The Supreme Court is set to hear arguments Thursday in the historic efforts to disqualify former President Donald Trump from office because of his role in the January 6, 2021, insurrection.

The case revolves around the 14th Amendment’s “insurrectionist ban,” a relic of the Civil War that hasn’t been touched in more than a century until the Trump-fueled attack on the US Capitol.

Here’s what you need to know for the high-stakes hearing:

What does the 14th Amendment say?

The 14th Amendment says Americans who take an oath to uphold the Constitution but then “engaged in insurrection” are disqualified from holding future public office.

The amendment’s key provision, Section 3, says in part: “No person shall … hold any office … under the United States … who, having previously taken an oath … 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.”

However, the Constitution does not spell out how to enforce the ban. And there is an open legal debate over how some of the terms in the vague provision should be defined. For instance, the amendment doesn’t explain what level of political violence is tantamount to “insurrection.”

The ban was applied against tens of thousands of former Confederates in the 19th Century. The provision hasn’t been touched since 1919.

How did this case begin?

A liberal-leaning watchdog group called CREW filed the lawsuit in September in Colorado state court. They filed the case on behalf of a group of Republican and independent voters, led by 91-year-old Norma Anderson, trailblazing GOP state legislator.

They sued Colorado Secretary of State Jena Griswold and sought a court order that would force Griswold to remove Trump’s name from the state’s GOP primary ballot. The primary is set for March 5.

Practically speaking, no matter what happens with the Supreme Court, Trump’s name will physically appear on the Colorado ballot. The deadline to print ballots has already come and gone. But whether votes cast for Trump are counted will be decided by the justices.

Griswold, a Democrat, was neutral while the case played out in Colorado, but has since come out in support of stripping Trump from the ballot.

What decision is SCOTUS reviewing?

The US Supreme Court is reviewing a decision from the Colorado Supreme Court, which said in a landmark 4-3 ruling in December that the “insurrectionist ban” applies to Trump.

To reach that conclusion, the Colorado justices also ruled against Trump on several other key matters.

They concluded that the ban applies to the presidency, even though the presidency isn’t explicitly mentioned in the provision. They concluded that courts have the power to enforce the ban, and don’t need to wait for authorization from Congress. They also concluded that the Denver-based trial was properly conducted under Colorado’s election laws that govern ballot access challenges.

Trump wants the US Supreme Court to overturn these findings. If he succeeds on just one of these fronts, it would be enough to implode the Colorado ruling and restore his spot on the state ballot.

What has happened in other states?

Only two states have removed Trump from the ballot based on the 14th Amendment and January 6.

The top election official in Maine reached a similar conclusion and determined that Trump is constitutionally barred from office. Trump is appealing that decision in state courts, which paused the proceedings while the Supreme Court deals with the Colorado case.

Similar 14th Amendment cases have been rejected – all on procedural grounds – in several other states, where well-funded legal groups filed lawsuits. This includes Minnesota, Michigan, Illinois, Massachusetts and Oregon.

How has Trump responded?

Trump has ridiculed these lawsuits at his campaign rallies. His lawyers and advisers have argued that it would be “un-American” to deprive voters the opportunity to decide whether the former president should return to the White House by removing him from the ballot.

They warned in a Supreme Court filing last month that there would be “chaos and bedlam” if states are allowed to block him from the ballot.

In his attempts to throw out the lawsuit before the trial in October, Trump unsuccessfully argued that the case misinterpreted Colorado’s ballot access laws, that the lawsuit raised a “political question” that only Congress could decide and that it violated his free-speech rights.

Some of his latest arguments might find a more receptive audience with the US Supreme Court, with its conservative supermajority.

Has this happened before?

It would be unprecedented to apply the 14th Amendment “insurrectionist ban” to a presidential candidate. But there hasn’t been a case like this in history because no US president has ever participated in anything resembling an insurrection as Trump did while trying to overturn the 2020 election.

The ban has been applied only once in the modern era – and CREW, which brought the Colorado case, was behind that successful effort.

A convicted January 6 rioter who was also a New Mexico county commissioner was removed from office in fall 2022 on 14th Amendment grounds, through a different but related legal mechanism.

In that case, the official had already been convicted of a January 6-related offense. Trump is facing state and federal charges related to the Capitol riot and his attempts to overturn the 2020 election – but he pleaded not guilty and hasn’t gone to trial yet.

The provision does not say that a criminal conviction is required to trigger a disqualification, though some legal scholars have concluded that a conviction would help ensure there was due process before someone is barred from office.