The US Supreme Court has found that it lacked jurisdiction to hear a case on California's same-sex marriage ban, thereby sending the case back to a lower court which already nixed the law for California on constitutional grounds—but not other states.

In the case of Hollingsworth v. Perry, the State of California had refused to defend its gay-marriage ban. The ban was passed by citizens initiative and the sponsors of that initiative defended the law in court. "We have never before upheld the standing of a private party to defend the constitutionality of a state statute when state officials have chosen not to. We decline to do so for the first time here," the court majority writes.

The justices sent back the case to the lower courts. As SCOTUS Blog's wonderful Amy Howe explains, "the U.S. Court of Appeals for the Ninth Circuit, the intermediate appellate court, has no legal force, and it sent the case back to that court with instructions for it to dismiss the case." That would let an earlier federal district court ruling stand—which found Prop 8 unconstitutional in 2010—thus allow same-sex marriages to proceed in the nation's most populous state.

The opinion is here.

UPDATE at 8:06 AM: Bloomberg reports that the decision didn't fall along the court's typical ideological lines:

In the California case, the court said the sponsors of Proposition 8 lacked power to appeal the trial judge’s order. California officials had refused to defend the measure. The justices split along unusual lines, with Roberts, Scalia, Ginsburg, Breyer and Kagan in the majority. Kennedy, Thomas, Alito and Sotomayor said the court should have ruled on the constitutionality of the California ban.

I'm just guessing here—but not really—that Justice Thomas (friend of bigots and corporations) and Justice Sotomayor (who actually has human DNA) had very different motivations to try ruling on the constitutionality of gay marriage.