California Code, Probate Code - PROB § 2590

(a) The court may, in its discretion, make an order granting the guardian or conservator any one or more or all of the powers specified in Section 2591 if the court determines that, under the circumstances of the particular guardianship or conservatorship, it would be to the advantage, benefit, and best interest of the estate to do so.  Subject only to the requirements, conditions, or limitations as are specifically and expressly provided, either directly or by reference, in the order granting the power or powers, and if consistent with Section 2591, the guardian or conservator may exercise the granted power or powers without notice, hearing, or court authorization, instructions, approval, or confirmation in the same manner as the ward or conservatee could do if possessed of legal capacity.

(b) The guardian or conservator does not have a power specified in Section 2591 without authorization by a court under this article or other express provisions of this code.