Here are the lawyers arguing the case.

The two lawyers who will appear in court Tuesday to debate whether former President Donald J. Trump is immune from charges of attempting to overturn the 2020 election both have experience in high-profile professions, but they come from different sides of the legal process.

The case will be argued on behalf of Special Counsel Jack Smith by James I. Pearce, a federal prosecutor who has worked in both the Justice Department’s Public Integrity Division and the Criminal Division’s Appellate Division. Mr. Pearce has not only participated in several of Mr. Smith’s sensitive legal battles during Mr. Trump’s prosecution on the election interference charges, but he has also played a crucial role in supporting the cases against hundreds of rioters who attacked the Capitol on January 6, 2021.

It was Mr. Pearce, for example, who argued the government’s side during numerous hearings in Federal District Court in Washington, when riot defendants sought the dismissal of an obstruction charge at the center of the Jan. 6 prosecutions. Mr. Pearce also pleaded guilty to the charges before the same federal appeals court before which he appears today.

Last month the Supreme Court said it would consider the scope of the obstruction law, and Mr Pearce is also likely to play a role in defending it before the nine justices.

In his work for Mr Smith, Mr Pearce has gone to court to battle with Twitter – now known as X – over obtaining data from Mr Trump’s account and helping prosecutors secure communications from the mobile phone from one of Mr. Trump’s top congressmen. allies, Representative Scott Perry, Republican of Pennsylvania. He has also filed papers arguing against televising Trump’s election interference trial.

In addition, Mr. Pearce took the lead in pushing back on Mr. Trump’s immunity defense as soon as it was filed, saying in an early administration memo that the former president should be treated like anyone else.

“The suspect is not above the law,” he wrote. “He is subject to federal criminal laws, as are more than 330 million other Americans, including members of Congress, federal judges and ordinary citizens.”

Mr. Pearce’s opponent before the appeals court will be D. John Sauer, a lawyer based in St. Louis who once served as attorney general of Missouri. Mr. Sauer joined Mr. Trump’s legal team late last year to handle appeals, including his challenge to a silence order imposed on him in the Washington election case.

He also joined a failed bid with Texas by asking the Supreme Court to block the Biden administration from repealing a Trump-era immigration program that forces certain asylum seekers arriving at the southwest border to seek approval in Mexico to wait.

When he left the attorney general’s office last January, Mr. Sauer, who once clerked for Supreme Court Justice Antonin Scalia, returned to his private firm, the James Otis Law Group. The firm is named after a prominent Revolutionary War-era lawyer who built a career exposing abuses by British colonial forces.