California Code, Probate Code - PROB § 4690

(a) If the principal becomes wholly or partially incapacitated, or if there is a question concerning the capacity of the principal, the agent may consult with a person previously designated by the principal for this purpose, and may also consult with and obtain information needed to carry out the agent's duties from the principal's spouse, physician, supervising health care provider, attorney, a member of the principal's family, or other person, including a business entity or government agency, with respect to matters covered by the power of attorney for health care.

(b) A person described in subdivision (a) from whom information is requested shall disclose information that the agent requires to carry out his or her duties. Disclosure under this section is not a waiver of any privilege that may apply to the information disclosed.