The psychiatrist's guide to right and wrong: judicial standards of wrongfulness since M'Naghten

In insanity defense litigation, the precise legal definition of wrongfulness is often critically important. References in the M'Naghten Rules to the appropriate standard of wrongfulness were ambiguous, resulting in a divergence of judicial opinion as to whether wrongfulness means legal wrong, subjective moral wrong, or objective moral wrong. This article reviews and analyzes these three judicial standards of wrongfulness in the context of case law from jurisdictions that follow each of the respective standards. The evolution of knowledge of right and wrong tests of criminal responsibility is traced back to its philosophical roots. Most psychiatrists claim no expertise in matters of morality or law. The American Psychiatric Association would bar psychiatric expert testimony on the ultimate issue of insanity, on the grounds that there are "impermissible leaps in logic" when psychiatrists opine on the probable relationship between medical concepts and moral-legal constructs. Whether or not they testify on the ultimate issue, psychiatrists should ascertain the applicable standard of wrongfulness in order to properly relate their findings to the relevant legal criteria for insanity and thereby enhance the probative value of their testimony.