"At issue is the president’s authority to deploy the military for domestic purposes. A federal law, the Posse Comitatus Act of 1878, generally bars the president from using federal troops — the Army, Navy, Marines, Air Force or Space Force — to enforce domestic laws. But there are exceptional circumstances when the president can use troops domestically. The most prominent exception is the Insurrection Act, which authorizes the president to deploy the military to suppress insurrections, “domestic violence” or conspiracies that undermine constitutional rights or federal laws. At the end of Trump’s first term, some of his most ardent supporters urged and expected him to invoke the Insurrection Act to push aside state election authorities and essentially void the 2020 presidential election results, although he never did so. During his 2024 campaign, he said he would invoke the act to subdue unrest if reelected. But so far, Trump has not invoked the Insurrection Act. Instead, in a Saturday order, he cited a different statutory provision: a terse section of the U.S. code that allows the president to use the National Guard — but not any other military forces — to suppress the “danger of a rebellion” or to “execute” federal laws when “regular forces” are unable to do so. Notably, his order did not outright declare the unrest in L.A. to be a “rebellion,” but suggested it was moving in that direction. “To the extent that protests or acts of violence directly inhibit the execution of the laws, they constitute a form of rebellion against the authority of the Government of the United States,” the order said."