The Obama administration Wednesday defended its right to define marriage as a heterosexual union before a federal judge considering the constitutionality of the Defense Of Marriage Act (DOMA), the AP reported.

The Massachusetts attorney general's office is challenging the section of the law that denies married gay and lesbian couples federal benefits such as income tax credits, employment and retirement benefits, health insurance coverage and Social Security payments.

Representing the nearly 16,000 gay couples who have married in Massachusetts since gay marriage became legal in 2004, Assistant Attorney General Maura Healey argued that the right to define marriage has historically been held by the states.

“Never before has the federal government told a married couple that they are married under state law but not under federal law,” Healey said, adding that states “have always had exclusive control over defining and regulating marriage.”

DOMA also allows states to ignore legal gay marriages performed in other states, but the attorney general is not challenging this section of the law. A win then would only affect states that have legalized such unions.

Christopher Hall, a Justice Department lawyer, argued the federal government has the right to define marriage and set eligibility requirements for federal benefits.

Healey also argued that DOMA “forces Massachusetts to discriminate against its own citizens” because it interferes with the state's authority to regulate marriage.

Hall disagreed, saying the law doesn't forbid states from legalizing gay marriage.

In a brief submitted to the court, the attorney general also claims that the law “codified an animus towards gay and lesbian people.”

Two additional federal challenges to limiting marriage to a heterosexual union have already been heard.

The first federal trial to challenge the constitutionality of a gay marriage ban wrapped up in January after more than three week's worth of testimony. Lawyers representing a gay and a lesbian couple argued that California's gay marriage ban, Proposition 8, violates their constitutional rights. Closing arguments are expected to be heard in June.

A second federal challenge to DOMA has also been filed in Massachusetts by 17 gay men and lesbians who were married in the state. Judge Tauro is also presiding over that case.

Gay advocates believe all three cases will likely reach the Supreme Court.

Legislation that would repeal DOMA has not gained sufficient traction.