Tensions are growing over the potentially harmful effects of a showdown in Congress when it meets on Wednesday to take up the normally benign process of validating the Electoral College votes that would formalize Joe Biden’s election as president. Trump’s call for protests that day in the nation’s capital — and the potential for violence — has sparked fears he would use the chaos to justify invoking the Insurrection Act to deploy U.S. military forces on U.S. soil.

There is general consensus that the president does not have legal authority to invoke the Insurrection Act to alter the outcome of the election. And what powers the president does and does not have under the act has come under greater scrutiny than perhaps ever in its 213-year existence.

The Insurrection Act, originally signed by Thomas Jefferson in 1807, gives the president the power to act unilaterally and deploy the U.S. military to quell riots across the nation.

While a separate law called the Posse Comitatus Act, according to the Congressional Research Service Report, prohibits “the willful use of any part of the Army or Navy to execute the law unless expressly authorized by the Constitution or an act of Congress,” the Insurrection Act sidesteps that, giving the president authorization to utilize the military under certain circumstances, writes Stephen Vladeck, a professor at the University of Texas Law School.

According to the service report, the act has been invoked “on dozens of occasions,” but notes that since the end of the disturbances seen during the 1960s civil rights movement, its use has become “exceedingly rare.”

Jefferson was the first to use the act that he had signed into law, sending troops to the Lake Champlain region in New York and Vermont in 1808 after citizens continued to violate the Embargo Act.

In 1871, two years into office, President Ulysses S. Grant invoked the act largely to target the Ku Klux Klan operating within South Carolina. Over 1,000 soldiers rounded up Klansmen and, utilizing the Justice Department — which Grant oversaw the creation of — more than 600 men were detained, many of whom were then indicted and convicted in federal court.

“In the majority of cases where the President has invoked the Insurrection Act or the Stafford Act,” writes Major Mark M. Beckler, “he has done so at the request of a governor. However, in the case of President Dwight D. Eisenhower, who sent the Army into Little Rock to desegregate its schools in 1957, the president only intervened after National Guardsmen had barred the students from entering the school earlier that month.

The act was last invoked in 1992 in the city of Los Angeles, California after four police officers were acquitted on the charges of beating Rodney King. On that occasion, then-governor Pete Wilson requested that President George H.W. Bush send help.

The act itself has been amended over the years, with one provision passed in 1956 giving the president wide latitude: “Whenever the President considers 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, he may call into Federal service such of the militia of any State, and use such of the armed forces, as he considers necessary to enforce those laws or to suppress the rebellion.”

In an article for NBC News, Vladeck also cites that Congress has “eliminated the procedural checks it had initially placed on the president. Whereas the 1792 act provided that the president’s power to use the militias for domestic law enforcement would expire 30 days after the beginning of the next congressional session, the statute today includes no such sunset.”

He continues by writing, “Congress also initially required the president to go before a judge before he could use the military — to confirm that he met the terms of the statute. That requirement, too, has long-since disappeared.”

This is not the first time in Trump’s presidency that the Insurrection Act was suggested to be enacted. Last June, in a short televised speech, President Donald Trump recommended every governor “deploy the National Guard in sufficient numbers that we dominate the streets.”

From the Rose Garden, amid the nationwide protests over the death of George Floyd, President Trump urged that “Mayors and governors must establish an overwhelming law enforcement presence until the violence has been quelled. If a city or a state refuses to take the actions that are necessary to defend the life and property of their residents, then I will deploy the United States military and quickly solve the problem for them.”

Many deemed Trump’s threat not only as an escalatory move, but an aberration of past precedent.

As reported by the Associated Press, Kent Greenfield, a constitutional law professor at Boston College, said that “The president…has the power to enforce his law, but he is not saying that the laws aren’t being enforced. He is saying they’re not being enforced the way he wants them to be enforced.”

Any recent consideration of imposing the Insurrection Act or martial law to alter the election results has been roundly rejected by top military and defense authorities.

Former Defense Secretary Mark Esper resisted the president’s attempts to use troops to quell civil unrest over the summer.

“I was really concerned that that continued talk about Insurrection Act was going to take us in a direction, take us into a really dark direction,” Esper told Military Times shortly before Trump fired him in early November.

In a January 3 letter to the Washington Post, all 10 living former defense secretaries warned against interfering with the peaceful transfer of power from Trump to Biden on January 20.

“Efforts to involve the U.S. armed forces in resolving election disputes would take us into dangerous, unlawful and unconstitutional territory,” they wrote.

For further reading: The ‘Bonus Army’ War in Washington

This story was updated from a previous June 3, 2020 article.