California Supreme Court decides that Prop 8 sponsors have standing to defend it.

The Court was responding to a state law question referred to it by the 9th Circuit Court of Appeals, which is considering whether the ban on same-sex marriage violates the federal Constitution.

The Supreme Court was emphatic that it would "undermine" the California ballot initiative process if the governor and attorney general can trump the voters by declining to defend such laws in the courts.

"The inability of the official proponents of an initiative measure to appeal a trial court judgment invalidating the measure, when the public officials who ordinarily would file such an appeal decline to do so, would significantly undermine the initiative power," Chief Justice Tani Cantil-Sakauye wrote for the [unanimous] court....

"This frees up the 9th Circuit to go ahead and decide the constitutional issues on the merits," said Theodore Olson, former U.S. Solicitor General during the Bush administration. "We're anxious to get to a decision on the merits that Proposition 8 is unconstitutional."

ADDED: Here's the California Supreme Court opinion (PDF). The California Supreme Court observes that the 9th Circuit saw the federal issue of standing as hinging on a state law question: whether "the official proponents of an initiative have authority under California law to assert the state‘s interest in the initiative measure‘s validity." The California Supreme Court's opinion stresses the nature of the initiative power, which was adopted "as one means of restoring the people‘s rightful control over their government":

The initiative power would be significantly impaired if there were no one to assert the state‘s interest in the validity of the measure when elected officials decline to defend it in court or to appeal a judgment invalidating the measure. Under article II, section 8 and the Elections Code, the official proponents of an initiative measure have a unique relationship to the voter-approved measure that makes them especially likely to be reliable and vigorous advocates for the measure and to be so viewed by those whose votes secured the initiative‘s enactment into law....

Thus, regardless of the initiative‘s effect on their personal and particularized legally protected interests, the official proponents are the most logical and appropriate choice to assert the state‘s interest in the validity of the initiative measure on behalf of the electors who voted in favor of the measure....

[E]ven though the official proponents of an initiative measure are not public officials the role they play in asserting the state‘s interest in the validity of an initiative measure in this judicial setting does not threaten the democratic process or the proper governance of the state, but, on the contrary, serves to safeguard the unique elements and integrity of the initiative process.