“According to the New York Times, Trump is planning to invoke the Insurrection Act to bring in the military to carry out mass deportations. The law is a key exception to the Posse Comitatus Act, which prohibits the use of the military to enforce federal law without the permission of Congress or the Constitution.
Only in rare instances have presidents invoked the Insurrection Act. President George H.W. Bush was the last one to do so amid the 1992 Los Angeles riots that broke out in response to the acquittal of police officers in the beating of Rodney King. President Dwight D. Eisenhower also notably used the Insurrection Act to facilitate the desegregation of schools in Little Rock, Arkansas.
The provision of the Insurrection Act most likely to apply in Trump’s case is one that allows the president to unilaterally activate the military domestically to enforce federal law whenever they determine that “unlawful obstructions, combinations, or assemblages, or rebellion… make it impracticable [to do so] by the ordinary course of judicial proceedings.”
Mirasola said Trump would have a “relatively easy time” making the case that cartels trafficking immigrants across the border constitute an “unlawful obstruction” to the enforcement of US immigration law. Trump has in some ways appeared to begin building his case for invoking the Insurrection Act through his rhetoric on the campaign trail this year by describing an “invasion of criminals” coming across the border.
But Mirasola said it would be harder for Trump to argue that it is impracticable to enforce immigration laws through the “ordinary course of judicial proceedings.” That’s because presidents have done so for decades, and border crossings are no longer unusually high: They have sharply declined this year and are down even from certain points in the first Trump administration.
However, the law gives the president “sole discretion, in most instances” to determine whether the criteria necessary to activate the military have been met, according to 2022 congressional testimony given by Elizabeth Goitein, co-director of the liberty and national security program at the Brennan Center for Justice, and Joseph Nunn, the Center’s counsel in the national security program.
Goitein and Nunn also argued that the “vague and broad criteria for invoking the Act, combined with the lack of any provision for judicial or congressional review, render it ripe for abuse.” At that point, their concern was that Trump could have used the Insurrection Act to interfere with the certification of the 2020 election results. The use case is now different, but the potential for overreach is the same.
That is to say, while advocates may challenge Trump on whether the two key criteria for invoking the law have been met, the law gives presidents a wide berth — and the courts little power.
“For all practical purposes, courts have been cut out of the process,” Goitein and Nunn write.”