How I Created a Monster

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I never thought that as a trial lawyer, I would ever have anything in common with the creator of the monster in Mary Shelley’s Frankenstein. But like Shelley’s “modern Prometheus,” I learned that a natural, human striving for a greater understanding of scientific knowledge can have unintended and even dangerous consequences.

In my case, a 2009 pro bono court appointment in a federal drug prosecution, I dared to challenge a gold standard of so-called “scientific” evidence. I dared to argue that everything we have been told about fingerprint examiners’ ability to claim a match between a fingerprint deposited on a surface somewhere and a particular individual is without any real scientific basis, and that without an adequate showing of validity or reliability these claims should not be admitted as proper expert testimony.

Immersed in the task and thrill of the exploration, I thought I was pioneering, and in many senses, I was. I thought I was on the cutting edge of science or law, or even both. Only after my creation came to life and began terrorizing the countryside did I realize the horror I had wrought.

Others had challenged fingerprint identification testimony before, but the courts widely rejected all of those challenges under a line of cases dating back at least 100 years. Those cases stretched to a time when the notion of the infallibility of fingerprint identification first entered the public consciousness following the publication of Mark Twain’s Pudd’nhead Wilson in 1894. In Twain’s story, the protagonist lawyer wins the acquittal of his clients by matching the fingerprints on the murder weapon to someone else. Twain apparently had read the work of Sir Francis Galton, published two years earlier. Galton, in short, had dropped cut-up images of fingerprints onto a piece of paper and concluded that the chances of one person’s print being identical to that of another specific person were 1 in 64 billion.

None of those earlier court challenges had the benefit of a watershed 2009 report by the National Academy of Sciences (NAS), the leading scientific research arm of the U.S. government. See Nat’l Research Council, Nat’l Acad. of Scis., Strengthening Forensic Science in the United States: A Path Forward (Feb. 2009), available at www.ncjrs.gov/pdffiles1/nij/grants/228091.pdf. The NAS report concluded that, with the exception of nuclear DNA evidence, “no forensic method has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source.” Id. at 7. The report says, among other things, that fingerprint examiners are “unjustified” in claiming they can match a latent fingerprint to a particular individual, that broad claims about the uniqueness of individual prints across the population are unsubstantiated, and that the most commonly accepted fingerprint identification method “is not specific enough to qualify as a validated method for this type of analysis” and does not guarantee that two analysts following the method will reach the same results. Id. at 142–44.