Missouri Constitution
Article I - Bill of Rights
Section 22(a) Right of trial by jury—qualification of jurors—two-thirds verdict.

That the right of trial by jury as heretofore enjoyed shall remain inviolate; provided that a jury for the trial of criminal and civil cases in courts not of record may consist of less than twelve citizens as may be prescribed by law, and a two-thirds majority of such number concurring may render a verdict in all civil cases; that in all civil cases in courts of record, three-fourths of the members of the jury concurring may (b)

render a verdict; and that in every criminal case any defendant may, with the assent of the court, waive a jury trial and submit the trial of such case to the court, whose finding shall have the force and effect of a verdict of a jury.

Source: Const. of 1875, Art. I, Sec. 28 (Amended November 6, 1900).