Mo. Rev. Stat. § 547.050: Court of its own motion may arrest judgment.

Judgment shall be arrested or set aside whenever it shall be made to appear to the court that the grand jury which found the indictment had no legal authority to inquire into the offense charged; or that the facts stated do not constitute any offense under the laws of this state; and the effect of such an arrest of judgment shall be to place the defendant in the same situation in which he was before indictment was found or information filed and the court may upon its view of any of these defects, arrest the judgment without motion.