delivered the opinion of the Court. The Court are of opinion, that an American consul, residing in a foreign country, and who has been duly accredited there, is a magistrate, authorized to take affidavits and depositions in such foreign state or country, within the meaning of the rules of this Court, directing commissions to take depositions, and that the depositions taken in this case by Mr. Baker, the American consul, in the absence of the special commissioners, to whom it was first addressed, was duly and properly taken. Brancker v. Parker, in Suffolk, March term 1837.

Another exception to the depositions was, that some questions propounded by the plaintiff were not answered.

So far as the objection goes upon the assumption, that a deposition must be rejected because some of the questions of the adverse party are not answered, as a general rule it is untenable. Where many interrogatories are addressed to several witnesses, it may well happen that no one can answer them all, especially where the adverse party cross-examines to new matter, not embraced in the direct interrogatories ; in which case a failure to answer would be no impeachment of the witness. Cases may be supposed, where if a witness is manifestly favorable to the party taking the deposition, and declines answering pertinent and material questions, to facts apparently within his knowledge, it would be a good ground for excluding the deposition altogether. It would show that the witness bad violated his duty and his oath, in not telling the whole truth, and the deposition would in effect be taken ex parle. In general however the objection would go to the credit of the witness, as indicating prejudice or partiality.

In the present case, -as to the failure of the witness mostly *173relied on, we think there is an obvious answer. The witness, a clerk of the defendants, or one who had stood in that relation, was requested to examine the defendants’ books, to make large abstracts, tables and statements from them, and to call on the commissioner to compare them with the originals and verify them. This we think the witness was not bound to do, and is well excused in not doing. It was an attempt to make these abstracts evidence, by the joint certificate of the witness and the commissioner, not as facts known to either of them, but as admissions, having their efficacy from the fact of being found in the defendants’ books. But if the defendants’ books were to be used at all, the defendants were entitled to the benefit of having the whole contents of them introduced, so far as pertinent to the same subject, under a proper case for that purpose. In this case, the objection to the deponent, if there was any, was to his credit and not to his competency.

There was also an exception to the instruction of the judge who tried the cause. A passage was extracted from Mayor’s deposition, in relation to the transactions of the defendants, respecting the negotiation and sale of exchange, and thereupon the plaintiff’s counsel requested the judge to instruct the jury, that such acts were conclusive evidence of unskilfulness and neglect of the plaintiff’s interest. This he refused to do, but0 submitted it for their consideration in connexion with all the other evidence on this point.

There are few cases, in which a judge can instruct the jury, upon a detached portion of evidence, that it is conclusive. It may sometimes occur that a witness testifies to a precise fact, of such a character, that if true it will be decisive of the cause. In such case a judge may safely tell the jury, that if they believe the witness, it is conclusive. But the testimony must be to a fact, which if pleaded and demurred to, or otherwise admitted in the pleadings, would be a legal ground for a judgment. But if the fact can be explained, controlled or modified, by other facts and circumstances, or if it be a fact, which if it appeared in pleading, could be confessed and avoided, it cannot be declared conclusive. To apply it to the present case, if the testimony respecting the sale and negotiation of exchange, by the defendants, could be accounted *174for by any supposable circumstances, consistently with the good faith and competent skill of the defendants, it could not be held legally conclusive. That they might be so accounted for, in many ways, from the peculiar condition of the country and the actual state of commerce at the place and time, or the'particular circumstances in which the parties were placed, appears to the Court very manifest; whether they were so, was a question for the jury on the evidence. For this purpose the testimony of Mayor was properly submitted to the jury with the other evidence, but could not be considered legally conclusive of negligence or want of due skill, on the part of the defendants.

Judgment on the verdict for the defendants