District court judge in California is third federal judge to issue a similar ruling over 1996 Defence of Marriage Act

This article is more than 8 years old

This article is more than 8 years old

A federal judge has boosted the campaign for gay marriage by overturning a law which denied federal benefits to same-sex couples.

Claudia Wilken, a district court judge for the northern district of California, ruled on Thursday that congress acted unconstitutionally in discriminating against gay couples in the 1996 Defence of Marriage Act (Doma).

Wilken became the first judge to rule against the controversial legislation since President Barack Obama threw his weight behind gay marriage earlier this month.

Gay rights campaigners welcomed the ruling. "This adds to the momentum for overturning this radical and discriminatory law," said Evan Wolfson, of Freedom to Marry, an advocacy group.

Wilken, a Clinton-era appointee based in Oakland, a liberal bastion, was the third federal judge to find Doma unconstitutional following a ruling by judge Joseph Tauro in Massachusetts in 2010 and one by judge Jeffrey White in California earlier this year. That ruling is under appeal and is due to go before a circuit court of appeals in September. Thursday's ruling is also expected to be appealed.

Doma, which was championed by opponents of gay marriage, defines marriage as "a legal union of a one man and one woman as husband and wife". It withholds multiple federal benefits, including joint tax filing and immigration sponsorship, from gay couples legally married under state law.

Wilken said gays and lesbians were constitutionally protected from "burdensome legislation that is the product of sheer antigay animus and devoid of any legitimate governmental purpose", according to the San Francisco Chronicle.

Wilken also overturned another 1996 law withholding federal tax benefits to long-term health insurance plans for state employees if they included domestic partners.

That, like Doma, was based on "moral condemnation and social disapprobation of same-sex couples," she said. The judge cited congressional debate transcripts that same-sex domestic partnership was "an attack on the family" and would "undermine the traditional moral values that are the bedrock of this nation".

Wilken was ruling in a lawsuit filed against the California Public Employees' Retirement System by same-sex couples whose spouses were barred from enrolling in the federally approved insurance programme. Wilken said there was no proof the Doma provision was "rationally related to a legitimate government interest".

The ruling followed signs public opinion was shifting behind the president. A Washington Post-ABC News poll found that 53% of Americans say same-sex marriage should be legal, a sharp rise. Just 39%, a new low, say it should be illegal.