[ninty]

[quote:321f9]The Posse Comitatus Act is a federal law of the United States (18 U.S.C. § 1385) passed in 1878, after the end of Reconstruction, and was intended to prohibit Federal troops from supervising elections in former Confederate states. It generally prohibits Federal military personnel and units of the United States National Guard under Federal authority from acting in a law enforcement capacity within the United States, except where expressly authorized by the Constitution or Congress. The original act only referred to the Army, but the Air Force was added in 1956 and the Navy and Marine Corps have been included by a regulation of the Department of Defense. This law is mentioned whenever it appears that the Department of Defense is interfering in domestic disturbances.[/quote:321f9]

http://en.wikipedia.org/wiki/Posse_Comitatus_Act