Cal. Education Code § 44834

(a) Notwithstanding any other provision of law, on and after the effective date of this section the governing board of a school district may employ an individual in any administrative or supervisory position, irrespective of whether or not that person holds any supervisory or administrative credential if he or she meets all of the following criteria: (1) He or she holds a valid teaching credential. (2) He or she has completed 15 years service as a teacher, as defined in Section 41011, including 10 years of teaching service in the employ of the district which appoints him or her to an administrative or supervisory position. (3) The last 10 years of service immediately preceding his or her appointment to an administrative or supervisory position were as a teacher of the natural sciences, the social sciences (other than education or educational methodology), the humanities, mathematics, and the fine arts. (b) Commencing January 1, 1991, subdivision (a) shall apply only to persons who were employed by the governing board of a school district in a supervisory or administrative position on or before January 1, 1991, pursuant to the requirements of this section as it read on December 31, 1990.