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84 Indiana Law Journal Supplement 1 (2009)


This Article revisits a longstanding debate concerning the appropriateness of diagnostic evidence in criminal cases in which a defendant’s mental condition is at issue. As illustrated through a case study of Theodore Kaczynski, more widely known as the “Unabomber,” a diagnosis of paranoid schizophrenia poses a risk of confounding a judge or jury attempting to ascertain an accurate picture of the mental state of a criminal defendant, specifically by (i) suggesting symptoms not actually present, (ii) creating a distorted picture of symptoms that are present, and (iii) suggesting organic, determinative factors as the mechanism behind a defendant’s actions, even where deliberate choice is a more convincing explanation. The misleading nature of such a diagnosis, moreover, can lead to legal outcomes inconsistent with the theoretical goals of the criminal law, at least with respect to the insanity defense and the death penalty. This Article does not necessarily call for the complete abolition of the use of diagnostic evidence in criminal proceedings; instead, it highlights some of the perils associated with such evidence so that, at minimum, courts can employ an appropriate level of thoughtful caution when faced with such evidence in the future.