California Code, Government Code - GOV § 21095

(a) Participation in the plan afforded by this article shall be made available to any employee who was included in the federal system and who was a member of this system prior to the effective date of the employer's contract amendment to be subject to this article.  The election shall be irrevocable, shall be effective on the first day of the pay period following the member's election, and shall apply to all future service rendered by the member with that agency.  Each contracting agency shall ensure each eligible member receives sufficient information to permit an informed election, is counseled regarding the benefits provided by this article, and receives an election document.  The election document shall be filed with the contracting agency, and the contracting agency shall report the member's irrevocable election to the board.

(b) A member subject to this article shall be subject to all other provisions of this part.  However, in the event of a conflict, this article shall supersede and prevail over other provisions contained in this part.