The Posse Comitatus Act and Related Matters: The Use of the Military to Execute Civilian Law,” Congressional Research Service Report 95-964

The Posse Comitatus Act outlaws 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 provision for express constitutional authorization when in fact the Constitution contains no such express authorizations has been explained alternatively as a meaningless political face saving device or as an unartful reference to the President's constitutional powers. The express statutory exceptions include the legislation which allows the President to use military force to suppression insurrection, 10 U.S.C. 331-335, and sections which permit the Department of Defense to provide federal, state and local police with information and equipment, 10 U.S.C. 371-381. Existing case law indicates that "execution of the law " in violation of the Poss