The ruling clears the way for same-sex marriages in California to resume.
The 5-4 decision avoids, for now, a sweeping conclusion on whether same-sex marriage is a constitutional "equal protection" right that would apply to all states.
At issue was whether the Constitution's guarantee of equal protection under the law prevents states from defining marriage to exclude same-sex couples, and whether a state can revoke same-sex marriage through referendum, as California did, once it already has been recognized.
But a majority of the Supreme Court opted not to rule on those issues. Instead, it ruled on "standing" -- whether those who brought the suit to the court were entitled to do so.
"We have never before upheld the standing of a private party to defend a state statute when state officials have chosen not to," said Chief Justice John Roberts. He was supported by an unusual coalition: fellow conservative Justice Antonin Scalia and more liberal Justices Ruth Bader Ginsburg, Stephen Breyer, and Elena Kagan.
By dismissing the case, the court leaves in place the lower court decision in California that allows for same-sex marriage to be reinstated. The federal appeals court stay on the decision will be lifted.
It was act two in a closely watched pair of high court appeals over state and federal laws and the limits of recognizing the ability of gay and lesbian couples to wed. The outcome of the rulings gives same-sex couples much to be encouraged about.
California voters approved Proposition 8 in 2008 with 52% of the vote shortly after the state Supreme Court ruled same-sex marriages are legal. The measure put gay and lesbian marriages on hold in the state, but a federal appeals court later rule Proposition 8 was unconstitutional.
Two of the original plaintiffs -- Paul Katami and Jeff Zarrillo, a Burbank, California, couple who want to marry but could not because of Proposition 8 -- contended the state was discriminating against them because of their sexuality.
"This is about our freedom and our liberty," Katami told CNN. "We are not trying to topple marriage. We are not trying to redefine marriage. What we are trying to say is that equality is the backbone of our country."
Both they and Kristin Perry and Sandy Stier, the other plaintiff couple from Berkeley, were in the courtroom when the rulings came out. They were cheered when emerging from the court building.
Their views were echoed by fellow same-sex marriage supporters, who rallied outside the court with the hope that the justices will eventually issue a broad ruling to strike down bans nationwide.
In dissent, Justice Anthony Kennedy said the court's majority ignored the initiative process that led to the passage of Proposition 8.
"What the court fails to grasp or accept is the basic premise of the initiative process. And it is this. The essence of democracy is that the right to make law rests in the people and flows to the government, not the other way around. Freedom resides first in the people without need of a grant from government," he said. "The California initiative process embodies these principles and has done so for over a century. ... In California and the 26 other states that permit initiatives and popular referendums, the people have exercised their own inherent sovereign right to govern themselves. The court today frustrates that choice."
Kennedy was joined by Justices Clarence Thomas, Samuel Alito, and Sonia Sotomayor.
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The case is Hollingsworth v. Perry (12-144).