In the Proposition 8 case, the high court's grant of a hearing to the measure's supporters means there won't be a decision on the fate of the 2008 voter initiative until next year, possibly not until June.
In the meantime, the ban will remain in place.
The court agreed to take up an appeal by the initiative's sponsors and their committee, Protect Marriage, of a decision in which the 9th U.S. Circuit Court of Appeals in San Francisco earlier this year struck down the ban.
If the Supreme Court had denied review, the 9th Circuit decision would have gone into effect and gay and lesbian weddings in the Golden State could have resumed within days.
Proposition 8's lawyers, who lost their case before a federal trial judge in San Francisco in 2010 as well as in the appeals court this year, rejoiced in the high court action.
"Every one of the numerous legal steps we have taken for the past four years has been in anticipation of this moment," Protect Marriage attorney Andrew Pugno.
"Arguing this case before the Supreme Court finally gives us a chance at a fair hearing, something that hasn't been afforded to the people since we began this fight," Pugno maintained.
"We are delighted that the nation's highest court will decide whether to uphold the will of more than seven million Californians who voted to preserve the unique definition of marriage as only between one man and one woman," he said.
Lawyers for two couples who challenged Proposition 8 in a federal civil rights lawsuit said they also welcomed the high court review.
"It's a moment of mixed feelings," said attorney David Boies, since on one hand the lawyers want their clients to be able to marry soon, which would have been possible if the court had denied review.
But on the other hand, said Boies and co-lead attorney Theodore Olson, the review opens the possibility of a nationwide decision on whether there is a constitutional right to same-sex marriage.
"We argued all along that the court should not take the case; however, we also felt all along that this case was a perfect vehicle to decide the fundamental rights of all Americans with respect to right to marry," Olson said.
"We could not be more gratified that this is the case the Supreme Court will have before it with respect to rights of all citizens," said Olson.
Kris Perry of Berkeley, a plaintiff in the case, said, "We're elated with the possibility of great things happening.
"You might find this surprising," Perry said in a telephone news conference, "but what we ultimately wanted was the very biggest, very broadest outcome possible and that can only happen if the Supreme Court rules.
"It's better for couples across country to benefit and for everyone to have the same access that we want," she said,
Sandra Stier, Perry's partner and a co-plaintiff, said, "It's absolutely worth waiting for. Today I feel zero disappointment."
The court is expected to schedule a hearing this spring and to rule on Proposition 8 by the close of its current term at the end of June.
Its order granting review today called for written briefs and arguments on two issues: whether Proposition 8 violates the constitutional Fourteenth Amendment guarantee of equal treatment and whether its sponsors had standing, or legal authority, to appeal.
The standing issue arose because the California officials named as defendants in the lawsuit, including Gov. Jerry Brown and Attorney General Kamala Harris, have declined to defend Proposition 8.
With both issues in play, the Supreme Court has the option of ruling on a number of different grounds and could resolve the case without addressing whether there is a constitutional right to marry.
It could uphold Proposition 8 by accepting the sponsors' argument that individual states have a right to define marriage, working through their legislatures or voters.
If it strikes down the ban, it could do so with either a broad ruling holding that gays and lesbians have a constitutional right to marry, or a narrow ruling that would apply only to California.
The narrow ruling could be the reasoning adopted by a 2-1 panel of the 9th Circuit in February. That court concluded that since same-sex marriage was legal in California for several months in 2008, it was unconstitutional for Proposition 8 to withdraw that right for no reason other than animosity toward homosexuals.
Alternatively, the court could say that the sponsors had no standing to appeal. Boies and Olson said such a decision would erase the 9th Circuit ruling and leave in place a broader 2010 decision by U.S. District Judge Vaughn Walker, who said there is a constitutional right to same-sex marriage.
The two attorneys said they will argue all the issues in their briefs, but said they expect the high court to go beyond the standing issue to address the substance of the case.
Boies and Olson said they believe the Proposition 8 case is a good vehicle for review because it includes the evidence from a 12-day nonjury trial before Walker in 2010.
"This is a case where we have an unparalleled record that there is inequality that discriminates against gays and lesbians, harms them, harms their children in serious ways and does not advance any legitimate societal interest," Boies maintained.
San Francisco City Attorney Dennis Herrera, whose office represented the city in opposing Proposition 8, said, "The Supreme Court has signaled its readiness to consider the civil rights issues of our time.
"We look forward to a resolution that benefits folks not just here in California but throughout the country," Herrera said.
On the other side, Randy Thomasson, the president of SaveCalifornia.com, a group advocating heterosexual marriage, said, "The announcement from the Supreme Court is good news for everyone who knows, deep in their hearts, that children do best with a married father and mother under the same roof.
"This battle is not just about marriage, but about whether we still have a republic. We're relying on the Supreme Court to uphold the plain reading of the U.S. Constitution," he said.
Proposition 8, providing that "only marriage between a man and a woman is valid or recognized in California," was enacted by voters as a state constitutional amendment in November 2008.
It overturned a decision in which the California Supreme Court said earlier that year there was a state constitutional right to marry.
The 2009 lawsuit by Perry, Stier and Paul Katami and Jeffrey Zarrillo of Burbank took a different approach and was based on federal rather than state constitutional claims.
The Defense of Marriage Act case, also expected to be decided by June, concerns a section of the federal law that bars the U.S. government from granting legally married same-sex couples access to federal benefits, programs and tax advantages.
The court will review the case of 83-year-old Edith Windsor of New York, who is challenging a $363,000 federal estate tax levy on money left to her by her late wife, Thea Spyer.
Same-sex marriage is legal in nine states and Washington, D.C.