The Posse Comitatus Act of 1878: Can Trump Legally Send the Military to Fight Crime?

In early September 2025, President Donald Trump announced that he would deploy federal troops into several major U.S. cities to quell unrest — even if governors objected.The announcement immediately set off a wave of debate. Critics pointed to the Posse Comitatus Act of 1878, a law meant to prevent the use of the Army as a domestic police force. Supporters countered with the Insurrection Act of 1807, a much older law that presidents have invoked many times to justify troop deployments at home.So here’s the central question for us today: Is Trump doing something unprecedented — or is he following a long, if uneasy, American tradition of presidents sending troops into the streets?