Former President Donald Trump has long vowed to prosecute President Joe Biden if Trump wins November's election and the two trade places. He upped the stakes dramatically Tuesday, contending that if criminal charges against him aren't dropped, any current and future ex-presidents also could be prosecuted.

"I feel that as a president, you have to have immunity, very simple," Trump said after a court hearing where a panel of three federal judges seemed deeply skeptical of his attorneys' arguments that presidents have immunity from prosecution for official business. "It's the opening of a Pandora's box and it's a very, very sad thing that's happened with this whole situation."

Trump said Biden might not be the only one targeted. Former President Barack Obama could end up being prosecuted, he said, citing Obama administration drone strikes in the Middle East that killed a U.S. citizen who was identified as a leader of the terrorist group al-Qaida and that man's 16-year-old son, also a U.S. citizen. In court, Trump's attorney suggested that former President George W. Bush could be prosecuted for providing false information that launched the Iraq War.

The arguments, related to the federal charges Trump faces for attempting to overturn the 2020 election results, raised new constitutional issues that may only be settled at the U.S. Supreme Court because Trump's cases mark the first criminal prosecutions of a former president. They also dramatically raised the stakes of Trump's campaign to portray the charges as politically motivated attacks from Biden that would justify his own retaliation should he return to the White House.

Legal experts were skeptical that allowing the charges to go forward would lead to endless prosecutions of ex-presidents. Still, Trump has increasingly framed his bid to return to office as getting "revenge" against political enemies who have wronged him.

He made a point of being physically present in court for Tuesday's arguments. That maximized the attention he received, both for his legal battle against the federal government and his primary campaign, six days before Iowa holds the first contest of the Republican presidential nominating cycle. It also put him on camera as he vowed to repay what he portrayed as Democratic vindictiveness with his own should he win the election.

"That will be bedlam in the country" if the prosecution continues, Trump warned.

The former president's lawyers said they don't want a future of perennial payback when presidents leave office.

"The president is exactly right that if this prosecution is allowed to stand, no presidency in the future will ever be safe," Will Scharf, one of Trump's attorneys, said in an interview.

Legal experts said they were struck by those arguments. "You would think that somebody running for the presidency would not be trying to claim that they're immune to the criminal process but would be reassuring voters that he's following the law," said Claire Finkelstein, a law professor at the University of Pennsylvania.

Trump's argument is that he was simply doing his official duty as president when he tried to overturn his 2020 election loss to Biden, an act for which Biden's Department of Justice is now prosecuting him. While there is no evidence Biden has had any influence on the case, Trump has long portrayed it as political persecution and accused Biden of being the one trampling on democratic traditions.

The hearing came after Trump appealed a lower court ruling that presidential immunity did not protect him from charges that he conspired to defraud the United States by fighting his election defeat.

Trump has clearly become enamored of the reference to Pandora's box, the divine container from ancient Greek myth that was opened by an unsuspecting woman, releasing disease, despair and other miseries into the human world.

"If I don't get Immunity, then Crooked Joe Biden doesn't get Immunity, and with the Border Invasion and Afghanistan Surrender, alone, not to mention the Millions of dollars that went into his 'pockets' with money from foreign countries, Joe would be ripe for Indictment," Trump posted on his Truth Social platform Monday. "By weaponizing the DOJ against his Political Opponent, ME, Joe has opened a giant Pandora's Box."

Before a three-judge appellate panel in Washington, Trump's lawyer repeated the Pandora's box analogy, and his allies agreed, even if they didn't use the same reference.

"If these judges cannot set aside their Trump derangement and do not establish at a baseline level that presidents are immune from criminal prosecution, it's going to be very detrimental to the presidency," said Mike Davis, a former chief counsel for nominations for the Senate Judiciary Committee who runs The Article III Project, which pushes for conservative judges and rulings.

Davis said there's no statute of limitations on charges of murder, which he contended could be filed against Obama for the 2011 drone strikes on Anwar Al-Awklakiand his 16-year-old son, Abdulraham.

But Paul Coggins, a former U.S. attorney in Texas, said there's already well-established precedent that federal officials, including the president, are immune from prosecution for good-faith decisions they make while engaged in official business.

"Stealing an election," Coggins said, wouldn't fall into that category.

"That standard is one the courts are familiar with and one they can apply," Coggins said.

Filing indictments was part of his job as a federal prosecutor, he said, but he wouldn't have had legal protection if he decided to go out and personally serve a warrant.

There's precedent of previous presidents worrying about being prosecuted for actions they took while in office that may not have met the scope of their official duties. Richard Nixon, for example, received a pardon from his successor, Gerald Ford, implying that he was in criminal jeopardy for the Watergate scandal. In his final days in office, Bill Clinton reached a deal with the special counsel investigating his relationship with a White House intern. The deal spared him from prosecution but included the admission that he had lied under oath.

"Trump might be right about the future," Saikrishna Prakash, a University of Virginia law professor, wrote in an email. "But in any event, I believe he is wrong about whether presidents enjoy immunity from criminal prosecutions."