Lawyers for Edith Windsor on Thursday told a federal appeals court in New York that the Defense of Marriage Act (DOMA) discriminates against gay couples and should be declared unconstitutional.

The 83-year-old Windsor sued the federal government after she received an estate bill of more than $360,000 resulting from the death of her wife Thea Spyer. Windsor maintains that DOMA, which bars federal agencies from recognizing the legal marriages of gay and lesbian couples, violates the equal protection guarantee of the U.S. Constitution.

Windsor and Spyer shared their lives for 44 years and married in Toronto, Canada in 2007. In 2009, New York began recognizing the marriages of gay couples, although gay couples could not enter such unions in the Empire State until last year. Spyer died in 2009.

On June 6, New York District Court Judge Barbara Jones ruled in favor of Windsor.

The House's Bipartisan Legal Advisory Group (BLAG) at the direction of House Speaker John Boehner intervened to defend the law after President Barack Obama instructed the Department of Justice to no longer defend DOMA in court.

BLAG lawyer Paul Clement argued on Thursday that gay men and lesbians, as a group, have political clout and, unlike African-Americans and women, have never faced “structural impediments” such as being denied the right to vote.

Outside the courtroom, Windsor disagreed with Clement, telling reporters that DOMA is discriminatory.

“The Defense of Marriage Act discriminates against gay people,” she said. “Not only is it illegal, as my lawyers argued today, but it refutes, it really challenges the basic principles on which this country was founded: fairness and equality.”

The three-judge panel is not expected to issue a ruling for several months.