I was wondering if this was true. Sherrilyn A. Ifill at The Root answers the question:
Rumors about Judge Walker’s sexual orientation were well-known to attorneys for the state of California long before the trial concerning Prop 8. Why, then, didn’t the State of California file a motion seeking the recusal of Judge Walker? The simple reason is that Judge Walker’s sexual orientation — whether gay or straight — is not an appropriate basis for a recusal motion. In fact, the suggestion that Judge Walker’s sexual orientation is evidence of bias is the kind of argument that was firmly discredited in a series of cases challenging the impartiality of black judges to decide civil rights cases.
Under federal recusal statutes, judges should be disqualified from hearing cases in which they are actually biased, but should also withdraw from cases in which their impartiality might reasonably be questioned. In the late 1970s and early 1980s — as a bumper crop of minority federal district judges appointed by President Jimmy Carter presided over employment-discrimination cases brought under Title VII of the Civil Rights Act of 1964 — recusal motions were filed by defendants seeking to remove black judges from hearing these cases. Black judges pushed back firmly against attempts to question their impartiality and framed what has become the universally accepted understanding among the bench and bar: that judicial bias cannot be assumed based on the racial, gender or other status of the judge.
In perhaps the most famous of these cases, lawyers representing the New York law firm of Sullivan & Cromwell requested that federal district judge Constance Baker Motley recuse herself from hearing a case brought by women lawyers at the firm who charged discrimination in hiring and promotion. The law firm’s motion for recusal was based on Judge Motley’s status as a black woman and her professional experience as a former civil rights lawyer.