SCOTUS will have issues considering it's earlier sodomy ruling. They'd need to find some legitimate state interest in preventing gay marriage. This is assuming they want to be logically consistent (haha Scalia), but it's why Scalia was totally anti sodomy in the first place: because the logic used in striking it down is a back-door (haha) into allowing gay marriage. If this wasn't about those icky gays, small government conservatives would be all over their logic: government regulation needs to present a legitimate state interest in doing something. Not "because we think it's icky". I'd go 5-4 in favor of gay marriage. There's really no defense of it at this point beyond the "it's icky" view, and Roberts appears terrified that his court will wind up being the modern Dred Scot as far as "horrible decisions by the Supreme Court" references go.