A federal appeals court ruled today that California’s Proposition 8 is unconstitutional. Same-sex marriage is legal again in California—at least for the moment.

Proposition 8 had amended the California Constitution so that the state would recognize only marriages “between a man and a woman.” Proposition 8, which passed in 2008, was a response to the California Supreme Court’s ruling earlier that year that gay couples had the right to marry under the California Constitution. Since the California Constitution can be amended with a simple majority of votes, just a little more than 52% of the vote was enough make gay marriage in California illegal again.

Charles Cooper, the lead attorney defending Proposition 8, argued that because of its “procreative purpose,” restricting marriage to heterosexual couples is “fundamental to the survival of the human race.” But witnesses for the defense conceded that studies show that children raised by same-sex couples do as well as children raised by straight couples. And when Judge Vaughn Walker asked what evidence Cooper had to support his argument, Cooper said, “You don’t have to have evidence of this.”

Theodore Olson, the former Bush Solicitor General who argued the case against Proposition 8, suggested that in fact the proposition's supporters had campaigned on the idea “that there is something wrong, sinister or unusual about gays, that gays and their relationship are not okay, and decidedly not suitable for children, but that children might think it was okay if they learned about gays getting married like normal people.”

"Moral disapproval alone is an improper basis on which to deny rights to gay men and lesbians,” Judge Walker wrote his ruling. Because proponents of Proposition 8 could not offer any rational basis for denying same-sex couples the right to marry, he wrote, it does “nothing more than enshrine in the California Constitution the notion that opposite-sex couples are superior to same-sex couples.”

Judge Walker ordered that Proposition 8 be voided and same-sex couples to allowed to marry again immediately. Proposition 8's supporters have announced their intention to appeal the decision. They have already moved to seek a stay that would prevent any more same-sex couples from marrying before the appeal is decided. Judge Walker himself has said that his ruling simply lays the groundwork for the appeal process, which could take years.

The outcome of that process is far from certain. In spite of being located in San Francisco, the Ninth U.S. Circuit Court of Appeals is not necessarily all that liberal. And, if the Supreme Court does decide to hear the case, it's no sure thing that there will be five votes for same-sex marriage. But for now gay and lesbian couples can get married again in California.