California Code, Code of Civil Procedure - CCP § 207

(a) The jury commissioner shall maintain records regarding selection, qualification, and assignment of prospective jurors.

(b) The jury commissioner shall maintain records providing a clear audit trail regarding a juror's attendance, jury fees, and mileage.

(c) All records and papers maintained or compiled by the jury commissioner in connection with the selection or service of a juror may be kept on an electronic or microfilm medium and such records shall be preserved for at least three years after the list used in their selection is prepared, or for any longer period ordered by the court or the jury commissioner.