Who Are the Lawyers Arguing in the Trump Immunity Hearing?

The two lawyers who will be squaring off in court on Tuesday to debate the issue of whether former President Donald J. Trump is immune to charges of trying to overturn the 2020 election both have experience in high-profile appeals, but they come from different sides of the legal aisle.

Arguing the case on behalf of the special counsel, Jack Smith, will be James I. Pearce, a career federal prosecutor who has worked in both the Justice Department’s public integrity section and in the appellate section of its criminal division. Mr. Pearce has taken part not only in several sensitive legal battles that Mr. Smith has waged during the prosecution of Mr. Trump 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 Jan. 6, 2021.

It was Mr. Pearce, for instance, who argued the government’s side at countless hearings in Federal District Court in Washington when riot defendants sought the dismissal of an obstruction charge that is central to the Jan. 6 prosecutions. Mr. Pearce also argued in favor of the charge in front of the same federal appeals court he is appearing before today.

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

In his work for Mr. Smith, Mr. Pearce has gone to court to fight with Twitter — now known as X — about getting data from Mr. Trump’s account and to help prosecutors secure communications from the cellphone of one of Mr. Trump’s chief congressional allies, Representative Scott Perry, Republican of Pennsylvania. He has also filed papers arguing against televising Mr. Trump’s election interference trial.

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

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

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

He also joined in an unsuccessful bid with Texas in asking the Supreme Court to stop the Biden administration from rescinding a Trump-era immigration program that forces certain asylum seekers arriving at the southwestern border to await approval in Mexico.

When he left the solicitor general’s office last January, Mr. Sauer, who once clerked for the 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 out of challenging abuses by British colonial forces.