Mo. Rev. Stat. § 40.385: Fighting — promoting a fight or duel, failure to report — court-martial.

Any person subject to sections 40.005 to 40.490 who fights or promotes, or is concerned in or connives at fighting a duel, or who, having knowledge of a challenge sent or about to be sent, fails to report the fact promptly to the proper authority, shall be punished as a court-martial may direct.