Supreme Court hears historic Trump 14th Amendment case: Key moments

"It would seem to me to be plain if Colorado position is upheld, surely there will be disqualification proceedings on the other side and some of those succeed," Chief Justice John Roberts said.

"The fact that there are potential frivolous applications of a constitutional provision isn't a reason to ...," Murray began to respond before Roberts cut him off.

"You might think they're frivolous, I think people who are bringing them may not think they're frivolous," Roberts said. "Insurrection is a broad, broad term and there's some debate about it."

"There's a reason Section 3 has been dormant for 150 and it's because we haven't seen anything like Jan. 6 since Reconstruction," Murray countered.

Justice Elena Kagan asked Murray, the attorney for the Colorado voters, why a single state should be able to decide who gets to be president of the United States.

"That seems quite extraordinary doesn't it?" she asked.

"No, because ultimately it's this court that's going to decide that question of federal constitutional eligibility and settle issue for the nation," Murray replied.

Jason Murray, arguing the case for the Colorado voters seeking to bar Trump from the state's GOP primary ballot, opened by noting the unprecedented nature of the case.

"We are here because for the first time since the War of 1812 our nation came under violent assault," he said. "For the first time in history, a sitting president of the United States tried to disrupt the peaceful transfer of presidential power by engaging in insurrection against the Constitution."

"President Trump disqualified himself," Murray said.

Justice Ketanji Brown Jackson pressed Mitchell on the Colorado Supreme Court's finding that the violent attempts by Trump supporters to halt the electoral count on Jan. 6 qualified as an "insurrection" under Section 3.

"Why would this not be an insurrection?" Jackson asked. "What's your argument that it's not?"

"For an insurrection there needs to an organized, concerted effort to overthrow the government of the United States through violence. And this riot that occurred ..." Mitchell began.

Jackson interrupted, "So, the point that a chaotic effort to overthrow the government is not an insurrection?"

"We didn't concede that it's an effort to overthrow the government either Justice Jackson, right?" Mitchell continued. "None of these criteria were met. This was a riot. It was not an insurrection. The events were shameful, violent, all those things. It was not an insurrection as that term is used in Section 3."