Cal. Ed. Code § 89621
Any eligible employee electing to participate in the optional retirement program shall be ineligible for membership in the Public Employees' Retirement System so long as he or she is employed in any eligible position by the California State University. In the event an optional retirement program participant assumes a position in public service for which the optional retirement program is not available, the employee shall, at that time, cease participation in the program and shall begin participation in the Public Employees' Retirement System.
Employees who elect to participate in the optional retirement program shall remain eligible to participate in the Public Employees' Medical and Hospital Care Act (Part 5 (commencing with Section 22750) of Division 5 of Title 2 of the Government Code) as if they were members of the Public Employees' Retirement System.
Ca. Educ. Code § 89621