WASHINGTON -- Struggling with the gay marriage issue for the first time in history, the U.S. Supreme Court on Tuesday resembled the kid at the end of the highest diving board at the pool for the first time -- inclined to turn around and try another day rather than take a bold jump into an uncertain future.

During more than an hour of arguments in their jammed courtroom, the justices were clearly divided over California's Proposition 8 voter-approved ban on same-sex marriage, although reluctant to take the larger step of casting a broader ruling that would apply to gay marriage rights across the country. The only certainty is that the Supreme Court will leave the fate of California's gay marriage ban dangling until June, when it must rule.

But the justices' barrage of questions hinted at options that could open the door to same-sex nuptials in California by simply leaving intact lower court rulings declaring the law unconstitutional.

"Always hard to predict based on arguments, but I think it is more likely that they will dismiss (on procedural) grounds than decide the merits (of the gay marriage issue)," said Erwin Chemerinsky, dean of UC Irvine's law school.

As hundreds of gay marriage supporters and opponents waved placards and chanted for their causes on the Supreme Court steps outside, the justices expressed concern over whether the time is right for them to take on a state's right to ban gay marriage. Justice Anthony Kennedy, a key swing vote, wondered whether the court perhaps should not have taken on the controversy in the first place.

The justices considered the arguments as Berkeley's Kristin Perry and Sandy Stier and another California couple challenging Proposition 8 sat in the courtroom among a contingent of gay rights supporters such as Hollywood director Rob Reiner. Supporters of ProtectMarriage.com, Proposition 8's defender, also found coveted courtroom seats.

With both liberal and conservative justices particularly worried about a broader ruling that might apply to all states, 37 of which now ban gay marriage, the court pressed lawyers on both sides about how far they should go. "Is there any way to decide this case in a principled manner that is limited to California?" Justice Sonia Sotomayor asked Theodore Olson, who argued the case for same-sex couples.

The court has another opportunity Wednesday to deal with the gay marriage issue in a way that could continue to allow the political debate to unfold in the states. The justices are hearing arguments in a challenge to the 1996 federal Defense of Marriage Act, which bars federal benefits to same-sex couples. Among other questions, the court must resolve whether the government can deny benefits to gay and lesbian couples married in states where same-sex marriage is legal -- and they can decide that without granting broader marriage rights nationwide.

But on Tuesday, the justices' questioning cast doubt on Proposition 8's future, with some justices clearly concerned it may trample on the rights of gay and lesbian couples.

Kennedy, while acknowledging gay marriage is a new concept in a tradition that stretches back thousands of years, said there is an "immediate legal injury" to same-sex couples in California who are raising children but unable to marry legally. How does the law affect the roughly 40,000 children of those same-sex couples? Kennedy asked Proposition 8 lawyer Charles Cooper, who argued that preserving traditional marriage would protect children.

"The voice of those children is important in this case, isn't it?" Kennedy asked.

Other justices, including Chief Justice John Roberts, were skeptical of a court decision finding same-sex marriage bans unconstitutional. "Same-sex couples (in California) have every other right, it's just about the label (of marriage)," he told Olson. "All you're interested in is the label, and you insist on changing the definition of the label."

Justice Samuel Alito, considered a likely conservative vote against gay marriage, pressed U.S. Solicitor General Donald Verrilli about pushing for same-sex marriage rights in the states on behalf of the Obama administration.

"You want us to step in and render a decision based on an assessment of (gay marriage) which is newer than cellphones or the Internet," he said.

Some justices wondered whether Proposition 8's sponsors have the legal authority to defend the law for the state in place of the governor and attorney general, who consider it unconstitutional. A finding that the sponsors lacked such authority would result in enforcement of the lower court decision that the gay marriage ban is unconstitutional. That outcome would allow gay marriage in California.

Even there, however, the justices were splintered. Several indicated they were troubled by the possibility the governor and attorney general could trump a ballot measure they oppose simply by refusing to defend it in court.

The Supreme Court is reviewing a federal appeals court ruling last year finding Proposition 8 unconstitutional because it stripped away a previous right for same-sex couples to marry in California. In that ruling, the 9th U.S. Circuit Court of Appeals took a narrow approach that, if adopted by the Supreme Court, would limit the legal impact to California.

The seeds for Tuesday's courtroom drama were sown in early 2009, when same-sex couples challenged Proposition 8. The lawsuit prompted the nation's first full-blown trial over gay marriage rights, and in 2010 former San Francisco Chief U.S. District Judge Vaughn Walker declared the ban unconstitutional.

The Supreme Court's review of Proposition 8 is a milestone in the battle over same-sex marriage, particularly in California, where the state Supreme Court in 2008 struck down the state's previous laws forbidding gay nuptials. That decision allowed more than 18,000 couples to marry legally -- marriages that remain intact -- but also triggered a political backlash that led to voters passing Proposition 8.

Howard Mintz covers legal affairs. Contact him at 408-286-0236 or follow him at Twitter.com/hmintz.