In addition, public support for same-sex marriage continues to increase at a rapid pace. A Supreme Court decision on the issue a couple years from now would likely occur in a political atmosphere even more favorable to same-sex marriage than that of today. That is unlikely to sway justices with a strong preexisting commitment to one side or the other. But it could affect key swing vote Justice Anthony Kennedy, assuming he is indeed on the fence right now.
Conservative blogger John Hinderaker suggests that today’s developments might actually benefit opponents of gay marriage. If a Republican president is elected in 2016 and is able to replace Ruth Bader Ginsburg or Stephen Breyer with a social conservative, that might create a anti-gay marriage majority on the Court, thereby eliminating Kennedy’s role as the swing voter. Hinderaker speculates that some or all of the four conservative justices who dissented in United States v. Windsor might have voted against hearing the gay marriage cases right now, in hopes that this will happen.
While this scenario is possible, I don’t think it is all that likely. Even if the GOP does win the presidency in 2016 (which is far from a sure thing), Ginsburg and Breyer would likely try to stay on the Court long enough to decide the gay marriage issue. It could very well be decided even before the 2016 election happens. Finally, a close 5-4 decision upholding laws banning gay marriage may not last for long. If public and elite sentiment continues to turn against such laws, the ruling would likely suffer the same fate as Bowers v. Hardwick (1986), which upheld anti-sodomy laws, but was widely reviled and got overruled in 2003. In this case, the tide of opinion is moving faster, and a reversal could happen sooner than that.
In sum, we are now likely to get a Supreme Court decision striking down laws banning same-sex marriage sometime in the next few years. But there are several different rationales that the Court could use to reach such a decision. They could rule that laws banning gay marriage are invalid because they discriminate on the basis of sex, because they discriminate against gays and lesbians, because they violate a “fundamental” right to marriage, or because they fail even minimal rational basis scrutiny. Which option they choose is likely to have important implications for constitutional theory and for future decisions on other issues. We can now be fairly confident about where the train is going. But it isn’t yet clear what route it will take to get there.
UPDATE: I have made a few stylistic changes to this post.