Mo. Rev. Stat. § 311.326
After a period of not less than one year after reaching the age of twenty-one a person who has pleaded guilty to or has been found guilty of violating section 311.325 for the first time, and who since such conviction has not been convicted of any other alcohol-related offense, may apply to the court in which he or she was sentenced for an order to expunge all official records of his or her arrest, plea, trial and conviction. No records shall be expunged if the person who has pleaded* guilty to or has been found guilty of violating section 311.325 is licensed as a commercial motor vehicle driver or was operating a commercial motor vehicle as defined in section 302.700 at the time of the violation. If the court determines, upon review, that such person has not been convicted of any other alcohol-related offense at the time of the application for expungement, and the person has had no other alcohol-related enforcement contacts, as defined in section 302.525, the court shall enter an order of expungement. The effect of such an order shall be to restore such person to the status he or she occupied prior to such arrest, plea or conviction, as if such event had never happened. No person as to whom such order has been entered shall be held thereafter under any provision of any law to be guilty of perjury or otherwise giving a false statement by reason of his or her failure to recite or acknowledge such arrest, plea, trial, conviction or expungement in response to any inquiry made of him or her for any purpose whatsoever. A person shall be entitled to only one expungement pursuant to this section. Nothing contained in this section shall prevent courts or other state officials from maintaining such records as are necessary to ensure that an individual receives only one expungement pursuant to this section.
§ 311.326, RSMo