Kahler v. Kansas

Justia Summary

Kansas adopted the “cognitive incapacity” test for the insanity defense, which examines whether a defendant was able to understand what he was doing when he committed a crime. A defendant may raise mental illness to show that he “lacked the culpable mental state required as an element of the offense charged,” Kan. Stat. 21–5209. Otherwise, a defendant may use evidence of mental illness to argue for a lesser punishment. Kansas does not recognize a moral-incapacity defense, which asks whether illness left the defendant unable to distinguish right from wrong with respect to his criminal conduct.

Kahler, charged with capital murder after he killed four family members, unsuccessfully argued that Kansas’s insanity defense violated due process because it permits the conviction of a defendant whose mental illness prevented him from distinguishing right from wrong. Convicted, Kahler was sentenced to death.

The Supreme Court affirmed. Due process does not require Kansas to adopt an insanity test that turns on a defendant’s ability to recognize that his crime was morally wrong. A state rule about criminal liability violates due process only if it “offends some principle of justice so rooted in the traditions and conscience our people as to be ranked as fundamental.” Early common law reveals no consensus favoring Kahler’s approach. The tapestry of approaches adopted by the states indicates that no version of the insanity defense has become so ingrained in American law as to be “fundamental.” The defense sits at the juncture of medical views of mental illness and moral and legal theories of criminal culpability—areas of conflict and change–and is a matter for state governance, not constitutional law.