Mo. Rev. Stat. § 509.240
Current with changes from the 2023 Legislative Session
When any claim or counterclaim shall be founded upon any written instrument and the same shall be set up at length in the pleading or a copy attached thereto as an exhibit, the execution of such instrument shall be deemed confessed unless the party charged to have executed the same shall specifically deny the execution thereof.
§ 509.240, RSMo