Mo. Rev. Stat. § 300.340
Current with changes from the 2023 Legislative Session
No person shall open the door of a motor vehicle on the side available to moving traffic unless and until it is reasonably safe to do so, nor shall any person leave a door open on the side of a motor vehicle available to moving traffic for a period of time longer than necessary to load or unload passengers.
§ 300.340, RSMo