What's next for Trump's classified documents case? Experts weigh in

A federal judge's decision Monday to dismiss Donald Trump's classified documents case elevated a widely disputed theory about the legitimacy of special counsels to derail one of the most serious legal threats faced by the former president, legal experts told ABC News.

Judge Aileen Cannon ruled that special counsel Jack Smith's appointment "breaches two structural cornerstones of our constitutional scheme" because Congress did not authorize Smith's appointment and funding.

The decision -- a major victory for Trump on the heels of the Supreme Court decision that broadened the scope of presidential immunity -- not only sidelined the former president's documents case, but also could upend the longstanding practice of appointing special counsels to independently conduct investigations and bring charges, experts told ABC News.

"Special prosecutors like Smith have been the norm for decades," said Pace University School of Law professor Bennett Gershman. "It's never been held by the court in any of these cases that the special prosecutor had to be first created by Congress before the President."

A spokesperson for the special counsel said the Department of Justice has authorized an appeal of the ruling, which could trigger a lengthy process that could bring Cannon's decision all the way to the Supreme Court for review.

"I'm sure that Jack Smith will ... seek an expedited appeal," said former federal prosecutor Josh Naftalis. "This is probably another Supreme Court case, for better or for worse."

If the appeal continues through January and Trump becomes president, he could direct his own Justice Department to drop the case -- killing the appeal.

A 'bizarre' ruling

Some legal experts ABC News spoke with said they weren't surprised with Cannon's decision to dismiss the classified documents case, pointing to Cannon's previous rulings that favored the former president .

"It's completely expected," Michael Gerhard, a constitutional scholar at the University of North Carolina at Chapel Hill, told ABC News. "[Cannon] has had a pattern for some time of issuing rulings that favor Trump, and it's also been expected she would do whatever she could to help Trump."

David Sklansky, a law professor at Stanford Law, called the decision "not exactly a surprise" but expects the decision to be reversed.

"It's hard to see the great constitutional principle that the judge thinks that she's defending," Sklansky said of Cannon's position, which rejected longstanding Supreme Court precedent dating back to the Nixon administration.

Stanford law professor Robert Weisber described the dismissal of the case as "bizarre" because other courts have largely rejected similar arguments.

"A quick look at Cannon's ruling suggests that she engaged in a pretty bizarre form of statutory interpretation to find that they didn't authorize Smith's appointment," said Weisber. "There's been a general understanding for decades now ... that this sort of special counsel appointment is perfectly legitimate."

The Thomas factor

It was in February that Trump's team first filed their motion to dismiss the case based on Smith's appointment. Five months later, following a two-day hearing last month, Cannon dismissed the case Monday in a 93-page order.

On three occasions in her ruling, Cannon referenced Justice Clarence Thomas' concurring opinion in the Supreme Court's recent ruling on presidential immunity , in which he questioned Smith's authority as special counsel.

"It seems like Judge Cannon accepted Justice Thomas' invitation and concurrence to kick this on these grounds," said former federal prosecutor Jarrod Schaeffer.

"Justice Thomas's concurrence is really providing her with the rationale that she needed to get rid of the case," said Michael Gerhardt, a constitutional scholar at the University of North Carolina at Chapel Hill.

A new judge?

If Smith's appeal is successful, the case could be remanded back to the District Court to proceed to trial, according to Schaeffer. That could provide an opportunity to have a new judge oversee the case.

According to Shaeffer, Smith could ask the Court of Appeals or the District Court to disqualify Cannon from the case by proving "her impartiality might reasonably be questioned."

The bar for disqualification itself is high -- including proving a judge's personal bias or conflict of interest -- so legal experts appear to be split over the odds of getting a new judge assigned to the case.

"She hasn't really done anything that suggests that she's so out of line that she does not have the ability and the fitness to oversee the case," said Gershman. "Although I disagree with everything she's done in so many areas, I don't know that Smith has enough of a case that she should be recused."

Justin Levitt, a professor at Loyola Marymount University, said that Smith might be able to highlight a pattern of conduct based on past rulings and conduct in court that suggests she is partial to Trump.

"I think there's a pattern that's developing that is quite troublesome," Levitt said.