The issue arises because Gov. Arnold Schwarzenegger and Attorney General Jerry Brown have refused to defend Prop. 8 in court. That was also the case in Arizona, where state officials refused to appeal a lower-court decision overturning a ballot initiative, and the measure's sponsors then sought to defend it themselves.

Writing for a unanimous court 13 years ago, Justice Ruth Bader Ginsburg said state officials are normally the only ones who can defend their laws. There's an exception, she said, when a state passes a law allowing its legislators to represent its interests. But Arizona has no such law, she said, and the sponsors of the English-only initiative "are not elected representatives."