Defense support of civil authorities (DSCA) issupport provided by federal military forces,Department of Defense (DOD) civilians, DODcontract personnel, DOD component assets, andNational Guard (NG) forces (when the Secretary ofDefense [SecDef], in coordination with thegovernors of the affected states, elects and requests to use those forces in Title 32, United States Code, status or when federalized) in response to requests for assistance from civil authorities for domestic emergencies, law enforcement support, and other domestic activities, or from qualifying entities for special events.DSCA in the US presents a unique challenge basedon the history of the country and the interaction ofthe federal, state, local, territorial, and tribalgovernments and private and nonprofitorganizations. These relationships establish themultiple layers and mutually reinforcing structuresthroughout the state and territorial governments for interaction based on the US Constitution, as well as on common law and traditional relationships.