Cal. Code of Civil Procedure § 2024.050

(a) On motion of any party, the court may grant leave to complete discovery proceedings, or to have a motion concerning discovery heard, closer to the initial trial date, or to reopen discovery after a new trial date has been set. This motion shall be accompanied by a meet and confer declaration under Section 2016.040. (b) In exercising its discretion to grant or deny this motion, the court shall take into consideration any matter relevant to the leave requested, including, but not limited to, the following: (1) The necessity and the reasons for the discovery. (2) The diligence or lack of diligence of the party seeking the discovery or the hearing of a discovery motion, and the reasons that the discovery was not completed or that the discovery motion was not heard earlier. (3) Any likelihood that permitting the discovery or hearing the discovery motion will prevent the case from going to trial on the date set, or otherwise interfere with the trial calendar, or result in prejudice to any other party. (4) The length of time that has elapsed between any date previously set, and the date presently set, for the trial of the action. (c) 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 to extend or to reopen discovery, 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.