CLICK PLAYER LOCATED BELOW TO LISTEN TO AUDIO
WASHINGTON -- As partisans argued pointedly over same-sex marriage outside the U.S. Supreme Court building, either hoping for or dreading a landmark decision, justices inside seemed reluctant Tuesday to extend a sweeping constitutional right for gays and lesbian to wed in all 50 states.
In the first of two days of hearings on cases that have the potential to fundamentally alter how American law treats marriage, Justice Anthony Kennedy -- considered the likely deciding vote on the divided court -- questioned whether justices should even be hearing the issue.
"This was a deeply divided Supreme Court, and a court that seemed almost to be groping for an answer here," said CNN Senior Legal Analyst Jeffrey Toobin, who watched the arguments over California's Proposition 8, which bans same-sex marriage.
Voters approved the proposal 52% to 48% in November 2008, less than six months after the state Supreme Court ruled that marriage is a fundamental right that must be extended to same-sex couples.
The court will listen to arguments Wednesday on a separate challenge to the federal Defense of Marriage Act, which -- like the California law -- defines marriage as between a man and a woman.
The overriding legal question in the California case is whether the 14th Amendment guarantee of equal protection under the law prevents states from defining marriage as that state has.
Regarding allowing same-sex couples to marry, Justice Elena Kagan, a liberal member of the court, asked, "What harm is there to the institution of marriage?"
But more conservative members of the court took a go-slow approach. Justice Samuel Alito said the law on same-sex marriage is too new.
"There isn't a lot of data on its effect" on children and the institution of marriage, he said.
While the justices were clearly torn on the larger constitutional questions, they may be poised to dismiss the appeal on jurisdictional grounds.
A key question is whether the private citizens who put Proposition 8 on California's ballot have standing to defend it in court when the state's governor and attorney general have refused to do so.
If the court dismisses the appeal on those grounds, it might mean lower federal court rulings declaring the proposition unconstitutional would stand.
But it wouldn't allow for a broader, final rule outlining the power of states to say who can or can't get married.
Kennedy admitted the law's supporters are "not just any citizens."
But he later raised concerns about whether the possibility of same-sex marriage was enough to establish they had suffered harm, a key jurisdictional hurdle allowing them to appeal in the first place.
Justice Sonia Sotomayor said it is the state's responsibility -- through its elected leaders -- to defend laws in court, and that private individuals could not establish "how their injury was separate from everyone else."
Attorneys who represented the two couples seeking to overturn Proposition 8 said they couldn't tell how the court would rule.
"We are confident where the American people are going with this," said Theodore Olson. "We don't know for sure what the United States Supreme Court is going to do, but we're very, very grateful they listened, they heard, they asked hard questions, and there's no denying where the right is."
Andrew Pugno, general counsel for the Protect Marriage Coalition, the group defending Proposition 8, said their attorney had "credibly presented the winning case for marriage."
"We think the hearing went very well," he told reporters.
Two of the key plaintiffs are Paul Katami and Jeff Zarrillo, a Burbank, California, couple who want to marry but can't because of Proposition 8. They say the state is discriminating against them for their sexuality.
"It's as simple as that," Katami said after the hearing. "It's our constitutional right and I cannot wait to start my family with Jeff."
The court is unlikely to announce its decision until June.
During Tuesday's arguments, supporters of same-sex marriage rallied outside the Supreme Court, hoping justices would reach for a broad ruling that would strike down bans nationwide.
"We are not asking for anything more than our neighbors, friends and family, but certainly expect no less," said Todd Bluntworth, who spoke with his husband and their two children to a crowd of supporters hoping for a historic ruling from the Supreme Court striking down laws banning same-sex marriage.
But opponents who rallied nearby urged the court to keep out of the issue and leave the decision to states.
"If you want to get married, go to one of the states that allows gay marriage," said Carl Boyd Jr., a conservative Nashville talk-show host. "Stop trying to force your agenda down our throats. Quit trying to bully the American people with the homosexual agenda."
Some demonstrators carried sign reading "Kids do best with a mom & dad."
Patchwork state laws
If the court decides in their favor, it would mark a historic