For years, Carlton F. W. Larson, a treason scholar and law professor at the University of California, Davis, has swatted away loose treason accusations by both Donald Trump and his critics. Though the term is popularly used to describe all kinds of political betrayals, the Constitution defines treason as one of two distinct, specific acts: “levying War” against the United States or “adhering to their Enemies, giving them Aid and Comfort.” Colluding with Russia, a foreign adversary but not an enemy, is not treason, nor is bribing Ukraine to investigate a political rival. Ordering the military to abandon Kurdish allies in Syria, effectively strengthening isis, is not treason, either—though that is getting warmer. During Trump’s Presidency, Larson told me, his colleagues teased him by asking, “Is it treason yet?” He always said no. But the insurrection of January 6th changed his answer, at least with regard to Trump’s followers who attacked the Capitol in an attempt to stop Congress’s certification of the election. “It’s very clear that would have been seen as ‘levying war,’ ” he said.

Both of Trump’s impeachments, in 2019 and 2021, were for “high crimes and misdemeanors,” but the Constitution also names treason as an offense for which a President can be impeached. Individuals, including a former President, may also be criminally punished for treason, perhaps the highest offense in our legal system, carrying the possibility of the death penalty. Fearing abuse of treason charges, the Framers gave treason a narrow definition and made it extremely difficult to prove.

The Treason Clause dictates that a conviction can rest only “on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court.” Partly as a result, there have been around forty treason prosecutions. No American has been executed for treason against the U.S., although Hipolito Salazar (a Mexican who officials thought was American) was federally executed for treason during the Mexican-American War, and some states have executed people for treason, including the abolitionist John Brown.

Larson wrote in his book “On Treason: A Citizen’s Guide to the Law,” from 2020, that the Framers “had a very specific image in mind—men gathering with guns, forming an army, and marching on the seat of government.” Few events in American history, if any, have matched that description as clearly as the insurrection of January 6th, which, court documents suggest, was planned by milita members who may have intended to capture elected officials. The American most associated with treason was one who did not “levy war” but rather gave “aid and comfort” to the enemy: Benedict Arnold. He at first fought heroically in the Revolutionary War but then attempted to aid the British; he fled to the enemy when his betrayal was discovered, and so was never punished. Treason prosecutions for levying war were brought against some individuals who took part in the Whiskey Rebellion of 1794, in which armed men burned down a tax collector’s house, and the Fries Rebellion of 1799, in which armed men stormed a prison and forced the release of tax resisters. Both resulted in conviction followed by pardon. The Jefferson Administration prosecuted the former Vice-President Aaron Burr, in 1807, for allegedly conspiring with a group of armed men to overthrow the U.S. government in New Orleans, but he was acquitted. In connection with that planned rebellion, the Supreme Court held that a mere conspiracy to levy war does not count as actually levying war. Another treason case resulted from the Christiana Riot, in which dozens of men fought the return of slaves to their owners as required by the Fugitive Slave Act. Supreme Court Justice Robert Grier, presiding at trial (as Justices did in those days), held that “levying war” had to involve an intent to overthrow the government or hinder the execution of law.