCEC87BA4FCD077C21568E9DAC6B3F5_verboseLabel_en-US" xlink:label="lab_us-gaap_RealEstateRevenueNet_7BCEC87BA4FCD077C21568E9DAC6B3F5" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Segment revenues from real estate operations</link:label>
    <link:label id="lab_us-gaap_RealEstateRevenueNet_7BCEC87BA4FCD077C21568E9DAC6B3F5_label_en-US" xlink:label="lab_us-gaap_RealEstateRevenueNet_7BCEC87BA4FCD077C21568E9DAC6B3F5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Real Estate Revenue, Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RealEstateRevenueNet" xlink:label="loc_us-gaap_RealEstateRevenueNet_7BCEC87BA4FCD077C21568E9DAC6B3F5" xlink:type="locator" />
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    <link:label id="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_DA3B33F0016C19B5460168E9DAC6E0D7_terseLabel_en-US" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_DA3B33F0016C19B5460168E9DAC6E0D7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Less: Revenues from discontinued operations</link:label>
    <link:label id="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_DA3B33F0016C19B5460168E9DAC6E0D7_label_en-US" xlink:label="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_DA3B33F0016C19B5460168E9DAC6E0D7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Disposal Group, Including Discontinued Operation, Revenue</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_DA3B33F0016C19B5460168E9DAC6E0D7" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_DA3B33F0016C19B5460168E9DAC6E0D7" xlink:to="lab_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_DA3B33F0016C19B5460168E9DAC6E0D7" xlink:type="arc" />
    <link:label id="lab_ofc_ReconciliationOfSegmentPropertyOperatingExpensesToPropertyOperatingExpensesAbstract_F1F86399C3643E09788B68E9DAC6A45E_terseLabel_en-US" xlink:label="lab_ofc_ReconciliationOfSegmentPropertyOperatingExpensesToPropertyOperatingExpensesAbstract_F1F86399C3643E09788B68E9DAC6A45E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Reconciliation of segment property operating expenses to property operating expenses</link:label>
    <link:label id="lab_ofc_ReconciliationOfSegmentPropertyOperatingExpensesToPropertyOperatingExpensesAbstract_F1F86399C3643E09788B68E9DAC6A45E_label_en-US" xlink:label="lab_ofc_ReconciliationOfSegmentPropertyOperatingExpensesToPropertyOperatingExpensesAbstract_F1F86399C3643E09788B68E9DAC6A45E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Reconciliation of segment property operating expenses to property operating expenses [Abstract]</link:label>
    <link:label id="lab_ofc_ReconciliationOfSegmentPropertyOperatingExpensesToPropertyOperatingExpensesAbstract_F1F86399C3643E09788B68E9DAC6A45E_documentation_en-US" xlink:label="lab_ofc_ReconciliationOfSegmentPropertyOperatingExpensesToPropertyOperatingExpensesAbstract_F1F86399C3643E09788B68E9DAC6A45E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Reconciliation of segment property operating expenses to property operating expenses [Abstract]</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_ReconciliationOfSegmentPropertyOperatingExpensesToPropertyOperatingExpensesAbstract" xlink:label="loc_ofc_ReconciliationOfSegmentPropertyOperatingExpensesToPropertyOperatingExpensesAbstract_F1F86399C3643E09788B68E9DAC6A45E" xlink:type="locator" />
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    <link:label id="lab_ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment_015C233C0EB757000D9868E9DAC679EB_terseLabel_en-US" xlink:label="lab_ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment_015C233C0EB757000D9868E9DAC679EB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Segment property operating expenses</link:label>
    <link:label id="lab_ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment_015C233C0EB757000D9868E9DAC679EB_label_en-US" xlink:label="lab_ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment_015C233C0EB757000D9868E9DAC679EB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Segment Reporting Direct Costs of Leased and Rented Property or Equipment</link:label>
    <link:label id="lab_ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment_015C233C0EB757000D9868E9DAC679EB_documentation_en-US" xlink:label="lab_ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment_015C233C0EB757000D9868E9DAC679EB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Costs incurred and are directly related to generating revenues from leased and rented property or equipment for the reportable segment.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment" xlink:label="loc_ofc_SegmentReportingDirectCostsOfLeasedAndRentedPropertyOrEquipment_015C233C0EB757000D9868E9DAC679EB" xlink:type="locator" />
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    <link:label id="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertyOperatingExpense_844925B6847DEBCC9E2768E9DAC6219C_terseLabel_en-US" xlink:label="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertyOperatingExpense_844925B6847DEBCC9E2768E9DAC6219C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Less: Property operating expenses from discontinued operations</link:label>
    <link:label id="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertyOperatingExpense_844925B6847DEBCC9E2768E9DAC6219C_label_en-US" xlink:label="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertyOperatingExpense_844925B6847DEBCC9E2768E9DAC6219C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Disposal Group Including Discontinued Operation, Property, Operating Expense</link:label>
    <link:label id="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertyOperatingExpense_844925B6847DEBCC9E2768E9DAC6219C_documentation_en-US" xlink:label="lab_ofc_DisposalGroupIncludingDiscontinuedOperationPropertyOperatingExpense_844925B6847DEBCC9E2768E9DAC6219C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Amount of property operating expenses attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.</link:label>
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    <link:label id="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest_42E8B22CAE0E56804EA69A845B5C2DF3_negatedLabel_en-US" xlink:label="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest_42E8B22CAE0E56804EA69A845B5C2DF3" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US">Discontinued operations attributable to noncontrolling interests</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest_42E8B22CAE0E56804EA69A845B5C2DF3" xlink:to="lab_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest_42E8B22CAE0E56804EA69A845B5C2DF3" xlink:type="arc" />
    <link:label id="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasic_9110ED2D87253CB18F699A845B5C6454_totalLabel_en-US" xlink:label="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasic_9110ED2D87253CB18F699A845B5C6454" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Numerator for basic EPS on net income (loss) attributable to COPT common shareholders</link:label>
    <link:label id="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasic_9110ED2D87253CB18F699A845B5C6454_label_en-US" xlink:label="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasic_9110ED2D87253CB18F699A845B5C6454" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Net Income (Loss) Attributable to Common Stockholders, Basic</link:label>
    <link:label id="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasic_9110ED2D87253CB18F699A845B5C6454_documentation_en-US" xlink:label="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasic_9110ED2D87253CB18F699A845B5C6454" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the net income after adjustments for gain on sales of real estate, preferred share dividends, income from operations attributable to noncontrolling interests and income from operations attributable to restricted shares used to calculate the basic earnings per share.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NetIncomeLossAttributabletoCommonStockholdersBasic" xlink:label="loc_ofc_NetIncomeLossAttributabletoCommonStockholdersBasic_9110ED2D87253CB18F699A845B5C6454" xlink:type="locator" />
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    <link:label id="lab_ofc_DilutiveSecuritiesEffectofCommonUnits_F9567D9288D360CFB54A9A845B5CF31E_terseLabel_en-US" xlink:label="lab_ofc_DilutiveSecuritiesEffectofCommonUnits_F9567D9288D360CFB54A9A845B5CF31E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Dilutive effect of common units in COPLP</link:label>
    <link:label id="lab_ofc_DilutiveSecuritiesEffectofCommonUnits_F9567D9288D360CFB54A9A845B5CF31E_label_en-US" xlink:label="lab_ofc_DilutiveSecuritiesEffectofCommonUnits_F9567D9288D360CFB54A9A845B5CF31E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Dilutive Securities, Effect of Common Units</link:label>
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    <link:loc xlink:href="ofc-20171231.xsd#ofc_DilutiveSecuritiesEffectofCommonUnits" xlink:label="loc_ofc_DilutiveSecuritiesEffectofCommonUnits_F9567D9288D360CFB54A9A845B5CF31E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_DilutiveSecuritiesEffectofCommonUnits_F9567D9288D360CFB54A9A845B5CF31E" xlink:to="lab_ofc_DilutiveSecuritiesEffectofCommonUnits_F9567D9288D360CFB54A9A845B5CF31E" xlink:type="arc" />
    <link:label id="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_D2418762BD7003DEA7ED9A845B5C458B_totalLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_D2418762BD7003DEA7ED9A845B5C458B" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Numerator for diluted EPS on net income (loss) attributable to COPT common shareholders</link:label>
    <link:label id="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_D2418762BD7003DEA7ED9A845B5C458B_label_en-US" xlink:label="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_D2418762BD7003DEA7ED9A845B5C458B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Net Income (Loss) Available to Common Stockholders, Diluted</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_D2418762BD7003DEA7ED9A845B5C458B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_D2418762BD7003DEA7ED9A845B5C458B" xlink:to="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_D2418762BD7003DEA7ED9A845B5C458B" xlink:type="arc" />
    <link:label id="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted_0E047FA3A59ACC58B7F99A845B5DA86D_totalLabel_en-US" xlink:label="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted_0E047FA3A59ACC58B7F99A845B5DA86D" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Numerator for basic and diluted EPU on net income (loss) attributable to COPLP common unitholders</link:label>
    <link:label id="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted_0E047FA3A59ACC58B7F99A845B5DA86D_label_en-US" xlink:label="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted_0E047FA3A59ACC58B7F99A845B5DA86D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Net Income (Loss) Attributable to Common Stockholders, Basic and Diluted</link:label>
    <link:label id="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted_0E047FA3A59ACC58B7F99A845B5DA86D_documentation_en-US" xlink:label="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted_0E047FA3A59ACC58B7F99A845B5DA86D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the net income after adjustments for gain on sales of real estate, preferred share dividends, income attributable to noncontrolling interests and income from attributable to restricted shares used to calculate the basic and dilutive earnings per share.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted" xlink:label="loc_ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted_0E047FA3A59ACC58B7F99A845B5DA86D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted_0E047FA3A59ACC58B7F99A845B5DA86D" xlink:to="lab_ofc_NetIncomeLossAttributabletoCommonStockholdersBasicandDiluted_0E047FA3A59ACC58B7F99A845B5DA86D" xlink:type="arc" />
    <link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_E88998EF3084E910D5649A845B5D0D01_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_E88998EF3084E910D5649A845B5D0D01" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Denominator (all weighted averages):</link:label>
    <link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_E88998EF3084E910D5649A845B5D0D01_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_E88998EF3084E910D5649A845B5D0D01" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Weighted Average Number of Shares Outstanding, Diluted [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_E88998EF3084E910D5649A845B5D0D01" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_E88998EF3084E910D5649A845B5D0D01" xlink:to="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_E88998EF3084E910D5649A845B5D0D01" xlink:type="arc" />
    <link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_20EACBA9C9ABE657DA929A845B5DD539_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_20EACBA9C9ABE657DA929A845B5DD539" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Denominator for basic EPS (common shares)</link:label>
    <link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_20EACBA9C9ABE657DA929A845B5DD539_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_20EACBA9C9ABE657DA929A845B5DD539" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Weighted Average Number of Shares Outstanding, Basic</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_20EACBA9C9ABE657DA929A845B5DD539" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_20EACBA9C9ABE657DA929A845B5DD539" xlink:to="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_20EACBA9C9ABE657DA929A845B5DD539" xlink:type="arc" />
    <link:label id="lab_ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements_6E784E30F5A77940CDF49AB2E45E34C3_terseLabel_en-US" xlink:label="lab_ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements_6E784E30F5A77940CDF49AB2E45E34C3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Dilutive effect of forward equity sale agreements and share-based compensation awards</link:label>
    <link:label id="lab_ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements_6E784E30F5A77940CDF49AB2E45E34C3_label_en-US" xlink:label="lab_ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements_6E784E30F5A77940CDF49AB2E45E34C3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements and Forward Equity Sale Agreements</link:label>
    <link:label id="lab_ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements_6E784E30F5A77940CDF49AB2E45E34C3_documentation_en-US" xlink:label="lab_ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements_6E784E30F5A77940CDF49AB2E45E34C3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements and Forward Equity Sale Agreements</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements" xlink:label="loc_ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements_6E784E30F5A77940CDF49AB2E45E34C3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements_6E784E30F5A77940CDF49AB2E45E34C3" xlink:to="lab_ofc_IncrementalCommonSharesAttributabletoDilutiveEffectofSharebasedPaymentArrangementsandForwardEquitySaleAgreements_6E784E30F5A77940CDF49AB2E45E34C3" xlink:type="arc" />
    <link:label id="lab_ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits_DF67E5C535A85C91B1DA9A845B5D3F11_terseLabel_en-US" xlink:label="lab_ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits_DF67E5C535A85C91B1DA9A845B5D3F11" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Dilutive effect of common units</link:label>
    <link:label id="lab_ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits_DF67E5C535A85C91B1DA9A845B5D3F11_label_en-US" xlink:label="lab_ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits_DF67E5C535A85C91B1DA9A845B5D3F11" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Incremental Common Shares Attributable to Conversion of Common Units</link:label>
    <link:label id="lab_ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits_DF67E5C535A85C91B1DA9A845B5D3F11_documentation_en-US" xlink:label="lab_ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits_DF67E5C535A85C91B1DA9A845B5D3F11" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible common units using the if-converted method.</link:label>
    <link:loc xlink:href="ofc-20171231.xsd#ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits" xlink:label="loc_ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits_DF67E5C535A85C91B1DA9A845B5D3F11" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits_DF67E5C535A85C91B1DA9A845B5D3F11" xlink:to="lab_ofc_IncrementalCommonSharesAttributableToConversionOfCommonUnits_DF67E5C535A85C91B1DA9A845B5D3F11" xlink:type="arc" />
    <link:label id="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_66E049795BE423C1808A9A845B5D6FDE_totalLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_66E049795BE423C1808A9A845B5D6FDE" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Denominator for basic and diluted EPS (common shares)</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_66E049795BE423C1808A9A845B5D6FDE" xlink:type="locator" />
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    <link:label id="lab_us-gaap_EarningsPerShareBasicAbstract_04B07F58E0C7BCDB3C069A845B5D4E35_verboseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAbstract_04B07F58E0C7BCDB3C069A845B5D4E35" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Basic EPS:</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EarningsPerShareBasicAbstract" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_04B07F58E0C7BCDB3C069A845B5D4E35" xlink:type="locator" />
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    <link:label id="lab_us-gaap_EarningsPerShareDilutedAbstract_4598FF57C09DC1F59AF09A845B5E3DD7_verboseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareDilutedAbstract_4598FF57C09DC1F59AF09A845B5E3DD7" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Diluted EPS:</link:label>
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