Section 19-9-206 - Effect on members of prior plans(1) All provisions of this retirement system are effective as to a member whose retirement date occurred prior to July 1, 1977, except that the amount and mode of payment of the member's retirement benefit must remain unchanged.(2) This chapter may not decrease the benefits of a member under a prior plan.En. 11-1881 by Sec. 22, Ch. 456, L. 1977; R.C.M. 1947, 11-1881; amd. Sec. 183, Ch. 265, L. 1993; Sec. 19-9-106, MCA 1991; redes. 19-9-206 by Code Commissioner, 1993.