The document examiner expert is often asked in court, during voir dire or cross examination, if Questioned Document Examination is an art or a science. This question is sometimes posed in a condescending manner, in an attempt to discredit any subsequent testimony as nothing more than an abstract artist’s interpretation and comparison of letter formations. Sometimes the question takes the form of “This is not an exact science, is it’? This line of questioning may be easily answered and turned into an advantage by an explanation of how the Scientific Method is objectively employed by the competent Forensic Document Examiner.
While document examination is undertaken using the scientific method, there comes a point in the examination when the examiner has to decide what weight to assign the examination results. At this point the examination becomes more subjective. Using the Scientific Method, the Questioned Document Examiner formulates a hypothesis. This may be quite simply “Mr. Smith wrote the questioned signature” or “Mr. Smith did not write the questioned signature.” In reality, most Questioned Document Examiners start with a position of neutrality as a hypothesis (“I don’t know if Mr. Smith wrote the questioned material or not”), which may make the comparison more of a scientific experiment than examination.
The examiner then continues with the next step of the Scientific Method, gathering the data necessary to perform the experiment. This data is questioned material (usually the disputed document) and suitable standard material of sufficient quantity and quality. Once gathered, the data is tested (a side-by-side comparison) and similarities and dissimilarities which may prove or disprove the original hypothesis are noted. While these similarities and dissimilarities in the writings are objectively noted, they are subjectively weighed. This leads to opinions theoretically ranging from elimination to positive identification with areas of probability inbetween. In keeping with the scientific method, the examination is again repeated, often as a peer review.
Only in the area of interpretation is the questioned document examination really subjective. There being no set quantity or, for that matter, quality of points of comparison that can be quantitated to an opinion of identification or elimination, the examiner must decide what the results mean to him. Thus the similarities and dissimilarities are compared against the examiner’s “database” of knowledge and familiarity with similar characteristics that he has accumulated and stored mentally over years of practice. Only when the examiner has decided that the totality of similarity between the two writings is so great that it defies common logic to assume that any other person in the world could produce that same pattern of characteristics can he state that the questioned writing was produced by the writer of the standard material. Sufficient and significant dissimilarity may pave the way for an opinion of disassociation or elimination. As a subjective analysis, what may be enough for one examiner may not be enough for another.
Certainly the examiner’s appreciation for the moving line, form, and fluidity of movement may be associated with an “art”. As for an exact science, once we move away from mathematics, there is no exact science. Questioned Document Examination, which undertakes to look at the indeterminate characteristics of handwriting, does not fall into the exact science category but is, nevertheless, a recognized science.