Once an outlier on the nation’s highest court, Justice Clarence Thomas has become a towering figure in the conservative legal movement over the last decade as he helped secure landmark rulings on abortion, voting and Second Amendment rights.

The only justice with a longer tenure is liberal William O. Douglas. Thomas would overtake Douglas in 2028 if he remains on the court — and there’s no sign he plans to retire anytime soon.

“I think he’s more energized and excited now than when I first met him,” said John Yoo, a law professor at the University of California, Berkeley, who served in Republican President George W. Bush’s administration after his time as a Thomas clerk three decades ago.

Thomas was confirmed in 1991 after contentious hearings that included sexual harassment allegations. More recently, his acceptance of luxury trips has raised a storm of ethics questions. He’s nevertheless gone from near-silence at oral arguments to asking the first questions and penning a landmark ruling expanding Second Amendment rights.

Following the appointment of three conservative justices by Republican President Donald Trump, Thomas is now the most senior member of a supermajority that’s also overturned abortion as a constitutional right, ended affirmative action in college admissions and sharply limited the Voting Rights Act.

“The court has radically moved in his direction over the course of his time on the court,” said Stanford University law professor Pamela Karlan. Thomas’ seniority means he can decide who writes an opinion if he’s part of a majority that doesn’t include Chief Justice John Roberts, a factor that can nudge other votes behind closed doors, Karlan said.

Off the bench, Thomas’ sphere of influence also includes his large, close-knit network of former clerks, who have served in the Trump administration and are increasingly filling out the ranks of federal judges.

“That is an important legacy that he will leave,” said Sarah Konsky, director of the Supreme Court and Appellate Clinic at the University of Chicago Law School. “Even as justices’ own time on the court winds down, significant influence lives on through their clerks.”

That’s not to say Thomas’ time on the court is up. In a recent speech, Thomas tied the nation’s highest ideals to a conservative vision of limited government — and launched a broadside on progressivism seen by critics as unfair and inappropriate. In the room at the University of Texas, though, it earned a standing ovation.

Thomas, who became the second Black member of the court, now has a tenure that tops 34 years, putting him ahead of Justice Stephen J. Field, who was appointed by Lincoln before the end of the Civil War and served as the only 10th justice until 1897.

For Thomas, 77, it’s a long way from the hearings at which his nomination by Republican President George H.W. Bush was nearly derailed by allegations that he had sexually harassed Anita Hill, a charge he forcefully denied.

Thomas has more recently come under scrutiny for lavish, undisclosed trips from a GOP megadonor and the conservative political activism of his wife, who backed false claims that the 2020 election was stolen from Trump. The justice has said he wasn’t required to disclose the trips he took with friends and ignored calls to recuse himself from cases related to the election.

On the court, though, recent years have also brought perhaps the most significant work of his career, especially a 2022 opinion he wrote that found people generally have the right to carry a gun in public. The justice did not respond to a request for comment on his tenure.

His own jurisprudence has changed little over the years, said Scott Gerber, author of “First Principles: The Jurisprudence of Clarence Thomas.” Even as the majority moves his way, he’s continued to write dissents that get noticed.

“He’s incredibly consistent,” Gerber said. Once known for solo dissents, “now he writes majority opinions.”