UPDATE (March 20, 2018, 3:50 p.m.): On Tuesday, a New York judge rejected President Trump’s attempt to use presidential immunity to dismiss a lawsuit connected to sexual harassment claims from “The Apprentice” contestant Summer Zervos. Trump’s attorneys had argued that the president was immune from lawsuits in state court, but Judge Jennifer Schecter ruled that the president doesn’t have protection from state lawsuits for unofficial conduct. Though the decision is likely to be appealed, it’s the first to clarify that presidents can be sued in state as well as federal court.

President Trump, no stranger to litigation, is now facing the dual threat of criminal and civil legal action. As special counsel Robert Mueller marches forward with his investigation into Russian interference in the 2016 election, evidence is mounting for the possibility of obstruction of justice charges. And Trump is already being sued in state court for defamation by one of the women who came forward during the presidential campaign with claims of past sexual misconduct.

The stakes are high, for both Trump and his critics. With a Republican-controlled Congress that shows little appetite for impeachment, legal action could be a powerful tool for undermining Trump’s presidency — and, if there’s evidence that he committed a crime, the most effective means of holding him accountable. But while both the lawsuit and the possibility of criminal charges have the potential to severely damage or even derail his presidency, it’s not clear how much Trump should be worried about this multi-pronged threat while he’s in the White House.

It is undisputed, according to legal experts, that litigation over obstruction of justice or defamation could proceed after Trump leaves office. But the question of whether the president can be sued or prosecuted while in office is murkier.

In 1997, the Supreme Court ruled that Bill Clinton could face a civil lawsuit in federal court for actions outside the scope of his official duties. But the opinion pointedly noted that it was not addressing whether similar suits could proceed in state courts, which each have their own judges, juries and procedures. And although the Constitution provides instructions for how a president can be removed from office, it’s silent on whether the commander-in-chief can be indicted or criminally prosecuted.

Trump’s lawyers are contending that as president, he’s immune to civil lawsuits in the state courts as well as criminal charges like obstruction of justice because he holds the highest office in the land. And they could well be right. The courts have not ruled definitively on either issue — and it’s possible they would exempt him when presented with a chance to weigh in.

That’s one of several factors that could ultimately help Trump:

The courts could rule that presidents need to be impeached and removed from office before they can be prosecuted.

There are two schools of thought on why the Constitution doesn’t address the question of whether a president can be indicted. The first is that impeachment — rather than criminal prosecution — was seen as the appropriate course of action when there was evidence that the president might have broken the law. This interpretation can be traced as far back as the writings of Alexander Hamilton, who appeared to assume that the president would first be impeached and removed from office, then prosecuted for any crimes related to impeachment.

In this view, postponing prosecution until the president was out of office does not mean he is above the law; it simply avoids the impracticalities of bringing a president to trial.

“The case for impeachment is that a criminal prosecution of the president will inevitably have political overtones that would muddy the course of justice,” said Brian Kalt, a professor at Michigan State University College of Law. “So the idea is that you first put the president through a special political process — which is impeachment — and then he can go through the criminal justice system when he’s no longer in this special position of power.” If Congress chooses not to act even in the face of evidence that the president committed a crime, Kalt said, there’s another solution: The people can choose not to re-elect him.

Others have argued, however, that indictment wasn’t mentioned because it was obvious to the framers of the Constitution that criminal prosecution and impeachment were remedies for different kinds of misconduct.

“Presidents can behave in ways that make them unfit to be president, even if that action isn’t criminal, and that’s what impeachment is designed to deal with,” said Eric Freedman, a professor at Hofstra University’s Deane School of Law. “And there are criminal activities that are bad and deserve criminal action but aren’t necessarily impeachable. They’re essentially on different tracks.” A traffic violation might be an example of a criminal offense that isn’t impeachable, while ordering the firing of a special prosecutor might be impeachable but not criminal.

The ability to sue the president in state court is still an open question.

The debate over whether the president can be sued in state courts, on the other hand, is already in motion, and here Trump looks more vulnerable. In the case involving Clinton, the Supreme Court rejected his argument that a federal lawsuit would be an unconstitutional burden on his ability to perform his duties as president. “The case at hand, if properly managed by the District Court, it appears to us highly unlikely to occupy any substantial amount of petitioner’s time,” Justice John Paul Stevens wrote.

But there is some chance Trump could temporarily escape the legal process if the high court went his way in this case. Trump’s lawyers are arguing now that allowing state courts to rule in lawsuits involving the president would violate the supremacy clause of the Constitution, which says that state law is always subordinate to federal law.

University of Pennsylvania Law School professor Stephen Burbank thinks the distinction that the president’s attorneys are making between lawsuits in state and federal courts isn’t very convincing. “They’re appealing to a precedent that state courts can’t exercise too much control over the president,” he said. “But as long as the state courts are deferential to the president’s schedule, it’s hard to see how requiring a deposition or even testimony would fundamentally interfere with the president’s duties.”

Freedman also thinks it’s clear that presidents can be sued in state court while they’re in office, in part because such cases are likely to have less of an impact on Trump’s presidency than a criminal indictment would — although Zervos and her lawyers presumably think they have a better shot at winning in state court, since they chose to file the lawsuit there rather than federal court. “Being sued is, on the whole, perceived to be less invasive and serious than being criminally prosecuted,” Freedman said.

Mueller could force the issue, but he might not want to.

The dispute over whether a president can be put on trial was nearly settled in 1974, when special prosecutor Leon Jaworski wrestled with whether to indict President Richard Nixon for his role in the Watergate break-in. The Supreme Court ruled that Nixon did not have the power to block Jaworski’s subpoena for the infamous Watergate tapes, but Jaworski ultimately decided not to push for an indictment. Nixon resigned before he could be impeached — at which point he became vulnerable to prosecution, but he was pardoned by his successor, Gerald Ford.

The question of whether the president can be indicted re-emerged in the 1990s, when Clinton was investigated by independent counsel Kenneth Starr. In a 1998 memo, Starr concluded that he did have the authority to indict Clinton, but, like Jaworski, he decided instead to refer the case to Congress for impeachment.

The fact that ultimately neither Jaworski nor Starr chose to indict the president he was investigating illustrates the practical challenges faced by Mueller. Even if indicting Trump turns out to be legal, Mueller would likely be politically lambasted for taking the fate of the presidency into his own hands.

“Indicting Trump for something like obstruction of justice might prompt the courts to resolve whether it’s actually possible to indict the president, but it could also derail the investigation,” Kalt said. “Deciding to file criminal charges against Trump could easily be perceived as a politically motivated overreach — Mueller saying he gets to decide who’s the president.”

A better strategy might be to copy Jaworski and name Trump as an unindicted co-conspirator, Freedman said. In this scenario, Trump would not be formally charged, but any relevant evidence against him would be admissible in the trials of the people who were indicted, allowing it to be publicly disseminated and scrutinized.

It may be wisest, though, for Mueller to present his findings to Congress — and the people — and let them act first, rather than trying to settle a constitutional debate that’s been percolating since the 18th century. That’s one major reason why the question of whether the president can be indicted or prosecuted may not be answered anytime soon.

Another is that the special counsel is technically bound by a Department of Justice legal opinion that states that the president cannot be indicted or prosecuted. There’s debate about whether this opinion would really preclude Mueller from indicting Trump, but its existence provides an additional incentive for the special counsel to proceed cautiously, since a violation of DOJ rules would be grounds for ending his investigation. Mueller would be free of these limitations, according to Freedman, if Congress passed a statute giving him more protections — similar to a previous law that placed the special counsel under the authority of a three-judge panel, rather than DOJ — but that seems unlikely to occur.

All of this indicates that, even if we don’t know for sure whether Trump can be criminally prosecuted, he probably doesn’t have much to worry about for now — at least unless Mueller decides to take a big risk by indicting him.