Missouri constitution
Article III: legislative department
Section 21

Style of laws—bills—limitation on amendments—power of each
house to originate and amend bills—reading of bills.—The style of the laws of this
state shall be: “Be it enacted by the General Assembly of the State of Missouri, as
follows.” No law shall be passed except by bill, and no bill shall be so amended in its
passage through either house as to change its original purpose. Bills may originate in
either house and may be amended or rejected by the other. Every bill shall be read by
title on three different days in each house.