Cal. Gov. Code § 1233
Acting in accordance with Executive Order 11246 (30FR 12319), as amended, applicants for employment by, and incumbent employees of, public agencies may be solicited to voluntarily declare their ethnic identification, provided this information shall be used for research and statistical purposes only. Notwithstanding the provisions of this section, it shall be unlawful, for purposes of any appointment, hiring, or promotion, to use this information to discriminate against a prospective or incumbent employee or to give preference to a person identified as a member of an ethnic, racial, or religious group upon the basis of such membership or identification.
A separate or tear-off portion of the application shall be written and shall be kept in a separate nonpublic file, accessible only to those charged by the personnel director with research responsibility, for the purpose of discharging that responsibility. The separate sheet or tear-off may contain a number to be used as a cross index to the application. Safeguards to prevent misuse of the information shall be approved by the State Fair Employment Practice Commission, including the point in time at which the separate sheet or tear-off portion of the application shall be maintained in separate nonpublic file. As used in this section, "public agency" means every city, county, and city and county whether chartered or not and every district.
Ca. Gov. Code § 1233