A panel of three federal appellate judges expressed skepticism about Donald Trump’s claim to sweeping immunity from criminal prosecution and concerns about its implications, suggesting it would allow a future president to have a political rival assassinated by the military without repercussions.

Trump argues that he cannot be tried for trying to overturn the 2020 election results because he was acquitted by the Senate of inciting the Jan. 6, 2021, insurrection at the U.S. Capitol. James Pearce, a Justice Department attorney, called that “an extraordinarily frightening” proposition. The three judges on the U.S. Court of Appeals for the D.C. Circuit tasked with reviewing Trump’s claims, which were rejected by his trial judge last month, appeared to agree during the hour-long hearing.

“A president could sell pardons, could sell military secrets, could order Seal Team Six to assassinate a political rival?” Judge Florence Y. Pan asked. “Would such a president be subject to criminal prosecution if he’s not impeached?”

D. John Sauer, representing Trump, insisted that for any crime connected to a president’s “official duties,” the “political process” of impeachment and conviction by the Senate “would have to occur” before prosecution.” He predicted that if the president was involved in murdering someone, he would be “speedily” impeached.

The hearing — which invoked references dating back to George Washington’s tenure — showed how the historic prosecution of Trump has raised difficult questions largely avoided for more than two centuries about the limits of presidential power and the consequences of presidential crimes.

Trump was not required to attend the hearing but chose to be there. Speaking after the hearing at the former Trump hotel near the courthouse, he warned of “bedlam in the country” if he lost the case, saying it would be “the opening of Pandora’s box.” He left without taking questions from reporters.

Trump’s comments echoed those made by his attorney in court, who told the judges that if the prosecution went forward, it would “open a Pandora’s box from which this nation may never recover” and create “an endless cycle of prosecution” of former presidents. He suggested that President Biden could be indicted by a “Texas jury and a Texas judge . . . for mismanaging the border.” Trump has made clear that if reelected, he plans to use the Justice Department to go after his enemies.

Judge Karen L. Henderson, the lone Republican appointee on the panel, expressed some concern about that prospect. “How do we write an opinion that will stop the floodgates?” she asked Pearce.

The prosecutor responded that for 50 years, since the Nixon era, special and independent counsels have investigated presidents and never recommended criminal charges. “I think it reflects the fundamentally unprecedented nature of the criminal charges here,” Pearce said. “Never before have there been allegations that a sitting president has, with private individuals and using the levers of power, sought to fundamentally subvert the democratic republic and the electoral system.”

Henderson, historically protective of presidential power, otherwise joined her colleagues in skepticism of Trump’s arguments. “It’s paradoxical to say that his constitutional duty to take care that the laws be faithfully executed allows him to violate criminal laws,” she said. She also said that case law over the past two centuries indicates that “whether a man in the street, or a president … you can be held criminally liable.”

Trump is arguing that the judges should use the same reasoning that led the Supreme Court to give Nixon immunity from civil lawsuits for official acts in 1982. In that case, the justices said fear of lawsuits “could distract a President from his public duties” and was an “intrusion on the authority and functions” of the executive.

But as Judge J. Michelle Childs pointed out, Nixon was pardoned by his successor, indicating “an assumption that [he] could be prosecuted” criminally after leaving office.

Sauer said that case was different because Nixon’s alleged crimes involved “purely private conduct” — an assertion Pearce rebutted forcefully, noting that the Republican was accused of using the CIA to interfere in an FBI investigation. But Sauer later suggested that anything a president does while in office is likely to be an official duty, saying the fact that the indictment against Trump “focuses solely on acts before he left office” is “a telling indication that were dealing with official acts.”

A different panel of the D.C. Circuit ruled last month that in the context of a lawsuit brought by police officers and lawmakers injured on Jan. 6, 2021, Trump does not have absolute immunity because campaigning to stay in office is not an official act. Trump has said he plans to appeal that ruling to the Supreme Court as well.

Sauer countered that Trump’s meetings with members of Congress and the Justice Department about overturning the election, along with his tweets falsely claiming election fraud, all count as protected official conduct, not evidence of a crime as alleged.

Both Henderson and Pan noted that Trump was now making the exact opposite argument as the one he made at his impeachment trial, when his lawyers told senators that the criminal justice system was the appropriate venue for accountability. Pan quoted Trump’s lawyer in that case saying, “We have an investigative process in this country to which no former officeholder is immune.”

Sauer said he wasn’t bound by any concessions made by Trump’s previous lawyers. But Pan posited that he had made a fatal concession here as well — by acknowledging that a former president could be charged with a crime after impeachment, Trump was forfeiting all his arguments about the danger of such prosecutions. “Your separation of powers argument falls away, your policy arguments fall away,” she said.

Smith’s office asked the court to issue a final order within five days of its opinion, potentially putting Trump’s trial back on a fast track. If judges do so after ruling against Trump, the Supreme Court could, if it wishes, take up his legal challenge while letting the trial go forward.

When the court rules might be as important as how they rule. Trump is seeking to delay his trial, set for March, until after the presidential election in which he is the leading Republican candidate. Sauer asked at the hearing for any ruling against Trump to be put on hold for appeals to the full D.C. Circuit and the U.S. Supreme Court. Special counsel Jack Smith had asked the Supreme Court to take up the immunity question without waiting for the D.C. Circuit to rule first; that request was denied.

“He could lose before the Supreme Court nine to nothing and I think it would be a victory” because it would push back the trial, said Saikrishna Prakash, a professor at the University of Virginia’s law school who studies presidential authority. The Justice Department has taken the position in the past that a sitting president cannot be prosecuted.

Trump also claimed that he cannot be prosecuted by Smith because he was already tried and acquitted by Congress in his 2021 impeachment.

The judges also pressed both sides on a brief from the nonprofit American Oversight arguing that Trump does not have the right to appeal before trial because he is making a novel claim. That position is based on a line in a 1989 U.S. Supreme Court decision that was not about immunity, in which then-Justice Antonin Scalia wrote that a person must wait until after a trial to appeal unless there is “an explicit statutory or constitutional guarantee that trial will not occur.”

Both the Justice Department and Trump disagreed; Pearce called it “a small point of common ground” that a former president had a right not to be tried until courts had determined whether or not he is immune from prosecution. Even if it would help the government to have the appeal thrown out on jurisdictional grounds, Pearce said, “doing justice means getting the law right.”

Steve Vladeck, a national security law expert at the University of Texas, said the court was likely to agree with that position. “The one sentence version of the argument sounds super compelling,” he said. “But the more you pull apart the argument, the more you look at the precedent, the more you talk about the implications of the argument, the less I think it makes sense.”

A ruling by the D.C. Circuit will impact only one of the four prosecutions Trump faces. But Trump is making similar arguments in state court in Georgia, where he is charged in a conspiracy that covers much of the same conduct. The other two cases do not involve Trump’s conduct as president. In New York, state prosecutors accuse him of falsifying business records before he took office. In Florida, Smith’s office has charged him with mishandling classified documents after leaving office.

Walt Nauta, Trump’s longtime personal aide and his co-defendant in the Florida case, sat with the former president in court Tuesday.

Tom Jackman, Oliva Diaz, Issac Arnsdorf and Ann E. Marimow contributed to this report.

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