A federal appeals court in Boston, Massachusetts, has begun hearing arguments today about the constitutionality of the Defense of Marriage Act (DOMA), which denies federal benefits to married same-sex couples.

The case, whose legality is defended by the lawyers for the Bipartisan Legal Advisory Group of House of Representatives (BLAG), could have repercussions for equal marriage throughout the US.

The plaintiffs, including seven married same-sex couples and three widowers, are represented by Boston-based Gay & Lesbian Advocates and Defenders (GLAD). They say that DOMA unfairly discriminates against them, by denying access to equal protections and responsibilities available to heterosexual spouses.

It is not surprising that the first case to consider the constitutionality of DOMA occurs in Boston, as Massachusetts was the first state to extend the definition of marriage to include same-sex couples. Indeed, it was a federal judge in the state to first declare a key section of DOMA, which defines marriage strictly as a union between a man and a woman, unconstitutional in 2010.

Two other companion cases were heard on Wednesday: Gill vs. Office of Personnel Management, and Massachusetts vs. Health and Human Services. Mary Bonuato, of GLAD, said: “DOMA’s precise point was to create an across the board exclusion of same-sex couples in the US code… The promise of equal protection is that likes are to be treated alike – but DOMA treats married same-sex couples differently from all other married persons, making gay people and our marriages unequal to all others.”

The Department of Justice had announced in February of last year that it considered DOMA unconstitutional and would no longer defend it. The Department’s attorney, Stuart Delery, confirmed that position today.

Kris Mineau, president of the Massachusetts Family Institute, in opposing marriage equality said that it was a “national states rights issue.” He added: ”This would force a radical social agenda on the rest of the 50 states and we believe that is not in keeping with what our federal system is about.”

Among the widowers in the plaintiff is Dean Hara, who was married to Congressman Gerry Studds, who died in 2006. The pair married within a week of equal marriage becoming law in the state. Mr Hara is not eligible to receive federal pension provided to surviving spouses of former members of the Congress.

As we reported, another case in New York is looking into the constitutionality of DOMA as well, as it denies immigration rights to same-sex couples who are married in California and New York.