This month marks the twenty-fifth anniversary of Clarence Thomas’s confirmation to the Supreme Court. Conservatives like Thomas have dominated the Court throughout his tenure, and he has been in the majority in all of their victories. That raises a question: What’s the most important opinion Thomas has written for the majority during his tenure on the Court?

Thomas didn’t write Bush v. Gore, in 2000, nor did he write Citizens United, the campaign-finance case, in 2010. Thomas was in the majority for the Shelby County case, in 2013, which eviscerated the Voting Rights Act, but he didn’t write that one, either. When the Court upheld Congress’s ban on so-called partial-birth abortions, in 2007, Thomas voted with the majority (against abortion rights, as he has always voted), but he did not write for the Court. And Thomas has been in the minority in all the liberal victories of his era—in the Court’s rejections of the Bush Administration’s treatment of detainees at Guantánamo (Hamdan, Hamdi, and Boumediene), in the Court’s embrace of equal rights for gay people (Lawrence, Windsor, Obergefell), in its rejection of the death penalty for juveniles (Roper) and for the mentally retarded (Atkins).

It’s a trick question, in a way. Neither Chief Justice William Rehnquist, who presided over Thomas’s first fourteen years on the Court, nor Chief Justice John G. Roberts, Jr., who has run the court for the past eleven, ever assigned Thomas a landmark opinion for the Court. Thomas’s admirers cite such opinions as Good News Club v. Milford Central School, in 2001, which found that a public school had to allow a religious group to meet on campus after hours. That was indeed a conservative victory, but hardly comparable in magnitude to others handed down during his tenure. The truth is that Rehnquist and Roberts never trusted Thomas to write an opinion in a big case that could command a majority of even his conservative colleagues.

Why was this? It is because Thomas is not a conservative but, rather, a radical—one whose entire career on the Court has been devoted to undermining the rules of precedent in favor of his own idiosyncratic interpretation of the Constitution. By his own account, Thomas is an extreme originalist, one who is guided exclusively by his own understanding of what the words of the Constitution mean rather than what the other hundred and eleven people who have served on the Court in its history have judged them to mean. His vision is more reactionary than that of any Justice who has served on the Court since the nineteen-thirties, and his views are closest to those of the Justices who struck down much of the New Deal during that era. Indeed, in a concurring opinion in 1995, Thomas basically embraced this antediluvian view of the Constitution, writing, “I am aware of no cases prior to the New Deal that characterized the power flowing from the Commerce Clause as sweepingly as does our substantial effects test. My review of the case law indicates that the substantial effects test is but an innovation of the 20th century. . . . At an appropriate juncture, I think we must modify our Commerce Clause jurisprudence.”

Authorship is not the only measure of influence, and in dissenting and concurring opinions Thomas has introduced certain conservative ideas into the bloodstream of Supreme Court opinions that have later commanded majorities. In a concurrence in Printz v. United States, in 1997, Thomas suggested that the Second Amendment confers on individuals a right to bear arms, which the Court had never before held. Eleven years later, in Justice Antonin Scalia’s opinion in Heller v. District of Columbia, that view became the law of the land. Similarly, in a separate opinion in McIntyre v. Ohio Elections Commission, in 1995, Thomas laid some of the intellectual groundwork for the Citizens United decision and the Court’s deregulation of political campaigns. These cases, however, are exceptions. For the most part, Thomas has been on a Court of his own.

Thomas was a young man of forty-three when he joined the Court, and he is now sixty-eight. His views, which never really found favor even in the years of conservative ascendancy, appear headed even further from the mainstream. The Court is now evenly divided between liberals and conservatives, and Hillary Clinton appears poised to fill the ninth seat, giving liberals a majority for the first time in decades. After years at the periphery of the Court, Thomas looks destined to serve out his term at the even more distant fringe