A federal judge this week will hear only arguments in favor of striking down Oregon's ban on gay marriage.

U.S. District Judge Michael McShane on Wednesday will hear arguments in a case challenging Oregon's 2004 voter-approved constitutional amendment limiting marriage to heterosexual couples.

Attorney General Ellen Rosenblum has not only called the ban legally indefensible, she has encouraged McShane to throw it out, saying that the state is prepared to begin issuing marriage licenses to gay and lesbian couples.

“If this Court determines that Oregon's prohibition on same-sex marriage violates plaintiffs' rights under the federal constitutional, the state is prepared to implement that ruling,” Rosenblum wrote in a 35-page filing.

Not legal argument for upholding the ban has been submitted.

The case is also unique in that McShane, the state's most recently appointed federal judge, is one of just nine openly gay members of the federal judiciary, a wrinkle which has riled opponents of marriage equality.

“The question is not his sexual orientation,” said John Eastman, chairman of the National Organization for Marriage (NOM), the nation's most vociferous opponent of marriage equality, “but whether he is situated identically to the plaintiffs and will benefit from the exact relief he provides to them.”

Since December, federal judges have struck down all or part of similar bans in Utah, Oklahoma, Michigan, Texas, Virginia, Ohio, Kentucky and Tennessee.

Last week, challenges from Utah and Oklahoma became the first to reach an appeals court.

(Related: Appeals court reviews challenge to Oklahoma's gay marriage ban.)