Mo. Rev. Stat. § 534.347: Unauthorized sublessor or assignor of leased premises, double damages, when.

In any action against any tenant to recover rent, or possession of any premises pursuant to chapter 534 or 535, if it appears from the evidence that such tenant allowed another person or persons to come into sole possession of any lands or tenements under or by collusion with such tenant and without the permission of the landlord, the court may, in addition to the rent due, allow the prevailing party damages not to exceed twice the amount of the rent due. Nothing in this section shall be construed to limit the landlord's ability to recover attorney's fees, other expenses or damages, or to pursue other remedies provided in the lease.