Although the insanity defense is numerically insignificant, it remains profoundly important to the criminal justice system as the focal point of the ongoing debate on the relationship between legal responsibility, free will, mental illness, and punishment. The insanity defense has substantially survived in spite of persistent philosophical and political criticism. Its history reflects a balance and tension between changes in attitudes toward developments in psychiatry and psychology and changes in attitudes toward criminal justice, incapacitation, and the desire to punish. Probably no other area of criminal law and procedure reflects a jurisprudence that is so driven by myths as that of the insanity defense. Yet only a handful of American jurisdictions have legislatively abolished it.

Insanity defense issues have concerned the courts and legislative bodies for ...