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

Publication Date: June 2000

Publisher: Library of Congress. Congressional Research Service

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Research Area: Military and defense

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Abstract:

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 Posse Comitatus Act occurs (a) when the armed forces perform tasks which are assigned not to them but to an organ of civil government, or (b) when the armed forces perform tasks assigned to them solely for purposes of civilian government. Questions arise most often in the context of assistance to civilian police. At least in this context, the courts have held that, absent a recognized exception, the Posse Comitatus Act is violated, (1) when civilian law enforcement officials make "direct active use" of military investigators; or (2) when the use of the military "pervades the activities" of the civilian officials; or (3) when the military is used so as to subject "citizens to the exercise of military power which was regulatory, prescriptive, or compulsory in nature." The Act is not violated when the armed forces conduct activities for a military purpose which have incidental benefits for civilian law enforcement officials.

The language of the Act mentions only the Army and the Air Force, but it is applicable to the Navy and Marines by virtue of administrative action and commands of other laws. The law enforcement functions of the Coast Guard have been expressly authorized by act of Congress and consequently cannot be said to be contrary to the Act. The Act has been applied to the National Guard when it is in federal service, to civilian employees of the armed forces, and to off-duty military personnel.

The Act is probably only applicable within the geographical confines of the United States, but the supplemental provisions of 10 U.S.C. 371-381 appear to apply world-wide.

Finally, the Act is a criminal statute under which there has never been a prosecution. Although violations will on rare occasions result in the exclusion of evidence, the dismissal of criminal charges, or a civil cause of action, as a practical matter compliance is ordinarily the result of military self-restraint.

This report appears in abridged form as CRS Report RS20590, The Posse Comitatus Act: A Sketch.