Some of the principal tests applied to determine the genuineness of handwriting are these:  The actual and relative slant of the letters or the angles between their stems and the base; the constancy and accuracy with which a straight line is followed as a base; the amount of pressure used on the pen and the part of the stroke where it is applied, and the positions of the line as a whole relative to the edges of the paper.  The simplest punctuation mark under the microscope has its own individuality.  It would be difficult to find two writers whose semicolons and quotation marks cannot be distinguished at a glance.  The dotting of the i and crossing of the t afford an infinite number of relations between points and lines, and in both of these the time element and the freedom of muscular movement play important parts.  Even the health and self-control of the penman, as well as the physical circumstances, show their influence on these little strokes.

The identification of the individual by means of his handwriting is of great value in legal trials and outside of courts.  Its use cannot be dispensed with any more than can the knowledge obtained in any other line of science.

One often hears a man boast of his ability to successfully duplicate another person’s signature or handwriting, and to the casual observer the counterfeit really will bear a striking resemblance to the original.  However, let the two be placed in the hands of an expert on disputed handwriting and he will pretty quickly determine which is the original and which the forgery.  Furthermore, he will tell you what process was used to make the duplicate, for there are several methods in use among forgers, and can even tell the composition of the ink.

In the determination of any handwriting there is no actual rule to guide an expert, as each case must be a law unto itself.  The time of day that the signature was made and the condition for the moment of the individual have considerable bearing on the case, as has also the writer’s general physical condition.  Whether he was standing or sitting when the signature was made is a matter of importance.  The quality of the paper and the make of the pen also have to be taken into consideration.  In the case of forgery, where the forger has employed a finger movement writing with the muscles and apparently without education, there is scarcely any difficulty in arriving at a conclusion.  The long flowing hand is easy to detect.  When, however, the writing is finical a large mass of material has to be examined before a decision can be reached.

The testimony of an expert is without doubt the most dangerous kind of evidence when not supported by additional testimony; but, on the other hand, if the known facts fit in well, it is the strongest kind of testimony that can be submitted, and is usually known as “opinioned evidence.”  There probably is no class of professional witnesses which is subjected to such severe cross-examination as experts in handwriting, and, considering the great importance of their testimony, they should be ever ready and willing to explain the methods employed by them in arriving at their decision, which, of course, is the result of a comparison of the analyses of several pieces of writing, taking account of all exaggerations, idiosyncrasies and unusual peculiarities.