CAL. GOV. CODE § 6267 : California Code - Section 6267

All patron use records of any library which is in whole or in part supported by public funds shall remain confidential and shall not be disclosed by a public agency, or private actor that maintains or stores patron use records on behalf of a public agency, to any person, local agency, or state agency except as follows:

(a) By a person acting within the scope of his or her duties within the administration of the library.

(b) By a person authorized, in writing, by the individual to whom the records pertain, to inspect the records.

(c) By order of the appropriate superior court.

As used in this section, the term "patron use records" includes the following:

(1) Any written or electronic record, that is used to identify the patron, including, but not limited to, a patron's name, address, telephone number, or e-mail address, that a library patron provides in order to become eligible to borrow or use books and other materials.

(2) Any written record or electronic transaction that identifies a patron's borrowing information or use of library information resources, including, but not limited to, database search records, borrowing records, class records, and any other personally identifiable uses of library resources information requests, or inquiries.

This section shall not apply to statistical reports of patron use nor to records of fines collected by the library.