Missouri Revised Statutes Title XXI. Public Safety and Morals § 316.233. Passenger may not ride, when

(1) Has sufficient knowledge to use, get on, enter, or get off the amusement ride safely without instruction or has requested and received before getting on the ride sufficient information to get on, use, enter, or get off safely;

(2) Has located, reviewed and understood any signs in the vicinity of the ride and has satisfied any posted height, medical or other restrictions and abided by all rules, regulations and restrictions;

(3) Is not under the influence of alcohol or any drug that affects his or her ability to safely use the amusement ride or obey the posted rules or oral instructions; and

(4) Is authorized by the amusement owner or such owner's authorized servant, agent or employee to get on the amusement ride.