Mo. Const. art. X, § 24

(a) The provisions for voter approval contained in sections 16 through 23, inclusive, of this article do not abrogate and are in addition to other provisions of the constitution requiring voter approval to incur bonded indebtedness and to authorize certain taxes. (b) The provisions contained in sections 16 through 23, inclusive, of this article are self-enforcing; provided, however, that the general assembly may enact laws implementing such provisions which are not inconsistent with the purposes of said sections. [Effective - 04 Dec 1980 , see footnote]