science, which must be given by experts or scientific witnesses in court. Books are only hearsay, often of the most vague, inconsistent and remote character; statements made by absent, perhaps anonymous, witnesses, who write without being under the fear of the spiritual or secular penalties of an oath, and without being subject to cross-examination. It is plain, therefore, on the first principles of evidence, that they are without any of the elements of legal credibility.

The general rule will not be construed to exclude from the consideration of a jury anything which would assist them in making up their minds upon the facts in dispute, but is intended simply to prevent the functions of the jury being usurped by the witness, which would be done, were he allowed to lead their opinion by his own.

By Ord. 38, r. 3 of the R. S. C., 1883, in affidavits in support of interlocutory motions, statements as to the belief of the witness, with the grounds thereof, are admissible, but all other affidavits are to be confined to such facts as the witness is able of his own knowledge to prove. Proceedings which finally decide the rights of parties are not interlocutory within the meaning of this rule (7).

(2) Gilbert v. Endean, L. R., 9 Ch. D. 260; 27 W. R. 252.

CHAPTER VII.

PRIVILEGE.

EXCEPT when some positive rule intervenes, a witness is compellable to answer any question that may be put to him. It is generally understood now, that a witness may be asked any question (except questions tending to show that he has been guilty of adultery); but there are many questions which he will not be compellable, and some which he will not be permitted, i. e. is not competent, to answer. So in documentary evidence every writing is admissible, except when it is excluded by a similar principle of law.

Wherever a witness is not compellable or not competent to answer any question, it is because some privilege intervenes, which privilege is sometimes that of the witness himself, sometimes that of another person, and sometimes that of the state which asserts the right of excluding certain kind of evidence on grounds of public policy. Where the privilege is that of the witness himself, he may waive it and answer the question; where the privilege is that of another person, such person may waive it and permit the witness to answer, but the waiver cannot proceed from the witness himself. Where, in reliance on privilege, a witness refuses to answer, or is not allowed to answer any question, no presumption

arises that the evidence so withheld is unfavourable

to any person.

The different kinds of privilege will be gathered from the following rules, viz. :

Criminating Questions.

A witness is not compellable to answer any question tending to criminate himself.

I. e. on the principle nemo tenetur seipsum prodere, a witness, whether a party to a suit or not, cannot be compelled to answer any question, whether put vicâ voce or in the form of a written interrogatory, the answer to which may expose, or tend to expose, him to a criminal charge, penalty, or forfeiture of any kind. This rule is recognized and expressed by the Law of Evidence Amendment Act, 1851, which, after making the parties to civil actions and suits competent and compellable witnesses on behalf of either party, enacts that nothing in the act shall render any person compellable to answer any question tending to criminate himself or herself (a). On a similar ground, the production of a document may be refused.

In R. v. Garbett (b), it was held that a witness is not compellable to answer a question, if the court be of opinion that the answer might tend to criminate him. It was also held in the same case that the court may compel a witness to answer any such question; but that if the answer be subsequently

(a) 14 & 15 Vict. c. 99, s. 3.
(b) 1 Den. 236.

used against the witness in a criminal proceeding, and a conviction obtained, judgment will be respited and the conviction reversed. In R. v. Boyes (c) Cockburn, C. J., in delivering the judgment of the court, said: "To entitle a party called as a witness to the privilege of silence the court must see from the circumstances of the case and the nature of the evidence which the witness is called to give, that there is reasonable ground to apprehend danger to the witness from his being compelled to answer. We indeed quite agree that if the fact of the witness being in danger be once made to appear, great latitude should be allowed to him in judging for himself of the effect of any particular question; there being no doubt, as observed by Baron Alderson in Osborne v. London Dock Co. (d), that a question which might appear at first sight a very innocent one might, by affording a link in a chain of evidence, become the means of bringing home an offence to the party answering. Subject to this reservation a judge is, in our opinion, bound to insist on a witness answering, unless he is satisfied that the answer will tend to place the witness in peril." This statement of the law was approved and adopted by the Court of Appeal in the recent case of Ex parte Reynolds (e).

It is settled that it is no ground for a witness to refuse to go into the box, that the question will

(c) 1 B. & S. 311.

(d) 10 Ex. 698.

(e) L. R., 20 Ch. D. 294; 51 L. J., Ch. 756; 30 W. R. 651.

criminate him, and that he will refuse to answer it. The privilege can be claimed only by the witness himself after he has been sworn and the objectionable question put to him (f), and the witness must pledge his oath that he believes the answer will tend to criminate him. If he assigns a reason for not answering, which in the opinion of the court is insufficient, he will be compellable to answer. He can claim his privilege at any time, and does not waive it altogether by omitting to claim it at an earlier opportunity (g). A judge ought to caution a witness, where a privilege exists, that he is not bound to answer (h).

:

In R. v. All Saints, Worcester (i), Lord Ellenborough held that a wife was competent to answer questions criminating her husband, and that the answers were not excluded on the ground of public policy but Bayley, J., was of opinion that a wife who threw herself upon the protection of the court would not be compelled to answer. There is no doubt that a wife cannot be compelled to answer any question, which may expose her husband to a charge of felony (k).

A witness may waive his privilege and answer at his peril (7). The privilege extends to cases in

(f) Boyle v. Wiseman, 10 Ex. 647.

(g) R. v. Garbett, 1 Den. 258.

(h) Per Maule, J., Fisher v. Ronalds, 12 C. B. 762; Paxton v. Douglas, 16 Ves. 242.

(i) 6 M. & S. 194.

(k) Cartwright v. Green, 8 Ves. 410.

(Paxton v. Douglas, 16 Ves. 242.