Cal. Ed. Code § 87680
The administrative law judge shall determine whether there is cause to dismiss or penalize the employee. If he or she finds cause, he or she shall determine whether the employee shall be dismissed and determine the precise penalty to be imposed, and shall determine whether his or her decision should be imposed immediately or postponed pursuant to Section 87672.
No witness shall be permitted to testify at the hearing except upon oath or affirmation. No testimony shall be given or evidence introduced relating to matters which occurred more than four years prior to the date of the filing of the notice. Evidence of records regularly kept by the governing board concerning the employee may be introduced, but no decision relating to the dismissal or suspension of any employee shall be made based on charges or evidence of any nature relating to matters occurring more than four years prior to the filing of the notice.
Ca. Educ. Code § 87680