In order to keep junk science out of the courts, the courts require expert witnesses to offer opinions that are supported by sound science. The trained document examiner is prepared to answer the question, “Why do you believe this is true.”

Junk science occurs when only a subjective examination is performed. The result of a subjective handwriting analysis is the inability of the document examiner to properly support an opinion.

In deposition, an attorney asked a document examiner in San Diego whether his approach is objective or subjective. He said his methodology is purely subjective. s a result, the forensic document examiner was unable to describe the reason for his opinion. Similar problems have arising in court cases in which the document examiner’s opinion was dismissed by the court as being junk science.

Questioned document examination cannot state that a person is identified or eliminated as the writer of a document just because the writings look similar or different. Measurements are taken and compared between the known and questioned documents. These measurements are presented in understandable charts.

The document examiner collects enough samples of writing to determine the variability of the known writing. Using measurements, the document examiner determines whether the questioned writing falls within the range of the samples of known writing. This information cannot be determined with a simple visual inspection.

The methodology used by the forensic document examiner must be repeatable by the examiner and reproducible by another examiner. This means that the examiner’s report must explain in sufficient detail how the examination was performed. The purpose is to learn whether the subsequent analysis produces the same or similar results.

Each time a person writes, the letters and words are formed a little differently. The writer of a questioned documents can be eliminated only when enough samples of the subject’s writing are collected for the handwriting analyst to learn these differences. This is why the document examiner will ask a client for as many examples of the person’s known writing as possible.

Original documents are always better than photocopies. Original documents show all of the details, especially with handwriting. Photocopies have inherent distortion and stray marks on the page. The black copier toner obscures important details of the document.

Another quantitative method of determining whether a document was written by a suspect is to count the number of characters written in a given distance on the known documents and compare this with the number of characters written in the document in question. In this example, I counted the number of characters in a line of writing on each of the known documents. The number of characters written on a line was counted on the questioned document. Each line on the chart represents the number of characters on an individual line on a document. The average number of characters per centimetre was calculated for the bottom line on the chart. These numbers were compared to determine whether the writing on the questioned document was similar to that of the known documents.