I can't make any comments on the legal thinking that went into the Prop 8 decision - some supporters of gay marriage are saying it was a bad decision because its breadth makes it an easy target for Supreme Court conservatives.
However, I do think that Jews should be happy with the outcome. Why? Because the only arguments against gay people marrying are arguments grounded in religion. Wha? Judaism is a religion, so we agree with them, right? Wrong.
While certainly there are many Jews who feel that the Torah calls on them to oppose loving intimate relationships between members of the same sex, that is not really the point (the Orthodox Union supported Prop 8). If we could have the state of Colorado enforce the laws of Shabbat as described in the Torah would we want that? Of course not, because we accept the principal of separation of church and state - we wouldn't want that any more than we would want the state to force people to observe Christian holidays.
And this is why even those Jews who consider themselves religiously bound to oppose gay relationships should celebrate. It is a victory for value-neutral secular law. That is good because it permits us to practice our religion, and permits our neighbors to practice theirs, but is doesn't allow us to force our views on them and visa versa.
If you have any doubts about who has the most at stake in the anti-gay marriage side, look no further than the Alliance Defense Fund. Their lawyers are litigating the case. Their website describes them as a "servant organization that provides the resources that will keep the door open for the spread of the Gospel through the legal defense and advocacy of religious freedom, the sanctity of human life, and traditional family values." The first two lines of their "Statement of Faith": "We believe the Bible to be the inspired, infallible, authoritative Word of God. We believe that there is one God, eternally existent in three persons: Father, Son and Holy Spirit."
Do I want these people making laws about what kind of society I can live in? No more than I want the Orthodox Union to.
In a religiously diverse society, doesn't it make sense to have religiously-neutral laws that are non-coercive. Let's agree that no one should force anyone into a gay marriage - if you don't want one, don't have one. And no one should stop anyone else from having a gay marriage. Doesn't that allow for harmony in a diverse society?
And isn't it dangerous for Jews to support anti-democratic, religiously grounded arguments while living in a society that is 98% non Jewish?