WASHINGTON ― With the president and his lawyers claiming he is shielded from prosecution and simultaneously able to pardon himself for any federal crime, are there any checks on Donald Trump’s actions at all from the courts?

And what happens if the courts rule against him on a matter he believes could threaten his presidency or even his liberty?

As Trump’s claims of overarching, even regal powers have grown more fervid in recent weeks, those questions have become increasingly worrisome to constitutional experts.

“I don’t want to be an alarmist,” said Sarah Turberville with the Constitution Project, a group that has been urging Congress to pass a law protecting special counsel Robert Mueller and his investigation into Trump’s campaign. “But you could see this coming to a head.”

“There certainly is such a worry,” said Laurence Tribe, a constitutional law professor at Harvard Law School.

Thus far, Trump does not appear ready to directly challenge the power of the judiciary over him ― or at least his most talkative lawyer, former prosecutor Rudolph Giuliani, does not. When discussing a hypothetical subpoena by Mueller demanding that Trump appear before a grand jury, Giuliani said he would seek to quash it in court rather than just ignore it.

Mueller would surely go to court to enforce an ignored subpoena, Giuliani said in a recent interview with HuffPost. And the special counsel could have the president held in contempt if Trump’s lawyers lost that dispute. “We want to avoid the argument that the president is operating above the law,” Giuliani said.

Multiple legal scholars contend that Trump and his team are already arguing that he is above the law. In a 20-page letter sent to Mueller in January, Trump’s lawyers claimed that the president, as head of the executive branch, has the authority to end any investigation undertaken within that branch as well as to render them moot using his pardon power.