California Code, Government Code - GOV § 31691.2

The board of retirement in a county of the first class may permit active members and their dependents to enroll in any plan authorized in Section 31691. The board shall have exclusive control over the plan benefits and administration to the same degree and to the same extent it otherwise has control over plan benefits and administration for retired members, and may recover reasonable administrative costs from the county or plan participants.

This section shall not be operative until the board of supervisors, by resolution adopted by a majority vote, makes this section applicable in the county.