[JURIST] Rights groups filed a writ petition [PDF text; case materials] with the California Supreme Court [official website] on Wednesday seeking to invalidate a state constitutional amendment prohibiting same-sex marriage. Proposition 8 [text and materials], which was approved [unofficial results] by about 52 percent of California voters Tuesday, provides that "[o]nly marriage between a man and a woman is valid or recognized in California." The writ petition, filed by attorneys for the American Civil Liberties Union (ACLU), Lambda Legal and the National Center for Lesbian Rights on behalf of Equality California [advocacy websites] and six same-sex couples who want to marry, asks the court to stay enforcement of the amendment until the litigation is resolved. The petition alleges that Proposition 8 is not a valid amendment but rather a constitutional revision, which under provisions of the California Constitution [text] must be approved by the state Legislature [official website]. In a press release [text], Lambda Legal attorney Jenny Pizer said:

If the voters approved an initiative that took the right to free speech away from women, but not from men, everyone would agree that such a measure conflicts with the basic ideals of equality enshrined in our constitution. Proposition 8 suffers from the same flaw – it removes a protected constitutional right – here, the right to marry – not from all Californians, but just from one group of us. That's too big a change in the principles of our constitution to be made just by a bare majority of voters.

The ACLU noted that the California Supreme Court invalidated a constitutional amendment initiative in 1990. California Attorney General Jerry Brown [official website] has said he would defend the legality of Proposition 8 as well as the validity of thousands of same-sex marriages already performed in California should they be challenged by proponents of the amendment [advocacy website]. AP has more. The Los Angeles Times has local coverage. The San Francisco Chronicle has additional local coverage.

Proposition 8 was a response to the California Supreme Court's decision in May striking down [JURIST report] a statutory ban on same-sex marriage as violating the equal protection and privacy provisions of the state constitution. The measure generated more than $60 million in contributions [JURIST report] to committees representing both sides of the issue – a figure believed to be a US record. Voters in Arizona [Proposition 102 text, PDF] and Florida [Proposed Constitutional Amendment 2 text, PDF] also approved [JURIST report] similar measures Tuesday. More than half the states have adopted constitutional amendments [NCSL list] limiting marriage to opposite-sex couples, while most of the remainder have defined marriage by statute. Massachusetts and Connecticut [JURIST reports] are now the only US states that validate same-sex marriages, in light of decisions by their highest courts.