DNA Matches and Statistics: Important Questions, Surprising Answers
Judicature, Vol. 76, pp. 222-229, 1993
8 Pages Posted: 9 Sep 2009 Last revised: 17 May 2014
Date Written: November 23, 1992
Since its introduction at trial in a Florida case in 1987, DNA profiling evidence has been used to find against defendants in more than a thousand criminal and civil cases. The technique initially was received by the courts and news media as a nearly foolproof means of identifying vicious criminals who left blood, hair, or semen at the scenes of their crimes, as well as biological fathers implicated in paternity lawsuits. There is now an increased awareness that DNA analyses are subject to error and more deserving of careful scrutiny. This article asks and answers questions about the process involved in reporting DNA matches and their probative value. The validity of the underlying genetic theory is not questioned here. Instead, the focus is on the meaning and significance of reported matches, and the role the possibility of error should play in evaluating this evidence. These issues are not well understood by judges, attorneys, jurors, or, in many cases, DNA experts themselves.
Keywords: DNA, match statistics, probability
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