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Locard Exchange
The Science of Forensic Hair Comparisons and the Admissibility of Hair Comparison Evidence: Frye and Daubert Considered
by  Max M. Houck, West Virginia University
Richard E. Bisbing, McCrone Associates, Westmont, IL
Tani G. Watkins, Michigan State Police Laboratory
Rockne P. Harmon, Alameda County District Attorney's Office

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The Admissibility of Hair Comparison Evidence

The admissibility of hair comparison evidence will depend to a slight extent on which rule is applicable and the interest by the trial judge in being a gate-keeper. Any problems with admitting hair evidence can partly be solved if the trial court is educated better by forensic scientists to the methodology and reliability of hair comparison science. Forensic hair comparison evidence fits the requirements of science and the rules of admissibility including Frye and Daubert.



Why Do Forensic Hair Comparisons Pass the Frye Test?

While Frye (U.S. v. Frye, 1923) is based on general acceptance in the scientific community, which occasionally has been difficult to define (Green, 1992; Thornton, 1994), it is still used by many jurisdictions in the United States. The microscopic examination of hair using the comparison microscope has been the accepted standard technique for the examination and comparison of hairs for approximately the past 60 years, and, as such, this technique has been accepted by both State and Federal courts throughout the United States, in all U.S. Territories, Canada and in many European and Asian countries.


The Frye standard usually involves a two-point question: Is the field in which the underlying theory falls generally accepted in the relevant scientific community? For hair comparisons, the answer is “yes.” Comparative biology, including medicine and physical anthropology, has a long history of microscopic identification and comparison dating back to the 18th century. Comparison is the cornerstone of the majority of biology, both past and present. Microscopic techniques, combined with studied experience, provide for a highly discriminating means to examine and compare hair (Bisbing, 1982). A long history of research in physical anthropology and forensic science detailing the differences between peoples’ hair supports the credibility of the relevant science (Bisbing, 1982; Hausman, 1925a; 1925b; Hausman, 1928; Houck, 2001; Kirk, 1994; Trotter, 1930; Trotter, 1938).


The reliability of the identification and association of human hair, assuming a competent comparison, is based on extensive experience by forensic laboratories around the world since about 1932, including the FBI, Royal Canadian Mounted Police, state, and local forensic laboratories, as well as private laboratories and a body of peer reviewed scientific literature.

Forensic hair comparison has a generally accepted theory and basis for a reliable scientific practice, based on literature in the Journal of Forensic Sciences, the Journal of the Forensic Science Society (now Science and Justice), the Canadian Society of Forensic Science Journal and other related peer-reviewed scientific journals and publications, forensic science textbooks (for example, Saferstein, 1996), and technical reference books (for example, Saferstein, 1982) used by forensic scientists. State and Federal forensic science agencies, university forensic science programs, and private research institutes regularly hold specialized training courses that teach hair comparison theory and methodology (Proceedings of the International Symposium on Forensic Hair Comparisons, 1985). An extensive body of literature exists for hair biology and comparisons (Houck, 2001).


There is also a collection of court decisions from all over the country where hair evidence has been admitted over objection and upheld on appeal. Numerous case precedents exist for admissibility of forensic hair examinations as a valid and reliable science (U.S. v. Haskins, 1976; U.S. v. Cyphers, 1977; U.S. v. Brown, 1977; State v. Watley, 1989; State v. Faricloth, 1990; State v. Payne, 1991; State v. Bridges, 1992; Crawford v. State, 1992; People v. Wettese, 1992; Suggs v. State, 1995; McCary v. State, 1995; Beam v. State, 1995; U.S. v. Matta-Ballesteros, 1995).


Are there procedures available that can produce reliable results and are they generally accepted in the relevant scientific community? Specific techniques for hair comparisons do exist based on previously cited literature, the curriculum of the courses taught, the protocols that exist in most forensic science laboratories, specifically those that are accredited or are undergoing accreditation, and the experience of two generations of forensic scientists. Hair comparison tests can be constructed to have discrete answers and are, therefore, testable. Forensic hair examiners undergo testing during training and many take proficiency tests once qualified (Peterson and Markham, 1995a, 1995b).


Several clinical studies and research projects with published and peer reviewed reports have demonstrated that given a limited number of questioned and known hair samples, correct inclusions and exclusions are the rule rather than the exception (Bisbing and Wolner, 1984; Lamb and Tucker, 1994; Gaudette, 1976; Gaudette and Keeping, 1974; Strauss, 1983; Wickenheiser and Hepworth, 1990).

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