Former Mueller prosecutor Andrew Weissmann claimed on MSNBC that Americans died in the Civil War to bar candidates "who engaged in insurrection" from running for office.

Weissmann made the claim on Thursday while speaking in a panel discussion on the Colorado Supreme Court moving to keep Trump off the state's primary ballot.

"This is not new. It is true that this provision of the Constitution is new to lots of people, because we’ve never been in a situation where you would have somebody running for office who engaged in insurrection or a rebellion," Weissmann said.

DEM-APPOINTED COLORADO JUSTICE SAYS TRUMP BALLOT BAN UNDERMINES ‘BEDROCK’ OF AMERICA IN FIERY DISSENT

Andrew Weissmann

Former Mueller prosecutor Andrew Weissmann made the claim on Thursday while speaking in a panel discussion on the Colorado Supreme Court moving to keep former President Trump off the state's primary ballot. (Photo by Dimitrios Kambouris/Getty Images for National Board of Review)

Weissmann said it was "remarkable" to him that the ruling from the Democrat-appointed court justices "isn’t really the unanimous finding in the Colorado case because you had no one dissenting on the issue of did he do it."

"No one was saying, oh, no, this was insufficient proof," Weissmann said. "There were lots of procedural issues, and I don’t mean to minimize them, that the dissent raised, but there was a district court finding and there was a majority opinion with no dissents on the fact that the leading contender for the Republican nomination had done what we had a civil war about."

"And the reason for this amendment was because, after the Civil War, people said, if you have engaged in this kind of conduct you cannot be any longer the president, the vice president, or any federal position," Weissmann continued.

"So this is historically really important in terms of what many people died for in this country," he added.

Donald Trump

Former President Donald Trump (Photo by JOSEPH PREZIOSO/AFP via Getty Images)

Weissmann served on special counsel Robert Mueller's team investigating Russian interference in the 2016 presidential election.

The investigation probed the 2016 Trump campaign over alleged collusion between the campaign and Russia, but there was insufficient evidence found by Mueller linking the two.

The Colorado Supreme Court's decision to ban Trump from the state's primary ballot undermines a "bedrock principle" of American democracy, one of the court's Democrat-appointed justices wrote in a fiery dissent.

Justices Carlos Samour, Maria Berkenkotter and Chief Justice Brian D. Boatright all dissented, but Samour was particularly critical of the 4-3 ruling. Samour and Boatright were each appointed by Democratic former Gov. John Hickenlooper, and Berkenkotter was appointed by current Gov. Jared Polis, also a Democrat. 

Colorado justices

Colorado Supreme Court Justice Melissa Hart, left, makes a point as Justice Maria E. Berkenkotter looks on as attorneys argue before the court on Wednesday, December 6, 2023, in Denver.  (AP Photo/David Zalubowski, Pool)

"The decision to bar former President Donald J. Trump — by all accounts the current leading Republican presidential candidate (and reportedly the current leading overall presidential candidate) — from Colorado's presidential primary ballot flies in the face of the due process doctrine," Samour wrote.

"Even if we are convinced that a candidate committed horrible acts in the past — dare I say, engaged in insurrection — there must be procedural due process before we can declare that individual disqualified from holding public office," he wrote.

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Samour went on to argue that allowing states to decide individually whether to allow Trump's candidacy "risked chaos in the country." The justice conjured visions of state governments divided on the legitimacy of a victorious presidential candidate.

"This can't possibly be the outcome the framers intended," Samour argued.

The disqualification, which was made under the 14th Amendment of the U.S. Constitution, is related to the Capitol riot on Jan. 6, 2021.

The 14th Amendment states: "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."

While the 14th Amendment was one of the Reconstruction Amendments adopted in the aftermath of the Civil War, the war was largely fought over the issue of slavery, not whether a presidential candidate could be kept off the ballot.

Fox News Digital has reached out to Weissman for comment.

Fox News Digital's Anders Hagstrom contributed reporting.