Washington - The U.S. appeals court in Boston became the first such court to strike down as unconstitutional the federal Defense of Marriage Act, ruling Thursday that it unfairly denies equal benefits to legally married same-sex couples.

The ruling is a victory for gay-rights advocates and the Obama administration, which had refused to defend that part of the 1996 law.

The decision sets the stage for a ruling next year by the Supreme Court on the constitutionality of the law that limits federal recognition of marriage to the union of a man and a woman.