SAN FRANCISCO — Same-sex marriage moved one step closer to the Supreme Court on Tuesday when a federal appeals court ruled California’s ban unconstitutional, saying it serves no purpose other than to “lessen the status and human dignity” of gays.

Supporters of gay marriage react outside the James R. Browning United States Courthouse after a federal appeals court declared California’s ban on same-sex marriage unconstitutional on Tuesday in San Francisco. A federal appeals court on Tuesday declared California’s same-sex marriage ban to be unconstitutional, putting the bitterly contested, voter-approved law on track for likely consideration by the U.S. Supreme Court. Lea Suzuki/San Francisco Chronicle/AP Photo

A three-judge panel of the 9th U.S. Circuit Court of Appeals gave gay marriage opponents time to appeal the 2-1 decision before ordering the state to allow same-sex weddings to resume.

“I’m ecstatic. I recognize that we have a ways to go yet. We may have one or two more legal steps,” said Jane Leyland, who was gathered with a small crowd outside the federal courthouse in downtown San Francisco, cheering as they learned of the ruling.

Leyland married her longtime partner, Terry Gilb, during the five-month window when same-sex marriage was legal in California.

“But when we first got together, I would have never dreamed in a million years that we would be allowed to be legally married, and here we are.”

The ban known as Proposition 8 was approved by voters in 2008 with 52 percent of the vote. The court said it was unconstitutional because it singled out a minority group for disparate treatment for no compelling reason.

The justices concluded that the law had no purpose other than to deny gay couples marriage, since California already grants them all the rights and benefits of marriage if they register as domestic partners.

“Had Marilyn Monroe’s film been called ‘How to Register a Domestic Partnership with a Millionaire,’ it would not have conveyed the same meaning as did her famous movie, even though the underlying drama for same-sex couples is no different,” the court said.

The lone dissenting judge insisted that the ban could help ensure that children are raised by married, opposite-sex parents.

The appeals court focused its decision exclusively on California’s ban, not the bigger debate, even though the court has jurisdiction in nine Western states.

Whether same-sex couples may ever be denied the right to marry “is an important and highly controversial question,” the court said. “We need not and do not answer the broader question in this case.”

Six states allow gay couples to wed — Connecticut, New Hampshire, Iowa, Massachusetts, New York and Vermont — as well as the District of Columbia. California, as the nation’s most populous state and home to more than 98,000 same-sex couples, would be the gay rights movement’s biggest prize of them all.

The 9th Circuit concluded that a trial court judge had correctly interpreted the Constitution and Supreme Court precedents when he threw out Proposition 8.

The measure “serves no purpose, and has no effect, other than to lessen the status and human dignity of gays and lesbians in California, and to officially reclassify their relationships and families as inferior to those of opposite-sex couples,” Judge Stephen Reinhardt, one of the court’s most liberal judges, wrote in the 2-1 opinion.

Opponents of gay marriage planned to ask the Supreme Court to overturn the ruling, which came more than a year after the appeals court panel heard arguments in the case.

“We are not surprised that this Hollywood-orchestrated attack on marriage — tried in San Francisco — turned out this way. But we are confident that the expressed will of the American people in favor of marriage will be upheld at the Supreme Court,” said Brian Raum, senior counsel for the Alliance Defense Fund, a Christian legal aid group based in Arizona that helped defend Proposition 8.

Legal analysts questioned whether the Supreme Court would agree to take the case because of the narrow scope of the ruling. California is the only state to grant gays the right to marry and rescind it.

Douglas NeJaime, an associate professor at Loyola Law School in Los Angeles, said the California-specific scope of the 9th Circuit panel’s decision means the Supreme Court can uphold it without ruling “on marriage for same-sex couples on a national scale.”

“In effect, the 9th Circuit’s decision allows the Supreme Court to continue the incremental, case-by-case trajectory of marriage for same-sex couples in the United States,” NeJaime said in an email.

Weddings appeared unlikely to resume anytime soon. The ruling will not take effect until the deadline passes in two weeks for Proposition 8’s backers to appeal to a larger panel of the 9th Circuit. Lawyers for the coalition of conservative religious groups that sponsored the measure said they have not decided if they will seek a 9th Circuit rehearing or file an appeal directly to the Supreme Court.

The panel also said there was no evidence that former Chief U.S. Judge Vaughn Walker was biased and should have disclosed that he was gay and in a long-term relationship with another man.

Proposition 8 backers had asked the 9th Circuit to set aside Walker’s ruling on constitutional grounds and because of the judge’s personal life. It was the first instance of an American jurist’s sexual orientation being cited as grounds for overturning a court decision.

Walker publicly revealed he was gay after he retired. Supporters of the gay marriage ban argued that he had been obliged to previously reveal if he wanted to marry his partner. The 9th Circuit held a hearing on the conflict-of-interest question in December.

In its ruling Tuesday, the panel majority said it was unreasonable to presume a judge cannot apply the law impartially just because he is a member of the minority group at issue in a case.

“To hold otherwise would demonstrate a lack of respect for the integrity of our federal courts,” the opinion said.

Reihardt, who was appointed to the appeals court by President Jimmy Carter, was joined in the majority opinion by Judge Michael Hawkins, an appointee of President Bill Clinton.

Judge Randy Smith, who was appointed by President George W. Bush, dissented, saying he disagreed that Proposition 8 served no purpose other than to treat gays and lesbians as second-class citizens.

Smith said Proposition 8 could serve to promote responsible child-rearing among opposite-sex couples, adding that even if those beliefs were flawed, they would be enough to make the measure constitutional.

Voters passed Proposition 8 five months after the state Supreme Court legalized same-sex marriage by striking down a pair of laws that had limited marriage to a man and a woman.

The ballot measure added the one man-one woman provision into the California Constitution, thereby overruling the court’s decision. Its passage followed the most expensive campaign on a social issue in the nation’s history.

An estimated 18,000 couples tied the knot during the window before Proposition 8 took effect. The California Supreme Court upheld those marriages but ruled that voters had properly enacted the law.

Gov. Jerry Brown, in his previous role as attorney general, and former Gov. Arnold Schwarzenegger refused to defend Proposition 8 in court and left it to the ballot measure’s sponsors to appeal Walker’s decision to the 9th Circuit.