Briefly outline the conditions inherent in the M'Naghten ruling for finding a defendant not guilty by reason of insanity, and then discuss the changes that have occurred in U.S. law that have modified the conditions for its successful application

Answer:

The basic condition laid down in the M'Naghten ruling was that a defendant could be found not guilty by reason of insanity (NGRI) if suffering a "defect of reason" (mental disorder) that made it impossible for him to understand right from wrong. Subsequent developments first broadened and later narrowed the grounds for determining insanity. Parsons expanded it to include conditions in which the person might intellectually know that what he did was wrong, but he was overcome by an "irresistible impulse." Durham introduced the product test, which suggested that if someone's behavior was the product of a mental disorder or mental disease, they could be found NGRI. This ruling made no attempt to define either product or mental disease, and it led to circular reasoning: for instance, antisocial personality disorder is defined by criminal behavior, yet the same criminal behavior proved the perpetrator was insane. Durham was overruled in 1972 and replaced by the Insanity Defense Reform Act of 1984 in which an individual can be found NGRI if he suffers from a mental disorder and, as a result of that disorder, can't comprehend the nature and quality of his actions. This combines concepts from the M'Naghten case with the idea of irresistible impulses, stating: A person is not responsible for criminal conduct if, at the time of such conduct and as a result of mental disease or defect, he lacks substantial capacity either to appreciate the criminality [wrongfulness] of his conduct or to conform his conduct to the requirements of the law.