California Code, Code of Civil Procedure - CCP § 1026

(a) Except as provided in subdivision (b), in an action prosecuted or defended by a personal representative, trustee of an express trust, guardian, conservator, or a person expressly authorized by statute, costs may be recovered as in an action by or against a person prosecuting or defending in the person's own right.

(b) Costs allowed under subdivision (a) shall, by the judgment, be made chargeable only upon the estate, fund, or party represented, unless the court directs the costs to be paid by the fiduciary personally for mismanagement or bad faith in the action or defense.