The California Supreme Court accepted three lawsuits seeking to nullify Proposition 8, a voter-approved constitutional amendment that overruled the court's decision in May that legalized gay marriage.
All three cases claim the measure abridges the civil rights of a vulnerable minority group. They argue that voters alone did not have the authority to enact such a significant constitutional change.
As is its custom when it takes up cases, the court did not elaborate on its decision.
Along with the gay rights groups and local governments petitioning to overturn the ban, the measure's sponsors and Attorney General Jerry Brown had urged the Supreme Court to consider whether Proposition 8 passes legal muster.
The court directed Brown and lawyers for the Yes on 8 campaign to submit their arguments for why the ballot initiative should not be nullified by Dec. 19. It said lawyers for the plaintiffs, who include same-sex couples who did not wed before the election, must respond before Jan. 5. Oral arguments could be scheduled as early as March, according to court spokeswoman Lynn Holton.
Both opponents and supporters of Proposition 8 expressed confidence Wednesday that their arguments would prevail.
But they also agreed that the cases present the court's seven justices six of whom voted to review the challenges with complex questions that have few precedents in state case law.