In a legal brief, US Solicitor General Donald Verrilli's asked the court to uphold a federal appeals court ruling that found the Defense of Marriage Act unconstitutional, the San Jose Mercury News reported.
Passed in 1996, the act defines marriage as between one man and one woman.
It also prohibits the federal government from recognizing same-sex marriages, thus denying them federal benefits like Social Security.
In his brief, Verrilli argues that's wrong:
"The law denies to tens of thousands of same-sex couples who are legally married under state law an array of important federal benefits that are available to legally married opposite-sex couples. Because this discrimination cannot be justified as substantially furthering any important governmental interest, Section 3 is unconstitutional."
According to Politico, Obama administration has been urging lower courts to strike down DOMA for two years.
The Supreme Court is scheduled to hear the case March 27, The Huffington Post reported.