Special counsel Jack Smith urged a federal appeals court Saturday to reject President Trump’s claims that he is immune from prosecution, saying the suggestion that he cannot be held to account for crimes in office “threatens the democratic and constitutional foundation” of the country.

The filing from Mr. Smith’s team was submitted ahead of arguments next month on the legally untested question of whether a former president can be prosecuted for acts taken while in the White House.

Though the matter is now being considered by the U.S. Court of Appeals for the District of Columbia Circuit, it’s likely to come again before the Supreme Court, which earlier this month rejected prosecutors’ request for a speedy ruling in their favor holding that Mr. Trump can be forced to stand trial on charges that he plotted to overturn the results of the 2020 election.

The outcome of the dispute is critical for both sides especially since the case has been effectively paused while Mr. Trump advances his immunity claims in the appeals court.

Prosecutors are hoping a swift judgment rejecting those arguments will restart the case and keep it on track for trial, currently scheduled for March 4 in federal court in Washington. But Mr. Trump’s lawyers stand to benefit from a protracted appeals process that could significantly delay the case and potentially push it beyond the November election.

Mr. Trump’s lawyers maintain that the appeals court should order the dismissal of the case, arguing that as a former president he is exempt from prosecution for acts that fell within his official duties as president.

Mr. Smith’s team has said no such immunity exists in the Constitution or in case law and that, in any event, the actions that Mr. Trump took in his failed effort to cling to power aren’t part of a president’s official responsibilities.

The four-count indictment charges Mr. Trump with conspiring to disrupt the certification in Congress of electoral votes on January 6, 2021, when rioters motivated by his falsehoods about the election results stormed the U.S. Capitol in a violent clash with police. It alleges that he participated in a scheme to enlist slates of fake electors in battleground states who would falsely attest that Mr. Trump had won those states and encouraged Vice President Pence to thwart the counting of votes.

Those actions, prosecutors wrote, fall well outside a president’s official duties and were intended solely to help him win reelection.

“A President who unlawfully seeks to retain power through criminal means unchecked by potential criminal prosecution could jeopardize both the Presidency itself and the very foundations of our democratic system of government officials to use fraudulent means to thwart the transfer of power and remain in office,” Mr. Smith’s team wrote.

In their brief, prosecutors also said that though the presidency plays a “vital role in our constitutional system,” so, too, does the principle of accountability in the event of wrongdoing.

“Rather than vindicating our constitutional framework, the defendant’s sweeping immunity claim threatens to license Presidents to commit crimes to remain in office,” they wrote. “The Founders did not intend and would never have countenanced such a result.”

While Mr. Trump’s lawyers have argued that the indictment threatens “the very bedrock of our Republic,” prosecutors say the defense has it backwards.

“It is the defendant’s claim that he cannot be held to answer for the charges that he engaged in an unprecedented effort to retain power through criminal means, despite having lost the election, that threatens the democratic and constitutional foundation of our Republic,” they said.

A three-judge panel is set to hear arguments on January 9. Two of the judges, J. Michelle Childs and Florence Pan, were appointed by President Biden. The third, Karen LeCraft Henderson, was assigned to the bench by President George H.W. Bush.

U.S. District Judge Tanya Chutkan earlier rejected the immunity arguments, asserting that the office of the presidency does not confer a “get-out-of-jail free card.” Mr. Trump’s lawyers then appealed that decision, prompting Mr. Smith to seek to bypass the court and request an expedited decision from the Supreme Court.

The justices last week denied that request without explanation, leaving the matter with the appeals court.

Mr. Trump faces three other criminal prosecutions. He is charged in Florida with illegally retaining classified documents at his Mar-a-Lago estate and faces a state prosecution in Georgia that accuses him of trying to subvert that state’s 2020 presidential election and a New York case that accuses him of falsifying business records in connection with a hush money payment to a porn actress.

Associated Press