The Myth of Fingerprints 2

 Posted on October 26, 2007 in Uncategorized

A few weeks ago, inspired by the Brandon Mayfield case in district court in Oregon, I wrote about the myth of fingerprints. This week, inspired by the Brandon Mayfield Case a Baltimore Circuit Court judge in Maryland v. Bryan Rose, following a Frye hearing, excluded the testimony of a forensic fingerprint examiner because the "ACE-V" methodology of latent fingerprint examination is more likely than not "a subjective, untested, unverifiable identification procedure that purports to be infallible."

The State had argued that latent print evidence had been admissible for almost a hundred years, and therefore should continue to be admissible. Stephen Meagher, a "top FBI latent print examiner", had testified that "there is no error rate" for ACE-V, that ACE-V results in 100% certainty. The court found this testimony, along with other testimony by Mr. Meagher, not to be credible, and rightly so - Meagher was "involved in the withdrawal of the FBI's [ACE-V based] [mis]identification of Mayfield.

The court based its opinion in part on the FBI OIG's March 2006 Review of the FBI's Handling of the Brandon Mayfield Case.

ACE-V stands for:


This is pseudoscientific nonsense that is intended to make a purely subjective art appear to be objective and scientific. Each of these four stages is subjective (read about it in the opinion) and subject to confirmation bias (read about it in the OIG report), and the "verification" is meaningless. Four subjective steps do not add up to an objective process. ACE-V has not been subjected to scientific testing; its reliability is unknown. This is as true in Texas or federal court as it is in Bal'mer.

Cases in which latent print evidence is dispositive are few and far between (I've had only one case in which the fingerprint evidence could have been dispositive, and in that case the fingerprints were on the side of the glass that didn't matter). In Rose, though, a capital murder case, the exclusion of the latent print testimony gutted the State's case.

(Incidentally, the judge did the State a favor by excluding it pretrial instead of after the jury had been sworn and jeopardy had attached.)

Technorati Tags: expert witnesses, fingerprints

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