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The U.S. Department of Justice rolled out “uniform language” about how fingerprint experts could testify in federal courtrooms last month. Gone was “individualization,” in favor of “identification”—but with limits. Experts are supposed to explain their work to juries, without professing certainty, since match statistics like those found in DNA are not available. 

But now the American Association for the Advancement of Science tells the DOJ its new language rules don’t go far enough. Experts should not be able to state their “expectations” of a match, based on their experience and expertise, according to the AAAS, in a letter sent by CEO Rush Holt to Deputy Attorney General Rod Rosenstein.

“Although the Uniform Language you put forward forbids an examiner from making the unsupportable claim that the pattern of features in two prints come from the same source to the exclusion of all others, it does allow examiners to say they ‘would not except to see that same arrangement of features repeated in an impression that came from a different source,’” writes Holt.

There is “no empirical basis for examiners to estimate the frequency of any particular pattern observable in a print,” adds Holt, a trained physicist, who was also an eight-term member of the U.S. House of Representatives from New Jersey. 

“The proposed language fails to acknowledge the uncertainty that exists regarding the rarity of particular fingerprint patterns,” Holt continues in his letter. “Any such expectation that an examiner asserts necessarily rests on speculation, rather than scientific evidence.”

The AAAS otherwise commends some of the other DOJ changes, including eliminating the use of language stating, or even implying, certainty in a match.

The DOJ changes in the “uniform language” were announced by Rosenstein at the American Academy of Forensic Sciences meeting in Seattle in February. Both Holt and Rosenstein spoke as part of the plenary session panel on the scientific foundation of forensic science.

The International Association for Identification, the largest group representing fingerprint experts, told Forensic Magazine the latest suggestion by the AAAS is not in itself scientific. Ray Jorz, the IAI president, added that they fully support the DOJ language – and their overall goal is “to seek and find the truth.”

“I find it interesting that the AAAS has developed their own suggested verbiage, however it appears that they did so without the knowledge and experience of qualified practitioners and subject matter experts,” said Jorz, in an email. “There has been much research already done and I am confident that research will continue that will strengthen not only the friction-ridge science but all of the forensic disciplines as well.”

Latent fingerprint identification was one of a handful of forensic disciplines criticized in two reports during the Obama administration: the 2009 report by the National Academies of Science titled “Strengthening Forensic Science in the United States: A Path Forward,” as well as the 2016 document issued by the President’s Council of Advisors on Science and Technology, or PCAST. Both reports contended fingerprint evidence was not sufficiently quantitative.

Indeed, the AAAS released its own report last September blasting "decades of overstatement" by latent print examiners.

However, latent fingerprint identification is one of the disciplines that has proven to be consistently accurate. A critical paper published in 2005 identified 22 fingerprint misattributions internationally over the first century of the use of forensic fingerprint comparisons. Ten of those resulted in convictions that were later overturned. None of those convictions were reached after 2000.

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