Missouri Constitution Article III Sec. 31 – Governor’s duty as to bills — time limitations — failure to return, bill becomes law
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.