In a media blitz Wednesday night and Thursday, U.S. President Donald Trump’s lawyer Rudolph Giuliani told Fox and CNN he had received assurances that Special Counsel Robert Mueller will not indict the president while he is in office.

Whether a sitting president can be subjected to prosecution has never been tested at the U.S. Supreme Court, but Giuliani said Mueller’s team agrees it is bound by a U.S. Justice Department memo from October 2000. That memo concluded U.S. presidents cannot be indicted because the prosecution would interfere with their ability to execute their constitutional duties.

That is not all Giuliani said, though. He told Fox News Thursday morning not just that the special counsel cannot indict President Trump but that Mueller’s team cannot even subpoena the president to appear before a grand jury. Giuliani’s theory is that if the president cannot be prosecuted, he cannot be called to testify in an investigation of his conduct.

“We’re pretty comfortable, in the circumstances of this case, they wouldn’t be able to subpoena him personally,” Giuliani said. “They could probably require documents to be produced. That’s what was required of Nixon. We’ve provided 1.4 million documents. They probably could require you to testify in a civil case, possibly even as a witness in a criminal case, but they can’t require you to testify in what would be your own case.”

Mueller is investigating allegations that Russia interfered in the 2016 U.S. presidential election and possible collusion between Moscow and the Trump campaign. Trump has denied colluding with Russia and has called the Mueller investigation, which marked its first anniversary on Thursday, a witch hunt.

A Mueller spokesman declined to comment. A Giuliani representative did not immediately respond to a request for comment.

‘Delusional’

I talked Thursday to eight lawyers who have been involved in previous probes of U.S. presidents. Every one of them said Giuliani’s theory is incorrect.

Some of them had quite strong words.

George Conway wrote the Supreme Court briefs in Bill Clinton accuser Paula Jones’ case, which led to a unanimous ruling from the justices that the Constitution does not shield presidents from testifying in certain civil suits. He said Giuliani’s assertion that President Trump cannot be subpoenaed is “drivel.”

Lawrence Robbins, who represented White House officials in the Whitewater investigation, said Giuliani’s theory is “facially preposterous.”

Solomon Wisenberg, who worked on the Whitewater probe of Clinton, called the theory “delusional.”

“It’s an extraordinary stretch,” said another Whitewater veteran, University of Baltimore law professor Kimberly Wehle. “They are trying to thread a very, very fine needle.”

Giuliani’s comment to Fox referred obliquely to two key Supreme Court decisions addressing whether a president must comply with demands for information in a legal case. In 1974’s U.S. v. Nixon, the justices ruled unanimously that President Richard Nixon was required to comply with a special prosecutor’s subpoena for documents and tape recordings, rejecting Nixon’s claim that the materials were protected by executive privilege. Nixon subsequently turned over the subpoenaed material.

Then in 1997, in the midst of the Whitewater investigation, the Supreme Court ruled in Clinton v. Jones that Paula Jones was entitled to depose the president in a case claiming she experienced workplace retaliation after rejecting Bill Clinton’s sexual advances when he was governor of Arkansas. The justices held Jones’ case, which did not involve Clinton’s conduct as president, would not interfere with his constitutional responsibilities. Bill Clinton’s deposition in the Jones case eventually led to an impeachment charge of perjury.

‘Just wrong as a matter of law’

The lawyers I talked to said there is virtually no room, between the Nixon and Jones cases, for President Trump to claim he cannot be subpoenaed. The Nixon precedent involved a subpoena for materials, not testimony, but former Whitewater prosecutor Mark Tuohey said that distinction does not matter.

“Legal precedent suggests Rudy Giuliani’s comment is just wrong as a matter of law,” he said. President Clinton’s defense lawyers in the Whitewater case opted not to mount a court challenge to a grand jury subpoena from Independent Counsel Ken Starr, instead negotiating to appear before the jurors via closed-circuit television.

It would hardly make sense for prosecutors in important criminal investigations to be precluded from subpoenaing presidential testimony when civil litigators are entitled to depose the president, as the Supreme Court said they may in the Jones case.

On Thursday afternoon, for instance, a New York state appellate court affirmed a trial court ruling that the presidency does not shield Donald Trump from a defamation suit by onetime “Apprentice” contestant Summer Zervos. If the president is deemed to have time to testify in a civil suit, said former Clinton White House counsel Robbins, he has time to appear before a grand jury.

“There is a world of difference between an indictment — and the extent to which it is an intrusion on the president’s time — and a subpoena to appear before the grand jury,” Robbins said.

Giuliani seemed to draw a distinction between the president’s potential testimony as a witness in the Mueller investigation and testimony “in what would be (his) own case.” Experts said there is no such distinction. The special counsel has a broad investigatory mandate and Trump “could be a very key witness,” said former Whitewater prosecutor Wisenberg.

Executive privilege?

None of this is to say that President Trump and his lawyers cannot fight a grand jury subpoena from the special counsel, experts said. The president could cite executive privilege and refuse to appear before the grand jury, which would presumably spark litigation over the scope of the privilege and Mueller’s authority to contest the president’s assertion. If the president were not to succeed in completely quashing the subpoena, he could still assert executive privilege, or his constitutional right against self-incrimination, in response to particular questions at the grand jury.

The hypotheticals are fascinating. What if Mueller granted immunity to Trump for his testimony, considering that Justice Department policy counsels against the president’s indictment in any event? Could a judge fashion a remedy, such as a financial penalty, if the president were to defy a court order for his appearance?

But on the tangible question of the day — whether Justice Department policy precludes the special prosecutor from seeking a subpoena for the president’s testimony — there is no need to speculate, according to the experts I consulted. If Mueller wants to hear from the president, he can seek a subpoena.