The law, which has existed in various forms since the time of George Washington and in its current state since the Civil War, allows the president to dispatch the military or federalize the National Guard in states that are unable to put down an insurrection or are defying federal law.
It was last invoked in 1992 by George H.W. Bush during the unrest in Los Angeles after the acquittal of police officers who beat Rodney King.
What is the Insurrection Act?
The Insurrection Act gives the president authority to call on military and National Guard forces to suppress an insurrection if a state requests it, if there is an insurrection that makes it impossible to enforce federal law, or if there is an insurrection or domestic violence that deprives others of their Constitutional rights.
The Act also requires the president to issue a proclamation demanding those participating in the insurrection disperse.