The largest group representing gay troops on Thursday filed a lawsuit in federal court challenging the constitutionality of the Defense of Marriage Act (DOMA) as it relates to gay and lesbian service members.

Servicemembers Legal Defense Network (SLDN) is representing six gay couples in the lawsuit.

The legal challenge, filed in the same Boston federal court that ruled last year that DOMA is unconstitutional, argues that the 1996 law that bars federal agencies and the military from recognizing the legal marriages of gay couples violates gay military couples' Fifth Amendment right to due process.

“This case is about one thing, plain and simple. It's about justice for gay and lesbian service members and their families in our armed forces rendering the same military service, making the same sacrifices, and taking the same risks to keep our nation secure at home and abroad,” said SLDN Executive Director Aubrey Sarvis in a statement. “These couples are in long term, committed, and legally recognized marriages, and the military should not be forced to turn its back on them because the federal government refuses to recognize their families.”

Massachusetts Army National Guard Maj. Shannon McLaughlin, 41, and her wife, Casey, 34, are lead plaintiffs in the suit. The McLaughlins married in 2009 and are the parents of ten-month old twins, Grace and Grant.

“We've been serving our country too long, working too hard, and sacrificing too much to see our families denied the same recognition, support and benefits as our straight, married counterparts,” McLaughlin said.

According to SLDN, DOMA blocks the military from providing housing, health care, surviving spouse benefits and morale, welfare and recreation programs to the spouses of gay service members.

“As plaintiffs, we are fighting to receive the same benefits and opportunities as our married heterosexual counterparts,” said Chief Warrant Officer 2 Charlie Morgan of the New Hampshire National Guard, a plaintiff in the case. “This discrimination causes undue financial and emotional hardship for our families. As a cancer survivor, who has been recently diagnosed with a recurrence, I worry every day that my health may take a turn for the worse, and Karen would be unable to receive the survivor's benefits to help take care of our daughter. We are only asking for fair and equitable treatment as a recognized family.”

The list of legal challenges to the law continues to grow, even as the Senate has taken steps to repeal the law. However, the issue is a non-starter in the House, where its speaker, Rep. John Boehner of Ohio, is defending the law in court.