Can a party bring a motion to disqualify an opposing attorney from the witness list?

By 1979, the appellate court in White v. Superior Court (1979) 98 Cal.App.3d 51, 55-56, 159 Cal.Rptr. 278, ruled that a party seeking to challenge an attorney's qualification to represent an adversary party must proceed at the first reasonable opportunity and by proper motion to achieve that end. In White, the allegedly disqualified attorney had previously represented both parties during the preparation of their partnership agreement; now, he appeared for one of the partners in an action against the other. Counsel could become a witness; the moving party also argued some confidences would be disclosed.