WASHINGTON — The leak of a draft opinion has done irreparable damage to the Supreme Court, Justice Clarence Thomas said at a conference in Dallas on Friday night, adding that it had destroyed trust among its members.

“What happened at the court is tremendously bad,” Justice Thomas said. “I wonder how long we’re going to have these institutions at the rate we’re undermining them.”

The leak of the opinion, which would overturn Roe v. Wade, the 1973 decision that established a constitutional right to abortion, was “like kind of an infidelity,” Justice Thomas said.

“Look where we are, where that trust or that belief is gone forever,” he said. “And when you lose that trust, especially in the institution that I’m in, it changes the institution fundamentally. You begin to look over your shoulder.”

He drew a contrast with the court that sat for 11 years without a change in personnel before the arrival of Chief Justice John G. Roberts Jr. in 2005.

“This is not the court of that era,” Justice Thomas said, adding: “We actually trusted each other. We may have been a dysfunctional family, but we were a family.”

There have been many changes since 2005, and only Justices Thomas and Stephen G. Breyer, who is about to retire, are still on the court.

The setting for Justice Thomas’s remarks was a conference sponsored by several conservative and libertarian groups — the American Enterprise Institute, the Manhattan Institute and the Hoover Institution — that said it meant to “re-examine the problems of social, racial and economic inequality in America.”

Justice Thomas took part in an after-dinner conversation with one of his former law clerks, John Yoo, a law professor at the University of California, Berkeley, and answered questions from the audience. Professor Yoo was one of the architects of the Bush administration’s response to the Sept. 11, 2001, attacks, and Justice Thomas joked that his former clerk would face a confirmation battle were he nominated to the federal bench.

Justice Thomas said the left had adopted tactics that conservatives would not employ.

“You would never visit Supreme Court justices’ houses when things didn’t go our way,” he said. “We didn’t throw temper tantrums. It is incumbent on us to always act appropriately, and not to repay tit for tat.”

He added that conservatives had “never trashed a Supreme Court nominee.” He acknowledged that Merrick B. Garland, President Barack Obama’s third Supreme Court nominee, “did not get a hearing, but he was not trashed.”

“You will not see the utter destruction of a single nominee,” Justice Thomas said. “You will also not see people going to other people’s houses, attacking them at dinner at a restaurant, throwing things on them.”

He said Justice Brett M. Kavanaugh had been subjected to particular abuse, but he referred only glancingly to his own brutal confirmation hearings, during which he angrily denied accusations of sexual harassment.

Taking sides on a contested point, Justice Thomas said the Senate Republicans who blockaded Mr. Garland’s nomination were following a rule that President Biden, then a senator, had proposed, “which is you get no hearing in the last year of an administration.”

Justice Thomas, the longest-serving member of the current court, has been a fierce opponent of Roe.

On Friday, he said opposition to his nomination in 1991 was “by those people who were trying to keep me off the court over abortion.”

At his confirmation hearings, however, he said, to the astonishment of many, that he had never discussed Roe, even though it was issued while he was a student at Yale Law School.

The next year, he dissented in Planned Parenthood v. Casey, in which the majority reaffirmed the core of the Roe decision. Justice Thomas joined opinions saying Roe was “plainly wrong” and “should be overruled.”

In his memoir, he reconciled his 1992 vote with his statements at his confirmation hearings the previous year. “By then,” he wrote, “I’d had ample time to study Roe in detail, and concluded that it was wrongly decided and should now be overruled.”

In the intervening decades, Justice Thomas frequently voiced opposition to constitutional protection for abortion.

“Nothing in our federal Constitution deprives the people of this country of the right to determine whether the consequences of abortion to the fetus and to society outweigh the burden of an unwanted pregnancy on the mother,” he wrote in a 2000 dissent. “Although a state may permit abortion, nothing in the Constitution dictates that a state must do so.”

On Friday, he suggested that respect for precedent — stare decisis, in legal jargon — was no reason to retain an incorrect interpretation of the Constitution.

“I always say that when someone uses stare decisis that means they’re out of arguments,” he said. “Now they’re just waving the white flag. And I just keep going.”

Justice Thomas, who is 73, has had an eventful spring. He was hospitalized for a week in March after experiencing what the court said were flulike symptoms unrelated to the coronavirus.

Around the same time, a barrage of text messages from his wife, Virginia Thomas, to the Trump White House came to light. The messages, sent to Mark Meadows, President Donald J. Trump’s chief of staff, during the weeks between the 2020 election and the aftermath of the Jan. 6 attack on the Capitol, showed that Ms. Thomas had actively supported the legal effort to overturn the vote.

“Biden and the Left is attempting the greatest Heist of our History,” one message said.

Justice Thomas nonetheless participated in a ruling in January on an emergency application from Mr. Trump asking the court to block the release of White House records concerning the attack on the Capitol. The court rejected the request, in a sharp rebuke to the former president.

Only Justice Thomas noted a dissent, giving no reasons.

He also participated in the court’s consideration of whether to hear a related appeal, one in which Mr. Meadows filed a friend-of-the-court brief saying that “the outcome of this case will bear directly” on his own efforts to shield records from the House committee investigating the attacks beyond those he had provided.

The Supreme Court refused to hear the case, without noted dissent. There was no indication that Justice Thomas had recused himself.

Justice Thomas, who went a decade without asking a question from the Supreme Court bench, has lately shed his reticence and is an active participant in oral arguments. Indeed, in what appears to be a tacit agreement among the justices and a testament to his seniority, he routinely asks the first questions of lawyers on both sides.