Definitions of Mental Illness and the Insanity Defense

Abstract

Four versions of the insanity test are reviewed: the M'Naghten rules, the irresistible impulse test, the Durham rule, and the American Law Institute test. It is argued that the insanity tests, whatever their particular formulations, are inapplicable. Given present so-called definitions of mental illness based on behavioral patterns, the author suggests that it is impossible to show a causal connection between a “men al illness” and a criminal act. Therefore, claims of nonresponsibility cannot be based on the demonstration of contingent causal connections. It is also argued that the tests are irrelevant to the actual decisions that have to be made, either the disposition of the criminal or the detention of those found not guilty by reason of insanity.