Cal. Education Code § 48922

(a) The review by the county board of education of the decision of the governing board shall be limited to the following questions: (1) Whether the governing board acted without or in excess of its jurisdiction. (2) Whether there was a fair hearing before the governing board. (3) Whether there was a prejudicial abuse of discretion in the hearing. (4) Whether there is relevant and material evidence which, in the exercise of reasonable diligence, could not have been produced or which was improperly excluded at the hearing before the governing board. (b) As used in this section, a proceeding without or in excess of jurisdiction includes, but is not limited to, a situation where an expulsion hearing is not commenced within the time periods prescribed by this article, a situation where an expulsion order is not based upon the acts enumerated in Section 48900, or a situation involving acts not related to school activity or attendance. (c) For purposes of this section, an abuse of discretion is established in any of the following situations: (1) If school officials have not met the procedural requirements of this article. (2) If the decision to expel a pupil is not supported by the findings prescribed by Section 48915. (3) If the findings are not supported by the evidence. A county board of education may not reverse the decision of a governing board to expel a pupil based upon a finding of an abuse of discretion unless the county board of education also determines that the abuse of discretion was prejudicial.