HANDWRITING COMPARISONS
When children first learn to print or write, they are given exemplary samples of each letter and are told to copy them as neatly as possible. Then they are taught to put the letters together and make words. During this period, the handwriting of most children would be very similar. After learning how to form words, the children then put these skills to use in writing and teachers begin to focus on content. This means that the writers begin to focus more on what they are writing and less on how the letters are formed. Writing habits become internalized and the act of writing becomes subconscious and thus, individual characteristics develop, many of which the writer is unaware of. With time, handwriting becomes a sort of unconscious habit; however, this habit is not static. Handwriting changes with time. Over a period of years, one’s handwriting undergoes gradual changes that result in different characteristics. This can have a profound influence on the collection of known handwriting samples. Handwriting can also change with changes in physical and emotional condition. Depression, drug abuse, physical illness can all have effects on handwriting. Handwriting also varies by the type of writing instrument and medium (e.g., paper) used. Many of these variables are accounted for when known handwriting samples are obtained. The ability of a questioned document examiner to identify the author of a hand written document by comparison of unknowns with exemplars (known, authentic writing samples) depends upon two factors; first, there must be sufficient individual characteristics present in the unknown sample and second, there must be sufficient samples of the purported writer’s authentic handwriting. If both of these conditions are met, then questioned document examiners believe that it is possible to individualize an unknown handwriting exhibit to a particular person. If either of the above conditions is not met, then an equivocal conclusion may be necessary; that the suspect’s writing could be the source for the unknown writing. Of course, it is also possible to use class or individual characteristics to eliminate a suspect as being the source of questioned handwriting. As with other types of comparative evidence such as shoe prints, bullets, fingerprints, etc., there are no standards as to the minimum number of characteristics of handwriting that must be present in known and unknown handwrit ing samples in order to reach a conclusion of individuality. The minimum number is dependent upon the size of the questioned and exemplar samples, the nature of the characteristics, and the experience of the examiner. If a handwriting sample contains many unusual characteristics, then a questioned document examiner may need to find fewer of them than would be the case with a more “normal” handwriting. In any case, the individual examiner must find enough points on the questioned docu ment and exemplar to be convinced to a degree of reasonable, scientific certainty; that the questioned document was written by the same hand as the exemplar. Under no circumstances it is permissible to state a percent probability that the questioned document was written by the suspect. That is, it would not be permissible to state “I am 95% sure that the suspect wrote the will.” This is an important concept that also applies to other types of evidence such as fingerprints and tool marks. In order for an examiner to be able to cite numerical probabilities about the likelihood that known and unknown evidence have a common source, there must be studies that yield information about how common a particular set of characteristics are in a given population. Although this works well for DNA, where there is a finite set of types of DNA, it is not possible to do this for handwriting, where characteristics do not fall into discrete groupings. This gives rise to two perceived weaknesses in the conclusions of individuality often reached by document examiners: there are no agreed-upon standards for determining when authorship has been determined, and there are no probabilistic conclusions that can be reached in a document comparison examination. The National Academy of Sciences Forensic Science Committee, in its 2009 report, highlighted these weaknesses in questioned document analysis as well as
