What of the man who upon being arrested following the commission of murder, develops a psychosis while awaiting trial, or who having been found guilty of murder develops a psychosis while awaiting execution? The first question which the psychiatrist is called upon to decide in many instances is that of malingering. To the lay mind and to the minds of many of our eminent--but psychiatrically uninformed--jurists the question of malingering suggests itself at once. To them it is perfectly evident that this development of a mental disorder, in the wake of a criminal act, is nothing but a timely preparation for the "insanity dodge." The clinical pictures presented by the acute prison psychosis are especially apt to awaken suspicions of malingering in the minds of the untrained. We see individuals who apparently never before showed any evidence of mental disorder, and who immediately following the commission of a criminal act manifest pictures of grave alienation. Many of them don't know how much twice two is, are absolutely ignorant of the most elementary subjects, remember nothing of the deed, and most important of all fashion their deliria in such a way as to entirely negate the deed, or at any rate justify it. But why cannot all these manifestations be genuine? Many of us no doubt recall the effect which examinations have upon certain students. The emotional accompaniment of the examination, especially the emotion of fright, causes many a student to forget facts which he knew as well as his own name, and which he is able readily and fully to recollect as soon as the examination is over. Are we to assume that these students are malingering? Decidedly not. Why then should we question at all the genuineness of a mental disorder developing in an individual who faces the gallows or a life-long imprisonment? As a matter of fact cases of pure malingering are among the rarest things which the psychiatrist observes. Wilmanns,[1] in his study of 277 cases of insanity of prisoners, found but two cases of simulation, and in a later review of the diagnoses of the same series of cases, the two cases of malingering do not appear at all. Bonhoeffer[2] in a study of 221 cases of insane criminals found 0.5 per cent of malingerers. This is the experience of everyone who comes in contact with these cases, and there are others who go so far as to maintain that every malingerer of mental symptoms is mentally defective.