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Insanity plea: predicting not guilty by reason of insanity adjudications
R W Jeffrey1, R A Pasewark, S Bieber
1Wilford Hall (SGHMSO), USAF Medical Center, Lackland AFB 78236-5300.
The Bulletin of the American Academy of Psychiatry and the Law
|January 1, 1988
Summary
Researchers correctly classified 87% of male defendants pleading insanity using discriminant analysis. Schizophrenia diagnoses and psychiatric evaluations predicted insanity, while substance use and personality disorders predicted conviction.
Area of Science:
- Forensic Psychology
- Legal Psychology
- Psychiatry
Background:
- The insanity plea is a complex legal and psychological construct.
- Accurate classification of defendants is crucial for legal and ethical outcomes.
Purpose of the Study:
- To identify variables that accurately predict the outcome of insanity pleas.
- To improve the classification accuracy of defendants adjudicated insane versus convicted.
Main Methods:
- Discriminant analysis was employed using 35 variables.
- The study analyzed 133 male defendants in Colorado who entered an insanity plea.
Main Results:
- An overall correct classification rate of 87% was achieved.
- Psychiatric evaluations of insanity and schizophrenia diagnoses were positively associated with an insanity adjudication.
- Substance use and personality disorder diagnoses were negatively associated with an insanity verdict.
Conclusions:
- Discriminant analysis effectively differentiates defendants based on insanity plea outcomes.
- Specific diagnoses and evaluations are key predictors in insanity plea cases.