Donald Trump was wrongly removed from Colorado’s primary ballot last year, the US supreme court has ruled.

The court’s significant decision overturns a 4-3 ruling from the Colorado supreme court that said the former president could not run because he had engaged in insurrection during the January 6 attack on the US Capitol. The Colorado decision was a novel interpretation of section 3 of the 14th amendment, which bars insurrectionists from holding office.

Enacted after the civil war, the measure says that any member of Congress or officer of the United States who engages in insurrection after taking an oath to the constitution is barred from holding office. It has never been used to bar a presidential candidate from office.

During oral argument in February, nearly all of the justices signaled skepticism of Colorado’s authority to remove Trump from the ballot. They worried about the chaos it would cause if states had the unilateral authority to determine a candidate had engaged in insurrection and worried it could result in a chaotic, partisan tit-for-tat.

“I would expect that a goodly number of states will say whoever the Democratic candidate is, you’re off the ballot, and others, for the Republican candidate, you’re off the ballot. It will come down to just a handful of states that are going to decide the presidential election. That’s a pretty daunting consequence,” the chief justice, John Roberts, said during oral argument.

The Colorado supreme court reached its conclusion after a Denver trial court judge held a five-day hearing and ruled that Trump had engaged in insurrection on January 6, but was not disqualified from the ballot because he was not an officer of the United States.