The Posse Comitatus Act and Related Matters: The Use of the Military to Execute Civilian Law

The Constitution permits Congress to authorize the use of the militia to execute the Laws of the Union, suppress Insurrections and repel Invasions. And it guarantees the states protection against invasion or usurpation of their republican form of government, and, upon the request of the state legislature, against domestic violence. These constitutional provisions are reflected in the Insurrection Acts, which have been invoked numerous times both before and after passage of the Posse Comitatus Act, 18 U.S.C. Section 1385, in 1878. Congress has also enacted a number of statutes that authorize the use of land and naval forces to execute their objective. The Posse Comitatus Act outlaws the willful use of any part of the Army or Air Force to execute the law unless expressly authorized by the Constitution or an act of Congress. History supplies the grist for an argument that the Constitution prohibits military involvement in civilian affairs subject to only limited alterations by Congress or the President, but the courts do not appear to have ever accepted the argument unless violation of more explicit constitutional command could also be shown. The express statutory exceptions include the legislation that allows the President to use military force to suppress insurrection or to enforce federal authority, 10 U.S.C. Sections 251-255, and laws that permit the Department of Defense to provide federal, state and local police with information, equipment, and personnel, 10 U.S.C. 271-284. Case law indicates that execution of the law in violation of the Posse Comitatus Act occurs (a) when the Armed Forces perform tasks assigned to an organ of civil government, or (b) when the Armed Forces perform tasks assigned to them solely for purposes of civilian government. Questions concerning the acts application arise most often in the context of assistance to civilian police.