Mo. Rev. Stat. § 169.597
Notwithstanding any provision of this chapter to the contrary, the board of trustees of any retirement system or the governing body of any political subdivision which funds such retirement system shall have standing to seek a declaratory judgment concerning the application of Article X, Section 21 of the Missouri Constitution to the provisions of this chapter. In the event a final judgment is rendered by a court which judgment determines that any provision of this chapter constitutes a new activity or service or increase in the level of an activity or service beyond that required by existing law pursuant to Article X, Section 21 of the Missouri Constitution, or any successor to that section, that provision of this chapter shall be void ab initio and any new benefit or feature required by such provision of this chapter shall be deemed not to have accrued and shall not be payable to members.
§ 169.597, RSMo
Effective 7/1/1998 (S.B. 501) 8/28/1998 (S.B. 761)