Hession sued the City and County of San Francisco (P) for personal injuries. Hession's attorney's retained Dr. Catton to give Hession a neurological and psychiatric examination for use in the litigation. In his deposition, Catton testified that he had no physical-patient relationship with Hession; that the sole purpose of the examination was to aid Hession's attorneys in preparing his case; and that he was an agent of the attorneys. Catton refused to answer questions regarding Hession's condition. Hession's attorneys claimed that the information was protected by the attorney-client privilege. P seeks a writ of mandamus to compel the court to order Catton to answer questions.