The day may not be far distant when the term “moral depravity” will be unknown, and future generations, ceasing to believe in absurd superstitions, will come to look on crime as the result of disease of the brain, and learn to treat, instead of to punish, the morally diseased. (For a full discussion of this subject the reader is referred to the works of Dr. Henry Maudsley.) The fact of the sanity or insanity of the prisoner at the time the crime was committed is left to the jury to decide, guided by the previous and contemporaneous acts of the party; and it has been laid down by Lord Moncreiff in Scotland, and Lord Westbury in England, that the mental soundness or unsoundness of any individual is to be decided by the jury on the ordinary rules of every-day life, and that on these principles they are as good judges as medical men. The whole tendency of legal practice, when dealing with the plea of insanity, is to entirely ignore the medical evidence. On the question of medical evidence in cases of insanity, Doe J., of New Hampshire, remarks: “At present, precedents require the jury to be instructed by experts in new medical theories, and by judges in old medical theories,” and that in this “the legal profession were invading the province of medicine, and attempting to install old exploded medical theories in the place of facts established in the progress of scientific knowledge. If the tests of insanity are matters of law, the practice of allowing experts to testify what they are should be discontinued; if they are matters of fact, the judge should no longer testify without being sworn as a witness, and showing himself qualified to testify as an expert.” =Lunacy--What Constitutes?= (8 and 9 Vict. c. 100, secs. 90 and 114).--Imbecility and loss of mental power, whether arising from natural decay, or from paralysis, softening of the brain, or other natural cause, and although unaccompanied with frenzy or delusion of any kind, constitute unsoundness of mind, amounting to lunacy within the meaning of 8 and 9 Vict. c. 100 (R. _v_. Shaw, 1 C.C. 145). The above is the last definition of lunacy up to 1875; but as the law on this subject is so constantly changing, the student will find it best to consult the _Law Reports_ from time to time. (See the account in the case of R. _v_. Treadaway, _Law Reports_. Also the _Lancet_, on the same case, vol. i. 1877.) For some valuable remarks on the subject of the irresponsibility of madmen, the student is referred to the works of Maudsley, Pritchard, Ray, Hoffbauer, Georget, and others. The following suggestions are offered for consideration on this subject: 1. Was the act an isolated event in the life of the culprit? Has it the appearance of spontaneity, or was it the culminating point of a life spent in so-called criminal acts?