How has the Insurrection Act been used? Battling secession, segregation and riots.

WASHINGTON − President Donald Trump says he’d consider invoking the Insurrection Act of 1807 to fight crime and battle protesters in Democratic-controlled cities.

“I’d do it if it was necessary," if courts block his deployment of National Guard troops, Trump told reporters in the Oval Office on Oct. 6. "So far, it hasn't been necessary. But we have an Insurrection Act for a reason. If I had to enact it, I'd do that."

"It's been invoked before," Trump told reporters a day later. "We want safe cities."

The Insurrection Act, or its predecessors, have been invoked 30 times in American history since George Washington suppressed the Whiskey Rebellion in 1794. The last time it was used was George H.W. Bush’s defense of Los Angeles during the 1992 riots.

The law gives the president the power to deploy U.S. armed forces to suppress rebellions and civil unrest or when federal laws are being obstructed. Presidents have rarely deployed troops domestically against the wishes of state and local leaders − even though they have the authority to do so.