Washington (CNN) -- The divisive issue of same-sex marriage was expected to be discussed privately by the Supreme Court on Monday, and the justices could soon announce if they will hear a constitutional challenge to a federal law denying financial benefits to gay and lesbian couples.
An order from the court announcing whether it will take up either or both of two separate issues could come as early as Tuesday morning. If so, oral arguments and an eventual ruling would not happen until next year, but the current appeals are sure to reignite the hot-button social debate in a presidential election.
At issue is whether guarantees of "equal protection" in the U.S. Constitution should invalidate a California law -- and the separate 1996 Defense of Marriage Act (DOMA), which for federal purposes defines marriage as the legal union only between one man and one woman.
A New York woman sued, saying the federal law unfairly treats same-sex couples who are lawfully married under the laws of their own states.
A separate appeal from California over the state's voter-approved Proposition 8 banning same-sex marriage is also before the high court.
In the DOMA appeal, Edith "Edie" Windsor and Thea Spyer had lived for together in New York City's Greenwich Village for more than four decades, and had been engaged as a couple since 1967.
They eventually married out of state in 2007, but neither the federal government nor their home state of New York at the time recognized the legal union. Spyer died three years ago and left her estate to Windsor, who was then forced to pay federal taxes on the money -- about $363,000 in taxes -- because she was not considered a legal spouse.
New York now allows same-sex marriage.
A federal judge had ruled in favor of Windsor, but citing her age and health, the woman's lawyers are trying to bypass usual federal appeals court review of the case, and have asked the Supreme Court to hear the case now. Such legal leapfrogging is rarely accepted by the justices, since they typically want such cases to percolate through the entire judicial system before reaching the high court.
"Edie Windsor, who recently celebrated her 83rd birthday, suffers from a serious heart condition," said Roberta Kaplan, Windsor's attorney. "Edie cannot yet receive a refund of the unconstitutional estate tax that she was forced to pay simply for being gay. The constitutional injury inflicted on Edie should be remedied within her lifetime."
The Defense of Marriage Act was passed in 1996 by the GOP-controlled Congress and signed into law by President Bill Clinton. It bars federal recognition of same-sex marriages and says states cannot be forced to recognize such marriages allowed in other states.
The Obama administration, which normally would defend federal laws in judicial disputes, announced earlier this year it believed the Defense of Marriage Act, often referred to as DOMA, to be unconstitutional.
House Speaker John Boehner said that with the Justice Department not participating, the Republican majority had "no choice" but to act unilaterally, and has moved to lead the legal defense of the law.
Three other separate appeals challenging DOMA have been filed with the high court, but have not yet been scheduled for an initial, internal review. Plaintiffs include 17 married or widowed men and women suing for federal benefits.
The justices may wait until all pending same-sex marriage cases have been debated in their closed-door conference before deciding whether any or all of the cases are accepted for full review.
A federal appeals court based in Boston last spring struck as unconstitutional a key part of DOMA, ruling the federal government cannot deny tax, health and pension benefits to same-sex couples in states where they can legally marry. That ruling was a boost for gay rights advocates and the Obama administration.
Marriage between two males or two females is legal in the District of Columbia and six states -- Massachusetts, Connecticut, Iowa, Vermont, New Hampshire and New York.
Washington state and Maryland passed similar laws that will not take effect until voters decide in referendums in the November elections.
Many other states, including New Jersey, Illinois, Delaware, Rhode Island and Hawaii, have legalized domestic partnerships and civil unions for such couples -- a step designed in most cases to provide the same rights of marriage under state law.
But other states have passed laws or state constitutional amendments banning such marriages.
A bill known as the Respect for Marriage Act is working its way through Congress and would repeal DOMA. President Barack Obama, who previously opposed same-sex marriage, said in June he now supports it.
The larger issue has been working along two legal tracks, originating on opposite coasts.
A federal appeals court last month ruled against California's voter-approved ban on same-sex marriage, arguing the ban unconstitutionally singles out gays and lesbians for discrimination.
In a split decision, a three-judge panel of the 9th U.S. Circuit Court of Appeals found the state's Proposition 8 "works a meaningful harm to gays and lesbians" by denying their right to civil marriage in violation of the 14th Amendment.
The "Prop 8" case, as it has become known, has been down a complicated legal road. California's Supreme Court ruled that same-sex marriages were legal in 2008. About 18,000 gay and lesbian couples then legally obtained marriage licenses in the state. But after the statewide ballot measure banning the practice passed with 52% of the vote later that year, same-sex marriages were put on hold.
California is the only state that accepted, then revoked, same-sex marriage as a legal right.
The somewhat narrow federal appeals court ruling tossing out Proposition 8 never reached the right-to-marry question -- but instead ruled only on whether voters can decide such issues.
The Supreme Court has complete discretion to frame the same-sex marriage issues as the justices see fit. The court could determine whether a fundamental right is at stake, potentially striking down the laws of some states allowing only "traditional" marriages.
Or the justices could take a more narrow approach, and require the states to recognize same-sex marriages created in other states, without exception, without being forced to change their own laws.
It is unclear whether the first high court debate over same-sex marriage would be over federal, not state, laws -- or whether both questions will be addressed at the same time.
The justices would have ultimate discretion to accept one, both, or neither of the cases -- perhaps deferring judicial review until a later time, after other lower courts have had time to debate the matter. Or they may wait until Congress has had a chance to repeal or modify the current federal law.
The New York appeal is Windsor v. U.S (12-63).
The California appeal is Hollingsworth v. Perry (12-144).