mental disorder thatprevented him from knowing his actions were wrong. The lawyer used testimony given bya psychiatrist and excerpts from a book called "A Treatise on the Medical Jurisprudence ofInsanity, written by an American doctor named Isaac Ray. This was the first insanitydefense case in which an acquittal was granted based on the use of expert testimony, notan eyewitness account. This case also provided Englands legal system with a method totest alleged criminals for legal insanity. To be regarded as legally insane under theMNaghten rule, alleged criminals must be so disordered that they do not realize they arecommitting a criminal act. A psychiatrist (or expert witness) talks with the alleged criminal to see if he or she understands the difference between right and wrong. Then thepsychiatrist forms an opinion about whether or not the person knew it was wrong tocommit the crime. The possibility of unconscious impulses is not taken into account (1). Three methods for measuring legal insanity, in the United States, have followedEnglands MNaghten rule. The Durham rule of 1954 attempted to broaden the U. S.legal systems understanding of legal insanity. Under the Durham rule, it was stated that adefendant is not criminally responsible if the activity was a product of mental disease ordefect (1). In 1962, the American Law Institute proposed a set of guidelines for defininglegal insanity. These guidelines provide that, a person is not responsible for criminalconduct if at the time of such conduct, as a result of mental disease or defect, he lackssubstantial capacity either to appreciate the criminality (wrongfulness) of his conduct or toconfirm his conduct to the requirements of law (5). The second test is known as the"product" test. For this test, a psychiatrist attempts to discover the unconscious,irresistible impulses of the accused criminal. The accused's ability to distinguish right fromwrong is not considered. ...
