Here's a fascinating read courtesy of the Seattle Times:

In addition to state laws against discrimination, judges are subject to an even higher bar — the code of judicial conduct — which requires them to discharge their duties without bias or prejudice.

Those same canons bar judges from joining organizations with invidious and discriminatory practices, such as the Ku Klux Klan, or engaging in outside activities that cast doubt on their ability to be impartial.

While the state’s marriage law authorizes who can perform marriages, it does not require anyone to. Performing weddings is not a judicial duty but a discretionary function judges conduct on their own time and are compensated for privately.

“Judges may perform them or not,” said Thurston County Court administrator Marti Maxwell.

“Some elect to do them, some elect to do none,” she said. “There are some who will only do them during the week or during their lunch hours or after hours or for family and friends and some who will travel to the ends of the earth to do them.”

But Anne Levinson, a retired Seattle judge who was also a key adviser in the campaign to legalize same-sex marriage, said that “if a judge says he or she is available to perform weddings, then he can’t decline some of them based on any reason that has the appearance of bias or prejudice.”