Anniversary stories about Justice Clarence Thomas tend to focus on February 22, 2006—the last day Thomas asked a question from the bench. But we are fast approaching a more important date: On October 23, shortly after the Court’s new term starts, Thomas will begin his 25th year as an associate justice. Despite his long service, Thomas is, for a justice, a mere sprat—he turned 67 last month. Four current justices are older: Ruth Bader Ginsburg (82); Antonin Scalia (79); Anthony Kennedy (turning 79 in two weeks); and Stephen Breyer (77 next month). The actuarial tables give Thomas an excellent chance of becoming the longest-serving justice in American history. The current record-holder, William O. Douglas, served nearly 37 years; Thomas will pass that milestone just as he turns 80—younger than Ginsburg is today.

Thomas’s career has been distinctive from the first. His confirmation hearings featured graphic testimony by a former subordinate, Anita Hill, that Thomas had sexually harassed her while he was chair of the Equal Employment Opportunity Commission. No other justice in history has had to discuss, under oath, his taste in video pornography. His supporters contended that Thomas was being smeared because he is a black conservative; the American public split into two sizeable camps, one of which thought Thomas was a perjurer.

Thomas was eventually confirmed by a narrow margin, but the experience left him embittered. (“Whoop-dee-damn doo,” he wrote about the vote in his searing memoir, My Grandfather’s Son.) Soon after, he told his clerks he would remain faithful to his conservative principles. “I ain’t evolving!” he would say.

But whether made by a lover or a jurist, that oath—I will always feel this way—is always eventually broken. Time and chance happen to us all. Thomas does seem to be evolving.

One important sign of change was his visit last fall to his alma mater, Yale Law School. Thomas has always scorned his Yale education, and once put a 15-cent sticker on his diploma to indicate its worthlessness to him. But in October, in a rare moment of public self-examination, he took responsibility for the bad time he had at Yale: “I wish that I came here at a time when I could have been more positive because there was so much here that I walked right by, that I closed my eyes and my heart to,” he told an audience there.

If Thomas is “evolving,” though, that doesn’t likely mean “becoming less conservative.” Far from it; no matter how long he serves, Thomas will probably leave the Court with the most conservative record in its history. But he has always marched to the beat of his own conservative drum, and lately the rhythms of that drum have become more distinct.

This term, Thomas was the author of 36 opinions—counting, that is, all his majority opinions, concurrences, and dissents. Of those 36, 18—fully half—were dissents, some written with others and others written only for himself. The total number of opinions is a personal best, and makes him number one for the term by a long shot. And it doesn’t even count his separate opinions dissenting from the Court’s orders denying cert or refusing stays in lower-court cases. Thomas hasn’t written this much in over a decade.

Some of his dissents were joined by other justices; even those sometimes had a strange tone about them. In Brumfield v. McCain, the petitioner, a death-penalty defendant, argued that the lower court used deficient procedures to determine whether he was intellectually disabled. Thomas’s opinion wandered into a discussion of the murder victim’s son’s National Football League career. The oddness of that passage spurred two of his fellow dissenters to step away from that part of the opinion. “The story . . . is inspiring and will serve a very beneficial purpose if widely read,” Justice Samuel Alito wrote in a one-paragraph separate dissent joined by Chief Justice John Roberts, “but I do not want to suggest that it is essential to the legal analysis in this case.”

Even stranger are Thomas’s solo dissents. The other eight justices, taking their cue from the lawyers, often debate the meaning of the Court’s precedents. Thomas seems to find little profit in that; instead, he often suggests that the question will be easy if the Court simply overturns a century or so of precedent.

His dissent in Obergefell, the same-sex marriage case, was an extreme example of the genre. Thomas did not even mention the key gay-rights precedents, Romer v. Evans, Lawrence v. Texas, and United States v. Windsor; instead, he mashed up John Locke, Magna Carta, 18th-century British legal philosophy, natural law, and the Declaration of Independence.

“Never before has a Supreme Court justice cited the Declaration so frequently,” Scott Douglas Gerber of Ohio Northern University, a leading student of Thomas’s jurisprudence, wrote after the decision. True. Why not? Well, maybe because the Declaration of Independence is not actually a source of law, any more than is Locke’s Second Treatise of Government or a “1756 editorial in the Boston Gazette.” Thomas, consulting these “sources,” concluded that “liberty” means one thing only—“freedom from physical restraint.” It’s a perfectly logical argument—if one concludes that every “due process” liberty case ever decided is wrong. Under the new Thomas rule, the same-sex couples in Obergefell had not been injured, because they had not been “imprisoned or physically restrained by the States for participating in same-sex relationships.” They could even, he noted, hold same-sex wedding ceremonies if they really wanted to; the state would not recognize the resulting unions, but that was of no concern to the Constitution. In fact, he suggested, the challengers were not claiming basic constitutional rights at all but rather, like greedy welfare recipients, demanding undeserved “governmental recognition and benefits.”

Thomas receives a lot of unmerited criticism. Critics disparage his intelligence; but read enough of his work and that illusion becomes unsupportable. He is not disengaged on the bench; indeed, he follows oral argument carefully, if silently. He is clearly on good terms with his colleagues, and is a beloved figure within the small world of Court personnel.

He has, of course, scarcely bothered to conceal his bitterness at what happened in his confirmation hearings. Other giants of the bench, however, went through difficult confirmations and then, to use a phrase of Justice Scalia’s, got over it.

Louis D. Brandeis faced four months of delay in confirmation, during which his ethics, character, and religion were cruelly disparaged by legal figures including a former president and a former secretary of state. Hugo Black, between the time of his confirmation and the opening of the Court’s October term, was revealed to have been a member of the Ku Klux Klan—and to have at the very least misled his supporters about that fact. Before taking the bench, Black was forced to take to the radio to reassure the public that he had foresworn racial terror.

Thurgood Marshall was nominated to the Second Circuit in 1962; Southern Democrats, raising spurious ethics charges, delayed his confirmation for a year. When Lyndon Johnson nominated Marshall to the Supreme Court, Sen. Strom Thurmond suggested to his face that this first black nominee was unfit to serve because he was ignorant of the law and the Constitution.

In his two decades on the Court, Brandeis left an indelible impression in the law. Black, too, faced down his critics and, by diligent study, forged a legacy that is powerful today. Marshall was less successful on the bench; his influence lives on in his work at the NAACP Legal Defense Fund as an advocate for civil rights.

Whether Thomas’s influence will be more profound than Marshall’s is a vexed question. His supporters find a kind of prophetic power in some of his separate opinions, which tend to espouse relatively extreme conservative positions. Thus, for example, in Printz v. United States, the Court struck down a federal law requiring county sheriffs to conduct firearms background checks; the majority said the direct order to a state official violated the Tenth Amendment. Thomas wrote separately to suggest that the Court ought to rewrite its Second Amendment jurisprudence and recognize an individual right to bear arms. Eleven years later, the Court did that. This fall, the Court will consider a case that may upend redistricting practices nationwide, to the immense advantage of the Republican Party; a 2001 Thomas concurrence teed up that issue. Currently, Thomas takes every opportunity to argue that the Court’s radical campaign-finance cases do not go far enough—donors, he thinks, should be able to contribute and spend freely without ever disclosing their names.

Perhaps these entrepreneurial efforts will shape a powerful Thomas legacy; but I tend to think not. Thomas on the bench simply does not conform to expected judicial norms. He does not take part in the arguments before the Court. His decisions rest on unusual grounds, often not even mentioned in the briefs; he will not even air his idiosyncratic ideas at a time when others might engage them. He does not tend to limit himself to the issue presented or the factual context within which it is embedded.

He is, in other words, not a judge at all. He seems instead to operate as a kind of would-be Platonic guardian, eager to govern the nation according to his own personal opinions—opinions to which law, and fact, and indeed reasoned argument, are all but irrelevant.

A non-judge who wanders onto the bench may leave a legacy; but no matter how long he silently sits on the bench, it will most likely be a strange and evanescent one.