“How can the California Supreme Court rule a constitutional amendment “unconstitutional”?”
They didn’t. The CA Supreme Court ipheld Prop 8, and that’s why the gay marriages stopped. The appeal to US District Court (Perry vs. Schwarzenegger) said it was unconstitutional. And the 9th circuit agreed (Perry vs. Brown), but that’s the one that is being vacated because of standing.
Then this wasn’t a state’s right issue at all. Again, if a gay man can challenge the constitutionality of it, then so can any citizen challenge the constitutionality of the DECISION.
Can’t have two sets of citizens “one with standing and one without”.