A Massachusetts appeals court has ruled against a U.S. marriage law that denies federal benefits to same-sex married couples.

The First U.S. Circuit Court of Appeals in Boston ruled Thursday that the Defense of Marriage Act (DOMA) was unconstitutional.

The 1996 law defines marriage as a union between a man and a woman, and absolves states from recognizing same-sex marriages performed in states where they are allowed.

The issue of gay marriage has sparked fierce debate from both sides. Thursday's decision is the latest in a series of high-profile rulings declaring the law in violation of the equal protection rights guaranteed under the U.S. Constitution.

The Gay and Lesbian Advocates and Defenders group, which argued against the law, said the decision reaffirms the lower court ruling that “all married couples and surviving spouses deserve the same opportunities to care and provide for each other and their families.”

President Barack Obama, who had previously said his stance on same-sex marriage was “evolving,” declared support for gay marriage earlier this month.

Last year, he and Attorney General Eric Holder said they would no longer defend the Defense of Marriage Act. White House spokesman Jay Carney said Thursday's ruling was in “concert with the president's views.”

Ari Ezra Waldman, a visiting law professor at New York's Brooklyn Law School, told VOA that what makes this ruling “substantively impactful” is that it is the first U.S. appellate court to declare the law unconstitutional, adding that these types of rulings often offer a blueprint for other courts to follow.

Last month, a U.S. district court in the western state of California ruled against it in a case where same-sex spouses of state workers were denied long-term care insurance. Several other challenges to the law are pending.

Several states have legalized gay marriage, but it is not recognized on the federal level.

The Supreme Court will likely take up the issue, and it is also expected to be an election-year topic.