Which act of legislation strictly limits U.S. Armed Forces involvement in law enforcement activities in the United States?

The Posse Comitatus Act of 1878 is the legislation that strictly limits the involvement of U.S. Armed Forces in law enforcement activities within the United States. It was enacted to restrict the power of the federal military personnel to act as law enforcement agents on U.S. soil, thus maintaining a distinction between military and civilian law enforcement roles. This act reflects the principle that the military should not be deployed for domestic law enforcement unless explicitly authorized by Congress or the Constitution.

The intent behind the Posse Comitatus Act is to prevent the potential abuse of power by the military and to protect individual liberties by ensuring that military authority does not infringe upon civilian law enforcement responsibilities. Over the years, it has shaped the framework for how military forces can engage in domestic situations, particularly following civil disturbances or emergencies.