Cal. Gov. Code § 21192
The board, or in case of a local safety member, other than a school safety member, the governing body of the employer from whose employment the person was retired, may require any recipient of a disability retirement allowance under the minimum age for voluntary retirement for service applicable to members of his or her class to undergo medical examination, and upon his or her application for reinstatement, shall cause a medical examination to be made of the recipient who is at least six months less than the age of compulsory retirement for service applicable to members of the class or category in which it is proposed to employ him or her. The board, or in case of a local safety member, other than a school safety member, the governing body of the employer from whose employment the person was retired, shall also cause the examination to be made upon application for reinstatement to the position held at retirement or any position in the same class, of a person who was incapacitated for performance of duty in the position at the time of a prior reinstatement to another position. The examination shall be made by a physician or surgeon, appointed by the board or the governing body of the employer, at the place of residence of the recipient or other place mutually agreed upon. Upon the basis of the examination, the board or the governing body shall determine whether he or she is still incapacitated, physically or mentally, for duty in the state agency, the university, or contracting agency, where he or she was employed and in the position held by him or her when retired for disability, or in a position in the same classification, and for the duties of the position with regard to which he or she has applied for reinstatement from retirement.
Ca. Gov. Code § 21192