Lawyers defending Proposition 8, California's gay marriage ban, return to court Monday to ask a judge to scrap the ruling of U.S. District Judge Vaughn Walker because he's gay.

Last August, Walker ruled that the 2008 voter-approved law was unconstitutional after presiding over a 13-day trial in San Francisco.

In April – three months into his retirement from the bench – Walker acknowledged that he's gay and in a ten-year relationship with a physician, confirming for the first time reports published in February.

Lawyers for Protect Marriage, the coalition of socially conservative groups defending the law, have asked Chief Judge James Ware to set aside Walker's ruling striking down the law. They argue that Walker should have recused himself because he's in a same-sex relationship.

“If at any time while this case was pending before him, Chief Judge Walker and his partner determined that they desired, or might desire, to marry, Chief Judge Walker plainly had an interest that could be substantially affected by the outcome of the proceeding,” lawyers wrote.

Andrew Pugno, general counsel for Protect Marriage, also railed against Walker in a statement.

“The American people have a right to a fair judicial process, free from even the appearance of bias or prejudice. Judge Walker's ten-year-long same-sex relationship creates the unavoidable impression that he was not the impartial judge the law requires. He was obligated to either recuse himself or provide full disclosure of this relationship at the outset of the case. These circumstances demand setting aside his decision.”

Legal experts don't believe the argument will gain much traction in Judge Ware's chamber.

Chad Griffin, president of the American Foundation for Equal Rights, the group formed specifically to support the case, called the claim “desperate and absurd.”

“They're attacking the judge because they disagree with his decision,” Griffin told

Others have noted that Walker and his partner did have the opportunity to marry in 2008 before voters overturned a California Supreme Court decision legalizing the institution but chose not to.