A US act that defines marriage as a union between a man and a woman has been ruled by the American federal appeals court as unconstitutional.

Plantiffs in Boston argued that the The Defence of Marriage Act (DOMA) was discriminatory because federal social security, veterans and other benefits were denied to same-sex couples married in Massachusetts, where such unions are legal.

“The denial of federal benefits to same-sex couples lawfully married does burden the choice of states like Massachusetts to regulate the rules and incidents of marriage,” the appeals judges said in their opinion today, upholding the ruling of a lower court.

Judge Michael Boudin wrote, “This case is difficult because it couples issues of equal protection and federalism with the need to assess the rationale for a congressional statute passed with minimal hearings and lacking in formal findings. In addition, Supreme Court precedent offers some help to each side, but the rationale in several cases is open to interpretation. We have done our best to discern the direction of these precedents, but only the Supreme Court can finally decide this unique case.”