A federal judge in San Francisco on Tuesday upheld retired Judge Vaughn R. Walker ruling on California's Proposition 8, after supporters of the measure accused Walker of being prejudiced in the case.

Sponsors of Proposition 8, California's 2008 ban on same sex marriage, argued that Walker should have been disqualified because he failed to disclose his 10-year relationship with a male partner. Attorney Charles Cooper alleged that Walker, who overturned the same sex marriage ban in January 2010, had a personal interest in the outcome of the case.

U.S. District Court Judge James Ware upheld Walker's ruling that Proposition 8 violated the Constitution's equal protection clause, noting there was no evidence that Walker should have recused himself from the Proposition 8 trial because he was in a same sex relationship.

"Rather than being different, same-sex and opposite-sex unions are, for all purposes relevant to California law, exactly the same," Walker wrote in his 136-page ruling. "The evidence shows conclusively that moral and religious views form the only basis for a belief that same-sex couples are different from opposite-sex couples."

Walker served as chief judge in the Northern District of California for six years before retiring at the end of February. After retiring, he publicly acknowledged his own sexual orientation and said he had been in a relationship with a male physician for 10 years. Walker was nominated to the federal bench in 1989 by George H.W. Bush.

"The presumption that Judge Walker, by virtue of being in a same-sex relationship, had a desire to be married that rendered him incapable of making an impartial decision, is as warrantless as the presumption that a female judge is incapable of being impartial in a case in which women seek legal relief," Ware wrote in his decision.

Ware added that requiring a judge to recuse him or herself solely because he or she was the member of a class subjected to the law in question would force minority judges to recuse themselves in nearly all civil rights cases.

"It is not reasonable to presume that a judge is incapable of making an impartial decision about the constitutionality of a law, solely because, as a citizen, the judge could be affected by the proceedings," Ware added. "Although this case was filed by same sex couples seeking to end a California constitutional restriction on their right to marry, all Californians have an equal interest in the outcome of the case."