Cal. Government Code § 11125.3

(a) Notwithstanding Section 11125, a state body may take action on items of business not appearing on the posted agenda under any of the conditions stated below: (1) Upon a determination by a majority vote of the state body that an emergency situation exists, as defined in Section 11125.5. (2) Upon a determination by a two-thirds vote of the state body, or, if less than two-thirds of the members are present, a unanimous vote of those members present, that there exists a need to take immediate action and that the need for action came to the attention of the state body subsequent to the agenda being posted as specified in Section 11125. (b) Notice of the additional item to be considered shall be provided to each member of the state body and to all parties that have requested notice of its meetings as soon as is practicable after a determination of the need to consider the item is made, but shall be delivered in a manner that allows it to be received by the members and by newspapers of general circulation and radio or television stations at least 48 hours before the time of the meeting specified in the notice. Notice shall be made available to newspapers of general circulation and radio or television stations by providing that notice to all national press wire services. Notice shall also be made available on the Internet as soon as is practicable after the decision to consider additional items at a meeting has been made.