In the California case: It could leave California's ban on same-sex marriage in place unless voters there choose to revisit the question. It could allow same-sex marriage in California but not require it elsewhere. Or it could address the broader question of whether the Constitution requires states to allow such marriages.
Defense of Marriage Act: The court also will decide whether Congress can deprive legally married gay couples of federal benefits otherwise available to married people. Section 3 of the Defense of Marriage Act. Current federal law -- which defines marriage as between only a man and a woman -- requires the federal government to deny benefits to gay and lesbian couples married in states that allow such unions.
Where it's legal: By Jan. 1, same-sex couples will have the right to marry in nine states -- Connecticut, Iowa, Maine, Maryland, Massachusetts, New Hampshire, New York, Vermont, Washington -- and the District of Columbia. In Minnesota, voters in November rejected a bid to amend the state Constitution to bar the practice.
What's next: The cases probably will be argued in March, with decisions expected in June.