impressions “match,” they are communicating the notion that the prints could not possibly have come from two different individuals.

As noted in Chapter 3, Jennifer Mnookin of the University of California, Los Angeles School of Law summarized the reporting of fingerprint analyses as follows:

At present, fingerprint examiners typically testify in the language of absolute certainty. Both the conceptual foundations and the professional norms of latent fingerprinting prohibit experts from testifying to identification unless they believe themselves certain that they have made a correct match. Experts therefore make only what they term ‘positive’ or ‘absolute’ identifications—essentially making the claim that they have matched the latent print to the one and only person in the entire world whose fingertip could have produced it … Given the general lack of validity testing for fingerprinting; the relative dearth of difficult proficiency tests; the lack of a statistically valid model of fingerprinting; and the lack of validated standards for declaring a match, such claims of absolute, certain confidence in identification are unjustified … Therefore, in order to pass scrutiny under Daubert, fingerprint identification experts should exhibit a greater degree of epistemological humility. Claims of ‘absolute’ and ‘positive’ identification should be replaced by more modest claims about the meaning and significance of a ‘match.’28

Summary Assessment

Historically, friction ridge analysis has served as a valuable tool, both to identify the guilty and to exclude the innocent. Because of the amount of detail available in friction ridges, it seems plausible that a careful comparison of two impressions can accurately discern whether or not they had a common source. Although there is limited information about the accuracy and reliability of friction ridge analyses, claims that these analyses have zero error rates are not scientifically plausible.

ACE-V provides a broadly stated framework for conducting friction ridge analyses. However, this framework is not specific enough to qualify as a validated method for this type of analysis. ACE-V does not guard against bias; is too broad to ensure repeatability and transparency; and does not guarantee that two analysts following it will obtain the same results. For these reasons, merely following the steps of ACE-V does not imply that one is proceeding in a scientific manner or producing reliable results. A recent


J.L. Mnookin. 2008. The validity of latent fingerprint identification: Confessions of a fingerprinting moderate. Law, Probability and Risk 7:127. See also the discussion in C. Champod. 2008. Fingerprint examination: Towards more transparency. Law Probability and Risk 7:111-118.

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