Cal. Ins. Code § 791.10

(a) In the event of an adverse underwriting decision the insurance institution or agent responsible for the decision shall:
1. (1) Either provide the applicant, policyholder, or individual proposed for coverage with the specific reason or reasons for the adverse underwriting decision in writing or, except as provided in subdivision (e), advise the person that upon written request he or she may receive the specific reason or reasons in writing.
2. (2) Provide the applicant, policyholder or individual proposed for coverage with a summary of the rights established under subdivision (b) and Sections 791.08 and 791.09.
(b) Upon receipt of a written request within 90 business days from the date of the mailing of notice or other communication of an adverse underwriting decision to an applicant, policyholder or individual proposed for coverage, the insurance institution or agent shall furnish to such person within 21 business days from the date of receipt of such written request:
1. (1) The specific reason or reasons for the adverse underwriting decision, in writing, if such information was not initially furnished in writing pursuant to paragraph (1) of subdivision (a).
2. (2) The specific items of personal and privileged information that support those reasons; provided, however:
  1. (A) The insurance institution or agent shall not be required to furnish specific items of privileged information if it has a reasonable suspicion, based upon specific information available for review by the commissioner, that the applicant, policyholder or individual proposed for coverage has engaged in criminal activity, fraud, material misrepresentation or material nondisclosure.
  2. (B) Specific items of medical record information supplied by a medical care institution or medical professional shall be disclosed either directly to the individual about whom the information relates or to a medical professional designated by the individual and licensed to provide medical care with respect to the condition to which the information relates, whichever the individual prefers.
    Mental health record information shall be supplied directly to the individual, pursuant to this subdivision, only with the approval of the qualified professional person with treatment responsibility for the condition to which the information relates.
3. (3) The names and addresses of the institutional sources that supplied the specific items of information given pursuant to paragraph (2) of subdivision (b); provided, however, that the identity of any medical professional or medical care institution shall be disclosed either directly to the individual or to the designated medical professional, whichever the individual prefers.
(c) The obligations imposed by this section upon an insurance institution or agent may be satisfied by another insurance institution or agent authorized to act on its behalf.
(d) When an adverse underwriting decision results solely from an oral request or inquiry, the explanation of reasons and summary of rights required by subdivision (a) or (e) may be given orally to the extent that such information is available.
(e) Except as provided in subdivision (d), with respect to a declination, cancellation, or nonrenewal of a property insurance policy covered by Section 675 or an automobile insurance policy covered by Section 660, or an individual life, health, or disability insurance policy, the insurance institution or agent responsible for the decision shall provide the specific reason or reasons in writing at the time of the decision. The communication of medical record information for a life or health insurance policy shall be subject to the disclosure requirements of subparagraph (B) of paragraph (2) of subdivision (a). This subdivision shall become operative on July 1, 2006.