(CBSNews.com) - In what has already been a pivotal year in the debate over same-sex marriage, the Supreme Court may decide it should weigh in on the issue.
The justices meet today in a private conference to discuss 10 cases they could take up relating to same-sex marriage, including eight that challenge the how a federal law, the Defense of Marriage Act (DOMA), applies to legally married same-sex couples. The justices could also decide to review a 2009 Arizona law impacting state employees, or the circuit court ruling that struck down California's ban on same-sex marriage, Proposition 8.
If the court chose to rule on the Proposition 8 case or DOMA, it could end up changing rules throughout the country pertaining to same-sex marriage -- an issue that remains as tumultuous as ever, changing at the state level through ballot initiatives, state-based legislation and through the courts.
Public opinion seems to be shifting towards acceptance of same-sex marriage. In 2011, Gallup found for the first time that a majority of Americans supported it. And on Election Day this year, three states passed ballot initiatives allowing same-sex couples to marry -- making this year the first ever in which voters passed initiatives in favor, rather than against, same-sex marriage. The issue, however, is far from resolved. While nine states plus the District of Columbia allow same-sex marriage, many more -- 39 states -- prohibit it.
The Supreme Court is still far from handing down any rulings -- today, it only decides what cases it will accept this term. At least four of the nine justices must agree to hear a case, and the court could announce as early as Monday which cases, if any, it's agreed to take on.
DOMA: A likely court case
Constitutional experts agree that the Supreme Court is likely to accept a case challenging DOMA. The law, passed by Congress and signed by President Clinton in 1996, prohibits federal recognition of same-sex marriages. Both the first and second circuit court of appeals have struck down a provision of the law denying federal benefits, like Social Security benefits or the ability to file joint tax returns, to same-sex couples legally married.
"Here are two circuit courts that held a federal law unconstitutional, and if the Supreme Court doesn't intervene, that would be just sitting out there -- it would be unconstitutional in those circuits but not elsewhere," CUNY School of Law Prof. Ruthann Robson explained to CBSNews.com. In other words, DOMA would be unconstitutional in some regions of the country, but not others.
Not only is there compelling reason for the court to take up the DOMA challenges, but it also gives the court a way to settle a same-sex marriage issue without addressing the ultimate, controversial question of who has a "right to marriage."
"The couples in the DOMA cases are already lawfully married," explained UCLA School of Law Prof. Adam Winkler. "The question is if the federal government can deny those couples benefits it provides to every other couple. Seen in that way, the DOMA cases are a far easier case [than the Proposition 8 case]."
DOMA defenders argue that the federal government should clearly be able to use a uniform definition of marriage across the nation, so it can distribute federal benefits uniformly. "You've got a thousand [federal] programs" relating to marriage benefits, Chris Gacek, a senior fellow at the conservative Family Research Council (FRC), pointed out. Gacek co-authored amicus briefs on behalf of FRC in two federal court cases regarding same-sex marriage.
At the same time, Winkler said, "because defining marriage is something states do, the conservatives on the court may want to restore state authority in that area."
There have been a series of federalism cases, Winkler pointed out, where the court has said that even where the federal government has authority to act, they must respect state autonomy. For instance, in 2000, the court struck down parts of the Violence Against Women Act, saying the federal government does not have authority to provide remedies for domestic violence because family law is traditionally a matter of the states.
Meanwhile, the Obama administration last year decided it would no longer defend the constitutionality of DOMA in court, so House Republicans took up the cause, using the Bipartisan Leadership Advisory Group to defend the law in court.
Prop. 8: A more complicated case
The question of whether the Supreme Court should take up the Proposition 8 case is more complicated. The court would have to address whether same-sex couples have a right to get married -- but it could either apply that right to same-sex couples across the board, or just in California.
A Supreme Court ruling could apply just to California because of the case's unique circumstances. After the California Supreme Court granted same-sex couples the right to marry, California voters in 2008 passed Proposition 8, taking away that right. Then, a federal court followed by the Ninth Circuit Court of Appeals said Proposition 8 was unconstitutional.
"The Ninth Circuit decision is very narrow and about a proposition that passed after the State Supreme court had granted the right to marry," Robson said. "Much of [the Supreme Court] decision would rest upon a proposition taking that right away."
On the other hand, the court could make the scope of its decision much larger, deciding that all same-sex couples have the right to marry, in California or elsewhere.
"We feel in taking the case, the court could impact a much larger number of people across the country with a positive ruling," said Michael Cole-Schwartz, communications director for the gay rights group the Human Rights Campaign.
If the court decided to ignore the ruling and let the Ninth Circuit decision stand, that would also be a huge victory for gay rights, Cole-Schwartz said. "It would return marriage quality to California, almost doubling the number of Americans who live in a 'marriage equality' state, to 28 percent," he said.
Gacek said the court should take up the case and overturn the Ninth Circuit, to let the will of the voters stand.
"These are complex issues, and they need to be decided by the political branches," he said. "I think the worst thing you could do is get a judicial cramdown on this -- you'd have decades of fighting like you have over Roe v. Wade."
At that point, he pointed out, California voters could vote on another same-sex marriage referendum if they wanted to reverse Prop. 8.
"One of the things I think is interesting about recent developments -- in Maryland and Washington [where voters approved same-sex marriage] -- it makes the point that the political process here is working," Gacek said. "You don't have people frozen out of the process, unable to express their opinions. Given the complexity of the social relationships and the interaction here, it's just best to let the political branches work this out. It might take a while, but it seems to me it would really be not a good idea to have the courts stepping in and defining it."
Cole-Schwartz said if the court reversed the Ninth Circuit and reinstated Prop. 8, "it would be disappointing and out of sync with the court's tradition of siding with justice and liberty and moving our country forward."
"The heart of the Prop. 8 case is that marriage is a fundamental right," he said. "The court has ruled 14 separate times that marriage is a fundamental right -- there's no reason to exclude loving and committed gay couples from that institution."