California's highest court agreed Wednesday to hear several legal challenges to the state's new ban on same-sex marriage but refused to allow gay couples to resume marrying before it rules. 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 elaborated little. However, the justices did say they want to address what effect, if any, a ruling upholding the amendment would have on the estimated 18,000 same-sex marriages that were sanctioned in California before Election Day.