as doing; or if he did know it, that he did not know that he was doing what was wrong.
This test was cognitive, focusing on the ability of the defendant to be cognizant of his actions and know whether they are right or wrong.
Soon after it was announced, the M'Naghten rule became the subject of criticism. Most of this criticism was based upon the newly emerging conceptions of insanity, which held that insanity may not solely or even primarily affect the cognitive or intellectual faculties, but also the will and emotions of the patient. These criticisms eventually became the basis for the rule announced in Durham v. United States, which stated that a defendant "is not criminally responsible if his unlawful act was the product of mental disease or defect." Such a rule would give psychiatrists greater leeway in giving the factfinder all of the relevant information concerning the character of the defendant's disease or defect, while leaving the jury free to perform its traditional function of applying "our inherited ideas of moral responsibility" to the circumstances of the individual case.
The Durham test was applauded by most psychiatrists but criticized by most lawyers. Psychiatrists felt that they could now present testimony as to the mental condition of the defendant using concepts familiar to them. Critics, on the other hand, viewed the rule as providing the jury with no standard by which to judge the evidence and left the jury dependent entirely upon the testimony of the experts. In practice, the criticisms of the rule were generally borne out, with the jury often "rubber-stamping" the opinions of the expert witnesses. Within seven years of the announcement of the rule, more than 14% of all defendants in the District Court in Washington D.C. were being found not guilty by reason of insanity (NGRI), compared with 0.4% in the year the rule was announced.
Soon after the Durham decision, the American Law Institute ...