Retired federal judge Vaughn R. Walker did not disclose that he was gay, and in a 10-year relationship with his partner, before ruling that the challenge to Proposition 8, the 2008 California ballot measure that banned same-sex marriage, was unconstitutional. His decision is now before an appeals court, the Los Angeles Times reports

A conservative Christian group ProtectMarriage has asked a federal judge to void Walker's ruling on the grounds that he might benefit from his own decision if he wishes to marry his partner. The appeal, set for June 13, has sparked a debate over legal ethics.

Under federal law, judges can be disqualified from cases because of financial interests, friendships with litigants, or a personal bias or prejudice. Charles J. Cooper, representing ProtectMarriage, said that Walker would not be disqualified from all gay rights cases, e.g., he could rule on open homosexuality in the military, because that would not affect him. But Walker's long-term relationship, and determination that marriage offers benefits for those in "committed, long-term, same-sex relationships," suggest that Walker had a personal interest in the outcome.

Cooper may be fighting a losing battle, however. Most legal experts believe that Walker's relationship would not disqualify his decision, as long as he was not attempting to marry his partner in California. Hofstra Law School Professor Monroe Freedman pointed to "failed attempts to prevent a female African American judge from presiding over a sex discrimination case, a Jewish judge from a case involving an anti-Semitic pogrom and a Catholic judge from an abortion dispute."

But the line, even for Freedman, is not always so clear. In the past, Freedman defended U.S. 9th Circuit Judge John T. Noonan Jr. for refusing to remove himself from an abortion case even though he is a devout Roman Catholic. Later, Freedman amended his opinion after learning that Noonan had disparaged abortion doctors in a published article.

"The U.S. Supreme Court has held unanimously that if a judge manifests a bias against an entire category of litigants, that disqualifies him," Freedman said.

While finding that there was no reason to disqualify Walker, New York University Law School Professor Stephen Gillers said that the judge should have disclosed his situation before trial.

"A judge should always disclose facts that are not publicly available, as in public financial disclosure filings, to give the parties a chance to seek recusal," Gillers said, citing America Bar Association conduct guidelines.