SAN FRANCISCO — A sitting judge took the witness stand on Thursday and faced an unusual adversary — his former political opponent, who is now facing ethics charges and possible discipline over his campaign tactics.

On Day 3 of the State Bar of California's trial against Clinton Parish, Yolo County Superior Court Judge Daniel Maguire testified for the bar's Office of Chief Trial Counsel that Parish's 2012 judicial campaign had spread false allegations through mailers and a campaign website.