The ALI rule, or American Law Institute Model Penal Code rule, is a recommended rule for instructing juries how to find a defendant in a criminal trial is not guilty by reason of insanity. It broadened the M'Naghten rule of whether a defendant was so mentally ill that he is unable to "know" the nature and quality of his criminal act, or know its wrongfulness, to a question of whether he had "substantial capacity to appreciate the criminality of [his] conduct". It also added a volitional component as to whether defendant was lacking in "substantial capacity to conform his conduct to the law".