The Friction Ridge
Written by Kasey Wertheim   

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Current trends in latent print testimony

DURING THE PAST DECADE, one of the most actively changing aspects of latent-print examination has been in the legal arena. The Daubert hearing in the 1999 United States v. Byron Mitchell trial sparked a trend toward the “scientification” of latent-print examiner testimony. Practitioners hurried to brush up on their ACE-V and Ridgeology training so they could explain the scientific methodology they used in the case. The use of the word “identification” became old-fashioned, and while some examiners stuck with it, many were quick to change to the more scientific “individualization”. Readers of David R. Ashbaugh’s then-fresh book, Qualitative-Quantitative Friction Ridge Analysis, came away with a lexicon that would serve them well as they portrayed their science to a jury of laypersons. But since that time, the legal domain has continued to evolve.

Current “scientific” latent-print testimony has been portrayed by critics, academics, and some legal authorities as pushing too far into a certainty they claim cannot exist. We are told that the results of our examinations can never reach 100% “scientific” or “absolute” certainty, and any examiner claiming such should be disallowed to testify.

Some examiners will say this is just fine, and attaining that level of scientific certitude simply is not necessary. Their position is that the court’s acceptance of testimony is not based on its decision of whether or not the discipline can reach scientific certainty but, rather, if the technical expertise and opinion of the examiner will assist the trier of fact.

Just to be clear, I am not implying that ACE-V should be removed from testimony. Rather, I am suggesting that current trends indicate that examiners should reference it more as a “framework” or “process” they use instead of referencing it as an error-free scientific methodology.

One of the most widely cited cases, the 2004 Brandon Mayfield case, has provided much fodder for those who wish to emphasize “the error-prone nature” of our discipline. We hear about bias and other human factors, and how they can and do affect our decision-making thresholds. Frequently referenced sources—such as the Office of the Inspector General’s Review of the FBI’s Handling of the Brandon Mayfield Case or the National Academy of Sciences’ report, Strengthening Forensic Science in the United States: A Path Forward—and numerous legal challenges to the latent-print discipline have provided a trend over the last few years toward more caution being shown by latent-print examiners on the witness stand. That trend has caused latent-print examiners to venture back toward the more conservative manner of testifying to an “identification,” and has decreased the emphasis on scientific individualization.

With a careful look inside our own discipline, we can even recognize some indicators of this trend. Take, for instance, SWGFAST’s removal of “to the exclusion of all others” from the most recent definition of the word individualization in the latent-print glossary (which continues to cite identification and individualization as synonymous).

There are also some examples of examiners testifying in a fashion that does not invite challenges from the astute defense attorney. In a Minnesota case, we saw Josh Bergeron stating that person X “made” latent Y—and upon follow-up, stating that theoretically there could be two individuals that share enough ridge formations similar enough to each other that an examiner might be fooled:

We even saw a legal decision in Massachusetts (Commonwealth v. Gambora) that rebuked the examiner who used the term individualization, but praised the examiner who used the term made:’s-Opinion-Sept-2010.pdf

So what does the future hold in store? Continuing the trend toward more conservative testimony is one likely possibility. We can also expect more talk about the use of statistics to support our testimony and what it will take for examiners to actually use statistical modeling on the witness stand. I think we are still several years away from their acceptance in court, but indications are that we can expect a trend toward probabilities and likelihood ratios in the future. Take for example the International Association for Identification’s recent repeal of earlier resolutions prohibiting certified examiners to testify to probable or likely conclusions.

For now, a wise latent-print examiner should continue to stay abreast of current legal challenges to the discipline. SWGFAST provides access to many of the challenges on their “Resources” page at

Examiners should also consider the trend away from absolute testimony and consider how they can state their findings in a manner that is easier to defend and less likely to invite a challenge from the defense.

About the Author

This e-mail address is being protected from spam bots, you need JavaScript enabled to view it is an IAI Certified Latent Print Examiner and a Distinguished IAI member. He serves on SWGFAST as Webmaster and hosts, the largest web resource for latent-print examiners. He publishes an electronic newsletter focusing on latent-print examination, The Weekly Detail, every Monday morning. He is Co-Chair of the NIST Expert Working Group on Human Factors in Latent Print Examination.

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