As in all professions, document examiners have a range of expertise and experience. As important as it is for your client to make a clear assessment of your abilities to serve them successfully, it is up to you to determine in advance, with a high degree of accuracy, whether the document examiner you plan to hire will perform the most accurate assessments and be ready to back up those assessments with a scientifically-repeatable methodology in court.

You can improve the chances of proving your questioned document case (provided your client‘s claim is meritorious) by selecting an expert forensic document examiner who follows a generally-accepted practice for forensic document examiners. It is surprisingly common that not all experts do.

In Frye v. U.S., 293 F.2d 1013 (D.C. CA 1923), the D.C. Court of Appeals adopted the test for “general acceptance.”  As relevant in California, the Kelly rule, People v. Kelly (1976) 17 Cal.3d, provides that the expert testimony must be based on a technique that is “sufficiently established to have gained general acceptance in the particular field to which it belongs.”

Following are three examples of cases in which the opposing document examiner failed to follow generally-accepted practices for handwriting identification of a questioned signature.

1. In this case, the opposing document examiner eliminated the decedent as the writer of a holographic will (handwritten and not witnessed) based on observed differences between two known signatures and the questioned signature. The examiner failed to state that there were also differences between the two known signatures, which were stipulated to have been written contemporaneously (in this case during the same sitting) by the decedent.

No one writes their signature exactly the same way each time. Therefore, accepted methodology requires determining both similar and dissimilar traits between the questioned writing and the known writings. The variability in the handwriting of the author of the known writings must be analyzed.

An individual can only be eliminated as the writer of a questioned document when the range of variability of the known writer has been determined. Established authorities state that a sufficient number of samples of a person’s writing (exemplars) are required to show this variability.

The exact number of exemplars cannot be determined until the document examiner starts working the case. Exemplars written prior to the date of the questioned writing are best. I prefer to start with at least 15 exemplars.

Examining more exemplars increases the validity of the results. Generally, more exemplars are needed to opine that a person did not execute a writing than to opine that a person did execute a writing.

Only after a careful review of the findings can it be determined with a degree of accuracy the extent to which the questioned writing has the same traits as and falls within the known variability of the known writing.

The opposing examiner in this case made no effort to determine the variability of the decedent’s known handwriting. She made no attempt to examine the original will that was available in the court’s records room.

I examined the original holographic will and displayed the scanned copy as an exhibit.

2. In another case, the opposing examiner collected 43 exemplars of the decedent’s signature. This was proper, generally-accepted practice.

However, for the report, the examiner selected seven of the 43 exemplars. These seven exemplars supported the retaining attorney’s contention the decedent had not signed the will.

After we exchanged evidence, I discovered that most of the remaining exemplars he had collected supported the hypothesis the decedent did sign the will. Using his evidence at trial, I showed that he had cherry-picked the exemplars for the report. This is called confirmation bias.

3. In a federal criminal case, the opposing document examiner presented a report that was not in conformance with Rule 26 of Federal Rules of Evidence.

As a result, my retaining attorney said I did not need to drive to Los Angeles to testify at trial—that my report would stand on its own. He was correct. The judge threw out the other examiner’s report.

It is important for an attorney to ask an expert to describe the methodology he or she will use to research the case. After describing the methodology, the prospective document examiner should be able to cite authorities that support the claim that the methodology is accepted in the practice of forensic document examination.

A proper research methodology removes the expert’s bias from the analysis. The expert must be able to support their opinion with a scientific basis. The job of the expert is to research the evidence and report what the evidence uncovers. The expert is not an advocate for either side in a dispute.

Ask your prospective expert how he or she plans to follow generally-accepted practices during the examination. Learn whether the document examiner is able to support the methodology used.