I am not quite sure whether I think the tactic of challenging California's Prop. 8, which barred same-sex marriage, in court on federal constitutional grounds was a good idea or not. It's not that I'm not for gay marriage; the Register opposed Prop. 8 and I thought it was going to fail until late election night. There's simply no case against it that has more intellectual heft than that feeling of ickiness most of us had about "queers" when we were 14 or so. But I'm not sure every right I think is valid is a constitutional right, though you could make a case that the 10th amendment covers a lot of rights ground, and the right to marry just might be included. But the courts pay no attention to the 10th.
The case is being brought, however, on 14th-amendment grounds -- equal protection of the laws and due process. It's not a bad case, as Cato's Robert Levy, who is a constitutional lawyer, points out in this op-ed.
I would prefer that the State had nothing to do with marriage, but it does, and since it does it should treat same-sex couples equally. Politically, however, having gay marriage imposed by the courts is arguably less desirable than having it done legislatively or by referendum, which would reflect a pretty strong consensus. Court decisions to date have led to backlashes -- that's how Prop. 8 was filed -- and one worries that it could set the cause back.
On the other-other hand, if it's a right, and especially one that doesn't harm others when exercised (my definition of a real right), which gay marriage certainly wouldn't, despite ahistorical and ignorant claims to the contrary, a majority, no matter how large (and this one is shrinking) doesn't have the right (though it may have the power) to violate it. Justice delayed is justice denied, so maybe going to court is the best way to vindicate this right.