The Supreme announced on Friday that it would hear two same-sex marriages cases. The resulting rulings could determine the legality of same-sex marriage in the country for a generation.
The first case, Hollingsworth v. Perry, deals with Proposition 8, the California ballot initiative that banned same-sex marriage in 2008, after the California Supreme Court rules that it was legal.
Proposition 8 was challenged, and a federal judge in San Francisco struck down the measure. The Ninth Circuit Court of Appeal also agreed the initiative was unconstitutional, but that decision was split, 2-1.
Now the Supreme Court will decide the case. It could have declined to hear the case, which would have let the Ninth Circuit decision stand, allowing same-sex marriage in California.
Instead, same-sex marriage backers are hoping for a far-reaching decision that will require broad legalization of same-sex marriage throughout the country.
That is a possibility, but far from the only one. The court leans conservative, with only four liberal justices to five conservative ones. If the court rules along partisan lines, it could overturn the Ninth Circuit decision and rule that Proposition 8 is legal. While that would ban same-sex marriage in California, it would not affect any other state.
The court could also affirm the Ninth Circuit decision, but only in a narrow way, which would allow same-sex marriage in California, but again, affect no other states.
Or the court could use the opportunity to weigh in on same-sex marriage at the national level, either legalizing it across the country or banning it nationwide.
The latter option is unlikely, as the four liberal justices wouldn't opt to ban same-sex marriage, and Justice Anthony Kennedy, considered a moderate conservative, has supported gay rights in previous decisions on the court. There is also speculation that Kennedy has been wanting to cement his legacy with a landmark decision, though others argue that he has already done so, as he wrote the majority opinion in the Citizens United decision that allowed unregulated fundraising in political campaigns.
Justices Antonin Scalia, Clarence Thomas and Samuel Alito are likely to rule against same-sex marriage in any case. Chief Justice John Roberts has shown himself to be persuadable, as he provided the deciding vote in upholding the constitutionality of the Affordable Care Act, known as Obamacare.
The second case the court will hear, United States v. Windsor, deals with the Defense of Marriage Act, the 1996 congressional bill that defined marriage as a union of one man and one woman.
Edith Windsor and Thea Clara Spyer of New York married in a same-sex wedding in Canada in 2007. Spyer died in 2009, and Windsor inherited her estate. Had they been an opposite-sex couple, Windsor would have paid no taxes on the Spyer's possessions, as they would be shared marital property.
But under DoMA, federal law is banned from treating the two women as married, so Windsor was ordered to pay $360,000 in taxes on Spyer's property.
Many legal scholars say the case is fairly simple, and the court has almost no choice but to strike down DoMA.
In 2011, the Obama administration announced that it would no longer defend DoMA in the courts, so Republicans stepped up and provided lawyers who will be arguing for the bill in front of the Supreme Court.
The judges are expected to announce a ruling in both cases by June of 2013.