But it is not alone for this purpose that discrimination is required. A question of fact usually involves testimony on both sides, which must be collated, and the relative weight of which must be determined in order to reach a correct conclusion. Usually the court arranges and sifts the evidence in the instructions given to the jury, and it is obvious that without this aid the jury would be incompetent to analyze the evidence in a complicated case. Since the disqualification to testify by reason of interest has been abolished, the reasons which formerly were insisted upon as grounds of such disqualification are still proper to be considered with reference to the credit of the witness. It would be out of place to discuss these reasons at large in the brief summary of principles to which this article is necessarily limited. A single case may however be appropriately referred to, viz., the impeachment of a witness by direct testimony of other witnesses, showing that he is unworthy of credit. This kind of testimony is peculiar. The inquiry is limited to the general reputation of the witness whose veracity is in question, and the impeaching witness is not allowed to testify to particular facts.

The usual course of examination is to inquire what is the general reputation of the witness as to veracity, and formerly it was permitted then to ask the impeaching witness whether he would believe the other under oath, but the authorities are in this country not altogether uniform as to the latter practice. It may not be improper here to say that the rule as to impeachment of a witness is seldom of use, except where he is notoriously destitute of principle. A witness is also allowed to be impeached by showing that he has made out of court statements contradictory to his evidence in court; but before these are permitted to be shown his attention is called to them, that he may have opportunity for explanation.-Wo have thus briefly analyzed the general principles of the law of evidence. Our subject would however be imperfectly treated if we should not refer to some of the rules which have more particular relation to the practice of the courts. One is that the best evidence must always be produced; or in other words, that inferior evidence will not be received when a party has it in his power to produce better. But it does not follow, as be- fore remarked, that when a party has not the power to produce the best, any other without restriction is admissible.

The secondary proof must still be such as is held competent under other rules, or it will be rejected. The meaning of the rule is that inferior evidence, although otherwise competent, shall not be admitted when better can be had. We have before adverted to the distinction between writings or documentary proof, and oral or, as it is usually called, parol evidence. The distinction is founded upon the uncertainty of memory. Whatever has been put in writing can never be proved by mere recollection with perfect exactness; the writing itself is of course the most trustworthy, and according to the rule above mentioned it must be produced or its loss proved before its contents can be shown by other evidence; and this is true whether the writing relates to the principal fact or subject of the action, or is merely incidental. Again, when the question is as to a fact respecting which there is evidence in writing, but an offer is made to prove the fact by evidence aliunde without producing the writing or proving its contents, the rule is that if the writing was the concurrent act of both parties, as if it was signed by them or was prepared with the privity of both as an expression of their mutual understanding, it is thereby constituted the primary evidence of the fact to which it relates, and must be produced.

This includes not merely a written contract which is the subject of the action or defence, but any other writing which the parties have agreed upon as the expression of any fact incidentally involved in the action. There is this difference, however, between the two cases: that in the former no other proof can be received but the instrument itself, or if lost, proof of its contents; whereas in the latter there may be other evidence bearing upon the same point which is admissible, together with the writing, and in some instances without it, where it is not intentionally withheld. Thus a written correspondence between the parties may be material to show their understanding in respect to some transaction, but this would not preclude proof of conversations or other acts. If, however, the correspondence contains a contract, then, according to another rule, no other evidence can be received except what is necessary for the proper explanation of the meaning of the parties in the language used by them. It is not material which party has possession of the writing; the rule is the same in either case. If wanted by one party, and the other has possession of it, upon notice by him to the other to produce it, and its non-production, he may give parol evidence of its contents.

It is to be understood that the rule above mentioned applies only to a writing in which both parties have concurred. When it is a memorandum by one without the privity of the other, it cannot be evidence at all, except under the recent modification of the law of evidence allowing parties to be witnesses, and is subject to the same rule that applies to any other witness. The rule as to a memorandum made by a witness at the time of the transaction referred to in it is, that he may refer to it for the purpose of refreshing his memory; but having done so, he is to testify what with this aid he is able to recollect. But if he has no recollection independent of the memorandum, the later doctrine is that on proving that it was made at the time of the transaction referred to, and that he then had knowledge of the subject, the memorandum itself may be put in evidence. The mode of proving a writing which is attested by a subscribing witness is peculiar. In such a case the subscribing witness must be called if living and within the jurisdiction of the court; but if dead or absent from the country, proof of his handwriting or that of the party will be sufficient to make the instrument evidence.

The exclusion of proof of execution by any other person than the subscribing witness has often been the occasion of inconvenience; and the reason usually assigned for it, viz., that the subscribing witness is supposed to have some knowledge of the subject which another would, not have, is certainly very singular, as if he had such knowledge he would not be allowed to testify to it, if it would at all vary the effect of the instrument. In England, by acts 17 and 18 Victoria, c. 125 (1854), a subscribing witness to an instrument which is not required by law to be attested need not be called, but the instrument may be proved in the same manner as if there was no such witness. The rule that parol evidence is not admissible to contradict, vary, or explain a written instrument has been before referred to, and certain exceptions or qualifications were mentioned; but it should be added that in a proper proceeding instituted to reform the instrument, it may always be shown that, through accident, mistake, or fraud, it was not made to express the real intent and contract of the party.

Such a proceeding must be in chancery, except where the common-law courts are vested with equity jurisdiction.-In the examination of witnesses, a very different mode is prescribed to the party calling a witness from what is allowed to the opposite party. The counsel of the former must not put leading questions, and if the witness should make adverse or unsatisfactory answers, still he was deemed the witness of the party and could be examined only in accordance with that theory; that is to say, he could not be cross-examined by such party. This at least was formerly the rule, but it has recently been relaxed so far as to allow him to be treated to some extent as an adverse witness, when it is apparent that he is so. On the other hand, cross-examination by the other party is allowed to an almost unlimited extent, and the privilege is often used to pervert rather than elicit the truth. It would be difficult to fix a precise limit of restriction, as it necessarily rests very much in the discretion of the court; but the prevailing practice seems to be suited rather to a remote period, when from the disorders of society and consequent laxity of moral principle there was little reliance to be placed on the oath of witnesses, than to the present advanced state of social order.