Two Major Lawsuits Facing President Trump Hinge on This Constitutional Question

President Donald Trump faces two very different lawsuits, but their outcomes could depend on the same unanswered constitutional question.

On Thursday, New York Attorney General Barbara Underwood sued Trump and three of his children over allegedly misusing a family charity for personal business, such as paying off creditors.

That same day, New York’s highest court rejected an appeal from Trump’s lawyers to dismiss or delay a defamation case brought by former “Apprentice” contestant Summer Zervos against Trump.

The two cases are underpinned by the same contention: a sitting president can be subject to a civil lawsuit in a state court.

As it turns out, that’s an unresolved question, and Trump’s lawyers have tried to use it to his advantage.

Trump lawyer Marc Kasowitz argued in New York state court in early December that “state court can’t exercise any control over the president under any circumstances, and he argued that a motion to dismiss Zervos’ case is about “protecting the ability of the president to do his constitutionally mandated job.”

In court filings in the Zervos case, Trump’s team has cited the Supreme Court’s 1982 decision in Nixon v. Fitzgerald, which held that the president has “absolute immunity” from being held liable for damages in civil lawsuits for conduct within the “outer perimeter” of his official presidential duties.

“Because of the singular importance of the President’s duties,” the decision reads, “diversion of his energies by concern with private lawsuits would raise unique risks to the effective functioning of government.”

But there are limits to the decision in Nixon v. Fitzgerald: the case only applied to civil suits in federal court, not state court, and only to civil suits related to official actions as president, not personal conduct.

Indeed, in a later Supreme Court case, 1997’s Clinton v. Jones, the court furthered the understanding of that decision. In the 1997 case, in which former Arkansas state employee Paula Jones accused President Bill Clinton of sexual harassment, the Supreme Court said the Nixon v. Fitzgerald ruling on immunity from civil damages did not apply to “unofficial conduct” by the president.

But again, that case only was limited to civil suits in federal court and did not address the question of bringing a similar case in state court.

Read More: Why the Summer Zervos Lawsuit Against President Trump Matters

In fact, the Supreme Court explicitly decided not to decide that question, explaining that state court suits could raise different legal questions than the ones decided in Clinton v. Jones. “Because the Supremacy Clause makes federal law ‘the supreme Law of the Land,’ any direct control by a state court over the President, who has principal responsibility to ensure that those laws are ‘faithfully executed,’ may implicate concerns that are quite different from the interbranch separation of powers questions addressed here,” the majority opinion notes in a footnote. The power difference between state and federal court arises in part from the Supremacy Clause of the Constitution, which establishes that federal law bars states from interfering in federal functions.

As it stands now, Trump cannot be held liable for civil damages in conduct related to his presidential powers, but he can be held liable in federal court for civil damages related to his personal conduct before he became president. And now with both the Zervos and the Trump Foundation suits pending, it seems likely that Trump’s presidency will lead to a clear decision on whether the president can be subject to a civil suit on personal conduct in state court.

Zervos’ attorneys feel like the decision Thursday put the momentum on their side of the argument.

“New York’s highest court has rejected Defendant’s motion for a stay,” Zervos’s attorney Mariann Wang tells TIME in a statement. “This is now the third time the courts have rejected Defendant’s effort to block the progress of this case. We look forward to continuing the discovery process and exposing the truth.”

But a spokesperson for Kasowitz Benson Torres, the firm representing Trump, argued that the appeals court’s decision had nothing to do with the substantive legal question over whether Trump can be subject to these cases.

“The New York State Court of Appeals’ decision today was on purely procedural grounds — that the order appealed from was not within that court’s jurisdiction because it was not the final order in the case,” the spokesperson said in a statement provided to TIME. “The Court of Appeals did not address the merits of the issue at stake here (an issue first raised by the U.S. Supreme Court in Clinton v. Jones) — namely, that, under the Supremacy Clause of the U.S. Constitution, state courts do not have jurisdiction over a sitting President.”

Still, the progress in the Zervos case so far likely bodes well for the new case against the foundation moving forward. (These are far from the only cases facing Trump— he’s been sued numerous times since becoming president, and is involved in other high-profile cases including another defamation case brought by Stormy Daniels and a case involving alleged Emoluments Clause violations.) Stephen Vladeck, professor at the University of Texas School of Law, tweeted that the appeals court’s decision on Zervos “also cements the propriety of the major new suit by @NewYorkStateAG being brought in state—rather than federal—court.”

Amid the news that the Zervos case can move forward, Trump reacted to the new foundation lawsuit by tweeting, “I won’t settle this case!”

Even if courts find that Trump can be subject to both of these cases while he’s in office, presidents are entitled to deference in scheduling concerns and other burdens of litigation, so don’t expect either lawsuit to wrap up soon, legal experts caution.

“This starts a process that is often long and involved anyway,” says Ross Garber, defense attorney at The Garber Group. “But particularly given that it involves a sitting president, it may be even longer and more involved.”

In fact, the Paula Jones lawsuit lasted nearly four years. But depositions in the case about Clinton’s other relationships led to the uncovering of the Monical Lewinsky scandal, which ended with his impeachment in the House of Representatives.