California Code, Penal Code - PEN § 629.64

The contents of any wire or electronic communication intercepted by any means authorized by this chapter shall, if possible, be recorded on any recording media.  The recording of the contents of any wire or electronic communication pursuant to this chapter shall be done in a way that will protect the recording from editing or other alterations and ensure that the recording can be immediately verified as to its authenticity and originality and that any alteration can be immediately detected.  In addition, the monitoring or recording device shall be of a type and shall be installed to preclude any interruption or monitoring of the interception by any unauthorized means.  Immediately upon the expiration of the period of the order, or extensions thereof, the recordings shall be made available to the judge issuing the order and sealed under his or her directions.  Custody of the recordings shall be where the judge orders.  They shall not be destroyed except upon an order of the issuing or denying judge and in any event shall be kept for 10 years.  Duplicate recordings may be made for use or disclosure pursuant to the provisions of Sections 629.74 and 629.76 for investigations.  The presence of the seal provided for by this section, or a satisfactory explanation for the absence thereof, shall be a prerequisite for the use or disclosure of the contents of any wire or electronic communication or evidence derived therefrom under Section 629.78.