If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case. [This rule was amended in 2000 in response to Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) and Kumho Tire Co. Ltd. v. Carmichael (1999).]
In Daubert, the court, focusing on the admissibility of scientific expert testimony, held that the trial judge has the task of ensuring that an expert's testimony both rests on a reliable foundation and is relevant to the task at hand. In Kumho Tire, the court held that a trial judge's gatekeeping obligation applies not only to testimony based on scientific knowledge, but also to testimony based on technical and other specialized knowledge.
In Daubert, the court set out five factors for the trial court to consider when determining whether the testimony was reliable. The are: (1) whether the theory or technique can be and has been tested, (2) whether the theory or technique has been subjected to peer review and publication, (3) the known or potential rate of error, (4) the existence and maintenance of standards controlling the technique's operation, and (5) whether the theory or technique enjoys general acceptance within a relevant scientific community. However, these factors do not constitute a definitive checklist or test. The gatekeeping function must be tied to the facts of a particular case. The court finds that the above factors are pertinent to assessing the reliability of handwriting analysis. The government bears the burden of proving that its expert's proffered testimony is sufficiently reliable to be admissible under Rule 702.
Among the studies cited by Mr. Hammond is a study by Professor Sargur Srihara on the individuality of handwriting. Using handwriting of 1500 individuals, his conclusions were that, using computer software, they were able to establish with a 98% confidence that the writer can be identified. Taking the results over the entire population, they were able to validate handwriting individuality with a 96% confidence. By considering finer features, Professor Srihara opined that they should be able to validate handwriting individuality with a near 100% confidence. A study by Dr. Moshe Kam indicates that professional document examiners had only a 6.5% error rate compared to an error rate of 38.3% for nonprofessionals. Dr. Kam concluded by stating that professional document examiners possess writer identification skills absent in the general population. Another study by Professor Kam indicated that professionals concluded that forgeries were genuine 0.49% of the time whereas lay persons did so 6.47% of the time. Professionals mistakenly concluded that genuine signatories were forgeries 7.05% of the time; lay persons did so 26.1% of the time. Another study by Jodi Sita, Brian Found and others found that forensic document examiners made errors in 3.4% of their opinions, while 19.1% of the control group gave erroneous opinions.
The above studies provide solid evidence that handwriting individuality can be validated with a very high degree of confidence, and that professional forensic document examiners have developed an expertise and training that allow them to correctly identify a person's handwriting with a much lower error rate than laypersons. On the other hand, the affidavit of Dr. Saks raises legitimate questions concerning the validity of these studies and the accuracy of handwriting identification in general.
