A primer on major gay marriage cases pending before the Supreme Court

On Friday morning, the Supreme Court may announce whether it will hear two major cases that could have a sweeping impact on the definition of marriage in the United States and on same-sex couples' right to wed.

Ten cases dealing with gay marriage are pending before the court, but legal experts pinpoint two of them as the most likely for the court to consider.

The Defense of Marriage Act

The Defense of Marriage Act, or DOMA, recently has been struck down by two federal appeals courts, which means the Supreme Court is all but obligated to take at least one of the cases to settle the dispute between Congress and the courts. The case thought most likely to be picked up by the justices is Windsor v. United States, which challenges DOMA, a law passed by Congress and signed by President Bill Clinton in 1996 that prevents the federal government from recognizing same-sex married couples, even those in states that allow gay marriage.

The suit was brought by Edith Windsor, a resident of New York who paid $363,000 in estate taxes after her wife died because the federal government did not recognize their marriage. New York is one of nine states (and the District of Columbia) where gay marriage is legal, so Windsor argues that the federal government is discriminating against her by not recognizing her state-sanctioned marriage.

Doug NeJaime, an associate professor at Loyola Law School in Los Angeles, said that equal protection under the law, which is guaranteed under the 14th Amendment, is the key issue at stake in this case. Windsor argues that by singling out same-sex marriages and treating them differently from other marriages, the federal government is in violation of their rights. Since marriage has traditionally been regulated by the state, Windsor's lawyers say the federal government has no business interfering with New York's definition of marriage.

Windsor's attorneys are not arguing, however, that marriage is a fundamental right that all Americans are entitled to, no matter their sexual orientation. And few experts expect the Supreme Court to make such a sweeping decision.

If the justices do strike down DOMA, the decision will broadly affect gay couples who marry in states that recognize same-sex nuptials. Most importantly, they would begin to qualify for the same federal marriage benefits other couples receive, including tax breaks and Social Security survivor benefits. And according to advocates, the decision would send an even larger message -- that all marriages are equal under the law.

As with other recent major cases, Justice Anthony Kennedy appears to be the swing vote. For DOMA to be overturned, Kennedy would have to join the court's four liberal justices to form a majority.

Kennedy has a libertarian streak that makes his votes unpredictable, as well as a legal record in favor of gay rights. In 2003, Kennedy wrote the Court's opinion in Lawrence v Texas, a landmark decision that said the government cannot outlaw anal sex between consenting adults, whatever their sexual orientation. ("The liberty protected by the Constitution allows homosexual persons the right to choose to enter upon relationships in the confines of their homes and their own private lives and still retain their dignity as free persons," he wrote.) Kennedy also cast the deciding vote striking down a Colorado law that would have prevented local governments from passing laws specifically protecting gay and lesbian civil rights.

Because of Kennedy's history on the issue, many legal experts think there's a good chance the court will strike down DOMA if it takes the case.

"I think that Justice Kennedy knows that he has the choice: Does he want to write the next Plessy v. Ferguson or does he want to write the next Brown v. Education," said Erwin Chemerinsky, founding dean of the University of California, Irvine School of Law, and a proponent of gay rights. The landmark Brown civil rights case overturned Plessy, which had endorsed "separate but equal" segregation in public schools.

"There's no doubt where the world is going on this issue," Chemerinsky said of same-sex marriage.

But John Eastman, chairman of the anti-gay marriage National Organization for Marriage and a law professor at Chapman University, said it's still unclear how Kennedy will decide, despite his landmark opinion in Lawrence. "There's a pretty big difference between criminalizing conduct and redefining marriage," Chapman said, referring to the anti-sodomy laws Kennedy struck down. "He could draw the line there."

Proposition 8

Court watchers think the Supreme Court also will take up Proposition 8, California's gay marriage ban. Voters passed Prop. 8 in 2008 months after the state's high court had legalized same sex unions and thousands of gay Californians had already tied the knot. Two federal courts have struck down Prop. 8 as discriminatory, leaving the Supreme Court to render a final judgment.

The lower courts' decisions made an overt appeal to Justice Kennedy by repeatedly citing his decision in the Colorado gay rights case. The lower court judges argued that by revoking marriage rights after they had already been granted, same-sex couples had been illegally singled out for discrimination.

If the Supreme Court agrees with that interpretation and decides to let the lower courts' rulings remain in place, gay couples in California--the nation's most populous state --would be able to get married legally within the month. But the decision would only apply to California. If the court does take up the case, the justices will decide by June whether to strike down or uphold the state's gay marriage ban.

The Prop. 8 case differs from the DOMA case in one key respect: In Prop. 8, the pro-gay marriage side is arguing that marriage is a fundamental right that should not be denied to people based on their sexual orientation. That means the Supreme Court, in theory, could issue a sweeping decision on Prop. 8 that legalizes gay marriage throughout the country and invalidates state gay marriage bans.

Geoffrey Stone, a law professor at the University of Chicago, thinks that's unlikely. He says the justices will most likely wait for public opinion--which has just recently begun to swing in support of gay marriage--and state laws to coalesce around the issue before issuing a broad decision.

"The more this percolates, the easier it is to address this in the future," Stone said.