DNA Evidence: Probability, Population Genetics, and the Courts

72 Pages Posted: 30 May 2009

See all articles by David H. Kaye

David H. Kaye

PSU - Penn State Law (University Park); ASU - College of Law & School of Life Sciences

Date Written: 1993


To help meet the challenge of presenting properly performed DNA tests within the post-Daubert legal framework, this article outlines the statistical procedures that have been employed or proposed to provide judges and juries with quantitative measures of probative value, describes more fully how the courts have dealt with these procedures, and evaluates the opinions and the statistical analyses from the standpoint of the law of evidence.

Specifically, the article outlines the procedure used to declare whether two samples of DNA "match," and how shrinking the size of the "match window," as some defendants have urged, will decrease the risk of false matches, but will also exclude highly probative evidence of identity. It also demonstrates that a defendant's effort to show that a smaller match window would not permit the declaration of a match is irrelevant or misleading. Additionally, the article explains procedures for estimating the frequency of the incriminating genetic characteristics in various populations. These procedures have been the subject of an acrimonious debate, both in the courts and in the press, about the effect of "population structure." The population structure objection, which has proved so effective in court, applies most strongly to only a limited class of case, and therefore, courts have erred in excluding DNA evidence on the theory that the scientific community advocates that the most "conservative" procedures must be used in all cases. Finally, the article identifies more fundamental problems in the use of population frequency estimates, and advocates supplementary and alternative procedures that are essential if quantitative statements of the probative value of DNA evidence are to be admissible.

Keywords: DNA Evidence, Population Structure Objection, Daubert v. Merrell Dow Pharmaceuticals, Inc

Suggested Citation

Kaye, David H., DNA Evidence: Probability, Population Genetics, and the Courts (1993). Harvard Journal of Law and Technology, Vol. 7, 1993, Available at SSRN: https://ssrn.com/abstract=1411904

David H. Kaye (Contact Author)

PSU - Penn State Law (University Park)

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United States

HOME PAGE: http://www.personal.psu.edu/dhk3/index.htm

ASU - College of Law & School of Life Sciences ( email )

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United States

HOME PAGE: http://www.personal.psu.edu/dhk3/index.htm

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