His recent abortion dissent explains why Clarence Thomas is so cut off on the Supreme Court, even from his fellow-conservatives. PHOTOGRAPH BY DENNIS BRACK / BLOOMBERG VIA GETTY

This year’s Supreme Court term abounded in so much drama—the death of Justice Antonin Scalia, the tie votes among the remaining Justices, the liberal victories in the final days—that it was possible to miss a curious subplot: the full flowering of Justice Clarence Thomas’s judicial eccentricity.

Since his stormy confirmation, in 1991, Thomas has been the target of much unfair criticism. Some have argued, for example, that his years of silence during oral arguments meant he was not doing much work at all. In fact, Thomas is the most prolific opinion writer on the Court—and that is especially true this year. According to statistics compiled by Professor Steve Vladeck, of the University of Texas Law School, Thomas wrote opinions in thirty-eight of the sixty-two cases the Justices decided in the 2015-16 term. That’s twice as many as Justice Samuel Alito, a conservative, like Thomas, and the next-most active writer on the court. Likewise, Thomas’s critics have made the condescending charge that he was just a blind follower of Scalia, an idea that the results this year also rebut.

The truth is that Thomas’s view of the Constitution is highly idiosyncratic. Indeed, one reason he wrote so many opinions (often solo dissents and concurrences) was that no other Justice, including Scalia, shared his views. Thomas is a great deal more conservative than his colleagues, and arguably the most conservative Justice to serve on the Supreme Court since the nineteen-thirties.

While some Justices are famous for seeking consensus with their colleagues, Thomas seems to go out of his way to find reasons to disagree—often in the most provocative ways. Take, for example, his solo dissent this year in Foster v. Chatman, in which all the other Justices joined Chief Justice John G. Roberts, Jr.,’s opinion setting aside a death-penalty verdict in Georgia. Roberts said that records preserved by the prosecutors in that case showed egregious racial discrimination in jury selection. Prosecutors said one juror “represents Black,” another note said “No Black church,” and other notes identified black jurors as “B#1,” “B#2,” and “B#3,” as well as notes with “N” (for “no”) appearing next to the names of all black prospective jurors. “The contents of the prosecution’s file plainly belie the State’s claim that it exercised its strikes in a ‘color-blind’ manner,” Roberts wrote for the Court, adding, “the focus on race in the prosecution’s file plainly demonstrates a concerted effort to keep black prospective jurors off the jury.” Thomas, alone, was unpersuaded. The prosecutors’ notes, he wrote, provided “no excuse for the Court's reversal of the state court's credibility determinations." (The case reflects a long pattern at the court of Thomas, the only black justice, voting against programs designed to assist African-Americans, and rejecting findings of discrimination against African-Americans.)

The Foster case turned primarily on the facts, but it’s on constitutional law that Thomas is most isolated. Far more than even Scalia did, Thomas endorses originalism—the belief that the Constitution should be interpreted as its words were understood at the time it was written. By a vote of 5–3, the Court struck down Texas’s restrictions on abortion clinics in Whole Woman’s Health v. Hellerstedt, but neither of the other dissenters (Roberts and Samuel Alito) joined Thomas’s opinion. What’s most extraordinary about Thomas’s dissenting opinion in the abortion case is not that he objects to the ruling; as he noted, “I remain fundamentally opposed to the Court’s abortion jurisprudence.” But Thomas also took the opportunity to reject more than a century of the Court’s constitutional jurisprudence. He said that, since the Presidency of Franklin D. Roosevelt, the Court’s interpretation of the Constitution has become an “unworkable morass of special exceptions and arbitrary applications.”

The abortion dissent explains why Thomas is so cut off on the Court, even from his fellow-conservatives. He doesn’t respect the Court’s precedents. He is so convinced of the wisdom of his approach to the law that he rejects practically the whole canon of constitutional law. It’s an act of startling self-confidence, but a deeply isolating one as well. Even his ideological allies, who mostly come out the same way on cases, recognize that they must dwell within the world that their colleagues and predecessors created. Thomas, in contrast, has his own constitutional law, which he alone honors and applies.

Thomas just turned sixty-eight years old, and reports of his impending retirement briefly surfaced before his wife shot them down as “bogus.” Indeed, it is difficult to imagine that Thomas would allow any Democrat to choose his successor. Shortly after Scalia died, Thomas asked his first question in oral argument in more than a decade, but it’s highly unlikely that he will take on Scalia’s role as the pugnacious conservative in the Court’s public sessions. Rather, Thomas will continue his own way, increasingly alone, as the Court, for the first time in two generations, moves to the left. As for Thomas’s place on the Court, it’s difficult to improve on Scalia’s analysis, which I heard him give at a synagogue a decade ago. Scalia was asked about how his judicial philosophy differed from Thomas’s. “I’m an originalist,” Scalia said, “but I’m not a nut.”