How Trump could use the Insurrection Act to send troops to American cities

President Trump told reporters Monday that the U.S. has "an Insurrection Act for a reason" — implying he could turn to the rarely used executive power in his push to send federal troops to Democrat-led cities.Why it matters: Trump's deployment of National Guard troops to several cities have been slowed or temporarily blocked by judges. The Insurrection Act would help him effectively bypass the court rulings by tapping authority scholars have warned is overly broad and ripe for misuse.A president hasn't invoked the Insurrection Act in decades.Driving the news: Trump said Monday in the Oval Office he hasn't needed to use the Insurrection Act — "so far." But, he added, "we have an Insurrection Act for a reason."He continued, "If people were being killed, and courts were holding us up, or governors or mayors were holding us up, sure, I'd do that."Threat level: Legal experts have called for the Insurrection Act to be updated to curtail the nearly "limitless discretion to deploy the military domestically" that it gives the president, according to the the Brennan Center for Justice, a nonpartisan law and policy institute.However, the law has not been "meaningfully updated" in some 150 years, the Center notes.Here's what to know about the Insurrection Act:What is the Insurrection Act?The 1807 law gives the president the authority to deploy the military on American soil in certain situations.The fine print: U.S. code reads that "[w]henever the President considers that unlawful obstructions, combinations, or assemblages, or rebellion" against U.S. authority "make it impracticable to enforce the laws," he can federalize the "the militia of any State, and use such of the armed forces" as he deems necessary.One section states that whenever there is an insurrection in any state, the president can call in the troops as requested by the legislature or governor (if the legislature cannot be convened) "as he considers necessary to suppress the insurrection."Two other key sections, however, do not mention state consent.Between the lines: The Act is a major exception to the Posse Comitatus Act, which forbids federal troops from conducting civilian law enforcement.Illinois and the city of Chicago, where Trump has directed hundreds of Guard personnel, on Monday accused the administration in a lawsuit of violating the Posse Comitatus Act and exceeding its authority.A federal judge ruled in early September that Trump's use of the National Guard in Los Angeles violated the Posse Comitatus Act.How has the Insurrection Act been used in the past?The law has been used in response to 30 crises throughout American history, per the Brennan Center. But the Center notes that troops weren't deployed every time. Most recently, President George H.W. Bush invoked the law at the request of the governor of California amid the 1992 Los Angeles riots.Bush also used it to deploy troops to the Virgin Islands to restore order after Hurricane Hugo. Presidents Dwight Eisenhower and John F. Kennedy used the power to enforce desegregation orders. Flashback: In his first term, Trump's aides reportedly drafted a proclamation to invoke the act as the president fumed over the 2020 racial justice protests following the murder of George Floyd.Top Trump allies, including Project 2025 architects, have privately pushed to sue the Act to secure the border and preempt protests on Inauguration Day, Axios' Zachary Basu reports.Can states push back if Trump uses Insurrection Act?If Trump unlawfully invokes the law, states could sue the administration.The Brennan Center notes the wide discretion the president has in determining the prerequisites for a deployment, as the Insurrection Act does not define "insurrection," "rebellion," "domestic violence" or other key words.And in 1827, the Supreme Court ruled that the authority to decide "whether the exigencies" under which the president can call forth the militia have arisen is "exclusively vested in the President."The Brennan Center says the high court has since suggested that courts could interfere if the president acted in bad faith or made a clear mistake. The bottom line: The Supreme Court will be have to answer "whether the president can use a contrived crisis as a justification for sending troops into our cities," wrote Steve Vladeck, a Georgetown law professor, in a Tuesday New York Times essay."This, then, is the real legal test President Trump's deployments raise: Can the courts meaningfully scrutinize the president's claims, or must they blindly defer?"Go deeper: MAGA calls for Trump to overrule judges on National Guard deployments