A Northwestern University law professor who clerked for Supreme Court Justice Antonin Scalia is causing a stir as he makes the rounds of national media and lays out his case that special counsel Robert Mueller’s entire operation is unconstitutional.

Steven Calabresi, the Clayton J. and Henry R. Barber professor of law and a co-founder of the Federalist Society, reiterated that view Friday on a conference call with reporters and legal professionals. He said the appointment of Mueller violates the appointments clause of the Constitution.

The consequences of that conclusion, should it prove accurate, could be sweeping for Mueller’s open-ended investigation into allegations of Russian interference in the 2016 presidential election and possible collusion with President Donald Trump’s campaign.

“All actions taken by Mueller since his appointment on May 17, 2017, are, therefore, null and void,” he said.

That would include all the indictments Mueller has brought, the plea bargains he has negotiated, the controversial searches his team has conducted, and the referral he made of records seized from the home and offices of Trump lawyer Michael Cohen.

Calabresi predicted the courts would throw out any evidence given to the U.S. attorney’s office in Manhattan as the “fruit of a poisonous tree.”

Whether any of that will actually come to pass is hard to predict. It would require a target of the Mueller investigation to challenge the constitutionality of his appointment and then the courts — and most likely the Supreme Court — would have to adopt Calabresi’s argument.

Several factors weigh against that, most prominently the extreme reluctance of federal courts to issue decisions that would be as disruptive as one that would declare Mueller’s appointment unconstitutional and invalidate every action his team has taken over the past year.

And there is a Supreme Court precedent upholding the constitutionality of the law allowing for the appointment of a special prosecutor by a three-judge panel. That law, which eventually lapsed because Congress declined to renew it, was more suspect than the current statute because it involved questions of separation of powers — could another branch appoint an official of the executive branch who is completely independent of it?

The Supreme Court answered that question in 1988, with a 7-1 ruling in a case involving a special prosecutor who investigated possible false statements to Congress by Theodore Olson, who at the time was an official in the Environmental Protection Agency. (Olson later went on to serve as solicitor general in the George W. Bush administration, representing the federal government in matters before the Supreme Court.)

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Calabresi sees six votes on high court. But Calabresi — who clerked for Scalia when the late justice wrote the dissent in that case — said he believes there are five, and possibly six, votes on the high court to strike down Mueller’s appointment.

Liberal Justice Elena Kagan, speaking at a Stanford University event in 2015, called Scalia’s contrary opinion “one of the greatest dissents ever written, and every year it gets better.”

Calabresi pointed to a Supreme Court ruling in 1976 striking down a law that had allowed for the speaker of the House of Representatives and the president pro tempore of the Senate to make appointments to the Federal Election Commission. Only the president could make those appointments, the court ruled.

Under interpretation of the appointments clause, a “principal officer” must be nominated by the president and confirmed by the Senate. If he is an inferior officer, he can be appointed by another government official without input from the president or confirmation by the Senate.

“I really think Mueller has no clothes, and that everything he’s done since May 17 of last year has been unconstitutional and illegal.”

Scalia, who wrote the majority opinion in a 1997 case, laid out a test for analyzing whether an officer is a principal or an inferior. An inferior officer must have a boss who directs and supervises his work. Rehnquist, in a separate case, wrote that an inferior officer also must have limited jurisdiction and a job with a fixed ending point.

Calabresi offered the example of a U.S. attorney, who must be appointed by the president and confirmed by the Senate. But a U.S. attorney can hire prosecutors who are not subject to confirmation because they are working under the direction and supervision of the principal officer.

Calabresi argued that the special counsel in the Olson case was more like a front-line prosecutor. He said it was a narrow matter, involving two charges against a single subject, who by then was not even in the government anymore.

Mueller, theoretically, has a boss in Deputy Attorney General Rod Rosenstein and is subject to supervision by him. But in practice, Calabresi said, Mueller is a lone operator who has no real supervision.

“Mueller is not an inferior officer.” In addition, Calabresi added, Mueller (pictured above) has an extremely broad scope with nationwide jurisdiction, a large staff and no genuine limits on his budget. He said that in power and prestige, Mueller greatly exceeds the 93 U.S. attorneys. The special counsel functionally is much more like an assistant attorney general, a position that must be nominated by the president and confirmed by the Senate.

“It’s just absolutely clear that … Mueller is not an inferior officer,” he said. “He is a principal officer, and since he has not been nominated by the president and confirmed by the Senate, everything he has done since May 17, 2017, has been unconstitutional and has been illegal.”

The constitutional solution for the problem of how to investigate potential wrongdoing by a president is for Congress to create a standing office of special counsel headed by an official appointed by the president and confirmed by the Senate, Calabresi said. He said the approach has historical roots.

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In response to the Teapot Dome scandal in the 1920s, Congress created two special counsel officers, one Republican and one Democrat, who both had to agree before charges could be brought.

Calabresi’s view has not exactly caught fire in the legal community. Although some scholars have argued that the statute governing Mueller — and proposals in Congress to restrict Trump’s ability to fire him — are unconstitutional, many others disagree.

U.S. District Judge Amy Berman Jackson earlier this year rejected attempts by former Trump campaign Chairman Paul Manafort to throw out charges against him brought by Mueller. She ruled that Mueller’s efforts to prosecute him for conduct unrelated to Russian election meddling fall within the mandate that Rosenstein gave him.

Calabresi drew a parallel to the fable of “The Emperor’s New Clothes.”

“I really think Mueller has no clothes, and that everything he’s done since May 17 of last year has been unconstitutional and illegal,” he said.

PoliZette senior writer Brendan Kirby can be reached at [email protected]. Follow him on Twitter.