Raising The Insanity Defense: A Comparison Of Rates In Jurisdictions With Differing Insanity Commitment Release Laws

The use of the insanity plea for felony offenses in 18 counties in various parts of the United States is the focus of the study reported here. Two research hypotheses were tested: one predicted that use of the insanity defense would be less frequent in jurisdictions with indeterminate commitments after a successful insanity defense; a second predicted that the insanity defense would be used least frequently for relatively minor offenses in jurisdictions with indeterminate commitments after acquittal for insanity. Neither hypothesis is supported by these findings. The authors conclude that factors other than the laws governing release after a successful insanity plea affect the rate of use. This research shows that variation across study counties was great, and that reporting of statewide rates masks these large differences. Further, this study shows distinct regional variation in the use of the insanity plea, which is associated with degree of urbanization.