Posse Comitatus Act of 1878
This new legislation has also raised the prospect of federal government involvement in state and local law enforcement issues, which may violate long-standing federal law. The Posse Comitatus Act of 1878 is an arcane statute passed by Congress toward the end of the Reconstruction Era after the Civil War. The Reconstruction Era refers to the period after the defeat of the Confederate states during which the former rebellious states were reincorporated into the Union. Federal troops had occupied the former Confederate States to enforce federal law and to police state and local elections.
Posse Comitatus is Latin for “power of the county” and the doctrine arose in England in the 15th century to support the common law right of local sheriffs to impress citizens into a posse to enforce the law. In the American colonies, the doctrine referred to the military enforcement of civil or state laws, which was anathema to the colonists due to the use of British military forces in the colonies to enforce laws passed by the English Parliament prior to the American Revolution.
The Constitution of the United States specifically limits the role of the military in civil matters, and makes the military at all times subject to the oversight of civilian elected authority. The Constitution also limits the role of the federal government generally, reserving unto the states all powers not specifically granted by the Constitution to the federal government. During the Civil War some constitutional protections, like habeas corpus (which is a constitutional safeguard and mechanism to prevent unlawful or secret imprisonment of citizens) were suspended by President Lincoln under claim of “war powers.” After the Civil War ended, the federal military occupied the South as a conquered territory and became the primary tool of law enforcement.
The Posse Comitatus Act of 1878 was designed to remove federal military authority over the state and local governments of the southern states after 13 years of Reconstruction. The original law specifically prohibits the Army from enforcing civilian law, and by amendment in 1956, it also includes the Air Force. By a directive of the Department of Defense, the Navy and the Marines are also prohibited from interfering with or participating in state and local law enforcement. The Coast Guard, which is now lodged in the Department of Homeland Security, is not covered by the Act or by any federal directive because the Coast Guard is actively involved in coastal law enforcement and has a federal complementary mission with the states.
The use of military or federal government drones within the United States, therefore, will be a subject of constitutional and judicial scrutiny because of the Posse Comitatus Act as well as the Fourth Amendment to the Constitution.