Missouri Constitution
Article VII - Public Officers
Section 5 Election contests—executive state officers—other election contests.

—Contested elections for governor, lieutenant governor and other executive state officers shall be had before the supreme court in the manner provided by law, and the court may appoint one or more commissioners to hear the testimony. The trial and determination of contested elections of all other public officers in the state, shall be by courts of law, or by one or more of the judges thereof. The general assembly shall designate by general law the court or judge by whom the several classes of election contests shall be tried and regulate the manner of trial and all matters incident thereto; but no law assigning jurisdiction or regulating its exercise shall apply to the contest of any election held before the law takes effect.

Source: Const. of 1875, Art. VII, Sec. 8 (Amended February 26, 1924).