The Obama administration on Friday called for the U.S. Supreme Court to declare the federal government’s 1996 ban on same-sex marriage benefits unconstitutional, saying “gay and lesbian people have been subject to a significant history of discrimination in this country.”

U.S. Solicitor General Donald Verrilli’s legal brief urges the court to uphold a federal appeals court ruling that found the Defense of Marriage Act unconstitutional. The administration’s position was not unexpected because it has already expressed its legal position in challenges to DOMA, including in a case involving a San Francisco couple.

But the legal brief marked the first time a president has endorsed same-sex marriage rights in the Supreme Court. Administration lawyers expressed particular concern about federal law denying equal benefits to couples legally married in states that permit same-sex nuptials, including New York, where the case before the Supreme Court has unfolded.

“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,” the solicitor general wrote.

The brief did not address the separate legal challenge to Proposition 8, California’s voter-approved ban on same-sex marriage. The administration is expected by late next week to decide whether to take a position in the California case, which is to be heard in the Supreme Court on March 26.

The justices will hear the DOMA case on March 27. The case involves Edith Windsor, who originally married in Canada in 2007 and challenged the federal law when her spouse and partner of four decades died and she was required to pay more than $360,000 in federal estate taxes because she was not deemed married under DOMA. New York, Windsor’s home, has since become one of nine states that have legalized gay marriage.

House Republicans have intervened to defend the federal law, saying Congress had the authority to restrict marriage benefits to heterosexual couples. In a brief filed Friday that the high court requested, House Republicans argued that they have a legal right to defend the law in the Supreme Court in the absence of a defense from the executive branch.

In a separate brief filed Friday, Windsor’s lawyers agreed that the Supreme Court can decide the constitutionality of the law, saying it continues to be enforced against same-sex couples despite the administration’s position. Verrilli also backed that position in the government’s brief.

Howard Mintz covers legal affairs. Contact him at 408-286-0236 or follow him at Twitter.com/hmintz