Cal. Code of Civil Procedure § 2017.020

(a) The court shall limit the scope of discovery if it determines that the burden, expense, or intrusiveness of that discovery clearly outweighs the likelihood that the information sought will lead to the discovery of admissible evidence. The court may make this determination pursuant to a motion for protective order by a party or other affected person. This motion shall be accompanied by a meet and confer declaration under Section 2016.040. (b) The court shall impose a monetary sanction under Chapter 7 (commencing with Section 2023.010) against any party, person, or attorney who unsuccessfully makes or opposes a motion for a protective order, unless it finds that the one subject to the sanction acted with substantial justification or that other circumstances make the imposition of the sanction unjust. (c) (1) Notwithstanding subdivision (b), or any other section of this title, absent exceptional circumstances, the court shall not impose sanctions on a party or any attorney of a party for failure to provide electronically stored information that has been lost, damaged, altered, or overwritten as the result of the routine, good faith operation of an electronic information system. (2) This subdivision shall not be construed to alter any obligation to preserve discoverable information.