The Supreme Court, concluding two days of intense debate, has suggested it could strike down the law that prevents legally married gay couples from receiving a range of federal benefits that go to married people.

The court wrapped up its arguments Wednesday over the federal Defense of Marriage Act that bans recognition of same-sex marriages in the U.S., affecting several benefits available to married couples, including survivor benefits and tax breaks.

Justice Anthony Kennedy _ often the decisive vote in a divided court _ joined the four more liberal justices in raising questions about the provision of the act that is being challenged in the Supreme Court.

The debate in the high court has garnered huge interest as polls show that public opinion in the United States has been leaning toward being in favor of gay marriage, though religious conservative still strongly oppose it. Thousands of people marched outside the Supreme Court building Tuesday, loudly supporting one side or the other.

Same-sex marriage is legal in nine states and the district of Washington, while 12 others recognize “civil unions” or “domestic partnerships” that grant the same benefits without full rights of marriage. The other states ban gay marriage in their constitutions.

Kennedy said the law appears to intrude on the power of the states that have chosen to recognize same-sex marriages. Other justices said the law creates what Justice Ruth Bader Ginsburg called two classes of marriage.

The federal law affects a range of benefits available to married couples, including tax breaks, survivor benefits and health insurance for spouses of federal employees.

Lower federal courts have struck down the section of the law that defines marriage as being between one man and one woman, and now the justices, in nearly two hours of scheduled argument, were considering whether to follow suit.

In 2011, the Obama administration abandoned its defense of the law but continues to enforce it. President Barack Obama declared his support for gay marriage during last year's presidential election campaign.

It still is possible the court could dismiss the case for procedural reasons, though that prospect seemed less likely than it did in Tuesday's argument over a voter-approved gay marriage ban in California.

The motivation behind the 1996 federal law, passed by large majorities in Congress and signed by President Bill Clinton, was questioned repeatedly by Justice Elena Kagan.

She read from a House of Representatives report explaining that the reason for the law was “to express moral disapproval of homosexuality.” The quote produced an audible reaction in the courtroom.

Paul Clement, representing the House Republican leadership in defending the law, said the more relevant question is whether Congress had “any rational basis for the statute.” He supplied one, the federal government's interest in treating same-sex couples the same no matter where they live.

Clement said the government does not want military families “to resist transfer from West Point to Fort Sill because they're going to lose their benefits.” The U.S. Military Academy at West Point is in New York state, where same-sex marriage is legal, and Fort Sill is in Oklahoma, where gay marriages are not legal.

The argument follows Tuesday's case over California's ban on same-sex marriage, a case in which the justices indicated they might avoid a major national ruling on whether America's gays and lesbians have a right to marry. Even without a significant ruling, the court appeared headed for a resolution that would mean the resumption of gay and lesbian weddings in California.

The justices chose for their review the case of Edith Windsor, 83, of New York, who sued to challenge a $363,000 federal estate tax bill after her partner of 44 years died in 2009.

Windsor, who goes by Edie, married Thea Spyer in 2007 in Canada after doctors told them that Spyer would not live much longer. Spyer suffered from multiple sclerosis for many years. Spyer left everything she had to Windsor.

There is no dispute that if Windsor had been married to a man, her estate tax bill would have been zero.

The law is now even opposed by former President Bill Clinton, who says times have changed and the Supreme Court should strike it down. Clinton's wife, potential 2016 presidential candidate Hillary Rodham Clinton, recently came out in support of gay marriage.

On Tuesday, the justices weighed a fundamental issue: Does the Constitution require that people be allowed to marry whom they choose, regardless of either partner's gender? The fact that the question was in front of the Supreme Court at all was startling, given that no state recognized same-sex unions before 2003 when Massachusetts' high court ruled it was unconstitutional to bar same-sex couples from marrying in the state.

But it was clear from the start of the 80-minute argument in a packed courtroom that the justices, including some liberals who seemed open to gay marriage, had doubts about whether they should even be hearing the challenge to California's gay marriage ban.

Justice Kennedy suggested the justices could dismiss the case with no ruling at all.

Such an outcome would almost certainly allow gay marriages to resume in California, where the ban has been struck down by lower courts, but might have no impact elsewhere. The court is not expected to rule before late June.

There was no majority apparent for any particular outcome, and many doubts were expressed by justices about the arguments advanced by lawyers for the opponents of gay marriage in California, by the supporters and by the Obama administration. (AP)