(Washington) The Obama administration filed court papers Monday claiming a federal marriage law discriminates against gays, even as government lawyers continued to defend it.

Justice Department lawyers are seeking to dismiss a suit brought by a gay California couple challenging the 1996 Defense of Marriage Act. The administration’s response to the case has angered gay activists who see it as backtracking on campaign promises made by Barack Obama last year.

In court papers, the administration said it supports repeal of the law.

Yet the same filing says the Justice Department will defend the statute in this case because a reasonable argument can be made that the law is constitutional.

The government’s previous filing in the case angered gay rights activists who supported Obama’s candidacy in part because of his pledge to move forward on repealing the law and the “don’t ask, don’t tell” policy that prevents gays from serving openly in the military.

“The administration believes the Defense of Marriage Act is discriminatory and should be repealed,” said Justice Department spokeswoman Tracy Schmaler, because it prevents equal rights and benefits.

The department is obligated “to defend federal statutes when they are challenged in court. The Justice Department cannot pick and choose which federal laws it will defend based on any one administration’s policy preferences,” Schmaler added.

The law, often called DOMA, denies federal recognition of gay marriage and gives states the right to refuse to recognize same-sex marriages performed in other states.

“DOMA reflects a cautiously limited response to society’s still-evolving understanding of the institution of marriage,” according to the filing by Assistant Attorney General Tony West.

The administration also disavowed past arguments made by conservatives that DOMA protects children by defining marriage as between a man and a woman.

“The United States does not believe that DOMA is rationally related to any legitimate government interests in procreation and child-rearing and is therefore not relying upon any such interests to defend DOMA’s constitutionality,” lawyers argued in the filing.

Obama has pledged to work to repeal the law.

Monday’s court filing was in response to a lawsuit by Arthur Smelt and Christopher Hammer, who are challenging the federal law, which prevents couples in states that recognize same-sex unions from securing Social Security spousal benefits, filing joint taxes and benefiting from other federal rights connected to marriage.

Justice lawyers have argued that the act is constitutional and contend that awarding federal marriage benefits to gays would infringe on the rights of taxpayers in the 30 states that specifically prohibit same-sex marriages.

Earlier this year, Massachusetts became the first state to challenge the law in court.