Mo. Const. art. X, § 23

Notwithstanding other provisions of this constitution or other law, any taxpayer of the state, county, or other political subdivision shall have standing to bring suit in a circuit court of proper venue and additionally, when the state is involved, in the Missouri supreme court, to enforce the provisions of sections 16 through 22, inclusive, of this article and, if the suit is sustained, shall receive from the applicable unit of government his costs, including reasonable attorneys' fees incurred in maintaining such suit. [Effective - 04 Dec 1980 , see footnote]