The notion that criminal responsibility was involved only if will and intention were also present traces to the earliest history of Anglo-American criminal law. A variety of tests have been used to establish criminal responsibility. Insanity tests typically require three basic findings: 1) a mental disorder, 2) impairment in functioning, and 3) a clear and direct causal connection or relationship between the behavioral impairment resulting from the mental disorder and the criminal act. The common views that the insanity defense is overused, is used most often in violent crimes, is used to defend the wealthy and results in short periods of confinement and high recidivism rates are not supported by the available data. However, growing conservative and retributivist attitudes have produced pressures for changes in policies and procedures related to the insanity defense. The proposals aim both to restrict the insanity defense and thereby to reduce its use and to ensure greater protection of the public. Several national organizations have examined and issued recommendations regarding the insanity defense. Current policy dilemmas include the confusion regarding concepts, definitions, and roles; the nature and duration of confinement following an acquittal; and the effects of notorious cases on public perceptions and policies. 236 references.