The Insurrection Act

 Roll Call - The Insurrection Act is a law first passed in 1807 that gives the president broad authority to use military force to counter any “unlawful obstructions, combinations, or assemblages, or rebellion against the authority of the United States,” either at the request of a state or at the president’s own discretion.

The law includes no explicit provisions for judicial review, timeframes, or mechanism for congressional review.

Trump has already federalized the California National Guard, over the objections of California officials, and announced that 700 active-duty Marines would be added to the force moving into Los Angeles.

Mark Nevitt, a law professor at Emory University who served as a tactical jet aviator and attorney in the Navy, said that Trump’s invoked authority allows the Marines to operate in support roles and National Guard personnel to protect federal property and officials with “really murky” limits.

However, Nevitt said using Marines and National Guard for domestic law enforcement is generally prohibited by an 1878 law called the Posse Comitatus Act. That law that prohibits the use of military force for domestic law enforcement, except in cases “expressly authorized by the Constitution or Act of Congress.”

Nevitt said that if Trump decides to invoke the Insurrection Act, it would give him “much, much broader authority” for using the military in domestic law enforcement by bypassing the Posse Comitatus Act. Nevitt said that Trump has already pushed the bounds of the law with how he federalized the California National Guard.