Two conservative law professors argue that Donald Trump is ineligible to serve as president again due to a section of the Constitution that prohibits anyone who has engaged in insurrection from holding office.

William Baude of the University of Chicago and Michael Stokes Paulsen of the University of St. Thomas explain their conclusion in an article set to be published in the University of Pennsylvania Law Review. The constitutional scholars, both active in the conservative Federalist Society, studied the question for more than a year, according to The New York Times.

“When we started out, neither of us was sure what the answer was,” Baude told the Times, adding that they engaged in the research to settle “an important constitutional question.”

The answer, according to Baude: “Donald Trump cannot be president — cannot run for president, cannot become president, cannot hold office — unless two-thirds of Congress decides to grant him amnesty for his conduct on Jan. 6.”

The provision they studied is Section Three of the 14th Amendment, which states that any person who took an oath to support the U.S. Constitution and then “engaged in insurrection or rebellion against the same, or given aid or comfort to the enemies thereof,” is prohibited from holding any government office.

The ban can be lifted only by a two-thirds vote by each House of Congress, according to the provision.

The 14th Amendment was adopted in 1868, in the wake of the Civil War, and is most noteworthy for extending civil and legal rights to formerly enslaved people.

Baude and Paulsen noted that Section Three of the amendment was designed to address a specific problem that arose after the Civil War. Southern states sent men who had violated their oaths to the Constitution by supporting secession to serve in Congress after their defeat.

“Fast-forward a century and a half,” the academics wrote. “The events surrounding efforts to overturn the result of the presidential election of 2020 have sparked renewed scholarly, judicial, and political interest in Section Three of the Fourteenth Amendment.”

Despite facing dozens of charges from three felony indictments, Trump remains the front-runner for the 2024 Republican presidential nomination.

He was charged earlier this month over his attempted coup after the 2020 election, which culminated in a riot on the U.S. Capitol on Jan. 6, 2021, carried out by supporters seeking to stop the certification of electoral votes.

“This was undoubtedly a serious assault on the American constitutional order. Not since the Civil War has there been so serious a threat to the foundations of the American constitutional republic,” Baude and Paulsen wrote.

The professors explored the provision at length, parsing whether Trump violated it, and how it could be applied and enforced. They concluded that Section Three is “legally self-executing” and its “disqualification, where triggered, just is.”

As far as enforcement, the authors determined that it “may and must be followed — applied, honored, obeyed, enforced, carried out — by anyone whose job it is to figure out whether someone is legally qualified to office.”

This could include state election officials, state legislatures and governors, Congress, the White House and state and federal judges.

“The bottom line is that Donald Trump both ‘engaged in’ ‘insurrection or rebellion’ and gave ‘aid or comfort’ to others engaging in such conduct, within the original meaning of those terms as employed in Section 3 of the 14th Amendment,” they concluded.

The article provides a foundation for lawsuits debating the “vital constitutional issue” that could end up before the Supreme Court, Paulsen told the Times.