Lawyers and judges are not psychologists or psychiatrists, neither are juries.  Therefore the doctor must be called in.  As a rule, the lawyer has little respect for expert opinion.  He has so often seen and heard all sorts of experts testify for the side that employs them and give very excellent reasons for their positive and contradictory opinions, that he is bound to regard them with doubt.  In fact, while lawyers respect and admire many men who are expert witnesses, and while many such men are men of worth, still they know that the expert is like the lawyer:  he takes the case of the side that employs him, and does the best he can.  The expert is an every-day frequenter of the courts; he makes his living by testifying for contesting litigants.  Of course scientific men do not need to be told that the receipt of or expectation of a fee is not conducive to arriving at scientific results.  Every psychologist knows that, as a rule, men believe what they wish to believe and that the hope of reward is an excellent reason for wanting to believe.  It is not my intention to belittle scientific knowledge or to criticise experts beyond such general statements as will apply to all men.  I have often received the services of medical experts when valuable time was given without any financial reward, purely from a sense of justice.  But all men are bound to be interested in arriving at the conclusion they wish to reach.  Furthermore, the contending lawyers are willing to assist them in arriving at the conclusions that the lawyer wants.

It is almost inevitable that both sides will employ experts when they have the means.  The poor defendant is hopelessly handicapped.  He is, as a rule, unable to get a skillful lawyer or skillful experts.  A doctor’s opinion on insanity is none too good, especially in a case where he is called only for a casual examination and has not had the chance for long study.  The doctor for the prosecution may find that the subject can play cards and talk connectedly on most things, and as he is casually visiting him for a purpose, he can see no difference between him and other men.  This may well be the case and still have little to do with insanity.  Experts called for the defense cannot always be sure that the patient truthfully answers the questions.  A doctor must make up his mind from examining the patient, except so far as hypothetical questions may be used.  In all larger cities, certain doctors are regularly employed by the prosecution.  While it would be too much to say that they always find the patient sane, it is safe to say that they nearly always do.  Especially is this true in times of public clamor, which affects all human conduct.  A court trial with an insanity defense often comes down largely to the relative impression of the testimony of the experts who flatly contradict each other, leaving with intelligent men a doubt as to whether either one really meant to tell the truth.  The jury knows that they are paid for their opinions and regards them more or less as it regards the lawyers in the case.  It listens to them but does not rely upon their opinions.  Expert testimony is always unsatisfactory in a contested case.  Under present methods, it can never be any different.