Story highlights Tracey Cooper-Harris is suing to ensure death benefits go to her wife, Maggie

Cooper-Harris, who served in Iraq and Afghanistan, was diagnosed with MS

She also wants Maggie to be buried beside her in a veteran's cemetery

A U.S. Army veteran of both the Iraq and Afghanistan wars is suing the federal government, claiming she and her wife are being denied military benefits that are available to heterosexual married couples.

A complaint filed Wednesday in Los Angeles says that the government's definition of marriage is unconstitutional and violates equal protection.

"We're only asking for the same benefits as other married couples, we simply want the same peace of mind," Tracey Cooper-Harris, the plaintiff, said at a press conference in Washington announcing the lawsuit.

Cooper-Harris, who served 12 years in the Army, says she wants the same military benefits that a heterosexual married couple would receive.

Cooper-Harris said she was diagnosed in 2010 with multiple sclerosis, a disease that attacks the central nervous system.

The suit claims that her disease is "service-connected" and she does get disability compensation for it. But Cooper-Harris says she wants to make sure that after she dies, her spouse, Maggie, whom she married in 2008, is taken care of financially.

She also wants Maggie to be buried next to her in a veterans cemetery. These requests were denied by the Department of Veterans Affairs, the suit says, because "spouse" is defined as "a person of the opposite sex who is a wife or a husband."

The complaint says even if the VA recognized the marriage, the federal government would not. The Defense of Marriage Act (DOMA), passed in 1996, bars federal recognition of same-sex marriages and says states cannot be forced to recognize such marriages allowed in other states.

Cooper-Harris says she was married in California, where her marriage is legally recognized. "Tracey shouldn't have to endure discrimination that belittles her marriage and her service to this country," said Christine Sun, an attorney for Cooper-Harris.

Sun said she believes this is one of the first lawsuits filed by a veteran challenging same-sex marriage benefits from the military and says it could take years for a decision to be reached.