INTRODUCTION.

EXPERT EVIDENCE.

LEGAL medicine, medical jurisprudence, or forensic medicine, may be defined as that branch of jurisprudence which pertains to the elucidation and determination of questions in law requiring technical knowledge of the medical sciences. Among the questions arising at times in legal procedures are such as concern the causes of death, the identity of the living and the dead, the results of wounds and injuries of all kinds, life and accident insurance, mental incompetence from various causes, malingering, legitimacy, abortion and infanticide, impotence, sterility and unnatural offenses, marriage and divorce, malpractice, and, finally, the many questions in relation to the science of toxicology.

To aid in the elucidation of these problems before the court, medical men who are especially skilled in some one branch or other of the medical sciences are called upon to testify as to their opinions or as to the facts and the deductions to be made from the facts set before the judicial body. These experts are general practitioners, specialists in medicine, surgeons, and chemists. Sometimes the questions are such that any general practitioner of skill and experience is qualified to determine them. Sometimes only a skilled pathologist, neurologist, alienist, obstetrician, surgeon, or chemist is able to unravel the intricate problem. The domain of scientific medicine has expanded so widely of late years that no single mind can now compass the details of all branches of medical science. The omniscient mind of the expert of other days is now impossible. The literatures of neurology and toxicology as related to law have in themselves become voluminous beyond the grasp of the general practitioner of medicine or of any single medicolegal expert.

The difficulties that enter into the interpretation of all sorts of matters pertaining to the art and science of medicine are especially noteworthy in many departments of medical jurisprudence. There are numerous questions which must be decided from the standpoint of the value of human evidence, and there are several conditions which modify the value of evidence and vitiate our inferences and judgments. There is no difficulty with facts which are known and accepted by all mankind. The accumulated experience of ages has thoroughly sifted the evidence as to matters of common knowledge, such as the roundness of the earth, the certainty of death, the accuracy of figures. But there are several sources of error in the critical balancing of testimony in relation to doubtful things, theories, hypotheses, and a host of matters

pertaining to "the million acres of our ignorance." In an inquiry of this nature there are obviously two important factors: first, the quality of the phenomenon observed; second, the character and quality of the observer. The phenomena we are called upon to consider in forensic medicine are often indefinite, shadowy, and illusory. The observer himself is hampered by the uncertain evidence of his more or less imperfect senses, sometimes by his undisciplined intellect, by the perversions of hazy memory, by the limitations of his general knowledge and experience, perhaps by the modifying influence of emotions, and, very rarely, it is true, by a tendency to deliberate deception and misrepresentation of the matters under consideration. We are constantly confronted in our study and practice of medicine with the mass of our ignorance of the things yet to be known, and with the defects and limitations of the students of these things. Despite this, however, we are constantly wresting from nature her marvelous secrets, and surprising and uplifting the world with our discoveries. It is interesting to examine the practical psychology involved in the elucidation and acceptance of any new fact or problem. Compare the knowledge of cerebral localization at the time of Hippocrates and at the present day, and contemplate the shifting mass of ignorance concerning this subject during those twenty-three centuries. Think of the thousand preposterous assertions concerning the brain, the thousand absurdities current, the thousand errors promulgated, the work of the multitude of quacks, philosophers, psychologists, physicians, anatomists, physiologists, and pathologists, during all those centuries before what seem to us now such simple truths won the acceptance of the modern world. And with regard to the things yet to be discovered in this great unseen and unknown universe about us, the same process of sifting the good from the bad evidence goes ever on in the selfsame way.

Quacks and empirics are with us still, making all sorts of fraudulent claims and ridiculous assertions. We have them in our own profession -adventurers, seekers after notoriety and fortune, exploiting some panacea or other. On a plane but little higher than this we have a class of pseudo-scientists, men who occupy a quasi-reputable position in the profession, and seek by every means to enhance their reputations, even by deliberate falsification of their observations, proclaiming new discoveries in pathology and therapeutics which they know to be untrue, but which they feel may pass scrutiny for a long time because of the obscurity of our scientific data and the intricacies of the problems they pretend to solve. Then we come to the body of real workers in every field of medical science, men filled with that eager enthusiasm and burning love of truth which lead them to immolate themselves upon the best of sacrificial altars, that of human progress. chiefly upon the errors of these that we wish to dwell, to point out the conditions which often vitiate their evidence.

In the first place, there are our imperfect senses-1 -those narrow and dim avenues through which we gain all our knowledge of the outer world. They are more or less imperfect in all of us; the absolutely

unerring eye and the invariably unfailing ear have only a theoretic existence they are not found in real life. And what is true of seeing and hearing, may be repeated of the other senses, and possibly with even more emphasis. It is not, then, to be wondered at that the same occurrence often produces quite dissimilar impressions on different witnesses, and that sometimes no two persons will agree in every detail in regard to what has occurred. A certain degree of colorblindness, astigmatism, deafness, or other imperfection-often unknown and frequently only temporary-makes some people at times the victims of their unreliable senses and renders them more or less untrustworthy observers. But the senses may be cultivated like the muscles, and even to a greater degree, and the real expert, therefore, is far less liable to errors of observation than the untrained, and it is this fact largely that gives to true expert evidence its great value.

It is not alone the illusions to which our defective senses are so subject that lead to mistakes and misinterpretations, but there are even greater sources of error in the psychic processes connected with these faulty senses. There are few observers who possess that disciplined intellect, that even temperament, that calm judgment, so necessary to the critical and unprejudiced examination of phenomena. Many medical men have limited horizons, owing to a lack of thorough training and to a want of familiarity with the ascertained data of the many cognate sciences with which their own lines of research are more or less correlated. They are, in other words, deficient in their store of experiences. Another defect lies in want of the imaginative faculty. In studying the unknown we may be handicapped by an inability to conceive of the qualities and character of the phenomena that are hidden, by an unconsciousness of the very existence of such phenomena.

Still another fallacy in our interpretation of phenomena is due to the vitiating influence of the emotions upon the judgment. A man's character has been said to be the sum of his ethical emotions, and his judgment of natural phenomena, especially of what we may term preternatural phenomena, is almost sure to be biased in some degree by the feelings of fear, pleasure, reverence, awe, sympathy, or antipathy which they inspire. These feelings of his are a reflex of the sum of his emotional sensations experienced throughout his whole life in relation to events, customs, religious views, and all sorts of convictions and beliefs. Another and very intangible source of error in evidence, particularly in regard to occult phenomena, has been described as "the instinctive tendency of the imagination to dramatic unity and completeness." A pathologist begins a difficult piece of work, and in his eagerness and impatience to bring it to a successful issue he unconsciously perverts the evidence presented to fit some preconceived theory or idea, shaping it into a harmonious unity.

So to sum up, the chief sources of error in evidence as to even tangible and palpable phenomena and facts, such as those of physiology, diagnosis, pathology, therapeutics, forensic medicine, statistics, and the like, are very great and far-reaching. They consist of:

VOL. I.-2

1. Deliberate fraud, as in all species of quackery.

2. Wilful perversion of facts by pseudoscientists.

3. Objective errors through limitation and defect of the senses. 4. Limited horizon through defective experience and education. 5. Insufficience of the imaginative faculty.

6. Vitiation of evidence under influence of the emotions.

7. The innate tendency of the mind to completeness, to dramatic unity in unraveling a mystery.

a

The great progress of the last fifty years in scientific medicine has been manifested also in an elevation of the principles of forensic medicine. Many questions upon which formerly there would have been difference of opinion between doctors have now become established facts. We have a better knowledge and a better class of experts to aid in the cause of justice. But even so, there is much improvement to be desired, and expert testimony has still a reputation for uncertainty and difference which better methods in the selection of the expert witnesses and better methods of presentation of their really valuable testimony before the tribunal will finally overcome. Among the evils of the present system is that in some departments of legal medicine physicians who are really not experts in the true sense of the word can still qualify as such. A professorship of therapeutics and of insanity in an unimportant medical school, the honorary position of consulting physician to an asylum, or the position of a coroner's physician, does not really qualify a physician as an expert alienist or pathologist, and yet the court generally recognizes such nominal insignia of office as evidence of fitness to testify, though the professor of therapeutics may have no practical knowledge of insanity, though the physician may never have visited the asylum to which he has been made consultant by courtesy, and though the coroner's assistant has been created by purely political influence, with no regard to his attainments as a pathologist. An evil of this kind has perhaps no remedy save in the elevation of the ideals and standards of the whole body of medical practitioners. Its correction can be made by physicians alone or in coöperation with members of the legal profession, who can, in their choice of experts, select only such as are known to be of high reputation for honor and integrity. In some countries, as in Germany and France, there is a list of officially appointed experts in various branches of medical science from which the court may choose at its pleasure, but in this country no such list of specialists exists, and, indeed, there would be great difficulty in the selection and appointment of a body of experts, since there would be no means to determine the choice without political or social influence. It is possible that a committee of unbiased physicians appointed from a reputable medical society could establish a list of specialists qualified for court duties, but there are many medical societies in the regular profession, and there are several schools of medicine outside of the regular school which are legally recognized, so that a harmonious choice in the interests of righteousness and justice would be at present quite unattainable.