Mo. Rev. Stat. § 304.235
All commercial motor vehicles shall be required to stop at an official weigh station, or to be identified through automated means approved by this state and determined to be in compliance without the necessity of stopping, except those licensed for a gross weight of not more than eighteen thousand pounds shall not be required to stop or to be identified unless so directed by a peace officer or a commercial motor vehicle enforcement officer or inspector. The provisions of sections 32.057 and 32.091 which govern confidentiality and prohibit the release of information shall not apply to commercial motor vehicle enforcement officers or their licensees in the performance of their duties at weigh stations. Any person who does not stop at a weigh station or who otherwise improperly evades stopping at the weight station and who is later determined not to be in compliance with the provisions of this chapter governing weigh limits may be punished pursuant to section 304.570.
§ 304.235, RSMo