1788.
With refpect to the admiffion of teftimony, the law has been fo well eftablifhed, and is fo perfectly underftood, that it is needlefs to enter minutely into the doctrine. The whole, indeed, may be reduced to a fhort rule ; − if the witnefs fpeaks under an intereʃt, it is fatal to his competency ; if he is liable to an inƒluence, it taints his credibility. On the prefent occafion, we are of opinion that Captain M‘Cullough,, at t time of taking the depofition, was not an interefted witnefs ; and, therefore, if there was no other objection, we fhould certainly allow the Plaintiffs the benefit of his teftimony: For, in the authority cited from Atk. 15. Lord Hardwicks can only mean, that a witnefs, who has been once interefted, fhall be prefumed to be fo ftill, unlefs the contrary is proved by a releafe, or other fatisfactory evidence.
The Plaintiffs, however, have failed in another refpect. A Subpœna ought certainly to have been taken out, and, if poffible, ferved upon the witnefs ; for, it was his, and not their, province, to determine whether he would attend or not. The rule never was meant, indeed, to direct an ufelefs thing ; − fuch as iffuing a Subpœna after a witnefs actually refiding in London, or any other diftant country ; though even this was heretofore required in ftrict practice. But, in the prefent inftance, Captain M‘Cullough was known to be here a few days ago, his family always refides here, and he may himfelf, probably, be within a very fhort diftance of the city, at this moment. The Plaintiff, having taken it upon the rule, have acted in their own wrong ; and, upon this objection, we are of opinion, that the depofition ought not to be read in evidence.
II. The Defendant's counfel offered his books to prove, that in his account with, the United States, at the time of the tranfaction between him and M‘Cullough, there was a comfortable balance in his favor.
But it was objected, for the Plaintiff, that the books of a party are only evidence of goods fold and delivered, or work done ; and that, therefore, they were inadmiffible to the prefent purpofe, which was to fhew that the money was advanced upon a contract different from that which the Plaintiff's alledged.
To this it was anfwered, that although the books of a party are only evidence to charge in the cafes mentioned, yet, that they might well be received to eftablifh a matter collateral to the caufe.
And by M‘KEAN, Chieƒ Juʃtice.– This is a point, that I do not remember to have occurred before. The books are not offered to prove a charge againft the Plaintiffs, but only to determine a collateral queftion, whether a third perfon was the Defendant's debtor, at a particular period ? How can this be accomplifhed, but by the evidence of the books, fairly and regularly kept ? To make it a charge, other vouchers of the entry might be neceffary ; but for
