Mo. Rev. Stat. § 195.280
Any peace officer of the state of Missouri, or of any political subdivision thereof, may, within the boundaries of the political entity from which he derives his authority, arrest without a warrant any person he sees violating or whom he has probable cause to believe has violated any provision of this chapter.
(L. 1971 H.B. 69)
Transferred 2014; now 579.175; Effective 1-01-17