The Posse Comitatus Act and Related Matters: A Sketch (CRS Report for Congress)
| Release Date |
Revised Nov. 6, 2018 |
| Report Number |
R42669 |
| Report Type |
Report |
| Authors |
Jennifer K. Elsea, Legislative Attorney |
| Source Agency |
Congressional Research Service |
| Older Revisions |
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Summary:
The Posse Comitatus Act states that “Whoever, except in cases and under circumstances
expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army
or the Air Force as a posse comitatus or otherwise to execute the laws shall be fined under this
title or imprisoned not more than two years, or both.” 18 U.S.C. § 1385. It reflects an American
tradition that bridles at military involvement in civilian affairs. Congress, however, has approved
a number of instances where extraordinary circumstances warrant a departure from the general rule, particularly in cases
where the armed forces provide civilian assistance without becoming directly involved in civilian law enforcement. However,
a number of statutes, including the Insurrection Act, permit the military directly to execute federal law or provide assistance
to states in the throes of insurrection where state officials are unable to execute the law.
Three tests have developed to determine when the Posse Comitatus Act is violated. Courts examine whether: (1) civilian law
enforcement officials made a direct active use of military investigators to execute the law; (2) the use of the military pervaded
the activities of the civilian officials; or (3) the military was used so as to subject citizens to the exercise of military power
which was regulatory, prescriptive, or compulsory in nature. The Act has apparently been used for only a couple of
prosecutions, and it is more frequently invoked collaterally as a usually unsuccessful means to avoid jurisdiction or exclude
evidence acquired with the assistance of the military. Less frequently, plaintiffs have sought relief in the form of civil
damages for an alleged violation.
The Posse Comitatus Act does not apply where the Constitution expressly authorizes the use of the armed forces to execute
the laws in such a role. Although the Constitution does not seem to provide such an express exception, military doctrine
permits military commanders to exercise emergency authority and to take action to protect federal property.
Although the Posse Comitatus Act applies on its terms only to the Army and Air Force, Department of Defense regulations
governing military assistance to civil authorities limit the roles of all of the armed services, including civilian personnel, to
prevent their direct involvement in law enforcement activities. The National Guard is covered by the act only when acting in
federal service.
The most significant impact of the Posse Comitatus Act is attributable to compliance by the armed forces. As administrative
adoption of the act for the Navy and Marines demonstrates, the military has a long-standing practice of avoiding involvement
in civilian affairs which it believes are contrary to the Act.
This is an abridged version of CRS Report R42659, The Posse Comitatus Act and Related Matters: The Use of the Military to
Execute Civilian Law, in which the authorities for the statements made here may be found.
