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

The justices, so far, are avoiding thornier questions around Trump's conduct on Jan. 6 and instead focusing on Section 3 of the 14th Amendment.

The provision reads: "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 ..."

Key in the debate is whether Trump is an "officer of the United States" as described by Section 3 and whether or not it is self-executing.

Mitchell, continuing to argue Congress must enforce Section 3, argued state officials can't take action even if a candidate were to openly acknowledge they participated in an insurrection against the United States.

"Because even if candidate is an admitted insurrectionist, Section 3 still allows the candidate to run for office and even win election to office and then see whether Congress lifts that disability after the election," Mitchell said.

"This happened frequently in the wake of the 14th Amendment, where confederate insurrectionists were elected to Congress, and sometimes they obtained a waiver, sometimes they did not," he continued.

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.