Supporters of California's gay marriage ban filed an appeal Thursday of a federal judge's ruling striking down the voter-approved law.
The appeal to the 9th U.S. Circuit Court of Appeals was expected, as lawyers on both sides of the legal battle repeatedly vowed to carry the fight to a higher court if they lost.
On Wednesday, a federal judge in San Francisco overturned California's Proposition 8, which restricts a marriage to one man and one woman. U.S. District Court Judge Vaughn Walker ruled the law violates federal equal protections and due process laws.
The 9th Circuit court has no deadlines to hear the case, which will be randomly assigned to a three-judge panel. It's expected that the panel will order both sides to submit written legal arguments before scheduling a hearing.
The outcome in the appeals court could force the U.S. Supreme Court to confront the question of whether gays have a constitutional right to wed.
"This ruling, if allowed to stand, threatens not only Prop 8 in California but the laws in 45 other states that define marriage as one man and one woman," said Brian Brown, president of the National Organization for Marriage, which helped fund the 2008 campaign that led to the ban's passage.
Currently, same-sex couples can legally wed only in Massachusetts, Iowa, Connecticut, Vermont, New Hampshire and Washington, D.C.
Protect Marriage, the coalition of religious and conservative groups that sponsored Proposition 8 -- and wound up defending it in court after California Gov. Arnold Schwarzenegger and Attorney General Jerry Brown refused to -- said it would immediately appeal the decision.
Walker, meanwhile, said he would consider waiting for the 9th Circuit to render its decision before he makes his opinion final and requires the state to stop enforcing the ban. The judge ordered both sides to submit written arguments by Friday on the issue.
Hundreds of same-sex marriage supporters celebrated the verdict at public gatherings in San Francisco, West Hollywood and New York City, while acknowledging they have watched court victories evaporate before.
California voters passed Proposition 8 five months after the state Supreme Court legalized same-sex unions and an estimated 18,000 same-sex couples already had tied the knot.
Joe Briggs, 32, an actor who attended a West Hollywood gathering, said he was thrilled to hear about the ruling but was curbing his enthusiasm because of the legal fight still ahead.
"It's a long process. Last time we were allowed to marry for like a day and then they took it away," said Briggs, who wore a T-shirt with an image of Batman and Robin kissing. "But at the same time, we have a black president -- so let's just get on with it! It's about equality."
Walker's decision came in a lawsuit filed by two same-sex couples and the city of San Francisco that sought to invalidate Proposition 8 under the same constitutional principles that led to bans on interracial marriage being overturned.
The 13-day trial was the first in a federal court to examine if the U.S. Constitution prevents states from denying gays the right to wed.
Former U.S. Solicitor General Theodore Olson teamed up with David Boies to argue for the two couples, bringing together a pair of litigators best known as adversaries who respectively represented George W. Bush and Al Gore in the disputed 2000 election.
"We have other battles ahead of us, but with this decision carefully analyzing the evidence we are well on our way to victory," Olson said Wednesday.
Reveling in their joint victory, Boies said he and Olson's alliance would prove valuable if the Proposition 8 case, known as Perry v. Schwarzenegger, reaches the Supreme Court.
"Ted and I have a deal -- He is going to get the 5 justices that were for him in Bush v. Gore and I'm going to get the 4 justices that were with me in Bush v. Gore," he joked.
Standing in front of eight American flags at a news conference, the two couples behind the case beamed and choked up as they related their feelings of validation.
"Tomorrow will feel different because tomorrow I will have a sense of security I have not had," said Sandy Stier, as her partner of 10 years, Kris Perry, stood at her side. "Because of this decision I will know we are treated the same under the law as everybody else."
Defense lawyers argued at trial that the ban was necessary to safeguard the traditional understanding of marriage and to encourage responsible childbearing. They called just two witnesses, compared to the 18 put on by the plaintiffs, claiming they did not need to present expert testimony because the U.S. Supreme Court had never recognized a right to same-sex marriage.
In declaring Proposition 8 unconstitutional, Walker accepted every argument advanced by the plaintiffs and methodically rejected every claim made by the defense. Preventing gays from marrying does nothing to strengthen heterosexual unions or serve any purpose that justifies its discriminatory effect, but harms children with same-sex parents and "the state's interest in equality," he wrote.
Describing the defense case as "a rather limited factual presentation," he also said its proponents offered little evidence that they were motivated by anything other than animus toward gays -- beginning with their campaign to pass the ban, which included claims of wanting to protect children from learning about same-sex marriage in school.
"Proposition 8 played on the fear that exposure to homosexuality would turn children into homosexuals and that parents should dread having children who are not heterosexual," Walker wrote.
Associated Press Writers Juliana Barbassa in San Francisco, Raquel Maria Dillon in West Hollywood, Jennifer Peltz in New York City contributed to this report.