WASHINGTON (Courthouse News) – In an ongoing assail of the special counsel’s Russia probe, President Trump insisted Monday on Twitter that he has an “absolute” right to pardon himself.

“As has been stated by numerous legal scholars, I have the absolute right to PARDON myself, but why would I do that when I have done nothing wrong?” Trump tweeted.

The post continued with Trump’s familiar refrain that the investigation is a “never ending Witch Hunt.”

With Trump not quoting any legal scholars by name, however, experts told Courthouse News that the question of whether a president can pardon himself is far from settled.

“We have to make this answer up,” Caroline Polisi, a white-collar criminal defense attorney with Pierce Bainbridge, said in an interview. “We are a young republic, making things up as we go.”

Polisi identified the pardon issue as one of several important constitutional questions posed by the Trump presidency. Another is whether a sitting president can be indicted or subpoenaed for grand jury testimony.

“These questions have never been tested all the way up to the Supreme Court,” Polisi said. “Just like Gerald Ford famously said in 1970 amid the Nixon impeachment, that an impeachable offense ‘is whatever a majority of the House of Representatives considers it to be at a given moment in history’ – it is up to us in this moment in history to decide if a president can pardon himself.”

Jacob Frenkel with Dickinson Wright found the theory on self-pardoning less open to debate but still problematic for Trump because of political fallout.

“If he were to pardon himself, that would by definition require him require him to accept responsibility for conduct for which he would have to accept culpability,” said Frenkel, who worked in the independent counsel’s office during the 1990s.

Apart from Trump’s impeachment concerns, however, Frenkel said in a phone interview that it is his belief “that the president’s power to pardon – and let’s be clear it’s for federal offenses.”

Frenkel’s assessment echoes one offered by Trump’s attorney, Rudy Giuliani.

“Pardoning himself would be unthinkable and probably lead to immediate impeachment,” Giuliani had said Sunday on NBC’s “Meet the Press.”.

A day earlier, The New York Times published a 20-page confidential memo from Trump’s legal team to Robert Mueller on the special counsel’s investigation of collusion and obstruction of justice.

The memo claims that Trump cannot obstruct the Russia investigation because he is constitutionally empowered to terminate the probe or exercise his pardon authority.

Polisi with Pierce Bainbridge noted meanwhile that Mueller likely takes a different view of Trump’s pardon power based his reliance on decades-old guidances from the Office of Legal Counsel.

On the eve of President Nixon’s resignation in 1974, the office determined that Nixon could not use his pardon power to protect himself. The Clinton years meanwhile saw the office affirm its 1973 assumption that a sitting president cannot be indicted.

“So it seems likely that he would agree with the OLC guidance on this issue as well,” Polisi said of Mueller, “that a sitting president cannot pardon himself because of the fundamental legal concept that no one can be a judge in his own case.”

Trump labeled Mueller’s appointment unconstitutional Monday in a separate tweet, but attorney Frenkel said that the constitutional questions here lie in the breadth and scope of Mueller’s investigation, not in his appointment. Frenkel has previously written about when Trump might pardon his former campaign manager Paul Manafort, if he were to do so.

After performing lobbying work on behalf of a pro-Russia political party in Ukraine, Manafort is facing multiple indictments from Mueller in Washington, D.C., and Virginia.

Frenkel said he takes no position on whether Trump should pardon Manafort but that strategically it would make sense to pardon him right before trial to give Manafort an opportunity to constitutionally challenge Mueller’s appointment.

Although Manafort has not yet presented a direct constitutional challenge to Mueller’s appointment, his challenge to Mueller’s authority in his criminal cases is ongoing.

Back in April, U.S. District Judge Amy Berman Jackson refused to let Mueller raise the same challenge in civil court.

Frenkel said it’s unclear to him why Manafort challenged Mueller’s authority civilly, adding that he’s unsure whether Manafort challenged it correctly.

“I’m not necessarily convinced it was,” Frenkel said.

As for a constitutional challenge, Frenkel questioned why Manafort has not yet raised this issue.

“It really surprises me that he has not,” Frenkel said. “You wonder when there are good lawyers in the mix, if there’s a reason, if there’s a strategic reason for not making the challenge.”

Alex Whiting, a professor at Harvard Law School who specializes in criminal law and procedure, said any constitutional challenge to Mueller would be doomed.

“The notion that Mueller’s appointment is unconstitutional is simply wrong and is a very bizarre claim,” Whiting said in an email. “The independent counsel statute was challenged on constitutional grounds and was upheld by the Supreme Court. While some question whether the Supreme Court would decide the issue the same way today, the independent counsel statute was permitted to lapse and it was replaced by the special counsel regulations within the Department of Justice, pursuant to which Mueller was appointed.”

The charges against Manafort include tax and bank fraud, conspiracy, money laundering, and failure to register as a foreign agent. Manafort claims that Mueller exceeded his authority by charging him for crimes unrelated to Russian interference in the 2016 U.S. presidential election.

In the Washington criminal case, Judge Jackson on May 15 denied a bid by Manafort to get a superseding indictment dropped.

Jackson ruled that the special counsel had the authority to bring the charges, and she said that Department of Justice regulations cannot form the basis of a motion to dismiss.

Courthouse News reporter Adam Klasfeld contributed to this article from New York.