Cal. Government Code § 31485.18

(a) Notwithstanding any other provision of this chapter, in a county of the eighth class, as defined in Sections 28020 and 28029, as amended by Chapter 1204 of the Statutes of 1971, the board of supervisors may, by resolution adopted by majority vote, if authorized by a mutually agreed upon and negotiated memorandum of understanding with a bargaining unit that represents safety employees, require a safety employee of that bargaining unit first hired after approval of the resolution, and may also require an unrepresented safety employee first hired after approval of the resolution, to receive a pension calculation provided in Section 31664.2, with a highest compensation period determined pursuant to Section 31462, and with a cost-of-living adjustment provided in Section 31870. (b) The resolution described in subdivision (a) may provide a different formula or calculation of retirement benefits for new safety members in one bargaining unit or new unrepresented safety members than that provided for new safety members of other bargaining units or new unrepresented safety members.