Mo. Rev. Stat. § 630.183: Officers may authorize medical treatment for patient.

Subject to other provisions of this chapter, the head of a mental health or developmental disability facility may authorize the medical and surgical treatment of a patient or resident under the following circumstances:

(1) Upon consent of a patient or resident who is competent;

(2) Upon consent of a parent or legal guardian of a patient or resident who is a minor or legally incapacitated;

(3) Pursuant to the provisions of chapter 431;

(4) Pursuant to an order of a court of competent jurisdiction.