The Insurrection Act

Time -   The Insurrection Act, passed in 1807, allows the President to use the military as they deem “necessary” to enforce the law or suppress insurrection in the U.S. under certain conditions. 

The text of the law says it can be invoked at the request of a state, or at the President’s own volition when they believe that “unlawful obstructions, combinations, or assemblages, or rebellion against the authority of the United States, make it impracticable to enforce the laws of the United States in any State by the ordinary course of judicial proceedings.”

But those conditions are vague, and largely left to interpretation, Chris Mirasola, a professor of law at The University of Houston Law Center, tells TIME. 

“The statutes are variable, so they don't provide us any definitions about what these terms mean,” Mirasola says. 

He notes that it is a “common technique of statutory interpretation to use examples of past practice to give meaning to terms in the statute that are pretty ambiguous,” pointing to instances when the Insurrection Act has previously been used—and how they differ from the current situation.

.The Insurrection Act has been invoked on multiple occasions over the years.

The last time was in 1992, when President George H.W. Bush deployed the National Guard, at the request of former California Gov. Pete Wilson, to suppress unrest in Los Angeles following the acquittal of four white police officers who were filmed beating Rodney King, an unarmed black man.

The act has also been invoked without the permission or request of a state. President Dwight Eisenhower, for instance, sent the 101st Airborne Division to Little Rock, Ark., in 1957 against the wishes of the governor to quell opposition to the integration of Central High School.

Mirasola tells TIME that when the law was used before, it was in response to “situations that are far more extreme than what we currently see in Portland or Chicago,” in which there were “riots and civil disturbances that are so large that federal functions literally cannot be exercised” and necessitated the intervention of the military.

The current conditions, he says, “just don't rise to that level” seen in past uses of the act.