WASHINGTON - The same-sex marriage debate is entering a second day of arguments in the nation's highest court.

The U.S. Supreme Court will examine the 1996 Defense of Marriage Act, which defines marriage as a relationship between a man and a woman for purposes of federal law, regardless of a state's law.

The major question is whether legally married same-sex couples should be entitled to the same federal benefits available to married heterosexual couples, such as health insurance.

Justices already heard arguments this week on California's Proposition 8, a voter-approved ban on gay marriage.

A decision is expected later this year, but justices have raised doubts, suggesting that the court could dismiss the cases with no ruling at all.