delivered the opinion of the Court:
1. The controverted fact of this case is the genuineness of A. H. Pickrell’s endorsement. Its determination was submitted to the jury upon a mass of conflicting evidence, and their verdict precludes inquiry into the relative weight thereof. The judgment entered on this verdict must therefore stand, unless a material error can be shown in some ruling of the court made during the progress of the trial and duly excepted to.
2. The first of the exceptions questions the right of the defendant to introduce evidence to disprove the genuineness of the endorsed signature, under the plea of non assumpsit. The contention is that the execution of an instrument of the character of that sued on must be specially denied by plea in order to put it in issue. We cannot subscribe to this view. By the rule of the common law (in which no change has been made by statute or established rule of court in the District of Columbia) the general issue of non assumpsit not only puts the plaintiff upon proof of all his necessary allegations, but also lets in proof of all the ordinary defenses to the action. 2 Greenleaf on Ev., Sec. 6 ; Id., Sec. 135; 1 Chitly PL, *p. 476 et seq. This rule was in force in England until changed by rule of court made in 1834, by authority of a statute enacted the same year. Whilst a like change may be desirable here, it must await a similar authorization.
*204Under the pleadings then, as they stood, we must hold that it was incumbent upon the plaintiff to prove the execution of the note and endorsement in some of the modes known to the common law. Indeed, the plaintiff recognized this to be the proper practice, for, as we have seen, before offering the note he introduced evidence tending to prove its execution by both maker and endorser. The evidence objected to was in direct rebuttal of the plaintiff’s own testimony.
3. Succeeding assignments of error, based on formal exceptions, present some interesting and rather novel phases of that much argued rule of evidence respecting the proof of disputed handwriting by comparison. Upon few questions arising in the law of evidence has there been so much discussion, or so great contrariety of opinion among the courts of this country and of England. The first of these points arose as follows: As will be seen in the preliminary statement, plaintiff offered evidence of the genuineness of the endorsement, consisting of the opinions of witnesses more or less familiar with the handwriting of Pickrell, and then exhibited the letters written and signed by him, called W. B. T. 4, 5, 6. It appears that the will of Pickrell was in the record. How it came there is not apparent, though it would seem to have been brought in by plaintiff for some purpose or other on a former trial. Over plaintiff’s objection defendant was permitted to exhibit the signatures of Pickrell to this will and.to the letters W. B. T. 4, 5, 6, to the jury for comparison with the disputed signature, and in addition thereto to offer proof through the opinions of experts formed from a like comparison made in the presence of the jury. The objection is that these writings were not in evidence in support of, or relevant to, any issue of the cause, and therefore were not admissible or capable of being used as standards of comparison. The recognized rule of the common law, which prevailed in England until changed by statute in some *205important respects, is thus tersely stated in the headnotes of the reported case of Doe dem. Perry v. Newton, 5 Ad. & Ell. 514: “ On a question as to the genuineness of handwriting the jury may compare the document with authentic writings of the party to whom it is ascribed, if such writings are in evidence for other purposes of the cause, but not else.” See also Griffits v. Ivery, 11 Ad. & Ell. 322 ; Hickory v. U. S., 151 U. S. 303 ; Williams v. Conger, 125 U. S. 397.
The reasons usually assigned for adherence to this strict rule may be substantially stated as follows: 1. The admission of papers, otherwise irrelevant, would probably raise collateral issues respecting the genuineness of the signatures thereto which might be spun out indefinitely and to the utter confusion of the jury. 2. Opportunity might be given to the party offering the papers to obtain advantage by making an unfair selection of the test signatures. These reasons should be borne in mind in the application of the rule to the point as presented in this record. It may be granted that the will of Pickrell was not, strictly speaking, a paper in evidence in the case, there being no denial of the probate and letters testamentary as alleged. Had there been such denial, the plaintiff would have been compelled to put the will in evidence. Though answering no practical purpose as evidence, the will was, nevertheless, the foundation of the plaintiffs right to enforce the obligation of the endorsement against the executor named therein. It appears as the only will executed by Pickrell, and having sued defendant as executor thereof, the plaintiff is necessarily estopped to deny the genuineness of the signature. The admitted authenticity of this will and the propriety of its use as a test is within the principle of Williams v. Conger, 125 U. S. 397, and it is clearly as much a paper in the cause and as pertinent to its issues as the power of attorney by which the claimant authorized the institution of his suit in Moore v. U. S., 91 U. S. 270.
The rule is plainer still as regards the use made of letters *206W. B. T., 4, 5, 6. It is true that they had no relevancy to the case whatever, and had they been objected to by defendant, must necessarily have been excluded. But they were first exhibited by the plaintiff himself. By so doing he affirmed their genuineness in the most solemn manner and cannot now be heard to cast doubt upon it. Smyth v. Caswell, 67 Tex. 567.
The relation of the plaintiff to these several writings was clearly such as to prevent the possibility of a collateral issue as to their genuineness, and at the same time preclude the idea of unfairness in their selection as tests for the comparison. Therefore, even if the admission of these test signatures might not have been witbin tbe letter of the aforestated rule, it was clearly within the spirit thereof, and and the court did not err in its ruling.
4. Granting that the signatures to these papers were properly permitted to go to the jury for comparison with the one in dispute, it is contended, on another exception, that the court erred in permitting the experts, who had never seen Pickrell write, to make the same comparison in the presence of the jury, and to testify therefrom that the endorsed signature was not genuine. This is another branch of the general question upon which learned courts have greatly differed. In England it seems to have been early held that such evidence was inadmissible, save in the case of ancient instruments. Gurney v. Langlands, 5 B. & A. 330. The testimony of experts had been rejected on the trial, and the rule for a new trial was refused for the reason that such evidence is of no weight or value. Mr. Best, whose discussion of tbe whole question of comparison of handwriting is clear and critical, after an analysis of the above case says of expert evidence:
“ Its admissibility seems to be recognized, in the more recent cases of the Fitzwalter Peerage (10 0. & F. 198), the Tracy Peerage (Id. 154), and in Newton v. Ricketts (9 H. L. Ca. 262), and according to the present practice it is gen*207erally received without objection.” Best, Pr. of Ev. 253. Wharton says: “ When comparison of hands is permitted, an expert can be called to make such comparison,” and cites a great many authorities in support of his statement. 1 Whart. Ev., Sec. 719. Greenleaf says also: “ Where other writings, admitted to be genuine, are already in the case, the comparison may be made by the jury with or without the aid of experts.” 1 Gr. Ev., Sec. 578.
The rule and exceptions thereto, as established by decision and statute in the several States of the Union are concisely stated in the excellent treatise of Professor Rodgers upon Expert Testimony (Sec. 134 et seq.). From this review it appears that the large majority of the courts agree with the text writers quoted above.
The rule has not been definitely settled in the Supreme Court of the United States. True, it has been said that, save in the case of an ancient writing, “ evidence by comparison of hands is not admissible where the witness has no previous knowledge of the handwriting, but is called upon to testify merely from a comparison of hands.” Strother v. Lucas, 6 Pet. 763. It does not appear from the opinion in that case that the witnesses offered were in fact experts at all, and the question was one of no importance whatever, because, as the court observed, living witnesses to the signature had been examined, and “ besides the deed was received and read in evidence, and the plaintiff had the full benefit of it.” Id., 767.
In Rogers v. Ritter, 12 Wall. 317, the general doctrine of Strother v. Lucas was approved, but witnesses who had never seen Sanchez (whose signature was in dispute) write, were nevertheless permitted to testify to the genuineness of his signature from knowledge acquired by them through familiarity with his writings contained in the Mexican archives that had passed to and been preserved in the office of the recorder and surveyor general at San Francisco after the change of government in California.
*208In Hickory v. U. S., 151 U. S. 303, experts had been permitted to compare the writings offered in evidence, without objection on the trial, hence there was no decision on this point. The case turned on the right of the defendant to prepare a paper during the trial and submit it for comparison with the disputed writing alleged to be his. It was held that a standard prepared for the purpose could not be exhibited. Referring to the general rule of admission of handwriting, the chief justice, who delivered the opinion, says the comparison may be made by the jury “ with or without the aid of witnesses,” and cites 1 Gr. Ev., Sec. 578, where the exact expression is, “ with or without experts.” We think, however, that no significance can be attached to the mere change of words. Notwithstanding the frequent severe criticism of expert testimony, the tendency in modern practice has constantly been towards the extension of the field of its operations. In many instances the testimony of experts is indispensable. Unquestionably, the integrity of such testimony is often subject to grave doubt, and will be as long as the expert is not called by the court, or by the public authority as an unbiased and impartial adviser in the case, but is left to the selection of the interested parties who pay his fees, wherefore he too frequently takes on the character of a professional adviser and advocate of the party in whose interest he appears. The objections urged, however, may all be classified as affecting the credibility and weight of the evidence rather than its competency, and as such may be left to the consideration of the jury.
The testimony of all witnesses to handwriting who did not actually see the writing made is from comparison. The witness who has been in correspondence with the party, or who has become familiar with his writing in the public offices, or who has even seen him write his name one time only, is generally held to be competent, and yet he compares the writing shown him with one borne in his mind. The *209expert compares the same writing with others of undoubted authenticity and fairness of selection, and with time to study them carefully, expresses his opinion. With these signatures in juxtaposition he can be cross-examined and made to demonstrate his conclusions in the presence of the jury, who also make the comparison and test the soundness of his opinions, and the reasons therefor by their own perceptions. We are unable to see why the testimony of each witness is not of the same nature, nor why the examplar in the mind of a witness should be regarded as more reliable than one presented to the expert’s eye and at the same time to the eye of the jury. In the absence of an express decision to the contrary by the court of last resort we must hold that the evidence was admissible.
5. It follows from what has been said respecting the admissibility of the signature to the will and to the letters marked W. B. T. 4, 5, 6, that the court did not err in excluding the papers marked W. B. T; 14, 15, 16,17, 18, 19, as standards of comparison. They were not evidence in the cause, though the court allowed them to be used in the cross-examination of defendant’s experts, to which it seems there had been no objection. They had no relevancy to the matters involved in the litigation and occupied no relation thereto which could possibly have estopped the defendant to raise a collateral issue as to the genuineness of each one as offered.
6. This brings us to the consideration of the last of the series of exceptions taken to the rulings of the court on the admissibility of handwriting, for purpose of comparison. Under the plea of non assumpsit, as we have held above, it wag necessary for the plaintiff to prove the execution of the note by the maker also. In the course of his proof plaintiff introduced certain evidence tending to show the origin of the indebtedness of Hume to the bank, its reduction and renewal from time to time during several years, with the note of Hume payable to the order of Pickrell, with the latter’s *210name endorsed, and the possible knowledge by him thereof. The three letters of Hume to the cashier of the bank, marked W. B. T. 1, 2, 3, referring to the transaction in some of its earlier stages, were identified and read without objection. This was all admissible evidence forthe purpose of proving the existence of the debt, the genuineness of Hume’s own signature, and as furnishing a circumstance for the jury to consider with other testimony in determining the genuineness of Pickrell’s endorsement.
On behalf of the defendant it was shown, by the opinion .of witnesses, that the handwriting in the body of the note was that of Hume. Subsequently defendant submitted the body of the note and the endorsement thereon to the exami.nation of the witness Ames (one of her experts) who, having made the comparison in the presence of the jury, expressed the opinion that both were in the same handwriting, though executed with different ink.
The importance of this testimony is manifest. It is necessarily added weight to the opinion expressed by the same witness, and others, that the signature was not in the handwriting of Pickrell. There was not a shadow of suspicion that the officers of the bank had forged the endorsement, consequently the only person who had any motive therefor was the maker of the note, who thereby secured another extension of his debt. He lived some three years after the maturity of the note, and for several months after the suit was instituted. During this time no suspicion seems to have been cast upon the genuineness of the signature ; and it does not seem indeed, to have been questioned until some years after his death. No witness saw the preparation, execution or endorsement of the note.
In order to rebut and counteract the damaging effect of this testimony the plaintiff introduced an expert — Mr. E. B. Hay — as a witness, and submitting the letters W. B. T. 1, 2, 3, to him for comparison with the endorsement, proposed to elicit the opinion that they were not in the same handwrit*211ing, and to submit them to the jury for comparison. On objection of defendant this was refused, and plaintiff excepted.
It can readily be seen that if this fact of actual difference between the handwriting of Hume and the disputed signature of Pickrell could have been established to the satisfaction of the jury, it might have had great weight in the determination of the controverted fact.
The handwriting of Hume having been made an issue by the defendant’s evidence, we think these letters became proper standards of comparison and foundations for the opinion of the expert, within the scope of the rule of evidence recognized above. They were already in evidence for a legitimate purpose, without objection or challenge as to their genuineness, and subject to the examination of the jury. Their authenticity was established also by the proof that they were part and parcel of the transaction out of which the litigation grew, being communications between Hume and the cashier of the bank relating thereto, which had been acted upon at the time. 1 Greenleaf Ev., Sec. 577. No collateral issue as to their genuineness was or could well have been raised. They were free from suspicion of unfairness in their selection as tests, and their use could hardly have prejudiced the defendant in the nature of surprise.
The question as here presented is, in some respects, novel and difficult of right solution; but, after much consideration, we cannot avoid the conclusion that the comparison of the writings and the opinion of the witness thereon ought to have been allowed to go to the jury, and that for the error of the court therein the judgment ought to be reversed and a new trial awarded.
7. Some other and minor questions are presented in the bill of exceptions, which, as they may arise on another trial, will be briefly noticed.
It was not error to exclude either the record in the case of William B. Bowie v. Mary E. Pickrell, executrix, and *212Annie G. Hume, devisee, under the will of A. H. Pickrell, deceased, or the admission of their counsel made on the examination of witnesses therein, that the signatures of maker and endorser of this note were genuine. The admissions or recitals of facts made by a party in the pleading in another and different case are generally held not to be competent evidence. Davis v. Gallagher, 124 N. Y. 487 ; Dennie v. Williams, 135 Mass. 28. This rule, like most others, has its exceptions, but this case does not come within them. Still less are the verbal admissions of counsel, made on the trial of another cause, admissible against their client.
We may add also that there is no element of estoppel, as claimed, in such pleadings, or statements of counsel on the trial of another and wholly distinct case. Nor is there any estoppel in the mere delay of the defendant to raise the question of the genuineness of the endorsement, and the court did not err in so holding. Some exceptions were taken and have been here urged to the charge of the court; but after what has been said we think it unnecessary to discuss them.
We have confined our consideration to the points only which have been assigned as error and urged on the hearing, giving no attention to questions of practice which have heretofore been decided by the General Term and treated as settled thereby.
For the error pointed out, the judgment must be reversed, with costs to the appellant, and the cause remanded; and it is so ordered.