The original Posse Comitatus Act referred exclusively to the United States Army. The Air Force, established during the 20th century initially as a branch of the Army, was added in 1956. The Navy and Marine Corps were not mentioned in the Act but were subject to the same restrictions by Department of Defense regulation until their inclusion in the act in 2021. The Space Force, established in 2020, was also included in the Act in 2021. The United States Coast Guard is not included in the act even though it is part of the six armed services as it is explicitly given federal law enforcement authority on maritime law. The modern Coast Guard did not exist at the time the Act became law in 1878. Its predecessor, the United States Revenue Cutter Service, was primarily a customs enforcement agency and part of the United States Department of the Treasury. In 1915, when the Revenue Cutter Service and the United States Lifesaving Service were amalgamated to form the Coast Guard, the service was both made a military branch and given federal law enforcement authority.
The original Posse Comitatus Act referred exclusively to the United States Army The Air Force established during the 20th century initially as a branch of the Army was added in 1956 The Navy and Marine Corps were not mentioned in the Act but were subject to the same restrictions by Department of Defense regulation until their inclusion in the act in 2021 The Space Force established in 2020 was also included in the Act in 2021 The United States Coast Guard is not included in the act even though it is part of the six armed services as it is explicitly given federal law enforcement authority on maritime law The modern Coast Guard did not exist at the time the Act became law in 1878 Its predecessor the United States Revenue Cutter Service was primarily a customs enforcement agency and part of the United States Department of the Treasury In 1915 when the Revenue Cutter Service and the United States Lifesaving Service were amalgamated to form the Coast Guard the service was both made a military branch and given federal law enforcement authority