The justices are likely to divide 5 to 4, as they do on almost every important constitutional issue
On Nov. 6, for the first time in American history, a majority of voters in a state -- indeed, in three states -- approved same-sex marriage. On Friday, the U.S. Supreme Court decided to weigh in on the issue, granting review in cases challenging the constitutionality of the Defense of Marriage Act and in a case contesting the constitutionality of California's Proposition 8, which barred same-sex marriage.
DOMA is likely to prove the easier issue for the court, assuming the justices rule on the merits of either or both cases (there are procedural issues that, depending on how the justices are inclined, could block them from considering the merits). The relevant statutory provision bars congressional recognition of same-sex marriages lawfully performed in the states. This means, for example, that a same-sex couple lawfully married in Massachusetts is disqualified from receiving Social Security survivors' benefits that are available to married opposite-sex couples.
Several lower courts have invalidated DOMA on federalism grounds. Historically, Congress has usually deferred to state definitions of marriage. Supreme Court justices who care deeply about preserving traditional spheres of state autonomy ought to be troubled by DOMA, regardless of what they think of marriage equality. Conservative justices who prize federalism and liberal justices who endorse marriage equality may combine to invalidate DOMA by a sizable margin.
Indeed, for the court to uphold DOMA in 2013 would be surprising. Some sponsors of that law, enacted in 1996, defended it in blatantly homophobic terms, denouncing homosexuality as morally wrong and comparing it to polygamy and pedophilia. Supreme Court precedent forbids statutes to be rooted in animus or prejudice, and to a considerable degree DOMA was.
In addition, justices are not indifferent to public sentiment, and recent opinion polls show that Americans no longer support DOMA. One 2011 poll revealed that Americans favored its repeal by 51 percent to 34 percent. Even lower-court judges appointed by Republican presidents have been voting to strike down DOMA.
Predicting how the court will rule on the Proposition 8 case, which could clearly establish or deny a constitutional right to same-sex marriage, is harder. For starters, the justices are likely to divide 5 to 4, as they do on almost every important constitutional issue -- including abortion, affirmative action, campaign finance reform, capital punishment, gun control and federal health care reform.
As on most other issues, Justice Anthony M. Kennedy, probably the most powerful justice in the court's history, is likely to determine the outcome. His vote may turn on how he balances two seemingly opposing proclivities. On the one hand, Kennedy's rulings often turn dominant national norms into constitutional mandates to suppress outlier state practices. His decisions barring the death penalty for minors and the mentally disabled and invalidating state laws criminalizing same-sex sodomy fit this description.
On gay marriage, this propensity to use the Constitution only to suppress dissident practices would counsel restraint on the part of the court. Just nine states and the District of Columbia currently permit same-sex marriage. Intervening at this stage of a social reform movement would be somewhat analogous to Roe v. Wade, in which the court identified an abortion right that invalidated the laws of 46 states. Kennedy has rarely if ever used the Constitution so aggressively.