Following months of self-fueled speculation, former President Donald Trump made it official on Tuesday and announced his candidacy for a second term in the White House. And while his third run for office will take place under decidedly different circumstances than his first two bids for the presidency, he remains a uniquely potent force in conservative politics and, for now, stands as the dominating frontrunner for the Republican nomination. 

Faced with the very real prospect of a twice-impeached former president returning to office after instigating the Jan. 6 attack on the United States Capitol, some congressional Democrats — as well as several government accountability groups — have begun exploring whether they can bar Trump from the White House entirely. Their plan? Use a century-and-a-half-old constitutional amendment crafted in the wake of the Civil War. 

Here’s everything you need to know:

What is the 14th Amendment? 

Written in the wake of the Civil War as part of the Reconstruction effort to repair the rift between northern and southern states, the 14th Amendment to the United States Constitution deals primarily with questions of citizenship and the rights thereof. Crucially, it also states in Section Three that:

That prohibition on holding federal office was diluted by a series of subsequent congressional acts offering amnesty for many of those who would have otherwise been affected by the clause for their participation on the Confederate side of the Civil War. Still, the Amendment remained on the books, and has increasingly been seen by some Democrats and liberal-leaning groups as the most obvious means of preventing lawmakers who participated in the Jan. 6 attacks from remaining in, or entering, higher office. 

Has it been used before? 

Yes, but rarely. In the early 20th century, Wisconsin socialist Victor Berger was successfully blocked from assuming a seat in the U.S. House for having advocated against American involvement in World War I. He appealed the decision and, after the Supreme Court ruled in his favor, went on to several terms in office. 

More recently, lawsuits brought against Reps. Marjorie Taylor Green (R-Ga.) and Madison Cawthorn (R-N.C.) attempting to bar them from re-election in the 2022 midterms relied heavily on the 14th Amendment and the pairs’ anteceding behaviors in the run-up to the Jan. 6 insurrection. In both cases, the suits were blocked or found insufficiently convincing to actually apply to the two representatives. However, a similar suit successfully removed Jan. 6 participant Couy Griffin from his position as Otero County, New Mexico, commissioner this past September, with District Court Judge Francis Mathew noting that the events of that day met the definition of “insurrection.” 

“Because state law required Mr. Griffin to take an oath to support the Constitution as a county official, and he did so, the Court concludes he is subject to disqualification under Section Three,” Mathew wrote in his ruling. 

Sounds iffy, doesn’t it?

Legal experts agree. “We could have 51 jurisdictions coming out differently, really, on the same evidence,” former Judge Marcy Kahn told Bloomberg in a recent interview on the Amendment’s potential efficacy against Trump. “It really would be a constitutional crisis.”

This past year, Kahn served as the chair of the New York City Bar’s Task Force on the Rule of Law, which authored a study on whether or not the 14th Amendment could be applied to Jan. 6 participants. That study, published in September, determined that “a uniform federal standard for application of Section Three is sorely needed” to address the obvious disparities and “eliminate ambiguity and confusion” in state and local interpretations of the clause. “[A] federal civil enforcement statute … would assure a reasoned, evidence-based, due process approach to candidate disqualification,” the study further concluded in a call for Congress to enact its recommended reforms. 

University of Indiana law professor Gerard Magliocca offered a similar sentiment in an essay published this past spring in response to the Federal District Court’s decision allowing Cawthorn to remain on the ballot due to the Amnesty Act of 1872. “The Court ruled that a ballot challenge brought against Rep. Cawthorn by state voters under Section Three of the 14th Amendment could not proceed because Congress gave him amnesty 150 years ago,” Magliocca wrote, adding, “if that conclusion sounds ridiculous, that’s because it is.”

Like Kahn, Magliocca concludes that the solution lies ultimately in the federal arena, writing “Congress can give Section Three amnesty to the Jan. 6th insurrectionists. But only this Congress or a future one may do so.”

So where does this leave Trump?

It’s unclear. While Trump was cleared of his role in the Jan. 6 insurrection during his second impeachment trial, the letter being circulated by Rep. David Cicilline (D-R.I.) in response to the former president’s campaign announcement leans on subsequent testimony and evidence presented over the course of the Jan. 6 Committee hearings as the legal justification for his proposed legislation. 

If Congress does pass Cicilline’s bill, it would almost certainly be challenged by the former president’s legal team, who have shown a willingness to elevate any legal threats to the conservative-leaning United States Supreme Court. What’s more, the incoming Congress — which seems virtually certain to hold a slight Republican majority — could also move to counteract any legislation passed in the waning days of the current session.