As oral arguments approach in former President Donald Trump’s U.S. Supreme Court appeal of a Colorado Supreme Court decision, many friend-of-the-court briefs in the case bring up a subject not much found in public discussion of the case: treason.

Trump is appealing a Colorado ruling that the 14th Amendment bars him from holding office because he engaged in insurrection before, during and after Jan. 6, 2021. That decision – and several others in states around the nation, some agreeing and some disagreeing with Colorado’s conclusion – have roots in the Constitution’s definition of treason, and Congress’ intent to block traitors from serving in the government.

As a scholar of constitutional law, I have submitted legal briefs in several of those cases, explaining the history of the 14th Amendment’s drafting and passage, and discussing what Republicans immediately after the Civil War hoped to attain from constitutional reform.

What did Congress intend?

Section 3 of the 14th Amendment reads:

“No person shall be a Senator or Representative in Congress, or elector of President and Vice-President, or hold any office, civil or military, under the United States, or under any State, who, having previously taken an oath, as a member of Congress, or as an officer of the United States, or as a member of any State legislature, or as an executive or judicial officer of any State, to support the Constitution of the United States, shall have engaged in insurrection or rebellion against the same, or given aid or comfort to the enemies thereof. But Congress may by a vote of two-thirds of each House, remove such disability.”

When Congress was drafting Section 3 of the 14th Amendment the year after the Civil War ended, the purpose of that provision was clear: to prevent people from serving in the government if they had used force to resist or overthrow the United States. To Congress, those actions constituted treason.

In drafting the language, Congress drew inspiration from the framers of the Constitution that was ratified from 1787 to 1789. Article III of the Constitution declares that there are two ways to commit treason against the United States: “levying War against (the U.S.), or in adhering to (its) Enemies, giving them Aid and Comfort.”

Section 3 of the 14th Amendment, passed by Congress and ratified by the states in the late 1860s, makes the same division when describing the actions of people who should be barred from public office. There is one change: Republicans in Congress substituted the phrase “engaged in insurrection or rebellion” for “levying war.”

A significant offense

Treason has long been a serious crime, different from other crimes because the target was the government.

Since at least the 1760s, and almost certainly for centuries before that, English common law made clear that treason was not a regular crime like, say, murder: Someone who gave a weapon to a person knowing they intended to kill another person is an accessory to murder. But someone who gave a weapon to a person knowing they intended to commit treason is a traitor, not an accessory to treason.

In short, treason is treason, and a person either engages in treason or does not. There are no degrees of treason.

This rule applied in the U.S. too: Samuel Chase, who signed the Declaration of Independence and was appointed to the Supreme Court by George Washington, said so in 1800. His view was echoed in 1807 by Chief Justice John Marshall and in 1851 by Supreme Court Justice Benjamin Curtis.

The rule was also reiterated in an 1863 case, U.S. v. Greathouse, in which people were charged with treason for buying a ship and outfitting the vessel to break the U.S. blockade of Confederate ports.

Supreme Court Justice Stephen Field served on the bench of a lower federal court for that trial, as justices often did then. In directions to the jury, he declared, “all who aid … whether by open hostilities … or any part in the furtherance of the common object, however minute or however remote from the scene of action, are equally guilty of treason.”

Two forms of treason

In the Constitution’s Article III, and in the 14th Amendment, there are two ways a person can commit treason: by “levying war” – which in the 14th Amendment is replaced with “engaged in insurrection or rebellion” – or by giving “aid and comfort” to people determined to be “enemies” of the United States.

The distinctions were important enough for the Framers to make, and for Congress to repeat in the late 1860s, when the 14th Amendment was passed and ratified by the states.

But ever since the nation’s founding, the difference between those two has been clear, and it’s not whether a person took one treasonous action or another. Field made very clear the distinction is in the person’s nationality: By constitutional definition, U.S. citizens cannot be considered “enemies of the United States.” They can only be viewed as rebels or insurrectionists.

In the Greathouse case, another federal judge, Ogden Hoffmann, served alongside Field. When Hoffmann spoke to the jury, he agreed with Field that the distinction between the two categories was whether the fighters were U.S. citizens or not. And he was clear that any treasonous action a person took was covered by either category:

“Every act which, if performed with regard to a public and foreign enemy, would amount to ‘an adhering to him, giving him aid and comfort,’ will, with regard to a domestic rebellion, constitute a levying of war. And, conversely, every act which, with regard to domestic rebellion, will constitute ‘a levying of war,’ will, with regard to a foreign enemy, constitute ‘an adhering to him, giving him aid and comfort.’”

Trump’s defenders

Many of those who support Trump have argued his actions don’t amount to engaging in insurrection. They say that, therefore, he can’t be disqualified from office for that reason.

Several of his allies have even pointed out that nobody has accused him of giving “aid and comfort” to the insurrectionists.

At least one of those supporters has gone so far as to claim that the failure to accuse him of “aid and comfort” is a reason to overturn the Colorado ruling and declare Trump eligible to hold office.

Trump did not personally attack a police officer on Jan. 6, 2021, or aid and abet a foreign nation. In legal terms, then, Trump did not offer “aid and comfort” to “enemies” of the United States: The people he urged to march on the Capitol and said kind words to may have been enemies of democracy. But like Trump himself, they were American citizens, and therefore, constitutionally speaking, could not be enemies of the United States.

Rather, they were insurrectionists. And as Hoffman’s 1863 statement makes clear, the constitutional law of treason does not differentiate between supporting them and being among them.

Mark A. Graber filed an amicus brief in the Colorado case, and another in the U.S. Supreme Court, that was technically in support of the voters seeking to block Trump from the ballot, but focused specifically on the history of Section 3 of the 14th Amendment.