Mo. Rev. Stat. § 40.175: Cruel and unusual punishment prohibited.

Punishment by flogging, or by branding, or marking or tattooing on the body, or any other cruel or unusual punishment, may not be adjudged by any court-martial or inflicted upon any person subject to sections 40.005 to 40.490. The use of irons, single or double, except for the purpose of safe custody, is prohibited.