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A federal appeals court in California today struck down Proposition 8, the controversial ballot measure passed in 2008 with 52 percent of the vote that defines marriage as between a man and a woman.

About 18,ooo same sex couples had obtained marriage licenses in the state before the ballot initiative was passed.

Prop 8 "amounts to a distinct constitutional violation because the Equal Protection Clause protects minority groups from being targeted for the deprivation of an existing right without legitimate reason," the court said.

Judge Stephen Reinhardt, writing for the majority of a three-judge panel of the 9th Circuit Court of Appeals, said, "The Constitution simply does not allow for laws of this sort."

Reinhardt said the court was deciding the issue on the "narrowest grounds."

"By using their initiative power to target a minority group and withdraw a right that it possessed, without a legitimate reason for doing so, the People of California violated the Equal Protection Clause," Reinhardt said.

He said that "more general questions" concerning the fundamental right of same sex couples to marry will likely be resolved in other states, and for the nation as a whole, by other courts.

"For now, it suffices to conclude that the People of California may not, consistent with the Federal Constitution, add  to their state constitution a provision that has no more practical effect than to strip gays and lesbians of their right to use the official designation that the State and society give to committed relationships, thereby adversely affecting the status and dignity of the members of a disfavored class."

Reinhardt was joined in his opinion by Judge Michael Hawkins.

Judge N. Randy Smith dissented from the opinion. "I am not convinced," he wrote, "that Proposition 8 lacks a rational relationship to legitimate state interests."

Prop 8 proponents were quick to condemn the ruling.

"We will immediately appeal this misguided decision that disregards the will of more than 7 million Californians who voted to restore marriage as the unique union of only a man and woman. We are confident that the rights of California voters will finally win out," Andy Pugno, general counsel for the ProtectMarriage.com coalition said in a statement.

The case was brought by two same sex couples, Kris Perry and Sandy Stier, as well as Paul Datami and Jeff Zarrillo. They were represented in the case by the American Foundation for Equal Rights (AFER).

AFER Board President Chad Griffin praised the ruling. "Like many other Americans, our plaintiffs want nothing more than to marry the person they love.  Committed, loving couples and their families should not be denied this most fundamental freedom."

Margaret M. Russell of Santa Clara University School of Law said the ruling possibly makes it less likely the case will reach the Supreme Court.

"The court said it didn't need to rule on whether there is a fundamental right to marry of same sex couples, nor did they need to address the question of whether a state could ever outlaw a marriage between same-sex couples," she said. "Instead, the court said that same-sex couples already had the right to marry before Proposition 8, as well as the protections of the 2003 domestic partner law and therefore could not be denied."

But Stephen I. Vladeck, professor at American University Washington College of Law, said he thought the court would eventually step in to decide an issue of such importance.

He agreed that today's decision was narrow. "The ruling today is really only about those states like California that basically treat same sex couples the same as opposite sex couples in every way except marriage," he said.

Besides ruling on the merits of the case, the court also said that the  proponents of Prop 8 had the legal right to defend the law in the first place after California public officials declined to do so. And it rejected an argument by supporters of Prop 8 that the lower court judge, U.S .District Court Judge Vaughn Walker, should have recused himself from the case because he revealed upon retirement that he had been involved in a long-term, same-sex relationship.