Gov. Code, § 11521

(a) The agency itself may order a reconsideration of all or part of the case on its own motion or on petition of any party. The agency shall notify a petitioner of the time limits for petitioning for reconsideration. The power to order a reconsideration shall expire 30 days after the delivery or mailing of a decision to a respondent, or on the date set by the agency itself as the effective date of the decision if that date occurs prior to the expiration of the 30-day period or at the termination of a stay of not to exceed 30 days which the agency may grant for the purpose of filing an application for reconsideration. If additional time is needed to evaluate a petition for reconsideration filed prior to the expiration of any of the applicable periods, an agency may grant a stay of that expiration for no more than 10 days, solely for the purpose of considering the petition. If no action is taken on a petition within the time allowed for ordering reconsideration, the petition shall be deemed denied.

(b) The case may be reconsidered by the agency itself on all the pertinent parts of the record and such additional evidence and argument as may be permitted, or may be assigned to an administrative law judge. A reconsideration assigned to an administrative law judge shall be subject to the procedure provided in Section 11517. If oral evidence is introduced before the agency itself, no agency member may vote unless he or she heard the evidence.