The Obama administration says it will no longer defend the constitutionality of a federal law that bans recognition of same-sex marriage.

In a statement Wednesday, Attorney General Eric Holder says U.S. President Barack Obama has concluded that the administration can no longer defend the federal law that defines marriage as only between a man and a woman.

The Justice Department had defended the Defence of Marriage Act in court until now.

In a letter to Congress, Holder wrote that "the president and I have concluded that classifications based on sexual orientation warrant heightened scrutiny and that, as applied to same-sex couples legally married under state law, Section 3 of [the Defence of Marriage Act] is unconstitutional."

With files from CBC News