Former President Bill Clinton, who in 1996 signed into law an act defining marriage as between a man and woman, said on Thursday the measure was unconstitutional and should be overturned by the Supreme Court.
In an opinion piece in the Washington Post, Clinton, a Democrat who served as president from 1993 to 2001, said it was "a very different time" when he signed the Defense of Marriage Act into law. No U.S. state then recognized gay marriage, although some were moving in that direction, he said.
With federal lawmakers then debating various responses, "some quite draconian," many supporters of the Defense of Marriage Act, or DOMA, believed its passage would defuse moves to push for a constitutional amendment banning same-sex marriage, Clinton wrote.
Noting that the Supreme Court will hear arguments on March 27 challenging the constitutionality of DOMA, Clinton wrote the justices "must decide whether it is consistent with the principles of a nation that honors freedom, equality and justice above all, and is therefore constitutional.
"As the president who signed the act into law, I have come to believe that DOMA is contrary to those principles and in fact, incompatible with our Constitution."
The Obama administration has also urged the high court to strike down the law, saying it violates the guarantees of equal protection under the law by denying same-sex married couples federal benefits available to married heterosexuals.
Nine states and the District of Columbia allow same-sex marriage.
Clinton wrote that when he signed the law, he included a statement that its enactment should not "be understood to provide an excuse for discrimination."
"Reading those words today, I know now that, even worse than providing an excuse for discrimination, the law is itself discriminatory. It should be overturned," he said.
Writing by Peter Cooney; Editing by David Brunnstrom