A little more than a month ago, a law professor who helped found the Federalist Society, the conservative legal group, enthusiastically endorsed a new law review article arguing that Donald J. Trump was ineligible to be president.
The article was “a tour de force,” the professor, Steven G. Calabresi, told me. It demonstrated, he said, that Mr. Trump was subject to a provision of the Constitution that bars some officials who have engaged in insurrection from holding government office.
“Trump is ineligible to be on the ballot, and each of the 50 state secretaries of state has an obligation to print ballots without his name on them,” said Professor Calabresi, who teaches at Northwestern University.
He appeared to be offering considered views, and he elaborated on them in a blog post titled “Trump Is Disqualified From Being on Any Election Ballots.”
Last week, in an extraordinary about-face, the professor changed his mind.
In a letter to The Wall Street Journal, he said he had been persuaded by an opinion article in that newspaper that the provision — Section 3 of the 14th Amendment — did not apply to Mr. Trump.
In that article, Michael B. Mukasey, who served as attorney general under President George W. Bush, focused on a part of the provision that limits its scope to people who had taken an oath to support the Constitution “as a member of Congress, or as an officer of the United States, or as a member of any state legislature, or as an executive or judicial officer of any state.”
The only category that even arguably applies to Mr. Trump is “an officer of the United States,” Mr. Mukasey wrote. But that phrase, he asserted, “refers only to appointed officials, not to elected ones.”
That proposition is not self-evident, and the 126-page law review article that had set off the discussion, by William Baude of the University of Chicago and Michael Stokes Paulsen of the University of St. Thomas, considered the meaning of “officer of the United States” at length.
It concluded that “the ordinary sense of the text” of the Constitution, “the structure and logic of its provisions,” “the evident design to be comprehensive,” “the seeming absurdity of the prospect of exclusion of the offices of president and vice president from triggering the disqualification” and other factors “all convince us that the natural conclusion is the correct one: Section 3 includes in its coverage, or ‘triggering’ language, insurrectionists who once served as president and vice president.”
They added a plea for a little common sense: “A reading that renders the document a ‘secret code’ loaded with hidden meanings discernible only by a select priesthood of illuminati is generally an unlikely one.”
In his letter to The Journal, Professor Calabresi said he now agreed with Mr. Mukasey’s take on the relevant part of Section 3, which he called the “disqualification clause.”
“Former President Donald Trump isn’t covered by the disqualification clause, and he is eligible to be on the ballot in the 2024 presidential election,” Professor Calabresi wrote. “I am correcting the public record on this important issue by sending you this letter.”
Mr. Mukasey’s article was not met with universal approval.
“Let me be clear,” Akhil Reed Amar, a law professor at Yale, said last week on his podcast. “This is a genuinely stupid argument.”
On Saturday, Professor Calabresi issued another blog post, this one called “Donald Trump Should Be on the Ballot and Should Lose.”
“Trump is loathsome, but because of a technicality in the drafting of the disqualification clause of Section 3 of the 14th Amendment, the clause does not apply to Trump,” he wrote, adding: “So, Trump’s name should appear on election ballots in the 2024 presidential election, but I strongly urge my fellow Americans to vote against Trump, almost no matter what else is the alternative.”
Professor Calabresi wrote that his thinking had been influenced by a new article posted on Tuesday by two other professors, Josh Blackman of South Texas College of Law Houston and Seth Barrett Tillman of Maynooth University in Ireland, who have long pressed arguments that some provisions of the Constitution do not cover the president.
Their article, also 126 pages long, collected and considered what it said was “substantial evidence that the president is not an ‘officer of the United States’ for purposes of Section 3.”
It added: “Numerous sources that we cited discussed this issue; no one spoke in a ‘secret code,’ as Baude and Paulsen charge. If we are correct, Trump is not subject to Section 3 at all. If we are right, then states cannot unilaterally remove Trump from the ballot under the authority of Section 3.”
Professor Calabresi is, of course, entitled to change his mind. As Justice Felix Frankfurter put it in a 1949 dissent, “Wisdom too often never comes, and so one ought not to reject it merely because it comes late.”
In an interview on Saturday, Professor Calabresi said his revised position was the product of study and reflection.
“I carefully reread the materials on whether Section 3 of the 14th Amendment applies to Trump,” he said, “and concluded that it most likely does not.”
He added that politics had not figured in his thinking. “I will support,” he said, “any Republican or Joe Biden over Trump in the 2024 election.”