Supreme Court Justice Clarence Thomas, who recently marked 25 years on the high court, speaks at College of the Holy Cross in Worcester, Mass., in 2012. (Michael Dwyer/AP)

Justice Clarence Thomas marked 25 years on the Supreme Court last week, and if he remains for another dozen or so, he could become the longest-serving member in the court’s history.

But the unofficial title of the court’s most polarizing justice seems his to keep regardless of tenure.

Dedicated supporters are determined that the 68-year-old Thomas gets his due as one of the court’s most productive, if un­or­tho­dox, thinkers, and they seized on the 25th anniversary to make their point.

They have created websites and a Twitter account to remind the world of his accomplishments, held a symposium on his jurisprudence and flooded op-ed pages to defend him. They are pressuring the new National Museum of African American History and Culture to revise its fleeting, and they say insulting, reference to him.

His detractors continue to characterize his mostly silent demeanor on the bench during oral arguments as disinterest. In all his years on the court, he is still so much an outlier that his conservative colleagues do not rely on him to write the court’s most important decisions, they say.

The subject himself tends to leave the debate to others.

“I don’t spend a lot of time looking back,” he told an appreciative audience that gathered at the Heritage Foundation on Wednesday to congratulate him. His simple goal is to be a fair and “consistent” interpreter of the Constitution, he said.

“I’m not a navel-gazer,” he added.

But controversy is never far away. Before the event, Thomas had been told that the National Law Journal was preparing a story on an Alaskan attorney who alleges he groped her 17 years ago at a dinner party she had helped organize as a recent college graduate.

Through a court spokeswoman, Thomas told the publication, “This claim is preposterous and it never happened.”

Like the allegations of verbal harassment from Anita Hill that nearly derailed Thomas’s nomination in 1991, the allegations from lawyer Moira Smith involve private moments impossible to verify or disprove.

Smith said she was moved to make her allegations public because of controversy involving Republican presidential nominee Donald Trump. But Thomas’s supporters saw political motivation.

Mark Paoletta, a former assistant White House counsel who assisted in Thomas’s confirmation, said it was not a coincidence that the new charge came “as he celebrates 25 years on the court, and in the heat of a presidential election.”

Paoletta has helped publicize complaints about the new museum, where Thomas is mentioned only in the context of Hill’s allegations. In the museum’s narrative, Hill’s testimony to the Senate Judiciary Committee prompted “serious debates on sexual harassment, race loyalty and gender roles.” It does not say that Thomas denied the charges or that he was confirmed to the court.

Smithsonian Institution spokeswoman Linda St. Thomas said the museum’s exhibits “will continue to evolve and change over time as we interpret the African American experience.” She said the exhibit that mentions Thomas is meant to focus on “social, economic, political and cultural moments during the past four decades where issues of race dominated the national conversation and captivated the American public.”

Thurgood Marshall is celebrated in the exhibit, but for his role as a lawyer in Brown v. Board of Education, not because he was the first African American to sit on the Supreme Court. That achievement is not mentioned in the exhibit.

But the representation of Marshall is obviously more flattering than the one of Thomas, who replaced Marshall and became the court’s second black justice. “I think it is a deliberate slight” because of Thomas’s conservative views, Paoletta said in an interview. “It is an attempt at ‘disappearing’ him.”

Likewise, supporters say, his achievements on the bench largely have gone unrecognized because of a public fascination with the fact he rarely asks questions during oral argument.

At the symposium last week sponsored by the Claremont Institute and the Federalist Society, his fans and former clerks said his views on administrative law and the First Amendment have moved the court.

Fittingly, one panel focused on “The Lone Jurist.” Last term, Thomas wrote 39 opinions, double the amount of the next-most-productive justice’s total output, and many of them were lone dissents.

Jeffrey B. Wall, a Washington lawyer who clerked for Thomas about a decade ago, said at the forum that Thomas’s influence on the court “was almost criminally underestimated by the academy, bench and bar.”

“I think that has begun to change as people have taken deeper, richer and more nuanced looks at his jurisprudence,” he said.

Thomas can at times be stubbornly contrarian. Last term, he was the lone justice to say he would defer to a lower court that did not find Georgia prosecutors had engaged in racial profiling to keep blacks off a death penalty jury. The explanations he found plausible, Chief Justice John G. Roberts Jr., writing for the majority, called “nonsense.”

Wall dismisses as “pernicious and wrongheaded” criticism that Thomas has not left a lasting legacy in influential majority opinions in his quarter-century on the court. “You can dispute whether or not that’s true, but I think what it misses is his value as an intellectual catalyst,” Wall said.

Thomas, Wall said, is content to sow ideas that result later in changes in the law.

During his conversation Wednesday night with Heritage’s John Malcolm, Thomas acknowledged that often he is content with writing his own version of how he sees a case rather than trying to assemble a majority for a compromise outcome.

“I really don’t spend a lot of time on that,” he said.

At the event, Thomas was funny and relaxed, more like the version of the person his friends and colleagues say they see behind the court’s burgundy curtains.

He talked about growing up in the segregated South and living in poverty in the inner city; the joy he finds in traveling by RV to the small towns he did not feel welcome in as a child; his friendship with the late Justice Antonin Scalia, whose upbringing could not have been more different than his own.

Scalia could not understand why Thomas, raised in the South, did not want to go hunting with him. Thomas told him, “No good comes from being in the woods.”

More seriously, Thomas talked of Washington as a “broken” city, one whose institutions are failing. When asked whether citizens have lost confidence, he gave an answer that might appeal to both his supporters and detractors, who would apply it to him with different results.

“I don’t think people owe us, reflexively, confidence,” Thomas said. “I think it’s something we earn.”