CRIMINAL RESPONSIBILITY 395 Question IV.—" If a person under an insane delusion as to existing facts commits an offence in consequence thei-eof, is he thereby excused ? " Answer TV.—" The answer must of course depend upon the nature of "the delusion; but, making the same assumption as we did before, namely, that he labours under such partial delusion only, and is not in other respects insane, we think he must be considered in the same situation as to responsibility as if the facts with respect to which the delu- sions exist were real. For example, if, under the influence of his delusion, he supposes another man to be in the act of attempting to take away his life, and he kills that man, as he supposes, in self-Defence, he would be exempt from punishment. If his delusion was that the deceased had inflicted a serious injury to his character and fortune, and he killed him in revenge for such supposed injury, he would be liable to punishment." Question V.—" Can a medical man, conversant with the disease of insanity who never saw the prisoner previously to the trial, but who was present during the whole trial and the examination of all the witnesses, be asked his opinion as to the state of the prisoner's mind at the time of the commission of the alleged crime, or his opinion whether the prisoner was conscious at the time of doing the act that he was acting contrary to law, or whether he was labouring under any, and what delusions at the time ? " Answer V.—" We think that the medical man, in the circumstances supposed, cannot in strictness be asked his opinion in the terms above stated, because each of those questions involves the determination of the truth of the facts deposed to, which it is for the jury to decide, and the questions are not mere questions upon a matter of science, in which case such evidence is admissible. But where the facts are admitted, or not disputed, and the question becomes substantially one of science only, it may be con- venient to allow the question to be put in the general form, although the same cannot be insisted on as a matter of right." The crux of these answers is known as " the McNaughten rule" or "the legal test ", which is as follows : — " That to establish a defence on the ground of insanity, it must be clearly proved that at the time of committing the act, the party accused was labour- ing under such a defect of reason from disease of the mind, as not to know the nature and quality of the act he was doing, or, if he did know it, that he did not know he was doing what was wrong." This legal test has also been accepted in India as the law of criminal responsibility, and is embodied in section 84 of the Indian Penal Code, which runs as follows: — " Nothing is an offence which is done by a person who, at the time of doing it, is, by reason of unsoundness of mind, incapable of knowing the nature of the act, or that he is doing what is either wrong or contrary to law." In order to exempt a person from criminal responsibility under this section it must be proved that the unsoundness of mind existed at the time of committing the offence. Subsequent insanity does not affect the crime, though it affects the trial.27 It may be necessary to enquire into the previous mental condition to prove the state of mind at the time of committing the offence. Further, unsoundness of mind should be of such an extent as would render the sufferer incapable of knowing the nature and character of the act or would render him incapable of understanding that the act he was doing was morally wrong or was an offence against the law of his country. A person can thus be exonerated from criminal responsibility, if his cogni- tive faculties have been affected by unsoundness of mind. Hence idiots, imbeciles, and persons who are deprived of all understanding and memory are not responsible for criminal offences and do not present any difficulty in courts of law. Difficulty, however, arises in those cases where persons labour under a partial delusion only and are otherwise quite sane. In such cases these individuals should be placed as regards criminal responsibility, in the same situation as if the facts with which the delusion existed were real.28 For instance, if, in consequence of an insane delusion, a person thinks another man to be a wild beast or ,a jar made of clay, and kills him, he is exempted from criminal responsibility, as he does not know the physical 27. CrJP.C., sec. 466, Appendix m. 28. Gour, Penal Law of India, Ed. H, Vol. I, p. 487.