18 U.S.C. § 1385. This report provides an historical analysis of the use of the Armed Forces to execute domestic law and of the Posse Comitatus Act, including their apparent theoretical and constitutional underpinnings. The report then outlines the current application of the Posse Comitatus Act as well as its statutory exceptions, and reviews the consequences of its violation. After the deficiencies were corrected and a proclamation was issued, the general officer in charge of federal troops requested clarification as to the disposition of federal troops and espoused the doctrine that whenever a state government asks for assistance under the Insurrection Act, federal military power should supplant local civil authority:
When the governor of a State has declared his inability to suppress an insurrection and has called upon the President of the United States under the Constitution to do so, that from that time commences a state not of peace but of war, and that although civil local authority still exists, yet the only outcome is to resort to force through the Federal military authorities, and that can only be through a subordination of the State authorities for the time being and until lawful order is restored; otherwise there can be no complete exercise of power in a military way within the limits of the State by the Federal officers. It 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." When the Posse Comitatus Act Does Not Apply

In addition to any express constitutional exceptions, the use of the Armed Forces to execute federal law does not violate the Posse Comitatus Act when (1) an act of Congress expressly authorizes use of part of the Army or Air Force as a posse comitatus or otherwise to execute the law; (2) the activity in question does not involve use of part of the Armed Forces covered by the proscription; or (3) the activity in question does not constitute "execution of the law." § 251 (then codified at 10 U.S.C. Even if the Posse Comitatus Act were read to apply only to the use of personnel, would the use of military personnel to maintain equipment loaned to civilian authorities violate the act's proscription? Analysis of constitutional or statutory exceptions is unnecessary in such cases. Coverage of the Posse Comitatus Act

		Willful Use

The act is limited to "willful" misuse of the Army or Air Force. Existing case law and commentary indicate that "execution of the law" in violation of the Posse Comitatus Act occurs (a) when the Armed Forces perform tasks ordinarily 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. At least when suggested that the Armed Forces have been improperly used as a police force, the tests used by most contemporary courts to determine whether military activity in support of civilian authorities violates the Posse Comitatus Act were developed out of disturbances at Wounded Knee on the Pine Ridge Indian Reservation in South Dakota and inquiry:
1. whether civilian law enforcement officials made a "direct active use" of military investigators to "execute the law"; 2. whether the use of the military "pervaded the activities" of the civilian officials; or 3. whether the military was used so as to subject "citizens to the exercise of military power which was regulatory, prescriptive, or compulsory in nature." As a practical matter, however, the Coast Guard is statutorily authorized to perform law enforcement functions. And the courts have said that members of the National Guard when not in federal service are not covered by the Posse Comitatus Act. Congress does appear to have intended the authority and restrictions contained in 10 U.S.C. The regulations implementing 10 U.S.C. Consequences of Violation

		Prosecution

The Posse Comitatus Act is a criminal statute under which there has never been an officially reported prosecution, although it appears there were two prosecutions shortly after the act was passed. 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.
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 act's application 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 when (1) civilian law enforcement officials make "direct active use" of military investigators; or (2) the use of the military "pervades the activities" of the civilian officials; or (3) 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.
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 probably only applies within the geographical confines of the United States, but supplemental provisions of 10 U.S.C. §§ 271-284 appear to apply worldwide.
Finally, the act is a criminal statute under which there has been but a handful of known prosecutions. 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 provides an historical analysis of the use of the Armed Forces to execute domestic law and of the Posse Comitatus Act, including their apparent theoretical and constitutional underpinnings. The report then outlines the current application of the act as well as its statutory exceptions, and reviews the consequences of its violation. This report appears in abridged form as CRS Report R42669, The Posse Comitatus Act and Related Matters: A Sketch.