Congress Passes Posse Comitatus Act Barring Military from Domestic Policing

President Rutherford B. Hayes signed the Posse Comitatus Act into law on June 18, 1878, barring the US Army from enforcing domestic civilian law except where expressly authorized by Congress. The law was passed as a rider to an army appropriations bill following the end of Reconstruction, when Southern lawmakers sought to end federal military enforcement of civil rights protections in the former Confederate states. The Act became the foundational legal limit on military involvement in domestic law enforcement for the next 147 years.