It is difficult to arrange in logical order the subjects falling within the purview of forensic medicine ; but a more or less orderly arrangement may be made according to the nature of the court and the case before it. First in date and interest, if not in importance, is the institution, peculiar to the English-speaking peo ples (under the common law), of the court of the coroner (q.v.) whose duty it is to enquire into all deaths of which the cause is unknown, deaths from violence (accidental or criminal) or in cir cumstances of suspicion in prisons, lunatic asylums, etc., or from certain notifiable diseases. It is strictly an enquiry and not a trial: there is no suit and there are no parties. The question is—how and by what manner X came by his death. In the great majority of cases death will be found to be due to natural causes, and the in vestigation of those cases in which the physician in attendance is unwilling or unable to give a death certificate forms the routine work of the pathologist. Some diseases, such as acute haemor rhagic pancreatitis, are almost never diagnosed ante mortem. Then again, in cases of sudden death, the physician will be chary of giving a certificate in a case that he has not bqen attending regularly. Although the coroner enquires into all cases of sud den death, he is not always bound to have an autopsy. Some writers, Taylor among them, urge that there should always be an autopsy. Some go further and say that all autopsies should be done by pathologists and not by an "ordinary" medical man. Before 1927 where a certificate was refused and there were no circumstances of suspicion, the publicity of an inquest seemed unnecessarily painful to relatives and not perhaps required by the interests of justice. A useful compromise is found in s. 21 the Coroners Amendment Act 1926 whereby, if there are no circumstances of suspicion and he is not otherwise bound to hold an inquest the coroner may, upon the report of a medical man whom he has instructed to make an autopsy, dispense with an inquest if he thinks fit. • Next in order of frequency will be fatal vehicle accidents which since 1927 must be taken with a jury. It might be thought that in some of these the actual physical cause of death was obvi ous, as where a man is decapitated by a train. But suppose a man had a stroke and fell under a train : only an autopsy could reveal this and avoid, say, a wrong verdict of suicide, the next commonest case before the coroner.
Last in order of frequency, but of great interest for forensic medicine, will be deaths in respect of which a crime (murder, in fanticide, abortion, manslaughter) will be imputed to someone. The duplication of procedure which existed before 1927 has been wisely done away with by the act of 1926 and the coroner, when he learns that someone has been charged with a crime in respect of a body lying within his jurisdiction, adjourns his inquest until after the finding of the criminal court. It is upon the criminal courts that the weapons of forensic medicine have been whetted.
The study of murder (q.v.) has a peculiar fascination for many (not necessarily morbid) minds and a vast quantity of material has been collected on this subject. A medical man will usually be one of the first persons on the scene in such cases and it is his duty to note, not only the condition of the body, but also any sur rounding circumstances that may be of use in elucidating the crime ; for although it is no part of a doctor's business to play the detective, society expects him to take at least as much interest as any other of its members in the suppression of crime. Is an appar
ent case of suicide, for instance, really one of murder? Did a man found hanging in reality hang himself or was he in fact strangled and then hanged by his assailant? Louis, a French medical jurist of the Eighteenth century, taught us how to distinguish such cases. A man is found shot or with his throat cut, and a razor or revolver, by him or actually in his hand; was it murder or suicide? These and a host of similar questions are answered in any standard work on foren sic medicine. Reading, however, does not make the medico legal expert. Most of the serious contributions to legal medi cine have been made by men who have combined knowledge and experience with the ability to apply both these to an emergency. Some methods, however, have been worked out in the quiet of the laboratory. Of these the most striking is the precipitin test for blood. Blood may be detected by chemical, spectroscopic, micro scopic and immunological methods. The first three detect blood but not necessarily human blood, nor was the chemical test (since improved) free from fallacies. The second has no biologi cal specificity while the third enables one to distinguish the blood of the mammalia. The fourth, a veritable triumph of science, enables one to say definitely that the extract of blood stains examined contains human blood. The stain is extracted with salt solution and added to the serum of a rabbit which has been injected at intervals with human blood : a precipitate will form if the blood is human but not otherwise. The test is done after it has been established by one of the other methods that the stain is blood. In the strictly biological sense the test is generic rather than specific and is given (in a less marked degree) by the anthropoid apes.
The time that has elapsed since death in any given case is an important question to which, in the absence of evidence, the answer cannot in the present state of our knowledge be given with scientific precision. Yet the careful observation of genera tions has worked out certain rules which allow of an approxima tion of a fair degree of accuracy. The average rate of cooling of the body is about one degree per hour, depending, however, somewhat on surrounding temperature and moisture, and even, at times, on the mode of death. Post-mortem rigidity comes on three to six hours after death, and lasts, on an average, 16 to 24 hours, while decomposition usually begins on the third day. These are some of the data that are relied on, but they are inter preted in practice with great caution.
If poisoning is suspected, the examiner, under direction of the coroner, sends the stomach and contents and pieces of the solid viscera in sealed jars to the analyst. The study of poisons and their detection is called toxicology. Needless to say the methods have been elaborated with great care, as they must be susceptible of the closest scrutiny.