SAN FRANCISCO - The California Supreme Court is poised to release a decision that could prove pivotal to the future of the state's voter-approved ban on same-sex marriage.

The court says it will file a written opinion Thursday morning clarifying whether the sponsors of ballot initiatives can defend their measures from legal challenges without the co-operation of the governor and attorney general.

A federal appeals court considering the constitutionality of the 2008 ban, known as Proposition 8, asked the state high court to weigh in on that question before it gets to the merits of the case.

The 9th U.S. Circuit Court of Appeals has expressed doubts about the ability of Proposition 8's sponsors alone to challenge a lower court ruling that overturned the initiative. California's previous governor and attorney general both refused to appeal the decision.