Where a witness is called to testify to handwriting, from knowledge of his own, however derived, as to the hand of the party, he is not an expert, but simply a witness to a fact in the only manner in which that fact is capable of proof. Nor is he an expert who is called to compare a test writing, whose genuineness is established by others, with the writing under investigation, if he have knowledge of the handwriting of the party, because his judgment of the comparison will be influenced more or less by his knowledge, and will not be what the testimony of an expert should be, a pure conclusion of skill.
But when a witness, skilled in general chirography, but possessing no knowledge of the handwriting under investigation, is called to compare that writing with other genuine writings that have been brought into juxtaposition with it, he is strictly an expert. His conclusions then rest in no degree on particular knowledge of his own, but are the deductions of a trained and experienced judgment, from premises furnished by the testimony of other witnesses.
One of the palpable anomalies of the present practice regarding experts on handwriting is that a person who has seen another write, no matter how ignorant the observer may be, is competent to testify as to whether or not certain writing is by the hand of the person he has once seen engaged in the art of writing, while an expert handwriting witness may only testify that the hand appears to be simulated but may not point out the differences between specimens of genuine writing and the instrument in controversy.
It is safe to presume that the apparently unreasonable position of the law was assumed with a good object in view, and it is probable that the object was the protection of the court from the swarm of so-called experts which might be hatched by a laxity in the wording of the law. Few things would be easier for a dishonest person than to swear he was a competent expert, and then to swear that a document was, in his opinion, forged or genuine, according to the requirements of his hirer. The framers of the practice in reference to expert testimony on documents seem to have had in mind that the only possible kind of testimony as to documents was that based upon impressions; and that the only method of coming to a conclusion was by giving words to the first mental effect produced on a witness after he has looked at a writing.
For this reason the practice has grown up in many trials of preparing carefully forged signatures and producing them before the witness as a test of how far he is able to distinguish genuine from forged signatures.
However expert a witness may be, however successful in discriminations of this kind, self-respect and a becoming modesty should induce him to refuse to answer them without distinctly stating that his answer, which gives his best judgment at the time, must be subject to reversal if by longer and more thorough investigation it appear that the opposite view were the true one.
When there is presented before a court of law a document, of which it is important to know whether a part or the whole of the body, or the signature, or all, is actually in the handwriting of some person whose writing or signature in other exhibits is admitted to be genuine, the counsel on each side usually seeks the aid of one or more handwriting experts.
Usually a teacher of writing is called, but more often the cashier or paying teller of a bank is preferred. There seems to be a good reason for choosing a bank cashier or a paying teller, for the man upon whose immediate judgment as to genuineness of signatures, reinforced by a large and varied knowledge of human nature and quick observation of any suspicious circumstances depends the safety of a bank, has certainly gained much experience and is not apt to be easily deceived in the kind of cases coming daily before him. How much the average cashier and paying-teller depends upon the trifling circumstances attending the presentation of a check, the appearance of the person presenting it, the probability of the drawer inserting such a sum, etc., becomes apparent when one has heard a number of these useful officers testify in cases where they are deprived of all these surroundings, and required to decide whether a certain writing is by the same hand which produced another writing, both being unfamiliar to them.
In this case they are obliged to create a familiarity with the signatures of a man whose character and peculiarities they have never known.
They miss the aid of some feature, such as a dash, a blot, or the distortion of a letter, which would recall to them the character of the writer. Most of the best experts of this class confess that they cannot tell on what their judgment is based. They simply think that the writing is not by the same hand as that admitted to be genuine. "No," they will tell you, "it is not merely superficial resemblance. I don't know what it is, but I feel sure," etc. These witnesses are more frequently right than the more pretentious professional expert. The former trust to the instantaneous impressions which they receive when papers are handed to them; the latter too often give their attention to the merely superficial features of chirography without getting beyond the more obvious resemblances and differences which are frequently the least important.