We have at length arrived at the third, and most important division of our work, comprehending the consideration of the principal pleas of the crown, three of which, Rape, Arson, and Murder, are pre-eminently the subjects of Medical Jurisprudence.

It is in the investigation of these crimes that the law derives its greatest support from the lights of science, and that the profession of physic demonstrates the value and extent of her judicial utility. Let the physician then, who approaches the tribunal of justice in order that he may promote by his science the due execution of the laws, fully appreciate the heavy responsibility of his situation; let his evidence be so distinguished by its dispassionate and inflexible character, and his opinions be so matured by study, and fortified by experiment, as not only to ensure for himself the respectful attention of the court, but to afford a practical illustration of the just pretensions and importance of the liberal profession which he represents. The observations which we have already offered on the subject of medical evidence (page 153) render it unnecessary for us to enlarge on this occasion upon the various duties it involves; and yet we cannot forbear from again pressing upon the attention of all those, who are likely to be called upon to assist the ends of justice, the great importance of preparing their minds by preliminary studies; let it be remembered, that it is not during the hurry and anxiety of a coroner’s inquest, nor amid the tumult of popular prejudice and execration, that a medical practitioner should, for the first time, adopt the physiological or chemical opinions by which he is ultimately to decide upon the life of a fellow creature; and yet it would be folly to conceal the unwelcome truth, that such a fact has not unfrequently occurred on several of the more interesting trials, upon which the medical witness has evinced any thing rather than a well grounded acquaintance with the philosophical bearings of the question; and while he has endeavoured to conceal his ignorance under the veil of technical phraseology, he has artfully sought to shun the embarrassments it might create by a display of bold and sweeping assertions, alike hostile to the discovery of truth, and the administration of justice. There is yet another evil to which those who are but imperfectly informed on the question at issue are peculiarly exposed; their opinion is always liable to be warped by extraneous circumstances, and they are in consequence involuntarily apt to bend facts to their first view of the case under consideration, to seize on a few circumstances which suit their preconception, and to neglect or distort those which have a contrary tendency; while, on the other hand, the practitioner who has prepared his mind by study and experience, will, with equal diligence, seek every avenue to truth, and will suspend his conclusions, until the result of each investigation be fairly before him; in delivering to the Court the opinion to which his researches have led him, he will be ever careful to distinguish between the duties of an advocate, and those of an unbiassed witness; he will state whether the conclusion at which he has arrived amounts to certainty, or only to high probability, and will separate the doubts and difficulties with which the question has been encompassed by the sophistry of counsel, from those that belong intrinsically to the subject, and are inseparable from it. And it may be proper on this occasion to observe that the medical practitioner is not to withhold an opinion because it may be involved in doubt; he is to furnish the best evidence which the nature of the case will allow, and when he duly performs this task, he may feel proud in the consciousness that he occupies an important station in the administration of justice; and that he conscientiously discharges a duty, without the due performance of which, the laws of his country would be inoperative.