Forensic Fallacies and a Famous Judge

10 Pages Posted: 25 Jul 2014 Last revised: 11 Sep 2014

Date Written: July 23, 2014


Judge Richard Posner, one of the great quantitative legal minds of our time, relied on flawed and illogical arguments in several recent forensic science appellate decisions. He equated non-equivalent probabilities and offered non sequiturs to support his belief that fingerprint errors are rare. I speculate that his errors spring from cognitive biases that are activated when people are asked to support or prove that which we “know” to be so.

Keywords: errors, fallacy, fingerprint, forensic, Posner, statistical evidence

Suggested Citation

Koehler, Jonathan J., Forensic Fallacies and a Famous Judge (July 23, 2014). 54 Jurimetrics 211 (2014); Northwestern Public Law Research Paper No. 14-41. Available at SSRN:

Jonathan J. Koehler (Contact Author)

Northwestern University - Pritzker School of Law ( email )

375 E. Chicago Ave
Chicago, IL 60611
United States

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