Which law prohibits the armed forces from executing civil law in the United States?

The Posse Comitatus Act is the law that prohibits the armed forces from executing civil law in the United States. Enacted in 1878, this act restricts the use of the military in domestic law enforcement activities, asserting that military personnel cannot be used to enforce civilian laws without authorization. This separation is crucial for maintaining the balance of power between civilian and military authorities and protecting civil liberties.

The purpose of the Posse Comitatus Act is to uphold the principle of civilian control over the military, ensuring that military forces do not interfere with law enforcement duties that are traditionally the responsibility of state and local authorities. As a result, this act is a foundational element in American legal and constitutional law regarding the interaction between military and civilian law.