The high court agreed to review a case against a federal law that denies married same-sex couples the federal benefits heterosexual couples receive. It also took up a challenge to California's ban on gay marriage, known as Proposition 8, which voters narrowly approved in 2008.

Same-sex marriage is a politically charged issue in a country where 31 of the 50 states have passed constitutional amendments banning it, while Washington, D.C., and nine states have legalized it, three of them on Election Day last month.

Yet even where it is legal, married same-sex couples do not qualify for a host of federal benefits because the 1996 Defense of Marriage Act, or DOMA, passed by Congress, only recognizes marriages between a man and a woman.

Gays and lesbians married under state laws have filed suits challenging their denial of such benefits as Social Security survivor payments and the right to file joint federal tax returns. They argue the provision, known as Section 3, violates equal protection provisions of the U.S. Constitution.

Meeting in private on Friday at their last weekly conference before the court's holiday recess, the justices considered requests to review seven cases dealing with same-sex relationships. Five of them were challenges to the federal marriage law, one to California's gay marriage ban and another to an Arizona law against domestic partner benefits.