Missouri constitution
Article III: legislative department
Section 31

Every bill which shall have passed the
house of representatives and the senate shall be presented to and considered by the
governor, and, within fifteen days after presentment, he shall return such bill to the
house in which it originated endorsed with his approval or accompanied by his objections.
If the bill be approved by the governor it shall become a law. When the general
assembly adjourns, or recesses for a period of thirty days or more, the governor shall
return within forty-five days any bill to the office of the secretary of state with his
approval or reasons for disapproval. If any bill shall not be returned by the governor
within the time limits prescribed by this section it shall become law in like manner as
if the governor had signed it.