Mo. Rev. Stat. § 21.420: Lobbyists not to go upon the floor of the house or senate — penalty.

It is unlawful for any person employed for a pecuniary consideration to act as legislative counsel or legislative agent for any person, corporation or association, to go upon the floor of either house of the legislature, reserved for the members while in session, except upon the invitation of the house. Any person violating the provisions of this section is punishable by imprisonment in the county jail not less than ten days nor more than twelve months, and by a fine of not less than one hundred dollars nor more than five hundred dollars.