A lawsuit challenging a federal law that defines marriage as a union between a man and a woman is getting its first hearing in court Thursday.

A federal judge in Boston is hearing arguments on a constitutional challenge to the Defense of Marriage Act, reports the Advocate.

The case, brought by Gay and Lesbian Advocates and Defenders (GLAD), challenges Section 3 of DOMA, which prevents the federal government from recognizing same-sex marriages. The case does not extend to whether individual states can recognize same-sex marriages.

GLAD attorney Mary L. Bonatuo will argue on behalf of seven married same-sex couples and three widowers that the section of DOMA violates the federal constitutional guarantee of equal protection as applied to federal income taxation, Social Security benefits, and federal employee and retiree benefits.

"We think it's actually really simple," GLAD executive director Lee Swislow told The Advocate moments before heading to the court Thursday morning. "The government has carved out one set of legally married couples and excluded them from the federal benefits that every other legally married couple gets. Throughout its history, the federal government has always respected the state definition of marriage. But for same-sex couples, they're making the decision. We say there is a clear violation of equal protection."

A Justice Department lawyer says the Obama administration wants the act repealed, but that the department is obliged to defend the constitutionality of laws passed by Congress.

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