CNN  — 

Anti-Trump challengers have succeeded at using the 14th Amendment’s “insurrectionist ban” to remove former President Donald Trump from the ballot in Colorado and Maine, though those decisions have been paused pending potential appeals.

Other major challenges have been rejected on procedural grounds in MinnesotaMichigan and some other states.

Although there wasn’t a formal court challenge in California, the state’s top election official decided Thursday to keep Trump on the list of certified candidates for the state’s GOP primary, despite political pressure to remove him.

Other challenges are still pending, including in Oregon, as the 2024 primary cycle approaches.

Here’s a breakdown of the complicated legal questions at play.

What does the 14th Amendment say?

The 14th Amendment, which was ratified after the Civil War, says US officials who take an oath to uphold the Constitution are disqualified from holding future office if they “engaged in insurrection” or have “given aid or comfort” to insurrectionists.

However, the Constitution does not spell out how to enforce the ban, and the vague phrasing has led to questions about whether it even applies to the presidency.

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.”

Has this happened before?

The ban was used extensively to disqualify ex-Confederates in the late 1800s, but its application in contexts outside of the Civil War is less clear.

Congress used the 14th Amendment to disqualify a socialist lawmaker from office in 1919. In 2022, a New Mexico judge removed a convicted January 6 rioter from his position as a county commissioner based on the 14th Amendment.

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.

When it comes to Trump, there hasn’t been a situation like this in American history. No US president has ever done anything that raised the possibility that they engaged in insurrection – until now.

It is unprecedented to apply the 14th Amendment “insurrectionist ban” to any presidential candidate, let alone the clear front-runner for a major party nomination, as Trump is leading in the GOP polls.

The next major case likely to be decided is in Oregon

A ruling could be coming soon in a major 14th Amendment case in Oregon.

Free Speech For People, a liberal advocacy group, filed the lawsuit earlier this month directly at the Oregon Supreme Court. It wants the justices to order Oregon’s secretary of state to remove Donald Trump from the 2024 primary and general election ballots because of his role in the January 6 insurrection.

Trump’s lawyers urged the Oregon Supreme Court on Friday to dismiss the 14th Amendment case. Now that all of the legal briefs have been filed, the Oregon justices could weigh in at any time.

Oregon Secretary of State LaVonne Griffin-Valade, a Democrat, asked the court to throw out the case on procedural grounds.

Essentially, Griffin-Valade argued it isn’t the right time to examine Trump’s eligibility for office. She said the Oregon law that requires her to determine whether a candidate has “become disqualified” applies only to the general election, not the GOP primary.

In their filing Friday, Trump’s lawyers said they agreed with Griffin-Valade that the case should be tossed on procedural grounds based on the state’s ballot access laws.

“The Secretary (of State) correctly recognizes that Oregon law does not authorize her to police presidential primary candidates’ qualifications,” Trump’s lawyers wrote. “Oregon’s election statutes tell the Secretary exactly what criteria to apply in determining which presidential candidates shall appear on primary ballots. Those specific criteria do not include any inquiry into a candidate’s eligibility to be President.”

Oregon election officials say the names on the primary ballot must be finalized by March 21. The Oregon primary is May 21.

The impact of potentially removing Trump from the primary ballot may be limited. Oregon is one of the final states to hold its GOP contest, so the nomination race may be decided by then. And Oregon’s GOP delegates will be allocated based on the results of a vote at the state party convention on May 25, according to the Republican National Committee.

What happens next in Colorado and Maine?

Trump’s legal team is expected to appeal two decisions to remove him from primary ballots in Colorado and Maine on Tuesday, according to a source familiar with the plans.

Trump would appeal the Colorado ruling to the US Supreme Court and the Maine secretary of state’s decision in state court.

The Colorado Republican Party has already appealed the state Supreme Court ruling. Because that court paused its decision pending appeal, this means Trump will be included on the state’s primary ballot when it’s certified on January 5, unless the US Supreme Court declines to take the case or affirms the Colorado ruling.

Maine Secretary of State Shenna Bellows, a Democrat, put her decision on hold until Maine’s Superior Court issues a ruling. State law lays out timelines for that court and, if the decision is appealed, for the state Supreme Court to act by the end of January.

Bellows told CNN on Friday that her office has received threats since her decision to remove Trump from the 2024 primary ballot.

“We have received threatening communications,” Bellows told CNN’s Kaitlan Collins on “The Situation Room.”

“I certainly worry about the safety of people that I love, people around me, and people charged with protecting me and working alongside me,” she added. “That being said, we are a nation of laws, and that’s what’s really important. So, I have been laser-focused on that obligation to uphold the Constitution.”

This story has been updated with additional developments.

CNN’s Ethan Cohen and Katelyn Polantz contributed to this report.