The Posse Comitatus Act After Reconstruction
After federal troops were withdrawn from the South, Congress passed the Posse Comitatus Act, sharply limiting the Army’s role in domestic law enforcement. The law reflected deep suspicion of standing armies policing citizens, shaped by abuse of military power during Reconstruction and earlier conflicts.
The Act curtailed routine use of federal troops against civilians, forcing presidents to rely on narrow exceptions like the Insurrection Act.
For nearly 150 years, it has been the main legal bulwark against using the military as a national police force.
Current fights over National Defense Areas and federalized Guard units are essentially a live test of whether Posse Comitatus still has teeth in the age of permanent emergencies.
