Posse Comitatus Act

The Posse Comitatus Act is a United States federal law (, original at ) signed on June 18, 1878, by President Rutherford B. Hayes which limits the powers of the federal government in the use of federal military personnel to enforce domestic policies within the United States. Congress passed the Act as an amendment to an army appropriation bill following the end of Reconstruction and updated it in 1956, 1981 and 2021. The Act originally applied only to the United States Army, but a subsequent amendment in 1956 expanded its scope to the United States Air Force. In 2021, the National Defense Authorization Act for Fiscal Year 2022 further expanded the scope of the Act to cover the United States Navy, Marine Corps, and Space Force. The Act does not prevent the Army National Guard or the Air National Guard under state authority from acting in a law enforcement capacity within its home state or in an adjacent state if invited by that state's governor. The United States Coast Guard (under the Department of Homeland Security) is not covered by the Act either, primarily because although it is a armed service, it also has a maritime law enforcement mission. The title of the Act comes from the legal concept of posse comitatus, the authority under which a county sheriff, or another law officer, can conscript any able-bodied person to assist in keeping the peace. The Act, § 15 of the appropriations bill for the Army for 1879 (found at ) was a response to, and subsequent prohibition of, the military occupation of the former Confederate States by the United States Army during the twelve years of Reconstruction (1865–1877) following the American Civil War (1861–1865). The U.S. Constitution places primary responsibility for the holding of elections in the hands of the individual states. The maintenance of peace, conduct of orderly elections, and prosecution of unlawful actions are all state responsibilities, according to any state's role of exercising police power and maintaining law and order, whether part of a wider federation or a unitary state.