George and Kellyanne Conway arrive at an inaugural party in January. (Matt Rourke/AP)

On the morning of his 500th day in office, June 4, the president had a lot on his mind. Amid a string of tweets touting his greatest accomplishments and bemoaning the plight of farmers — who he said have been treated “unfairly” by Canada, China and Mexico — President Trump turned his attention to special counsel Robert S. Mueller III’s Russia investigation.

“The appointment of the Special Councel is totally UNCONSTITUTIONAL!” Trump wrote. “Despite that, we play the game because I, unlike the Democrats, have done nothing wrong!” (The spelling was later corrected.)

On Monday evening, George Conway, a conservative lawyer, published a 3,500-word essay in which he called Trump’s tweet a “meritless legal position” rooted in an assumption from a conservative legal scholar that is “uncomplicatedly, flatly wrong.”

“The ‘constitutional’ arguments made against the special counsel … have little more rigor than the tweet that promoted them,” Conway wrote. “Such a lack of rigor, sadly, has been a disturbing trend in much of the politically charged public discourse about the law lately, and one that lawyers — regardless of their politics — owe a duty to abjure.”

Conway’s essay was notable not just for its analysis but for its venue, Lawfare, a highly regarded legal blog that has featured some of the strongest expert critiques of Trump’s conduct as president — and also for its author, a respected lawyer who happens to be married to one of Trump’s most visible advisers, Kellyanne Conway.

George Conway started his law career in New York and gained recognition in Republican circles after secretly assisting lawyers for Paula Jones in her sexual harassment lawsuit against President Bill Clinton, the case that precipitated the Monica Lewinsky scandal. Although this is not the first time Conway has criticized Trump, his essay, titled “The Terrible Arguments Against the Constitutionality of the Mueller Investigation,” went well beyond his previous “sub-tweets” subtly targeting the president.

Trump provided no rationale for his view, Conway noted. “It isn’t very surprising to see the president tweet a meritless legal position, because, as a non-lawyer, he wouldn’t know the difference between a good one and a bad one,” Conway wrote.

Conway, who at one point was reportedly under consideration to lead the civil division within the Justice Department, speculated that Trump got the idea that Mueller’s appointment was unconstitutional from the legal scholar Steven Calabresi, a professor at Northwestern University’s Pritzker School of Law and a co-founder of the Federalist Society.

In a “legal opinion” and in a commentary for the Wall Street Journal, Calabresi argued that Mueller’s appointment by Deputy Attorney General Rod J. Rosenstein violated the appointments clause of the Constitution. The clause requires presidential appointment of “Ambassadors, other public Ministers and Consuls, Judges of the Supreme Court, and all other Officers of the United States” — except “inferior officers,” who may be chosen as “as Congress thinks proper.”

Calabresi’s argument rests on the distinction between “principal officers” and those “inferior officers.” Claiming that Mueller has “too much power for an inferior officer to have,” Calabresi argues that Mueller could have been appointed only by the president. Because he was not, his actions are unconstitutional, Calabresi contends.

“Unfortunately for the president,” Conway wrote, “these writings are no more correct than the spelling in his original tweet.”

Calabresi relies heavily on a 1988 Supreme Court decision in Morrison v. Olson that upheld a post-Watergate procedure for appointing an “independent counsel.” The case law required that, to qualify as an inferior officer, the independent counsel must have bosses who can remove them and hold them to “certain, limited duties.” Calabresi argues that Mueller meets none of those criteria, even though Rosenstein is Mueller’s supervisor and can remove him.

Using the indictment of Trump’s former campaign manager Paul Manafort as an example of how Mueller has exceeded his authority, Calabresi wrote in the Journal, “That’s too much power for an inferior officer to have. Only a principal officer, such as a U.S. attorney, can behave the way Mr. Mueller is behaving. Mr. Mueller is much more powerful today than any of the 96 U.S. attorneys.”

Conway said Calabresi’s claim rests on a “badly mistaken premise” — starting with the fact that courts have said U.S. attorneys are inferior officers, he said. Even though they are by law typically appointed by the president, Congress allowed for temporary appointments of acting U.S. attorneys, Conway noted. U.S. district courts can appoint U.S. attorneys as well when temporary appointments run out.

Additionally, Conway wrote, the scope of Mueller’s investigation is far narrower compared to the wide-ranging duties of U.S. attorneys. And although Calabresi argued that Manafort’s indictment is far beyond that scope, Conway said an appeals court already has rejected that argument.

The U.S. District Court for the District of Columbia ruled last month that Mueller’s prosecution of Manafort on charges of money laundering, tax and bank fraud, and conspiracy was “an appropriate exercise of the Special Counsel’s authority” — and said that Mueller “would have been remiss” if he ignored “such an obvious link” between the Trump campaign and Russia.

“So not only does Mueller have a boss, and not only is the boss keeping tabs on Mueller, but, according to this judicial decision, Mueller is also faithfully following his boss’s orders,” Conway wrote. “That disposes of Calabresi’s Appointment Clause contentions.”

This and other legal arguments may not ever reach the Supreme Court. In fact, they are aimed at a different audience: the public and members of Congress who hold the power of impeachment. In the event that Mueller’s investigation leads to an impeachment proposal, Republican supporters of the president will be looking to discredit the inquiry as a way to head it off.

Trump’s personal attorney, Rudolph W. Giuliani, has stopped short of calling Mueller’s appointment “unconstitutional.” But he has called it “illegitimate,” arguing that “illegal” leaked memos from former FBI director James B. Comey and reports that an FBI informant communicated with Trump’s campaign in 2016 became the basis of Mueller’s appointment.

In Kellyanne Conway’s attempts to raise questions about the Mueller investigation, she said on May 29 on Fox News Channel that talk of any collusion with the Russians is “phony” because “collusion doesn’t even have legal significance.”

Conway has been asked on CNN in the past about her husband’s starkly differing opinions about Trump. She responded indignantly, accusing CNN’s Dana Bash of seeking to “harass and embarrass” her and saying she would not have asked a man the same question.

“We’re now going to talk about people’s spouses or significant others just because they work in the White House or at CNN?” Conway told her. “You just went there. CNN just went there.”