California Code, Code of Civil Procedure - CCP § 95

(a) The court may, on noticed motion and subject to such terms and conditions as are just, authorize a party to conduct additional discovery, but only upon a showing that the moving party will be unable to prosecute or defend the action effectively without the additional discovery. In making a determination under this section, the court shall take into account whether the moving party has used all applicable discovery in good faith, and whether the party has attempted to secure the additional discovery by stipulation or by means other than formal discovery.

(b) The parties may stipulate to additional discovery.