The possibilities of posthypnotic suggestion would seem at first glance to open a wider field for criminal suggestion, but the evidence does not, I think, justify much apprehension on that score.
When the patient's consciousness is much disordinated by the suggestion, he is usually unable to co-ordinate himself to his environment, and is, of course, not fitted to do anything requiring alert mental powers, much less a crime. When the suggested idea expels inconsistent states the case is almost as bad. Prof. Liégeois dissolved a white powder in water and told Mme. C, one of his patients, that it was arsenic. "I said to her: 'See M. D, he is thirsty, he is always wanting something to drink; you will offer him this.' 'Yes, monsieur.' But D asked a question which I had not foreseen; he asked what was in the glass proffered him. With a candor which set aside all thought of simulation, Mme. C replied, 'It is arsenic.'" Clearly it would not do to intrust to Mme. C the execution of a suggested crime.
Again, when the emergence of the posthypnotic suggestion does not affect the upper consciousness at all but coalesces with it, it is apt, as I have already pointed out, to meet with resistance from the patient's habitual principles of conduct. Dr. De Jong reports that a little Jewish girl of ten, whom he found very suggestible, repeatedly obeyed his posthypnotic suggestion that she should steal a piece of money left lying upon the table, but one Saturday she disobeyed. When asked why, she said: "It is the Sabbath day; I can not touch money." Another of his patients performed all manner of make-believe crimes at his suggestion, but, when he suggested something the performance of which would have shocked her modesty, she refused, and she refused also to betray a trivial secret which he had got his cook to confide to her.
When one contrasts cases of this sort (and they are common) with the long series of "laboratory crimes" recorded in the annals of hypnotic literature—murder committed with sugared water, with a roll of newspaper, with an unloaded pistol, the theft of purely imaginary objects, or of articles obviously the property of the man who suggests that they be stolen, etc.—it is difficult to avoid the conclusion that for evidential purposes such experiments are almost worthless. And in the few cases where it seems probable that the patient has really committed what he believes to be a crime, it is often not shown that the crime would have been especially abhorrent to his normal self. This objection attaches, I think, to one of the most striking cases on record, recently reported by Prof. Liébeault. A certain Dr. X and himself gave a young fellow of seventeen or eighteen years of
