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

Justice Samuel Alito pressed Mitchell on the impact the Colorado decision may have on other states.

Mitchell warned about the possibility of national disuniformity.

"Your question gives rise to an even greater concern because if the decision does not have conclusive effect on other lawsuits, it opens the possibility that a different factual record could be developed in some of the litigation that occurs in different states and different factual findings could be entered by state trial judges," he said. "They might conclude, in fact, that President Trump did not have any intent to engage in incitement or make a finding that differs from what this trial court found."

The first question to Mitchell came from Justice Clarence Thomas, who has been in the spotlight due to his wife Ginni's role in Jan. 6.

Some called on Thomas to recuse himself from this case.

Thomas asked Mitchell if Section 3 is self-executing -- a key issue in this case. Mitchell said the provision needs congressional enforcement.

Jonathan Mitchell, Trump's attorney, in his opening statement, asserted that the Colorado Supreme Court decision is "wrong and should be reversed for numerous independent reasons."

Mitchell argued that Trump is not covered under Section 3 as an elected official and claiming he is not an "officer of the United States." He also said that Section 3 cannot apply to a candidate, only those who hold office.

He said that if the U.S. Supreme Court affirms the Colorado Supreme Court's decision, it would "take away votes of potentially tens of millions of Americans."

Ahead of the historic arguments, some anti-Trump demonstrators gathered outside the front of the building with banners and signs disparaging the former president.

Police also took steps to ramp up security by placing fencing around the court.