The examination in chief is usually a very simple matter. The trouble for the expert begins when counsel for the other side gets up to cross-examine.
In nearly every case the object of the cross-examining counsel is to ridicule the art and get the expert to admit the possibility of other writers possessing the same peculiarities which are said to distinguish the letters before the Court.
Counsel's favourite trick is to select some letter and ask the expert if he is prepared to swear that he has never seen something just like it in some other person's writing. The expert who knows his business will insist on keeping well to the front the bedrock basis of handwriting comparison, which is the application of the law of probability to cumulative evidence. It is not a question whether some other person may be in the habit of making a t or a k similar to those cited as evidences of common origin, but whether it is probable that two persons should make a dozen or more letters in precisely the same way under similar conditions and exhibit precisely the same peculiarities of style. He should reply with the unanswerable postulate that millions of persons possess red hair, snub noses, a scar on the face, blue eyes, bent fingers and a stammer; but it is millions to one against any two persons possessing all six of those peculiarities.
In the course of his replies the expert may justifiably help his own case by repeating, when opportunity occurs, such irrefutable axioms as, No writer can say off-hand what peculiarities he may exhibit; that there are scores of ways of dotting an i, or crossing a t, and that few persons know which form they mostly affect. Fifty such points may be gathered from this little volume alone, while acquaintance with the works of other writers on caligraphy will supply ample ammunition for meeting and repelling the customary form of attack on the handwriting expert.
Another method of discrediting a witness is to remind him that experts have differed, the Dreyfus case being usually cited. The answer is obvious. First it is essential to be assured that those experts were all competent, for there are degrees of competency in judging handwriting as in every other subject on which opinion may be called. It is a notorious fact that in the Dreyfus case the most competent experts testified that the Henry letters were forgeries, the authorities called on the other side being in most cases unknown men or amateurs of no standing. A number of these self-styled experts possessed no other qualification than presumed familiarity with the handwriting of Dreyfus. It is also worthy of note that several of the experts on both sides proved most inefficient witnesses, obscuring their explanations by the employment of technical phraseology which conveyed little meaning to the lay mind.
Exactitude and regularity in the choice of the words used in describing the parts of letters should be strictly observed by the student. The rules given in the chapter on "Terminology" should be mastered and adhered to. In most cases the terms there applied to letter-analysis will be found to be self-explanatory.