A panel of judges expressed scepticism over former president Donald Trump's claims that he is immune from being prosecuted on charges that he plotted to overturn the results of the 2020 election.
The appeals court's decision could have profound implications for Mr Trump, whose criminal trial in March is on hold during the appeals process. Mr Trump has pleaded not guilty to charges including conspiracy to obstruct an official proceeding and conspiracy against the right to vote.
D John Sauer, a lawyer for Mr Trump argued that a president must be impeached by the House of Representatives and convicted by the US Senate before they can be prosecuted. Mr Trump was impeached by the House twice, but never convicted.
"You're saying a president could sell pardons, could sell military secrets, could tell [Navy] SEAL Team Six to assassinate a political rival?" Judge Flornce Pan asked Mr Sauer.
In response, Mr Sauer said "yes" if the president was impeached and convicted by Congress.
Federal prosecutor James Pearce told the judges that granting Mr Trump immunity would enable future presidents to commit crimes.
"The president has a unique constitutional role, but he is not above the law," Mr Pearce said.
Mr Trump sat at the defence table during the proceedings, occasionally taking notes and speaking with his lawyers. It was his first court appearance in Washington since he was arraigned in August.
The criminal case is one of four that Mr Trump faces.
While also seeking to dismiss the 2020 election case in Washington altogether, Mr Trump's legal team is hoping that a prolonged appeals process could delay the start of the trial until potentially after the 2024 election.
“Of course I was entitled, as President of the United States and Commander in Chief, to Immunity,” Mr Trump wrote on his Truth Social media platform on Monday.
In the same post, the former president reiterated his false voting fraud claims.
Meanwhile, special counsel Jack Smith is hoping to get the trial under way well before Election Day.
His legal team has argued that presidents do not possess absolute immunity, and that Mr Trump had acted well outside his presidential duties when pressuring former vice president Mike Pence to reject the 2020 electoral outcome.
Tuesday's courtroom appearance underscores the legal complexities that Mr Trump faces as he seeks a return to the White House.
The front-runner to win the Republican Party's nomination for president, he has been campaigning in Iowa ahead of the state's caucus on January 15.
There, Republican voters will have their first say on who they want as their party's candidate.
Latest polling shows Mr Trump holding a lead of more than 30 points against Florida Governor Ron DeSantis and former UN ambassador Nikki Haley, according to data compiled by FiveThirtyEight.
Mr Trump's election interference trial in Washington is scheduled for March 4.
