Gay-rights supporters who thronged the Supreme Court plaza after justices declared same-sex marriage a constitutional right expect to have little to celebrate if Brett Kavanaugh replaces Justice Anthony Kennedy, the author of all the court's major gay-rights rulings.

None of Kavanaugh's roughly 300 opinions as an appellate judge deals directly with LGBT issues, but his approach to judging leads some scholars and activists to believe he is unlikely to echo Kennedy's votes.

Still, they said Kavanaugh might be reluctant to overrule the landmark 2015 same-sex marriage decision, even if he might have voted against it in the first instance.

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While LGBT advocates sound alarms about Kavanaugh, opponents of same-sex marriage are applauding his nomination, though not necessarily focusing on its potential impact on gay rights.

The Family Research Council, a major Christian conservative advocacy group, lauded Kavanaugh's rulings on religious freedom and "long and praiseworthy history of judging as an originalist," a term that means interpreting the Constitution as it was understood when written. The council describes homosexuality as "unnatural" and "harmful."

The high court is likely to confront a range of LGBT issues, perhaps as early as the coming term. These could include President Donald Trump's ban on transgender people in the military and whether federal civil rights laws banning discrimination in the workplace and education cover sexual orientation and gender identity. The justices also might be asked to decide an issue they passed over last term: whether businesses can invoke religious objections to refuse service to gay people.

At Kavanaugh's 2006 confirmation hearing for his current post as an appellate judge — before the Supreme Court ruling that legalized same-sex marriage nationwide — he was asked whether he had a view on the definition of marriage and whether courts or legislatures should establish it. Kavanaugh didn't say, instead responding to a part of the question about judicial restraint.

"Throughout our history, we've seen that some of the worst moments in the Supreme Court history have been moments of judicial activism, where courts have imposed their own policy preferences" instead of interpreting the law, he said.

With sparse evidence about Kavanaugh's views on LGBT matters, observers are parsing his record for clues to how he might vote.

"I think there's very little mystery here about how he is likely to view those issues," said Shannon Minter of the National Center for Lesbian Rights. "He has an extremely conservative judicial record, and it's highly likely he would be a consistently negative vote on any issue affecting LGBT people."

Dale Carpenter, an expert on LGBT issues at Southern Methodist University, said he considers Kavanaugh a careful and thoughtful judge. "I don't think he is going to be a knee-jerk judge in any direction, and I don't think he is anti-LGBT," Carpenter said.

Carpenter said Kavanaugh also is "a judicial conservative and he's a textualist" who probably would be hesitant to expand the reach of civil rights laws, including protections barring workplace discrimination on the basis of sex, that do not specifically mention sexual orientation or gender identity. Federal appeals courts in Chicago and New York have recently ruled that bias against gay people is sex discrimination under Title VII of the 1964 Civil Rights Act.

"He might see it as a very aggressive judicial decision to expand what have been seen to be the limits of Title VII protection, absent congressional action. But it's not unthinkable," Carpenter said.

Similarly, Kavanaugh's opinions and writings in favor of presidential authority suggest he could uphold Trump's ban on transgender people in the military, which has been blocked by lower courts, Carpenter said.

LGBT advocates point to two recent opinions Kavanaugh wrote on the U.S. Court of Appeals for the District of Columbia Circuit to highlight other concerns.

Last year, Kavanaugh dissented from a ruling that ultimately allowed a 17-year-old immigrant in federal custody to obtain an abortion.

If Kavanaugh were to form a court majority for overturning the landmark Roe v. Wade decision on abortion and the right to privacy, "that would have implications including on LGBTQ cases that were built upon that legal theory," said Sarah Warbelow, legal director of the Human Rights Campaign.

Sharon McGowan, legal director of Lambda Legal, noted that Kavanaugh's dissent said his colleagues were creating "a new right" for the teen. "That is a move that has historically been used whenever LGBT people are trying to access a right that has been accessed for other people," McGowan said.

Gay-rights advocates believe another Kavanaugh dissent — from a 2015 ruling against a challenge to the Affordable Care Act's requirements for contraceptive coverage — could signal how he might view arguments for religious exemptions from anti-discrimination laws. He said that requiring religious organizations to submit a form objecting to paying for the coverage "substantially burdened" the free exercise of religion.

"One of the primary battlegrounds for both LGBTQ rights and reproductive rights will be around religious exemptions, an area where we have already seen Judge Kavanaugh favor those seeking exceptions over those who are being denied services," GLAAD President Sarah Kate Ellis wrote in an email.

Kavanaugh subscribes to the view that courts should find in the Constitution rights that are not expressly mentioned only if they are rooted in history and tradition. This helps explain why Carpenter and other legal scholars believe Kavanaugh probably would not have been a vote for same-sex marriage on the Supreme Court.

But now that same-sex marriage is the law of the land, it probably is safe, said Douglas Kmiec, a Pepperdine University professor of constitutional law, who served in both Republican and Democratic administrations. "It would be extremely surprising if Judge Kavanaugh were to see the judiciary as capable of disavowing" Kennedy's opinion that is anchored in human dignity, Kmiec said.

Carpenter held out the prospect that Kavanaugh could surprise LGBT advocates.

"Judges are capable of surprising us. There was nothing in Kennedy's history to suggest he'd be anything like he was," he said.