(CNN) -- The federal judge who overturned California's ban on same-sex marriage is retiring, his court said Wednesday.
Vaughn R. Walker, 66, will step down as chief judge for the U.S. District Court Northern District of California at the end of the year and will formally leave the court in February 2011.
The lengthy legal fight over voter-approved Proposition 8, which defined marriage as a union between a man and a woman, continues in December, when the Ninth U.S. Circuit Court of Appeals considers an appeal of Walker's ruling.
In August, Vaughn ruled the measure violated the U.S. Constitution, saying it violated the equal protection clause.
"Proposition 8 fails to advance any rational basis in singling out gay men and lesbians for denial of a marriage license. Indeed, the evidence shows Proposition 8 does nothing more than enshrine in the California Constitution the notion that opposite-sex couples are superior to same-sex couples," Walker, who was appointed to the federal bench by former President George H.W. Bush, wrote in his opinion.
Wednesday's announcement said that Walker, a lawyer who was in private practice from 1972-1990, will return to the private sector. He has been a U.S. District Judge since 1990 and has been chief judge since 2004.
"Concluding 21 years of judicial service, I leave the bench with the highest respect and regard for the federal
judiciary, its judges and their staff and the essential role they fulfill in our constitutional system," Walker wrote President Barack Obama.