When Donald Trump began to claim presidential immunity from criminal prosecution related to his efforts to overturn his 2020 election loss, many legal analysts ABC News spoke with considered it a weak argument.

But last week, in nearly three hours of oral arguments, several Supreme Court justices seemed open to some limited protection for former presidents from criminal liability for official acts they undertook while in the White House.

It was a shocking turn of events, according to some veteran court observers.

“It was surprising to hear, at least from some of the justices, the possibility that a president could somehow commit criminal misconduct for which they could never be held liable in court,” Michael Gerhardt, a constitutional expert at the University of North Carolina, told ABC News. “I think that has struck many people as just, up until now, inconceivable.”

“That’s exactly the part that I think most of the American public is going to find fairly incredulous,” said David Schultz, a professor at the University of Minnesota and national expert in constitutional law. “The idea of saying that the president of the United States is above the law compared to the rest of us.”

While the justices seemed poised to reject Trump’s more sweeping claim of “absolute” immunity, how they attempt to devise what official acts are and are not exempt from criminal prosecution will set a new standard for presidential power.

“That is a whole new territory for the court that we’ve never seen before,” Schultz said, “and will make major new law in the United States.”

The justices grappled with the unprecedented nature of the case during Thursday’s hearing. Justice Neil Gorsuch said what they decide will be a “rule for the ages.”

While Trump is the first ever president to be criminally charged, the arguments were largely devoid of references to the former president and the specific allegations against him.

The immunity question came before the Supreme Court in the case brought by special counsel Jack Smith, alleging election interference; Trump is facing four felony counts: conspiracy to defraud the United States, conspiracy to obstruct an official proceeding, obstruction of and attempt to obstruct an official proceeding, and conspiracy against rights. He pleaded not guilty and denies all wrongdoing.

Puzzlingly, “in some sense, Trump did not seem to be important in this case,” Schultz said.

Instead, the debate largely focused on hypothetical scenarios as justices expressed concern about the consequences of too much or too little protection for future presidents.

“The question quickly became, ‘What’s the scope of official conduct?’ And that’s where, I think, the disagreements among the justices were revealing,” said Gerhardt.

At one point, Justice Elena Kagan pressed Trump attorney John Sauer if a president could order the military to stage a coup and be immune. Sauer said, in their view, a president could.

“The answer that she got was one of the most disturbing I’ve ever heard at the Supreme Court,” said Gerhardt.

Justice Sonia Sotomayor also asked Sauer if a president could order the military or someone else to kill a political rival, which Sauer also said could be considered an official act depending on the circumstances.

“If the potential for criminal liability is taken off the table, wouldn’t there be a significant risk that future presidents would be emboldened to commit crimes with abandon while they’re in office?” Justice Ketanji Brown Jackson asked.

On the other side, several conservative justices appeared primarily concerned about future bad faith prosecutions against former presidents and whether that would hamper their ability to make the “tough decisions” entailed by their job.

Trump’s attorney also made that case in his opening statement, stating the looming threat of prosecution would “distort the president’s decision-making precisely when bold and fearless action is most needed.”

Justice Samuel Alito even posited if, without immunity, presidents would be incentivized to commit crimes in order to stay in power rather than peacefully retire because of concern they will be prosecuted by a “bitter political opponent” after leaving office.

“Will that not lead us into a cycle that destabilizes the functioning of our country as a democracy?” Alito asked.

One expert described Alito’s line of questioning as stepping through the looking glass into an alternate reality.

“The fact that we haven’t had something like this happen before is consistent with the government’s position that there are institutional norms that have largely held,” said Ray Brescia, a professor at Albany Law School. “So, to upset that delicate balance because, in the words of Justice Alito, we can’t hold the president accountable for trying to subvert democracy in the fear that a future president might try to subvert democracy is just totally Alice in Wonderland.”

Though Stanley Brand, a former House general counsel and now an attorney for several former Trump aides, said he considered Alito’s question “timely.”

“What about Joe Biden when he leaves office? Is a Republican Department of Justice going to allege that some of the things he did were illegal? So I don’t think that was a hyperbolic or imaginary concern,” Brand said.

The conservative justices also highlighted controversial conduct by previous presidents, such as Franklin D. Roosevelt’s decision to inter Japanese Americans during World War II and John F. Kennedy’s scheme to undermine Fidel Castro’s rule in Cuba, and whether they could have been subject to prosecution.

“Presidents have to do a lot of things that in retrospect or under the microscope of a lawsuit might not look very good,” said Brand. “You have to look carefully at those, and I think that’s certainly what at least five of the justices expressed concern over.”

The back-and-forth reflected the difficult road ahead for the court in crafting an opinion.

“The path that they went down the other day is a very messy one and I don’t know how they’re going to come up with a clean answer on it,” said Schultz.

A trial for Trump’s election subversion case was originally set for March 4 but is delayed as the immunity question works its way through the courts. The Supreme Court agreeing to hear Trump’s immunity claim and its approach in crafting an opinion, which is not expected until well into June, is largely seen as a win for the former president as it makes it less likely than ever that the trial will proceed before the November election.

In some previous high-profile opinions involving presidential authority, including U.S. v. Nixon (in which the court said a president does not have executive privilege in immunity from subpoenas or other civil court actions) and Clinton v. Jones (which said a president has no immunity from civil damages for acts done before taking office or unrelated to the office) the Supreme Court ruled in unanimous fashion.

But experts said in this case, whatever the court decides, it is likely to be divided.

“It’s clear to me that this will likely be a split decision,” said Schultz. “I saw clear divisions and that’s just not good for the court and it’s not good for America in such an important case like this.”