Incompetency/ Insanity


Evidence that the defendant did or did not suffer from a mental disease or defect is admissible in a criminal trial to determine whether the defendant lacks capacity to understand the proceedings against him or to assist in his own defense.  V.A.M.S. § 552.015


A person is not responsible for criminal conduct if, at the time of such conduct, as a result of mental disease or defect such person was incapable of knowing and appreciating the nature, quality, or wrongfulness of such person's conduct. If the accused raises the issue (i.e. pleads not guilty by reason of mental disease or defect), there must be an examination.  V.A.M.S. § 552.030

Special Rules



Increased penalties if the victim was knowingly targeted due to disability (hate crime enhancement).  V.A.M.S. § 557.035

Death Penalty 

The trier of a capital murder case must limit the punishment to life imprisonment without eligibility for probation, parole, or release except by act of the governor if the trier finds by a preponderance of the evidence that the defendant is intellectually disabled (defined as a condition involving substantial limitations in general functioning characterized by significantly subaverage intellectual functioning with continual extensive related deficits and limitations in two or more adaptive behaviors such as communication, self-care, home living, social skills, community use, self-direction, health and safety, functional academics, leisure and work, which conditions are manifested and documented before eighteen years of age).  V.A.M.S § 565.030.1