Medical men are frequently called upon in our courts of law to give evidence in cases where it is doubtful whether persons found dead were murdered or committed suicide. The questions involved in these judicial inquiries are of great public importance, and it is the sacred duty of medical men, for the sake of their own characters, and for a much higher consideration—for the ends of justice, to make themselves thoroughly conversant with all the evidence which can be brought to bear in the elucidation of such important questions. Our criminal annals are replete with illustrations in which individuals accused of the atrocious crime of murder have been saved from a dreadful and ignominious death by medical evidence. Cases also are recorded in which death has been ascribed to suicide, but which after investigation have been proved to have been effected by other hands. In doubtful cases of this description, the evidence of the medical man is of the highest importance; without it, in the great majority of cases, justice would be defeated. In the cases of persons found hanging, two questions naturally suggest themselves to the mind:—1. Whether the individual was suspended before or after death. 2. Whether it was an act of suicide or murder. It is possible, and such cases have occurred, that a person may have been hanged up after having been murdered, or may have endeavoured to destroy himself by firearms, or by cutting his throat, and suspend himself afterwards, not being able to effect his purpose in any other way. In the first case we might mistake murder for suicide; and in the second, suicide for assassination. The following are the signs of death from strangulation:—The countenance is livid and distorted; the eyes protrude, and are often suffused with blood; the tongue projects and is wounded by the teeth. If the rope be placed below the cricoid cartilage, the tongue will protrude; but if it presses above the thyroid cartilage, the tongue will not be seen in the position described. It was formerly the generally received opinion that persons who were hanged died of apoplexy; but the experiments of Sir B. Brodie and other physiologists clearly prove that death is owing to suffocation. The livid or depressed circle which the rope is said to make round the neck is pronounced by M. Klein to be an uncertain sign; he saw fifteen cases of suicide in which it was not discovered. Remer, of Breslaw, who has recently directed his mind to the consideration of this important point, found, out of one hundred cases of persons who died from strangulation, eighty-nine with sugillation on the neck in an evident manner. In addition to the signs mentioned, others have been enumerated. The fingers are said to be found bent, the nails blue, hands nearly closed, with swelling of the chest, shoulders, arms, and hands.