Posse Comitatus Act 20 Stat. 145 (1878)
POSSE COMITATUS ACT 20 Stat. 145 (1878)
Representative James P. Knott (Democrat of Kentucky) introduced this act as an amendment to the Army Appropriation Act of 1878. It provides that "it shall not be lawful to employ any part of the Army of the United States, as a posse comitatus, or otherwise, for the purpose of executing the laws" except as specifically authorized by Congress. The act has applied to the Air Force since 1947; it has been extended to the Navy and Marine Corps by administrative regulations. Originally enacted as a step in the dismantling of reconstruction, this provision banned the practice implicitly authorized by the judiciary act of 1789, and used before the civil war to enforce the Fugitive Slave Act, of including military forces in the federal marshal's posse. The act remains on the books (section 1835, Title 18, United States Code) as an expression of the fundamental division between the military and civilian realms: the armed forces are not a law enforcement agency.
Congress has authorized the use of the armed forces to suppress insurrection, domestic violence, unlawful combination, or conspiracy that obstructs the execution of federal law or impedes the course of justice, or that deprives any class of people of constitutional rights that the state authorities cannot or will not protect. That provision of the Force Act of 1871 (now section 333, Title 10, United States Code) was invoked by President dwight d. eisenhower in 1958 when he used Army units to disperse the mob in Little Rock, Arkansas, that resisted a federal court's school desegregation order (see cooper v. aaron), and by President richard m. nixon, in 1970, when he ordered federal troops to assist in quelling a riot in Detroit, Michigan.
Dennis J. Mahoney