Every person is presumed to be sane, and to possess a sufficient degree of reason to be responsible for his crimes until the contrary is proved. In order to establish the plea of insanity set up, it must be clearly proved at the time of committing the act in question, that he was suffering from such defect of reason on account of the disease of mind so as not to know the nature and quality of the act he was doing or if he did know it, or that he did not know what he was doing was wrong.
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The question put to the jury is whether the accused at the time of doing the act knew the difference between right and wrong. This undoubtedly is not quite satisfactory mode of putting the question but, however, in practice it has not led to any serious difficulty.
ADVERTISEMENTS:
If the question was to be put as to the knowledge of the accused solely and exclusively with reference to the law of the land it might tend to confound the jury, by inducing them to believe that an actual knowledge of the law of land was essential in order to lead to a conviction; whereas the law is administered upon the principle that everyone must be taken conclusively to know it, without proof of that he does know it.
If the accused was conscious that the act was one which he ought not to do and if the act was contrary to the law of the land, he is punishable and it is left to the jury to determine whether he had sufficient reason to know that he was doing an act that was wrong, with such explanation as may be found necessary in the circumstances of each case.