to the extent of the inquiry into the private affairs of individuals to which courts of this nature might go under the cloak of law. And, in addition to the right to be secure from all unreasonable searches and seizures, was secured the privilege of refusing to disclose matters which would tend to incriminate the witness. This privilege was regarded with great concern, because of its far reaching importance to liberty, and became firmly and ineradically imbedded in the common law.

The framers of our government firmly implanted it in the Constitutional Amendments, Art. V, which provides: "No person * * * *shall be compelled, in any criminal case, to be a witness against himself," etc.

This privilege not only exists at common law, but is declared in many State constitutions and statutes. Matter privileged under this head includes any disclosure of facts which would tend to subject the witness to imprisonment, penalty or forfeiture, or confiscation of lands.

SECTION 43. BETWEEN HUSBAND AND WIFE.

In view of the high importance of preserving intact the confidence and security of the marriage state, the law regards confidential communications between husband and wife as privileged, and refuses to permit either to be interrogated as to what occurred in their confidential intercourse during their marital relations. The law has placed its protecting seal upon all such communications, and upon whatever else has come to the knowledge of either by means of the hallowed confidence which that relation inspires, and forbids its divulgence in testimony even though the other be no

longer living. The seal once fixed, remains forever, and neither death nor subsequent divorce removes it.

This wise rule of the common law has been very generally declared by statute in the United States.

' Griffeth vs. Griffeth, 162 Ill., 374.

CHAPTER VII.

EXPERT AND OPINION EVIDENCE.

SECTION 44. DEFINITION AND SCOPE.

Expert evidence is testimony given by one specially versed or skilled in a certain science, profession, or trade, concerning information beyond the range of ordinary knowledge and intelligence. Concerning matters of science, skill, or trade, or subjects of a kindred nature, persons who have made a special study or practice thereof, and who are well versed or skilled therein, may give either their opinion thereon or testify to facts within their knowledge. Persons so versed or skilled are called "experts."

Unless the matters under investigation involve some question beyond the range of ordinary knowledge or understanding, there is no province for the introduction of expert testimony. Opinions are never received so long as the facts in the case are readily intelligible to the court and jury, nor so long as the subject under inquiry is one readily understood by men of ordinary intelligence and knowledge.

The reason for the admission of expert or opinion evidence is one of necessity, the theory of the law being that a court or jury, having given a scientific subject, or trade requiring skill, no study, and having no knowledge or experience in a subject little known to the generality of mankind, are unable to form a correct judgment concerning it. One who, by practice, or observation, or special study, has become skilled or learned therein, is better able to form an accurate opinion concerning the same.

SECTION 45. QUALIFICATION OF EXPERTS.

After first determining whether the question under investigation is a proper subject of expert inquiry, the next question for the court to decide is: Has the witness offered the necessary qualifications of an expert? This is a matter resting largely within the discretion of the court. But if the witness be shown to have given the subject special study, or if he be a licensed member of a skilled profession or trade, having the years of experience usually sufficient for the ordinary members thereof to acquire a thorough knowledge of the subject, he will generally be permitted to testify and to give his opinions concerning hypothetical questions covering the facts proven in the case. He will not be permitted to express his opinion as to the general merits of the controversy, for to permit him to do so would be to allow the witness to usurp the province of the jury. It is for the court or jury to form opinions and judge of the merits of the case.

It is not necessary that the opinion of an expert be derived from his own observation and experience, but he may give his opinion based upon information derived from books.' In Mitchell vs. The State, 58 Ala., 417, which was an indictment for murder by poisoning by arsenic, a physician was allowed to give his opinion as to the cause of death, although it did not appear that he had ever attended cases of that character, and in passing upon the admissibility of the evidence, the court held that a physician, who has had long experience in the practice of his profession, and knowledge of the symptoms of the malady of the deceased, was competent to testify as an expert. State vs. Terrell, 12 Rich (S. C.), 321.

And in State vs. Wood, 53 N. H., 484, which was an indictment for murder caused by an abortion alleged to have been produced by the defendant, it was held that a physician, testifying as an expert, may give his opinion founded upon his reading and study, alone.

It is not required that the expert testimony be the best obtainable, nor that the witness at the time he testifies be actively engaged in the profession or trade concerning which he is about to testify. But where he has abandoned the same for twenty years, courts are loath to receive the opinions of experts whose knowledge is so antiquated, more recent and better expert evidence being readily obtainable.

It has sometimes been held that an expert in one occupation may testify in another and kindred one when the nature of the first occupation is such as to give him superior opportunities for acquiring special knowledge and experience in the other. This rule, however, has been severely and justly criticised by courts and should be applied with great caution.

Before proceeding with the examination of an expert witness, it is necessary to interrogate him regarding his special qualifications and to satisfy the court that he is competent to give his opinion on the subject to which his testimony relates. The question as to his fitness should be determined by the court at once, before he is allowed to testify, and should not be postponed to the cross-examination to determine his disqualifications. If a witness testify that he is unable to give his opinion on a certain subject or hypothetical question, he is disqualified by his own testimony.

The court may, in its discretion, permit opposing counsel to cross-examine the expert as to his qualifica