Legal groups and three city attorneys asked the California Supreme Court on Wednesday to invalidate Proposition 8, arguing that the voter-approved ban on gay marriage is a constitutional revision that should have been processed through the Legislature, not the ballot box.

The lawsuit throws the hot-potato issue of same-sex unions back to the high court just six months after four justices infuriated social conservatives by declaring that marriage rights extend equally to both gay and straight couples. And it snares Chief Justice Ronald George, author of the majority opinion in In re Marriage Cases, in a political vise as his scheduled 2010 retention election approaches.