Over at ScotusBlog, Tom Goldstein thinks the Court will either find that the Prop 8 defendants have no standing, or will just decline to rule on the case. Either would invalidate Prop 8:
The Justices seem divided on the constitutionality of Proposition 8 on ideological lines, four to four – i.e., all the members other than Justice Kennedy. For the more liberal members of the Court, there was no clarity on how broadly they would rule…
If those features of the oral argument hold up – and I think they will – then the Court’s ruling will take one of two forms. First, a majority (the Chief Justice plus the liberal members of the Court) could decide that the petitioners lack standing. That would vacate the Ninth Circuit’s decision but leave in place the district court decision invalidating Proposition 8… Second, the Court may dismiss the case because of an inability to reach a majority. Justice Kennedy takes that view, and Justice Sotomayor indicated that she might join him. Others on the left may agree. That ruling would leave in place the Ninth Circuit’s decision…The upshot of either scenario is a modest step forward for gay rights advocates, but not a dramatic one.
Although having Prop 8 invalidated would be a great step, we can’t help but wish that the Court was more in step with society on this issue. It’s painful to thin we may have to wait another 2 or 3 or 5 years to get a yes ruling on marriage equality in another case.