The Supreme Court in the US state of Colorado ruled on Tuesday evening that former President Donald Trump was disqualified from holding office over his role in the January 6 attack on the Capitol building in Washington DC.
The ruling blocks Trump from appearing on the ballot in Colorado for the presidential election set to take place in November next year.
"A majority of the court holds that Trump is disqualified from holding the office of president under Section 3 of the 14th Amendment," the court wrote in its 4-3 decision.
Trump's team to appeal decision
A Trump spokesman called the Colorado ruling "undemocratic" and vowed to appeal to the US Supreme Court, which has a two-thirds Conservative majority.
The same six members of the Supreme Court have banned affirmative action this year and last year overturned Roe vs. Wade protection for abortion rights.
"The Colorado Supreme Court issued a completely flawed decision tonight and we will swiftly file an appeal to the United States Supreme Court and a concurrent request for a stay of this deeply undemocratic decision," Trump campaign spokesman Steven Cheung said in a statement
His campaign has condemned 14th Amendment challenges as an attempt to deny millions of voters their preferred choice for president.
The ruling makes Trump the first presidential candidate in US history to be considered ineligible for the White House under a rarely used provision of the US Constitution that bars officials who have engaged in "insurrection or rebellion" from holding office.
Must-win states could follow Colorado's lead
The ruling applies only to the state's March 5 Republican primary, but its conclusion would likely also affect Trump’s status for the November 5 general election.
Nonpartisan US election forecasters view Colorado as safely Democratic, meaning that President Joe Biden will likely carry the state regardless of Trump's fate.
Trump lost Colorado by 13 percentage points in 2020 and doesn't need the state to win next year's presidential election. But the danger for the former president is that more courts and election officials could follow Colorado's lead and exclude Trump from must-win states.
Colorado officials say the issue must be settled by January 5, the deadline for the state to print its presidential primary ballots.
Dozens of lawsuits have been filed nationally to disqualify Trump under Section 3, which was designed to keep former Confederates from returning to government after the Civil War.
It bars from office anyone who swore an oath to "support" the Constitution and then "engaged in insurrection or rebellion" against it, and has been used only a handful of times since the decade after the Civil War.