Mo. Rev. Stat. § 302.780: Unlawful acts, penalty.

1. It shall be unlawful for a person to:

(1) Drive a commercial motor vehicle in a willful or wanton disregard for the safety of persons or property; or

(2) Drive a commercial motor vehicle while under the influence of any substance so classified under section 102(6) of the Controlled Substances Act (21 U.S.C. Section 802(6)), including any substance listed in schedules I through V of 21 CFR part 1308, as they may be revised from time to time.

2. Except as otherwise provided for in sections 302.700 to 302.780, whenever the doing of anything is required or is prohibited or is declared to be unlawful, any person who shall be convicted of a violation thereof shall be guilty of a class B misdemeanor.