Psychology, Department of


Date of this Version

March 2005


Published in Aggression and Violent Behavior, 10:3 (March–April 2005), pp. 289-309. Copyright © 2004 Elsevier Ltd. Used by permission.


This paper examines the significance of the Supreme Court’s Hendricks and Crane decisions, with focus given to how mental health professionals may conceptualize the notion of volitional impairment. The Hendricks decision authorized postsentence civil commitment for sex offenders having a mental abnormality or personality disorder, rendering them likely to engage in future acts of sexual violence. In the Supreme Court’s majority opinion, Justice Thomas implied that the Kansas Act was legitimized by limiting the class of offenders eligible for this specialized form of commitment to those who are “unable to control” their dangerousness. In Crane, the Court ruled that while the Hendricks decision does not require that a sex offender be completely unable to control behavior, it does require proof of serious difficulty in controlling conduct. In evaluating the meaning of this decision for mental health professionals, this paper notes the decline of volitional impairment standards in the insanity defense, summarizes case law regarding sexual predators and volitional impairment, and further reviews the empirical and theoretical literatures exploring the notion of volitional impairment.