its facts are controverted, though counsel may put to them a state of facts and ask their opinions thereon.1 It is only by a comparison of all the facts in issue that the expert can venture to express any opinion upon them; whence it follows, as a necessary consequence, that expert opinions are admissible if based upon a state of facts which the evidence on behalf of either party tends to establish. But the jury should know upon what facts the opinion is founded, for its pertinence depends upon whether the jury find the facts on which it rests.2 On the trial of an indictment for selling diseased meat, physicians were allowed to give their opinions as to the nature of the disease of which the animal died, founded on the descriptions which other witnesses had given of its ulcerated condition, and also as to the consequent unwholesomeness of the meat. Yet a physician was not allowed to express his opinion whether, from the condition of a slave, as described by two witnesses named, whose testimony was conflicting, "the attention of a physician was necessary. Had there been no conflict in the testimony, so as to present an admitted state of facts, even though the facts themselves were of variable interpretation, his testimony would have been valid. 994 , though counsel may put t assault with intent to kill, & tingencies more or less remote. A trivial cause has been known to destroy life in one man, and a great one to fail doing so in another, and since what has once happened may happen again, it is only an inference from a general proposition that the majority of men do succumb under a particular class of injuries, that justifies our announcing what the possibilities are in any given individual. The probabilities are even more conjectural, in all attempts at foreseeing the consequences of natural causes, when they pass beyond that first class, so patent in character as to amount almost to certainty. And it is in this view of the shifting processes of nature that the conjectures of medical men as to the probable duration of a disease have not per se the weight of proof of the fact of duration.1 This point was well sustained in a rehibitory action where, there happening to be a conflict of opinion between two physicians testifying to the nature of the disease of which a slave died, the court held that more weight was due to the opinion of the attending physician who made the post mortem examination, than to one who had only casually seen him; for, said Judge Martin,2 "From the extent of the internal ravages of the disease, he was better enabled to form an opinion of its duration and real character than the other physician, who, although he had seen and attended the boy shortly before the sale, could speak only from conjecture as to what happened afterwards, in relation to the disease of which the negro died, and the state in which his body was found." § 120. Inasmuch as serious internal lesions may exist without giving adequate external signs of their presence, and the grouping of symptoms may alone furnish to the expert indicia of morbid conditions, the rule of requiring specific data on which to found conclusions, has necessitated relaxation in this particular, so as to enable the expert to speak of matters of inference, not absolutely demonstrable. Under such circumstances a medical expert testifying to the character of a personal injury, may be asked on crossexamination, if it is not a fact in his experience that injuries may, and do exist, where there are no outward manifestations of them. And, in the same case, the surgeon who attended and prescribed for the plaintiff once, three months after the accident, and examined the injuries again after the action was brought, was allowed to testify to his opinion of the plaintiff's condition, and the lasting character of the injuries, derived from what he saw, but not from any statement of the plaintiff, and to testify also, that, at the last interview she went lame, although he did not remember the particulars of the injury, or of the treatment which he prescribed at his first visit.2 3 It is a proper question to ask, and experts are allowed therefore to express their opinions touching the permanency of any injury which forms the basis of an action to recover damages. In such cases, as in all those where testimony is required to explain the extent of personal injuries, likely to be produced under a given state of facts, the opinions of experts are admissible, provided the witness states the precise facts upon which he bases his opinion, and the court does not withdraw from the jury the right or liberty to consider whether these facts were established by the testimony. But 1 Rowell v. Lowell, 11 Gray, 420. 2 Ibid. Newell v. Doty, 33 N. Y. 83-94. Wendell v. Mayor of Troy, 39 Barb. 329; Goodrich v. People, 3 Parker, 622; People v. Lake, 2 Kern. (N. Y.) 358. conditions, the rule of requir d, , in the same case, the surg n to ask, and experts are all In such cases, as in all the ad the court does not within it is always necessary to avoid propounding such questions as seem to involve the very point at issue, since the expert will not be allowed to answer them, and the proper course is, to ask his opinion upon a supposititious statement, illustrative of the case on trial.1 CONFESSIONS OF PATIENTS. § 121. The relations of the patient to the physician being necessarily of a confidential character, communications are often made to him in the nature of confessions. These communications, which may relate either to the history of a transaction in which a wound has been received or a particular disease communicated, whenever essential to the treatment of the patient's case, are in some States considered privileged communications, which the physician is either expressly forbidden, or not obliged to reveal. This is the law in Arkansas, California, Indiana, Michigan, Iowa, Missouri, Minnesota, New York and Wisconsin.2 The confession in order to be protected against disclosure, must relate exclusively to such matters as are indispensable to the professional treatment of the patient. Communications made outside of this sphere, acquire no immunity from having been entrusted to physicians, for at common law such are not deemed privileged, and wherever so recognized they are the creatures of statutory enactment.3 1 Perkins v. Concord R. R. 44 N. H. 223. * Arkansas, Dig. of Statutes, 1858, ch. 181, 22; California, 1850–1864, 5336; Indiana, Acts, 1861, p. 51, 3; Michigan, R. S. 1846, chap. 102, 86; Minnesota, St. 1849-58, p. 682; Missouri, R. S. 1845, chap. 186, § 20; Wisconsin, St. 1858, p. 812; Iowa, Rev. Stat. 1860, 3985; New York, Rev. Stat. 5th Ed. Vol. 3, p. 690; Vid. Johnson v. Johnson, 4 Paige, Ch. R. 460, and 14 Wend. 637. 31 Grlf. on Evid. § 248. Yet, in some of the above mentioned states the party interested may waive the privilege, in which case the communication may be disclosed.1 But in New York it is expressly enacted that "no person duly authorized to practice physic or surgery shall be allowed to disclose any information which he may have acquired in attending any patient in a professional character, and which information was necessary to enable him to prescribe for such patient as a physician, or to do any act for him as a surgeon. Necessarily all communications, and however privileged, must be of a lawful character, and not against morality or public policy, hence, a consultation as to the means of procuring an abortion in another is not privileged; nor by parity of reason would any similar conference which was held for the purpose of devising a crime, or evading its consequences.3 PROFESSIONAL BOOKS. § 122. The object of calling an expert into court being to obtain a personal opinion from him, together with the reasons therefor, it has become a rule of very general adoption, both in this country and Great Britain, not to admit professional books in evidence, nor even to allow the expert to quote their opinions by substitution for his own. Yet he may be asked the ground of his judgment 1 On a motion for a new trial, supported by the affidavit of a physician that a party had confessed to having allowed an abortion to be committed upon herself, it was held that such proof was inadmissible, without first showing permission on the part of the female to the physician to reveal the same. Harris v. Rupel, 14 Ind. 209. R. S. ut supra. 3 Hewitt v. Prime, 21 Wend. 79. 1 Grlf. Evid. 440, n.; Comm. v. Wilson, 1 Gray, 337; Washburn v. |