In the Hobby Lobby case, Justice Ginsburg disavowed that statement, drawing a rebuke from the majority.

“Concerning that observation, I remind my colleagues of Justice Jackson’s sage comment,” she wrote, citing the quotation.

Both justices omitted the first part of Justice Jackson’s sentence, which appeared in a 1948 dissent. He, too, had joined an earlier decision without quite realizing its implications, but he was more direct about the possible roots of the problem. In the first part of the sentence, Justice Jackson mused about the “personal humiliation involved in admitting that I do not always understand the opinions of this court.”

No one likes to admit error, but judges are especially loath to own up to inconsistency or incompetence. They are, after all, meant to possess technical expertise, to respect precedent and to treat like cases alike. It may be bad for politicians to flip-flop. It is worse for judges.

“There is no reason why we cannot ask each justice to develop a principled jurisprudence and to adhere to it consistently,” Judge Frank H. Easterbrook of the federal appeals court in Chicago, then a law professor at the University of Chicago, wrote in 1982 in The Harvard Law Review. In a footnote, he thanked Justice Scalia, then a colleague on the law school’s faculty, for his “helpful comments.”

But there are limits to that unwavering ideal, as noted by Judge Richard S. Arnold, who served on the federal appeals court in St. Louis. Judge Arnold, who died in 2004, was seriously considered for the Supreme Court by President Bill Clinton. “Consistency is a virtue,” Judge Arnold wrote in 1991, “but it is not the only virtue, and people who have never changed their minds may have simply stopped thinking.”

That still leaves the problem of how to explain a shift in a judge’s thinking, and it is here that the quotation from Justice Jackson comes in handy. It is “one of three available quips held in reserve for such occasions,” Justin Driver, a law professor at the University of Chicago, wrote in 2011 in The Georgetown Law Journal.