The Heart of Mens Rea and the Insanity of Psychopaths

Abstract

Psychopaths are mentally ill — insane — but as a rule have no insanity defense against criminal liability. This article explains why.

The explanation hinges upon the doctrine of mens rea, the criminal mind necessary for criminal liability. The insanity defense is an excuse, an affirmative defense for those with mens rea enough to be guilty. But the defense should take its essential purpose and shape from the doctrine of mens rea.

This relation between mens rea and the excuse of insanity is why a defendant insane as a matter of mental health may not be insane as a matter of criminal law. Only an insanity that calls into question the usual workings of the doctrine of mens rea should excuse from criminal liability. If psychopathy is not such an insanity, it should not excuse.

Similarly, though philosophers may argue that psychopathy supplies an excuse from moral fault, the criminal law may have no qualms about punishing psychopaths if the doctrine of mens rea controls the insanity defense. The doctrine of mens rea may well entail an insanity defense far narrower than that entailed by general philosophical notions of human responsibility. This article explores the relation between mens rea, the insanity defense, and psychopathy. Part I describes psychopathy. Part II examines the doctrine of mens rea. Part III shows how the doctrine of mens rea entails an insanity defense. Part IV explains why such an insanity defense leaves psychopaths unexcused. In Part V the article briefly concludes.

Keywords: mens rea, insanity, psychopathy, excuse, legal history, legal philosophy

JEL Classification: K14