April, 2018

Justice Department Issues Updated
Latent Print Policy for Experts

The Department of Justice issued new guidelines for experts concerning reports and potential testimony relating to forensic examination of latent print evidence. Among the goals of the guidelines is the standardization of language to be used. Another goal is to assist judges and legal practitioners “by describing the acceptable range of conclusions that may be provided by Department examiners.”

Three possible conclusions by experts comparing friction ridge skin impressions are permitted: 1) source identification; 2) inconclusive; and 3) source exclusion.

“Source identification” is the conclusion that two friction ridge skin impressions originated from the same source. The basis for such a conclusion “is an examiner’s decision that the observed corresponding friction ridge skin features provide extremely strong support for the proposition that the two impressions came from the same source and extremely weak support for the proposition that the two impressions came from different sources.” The conclusion is “a statement of an examiner’s belief (an inductive inference) that the probability that the two impressions were made by different sources is so small that it is negligible,” and it is not based upon statistically-derived or verified measurements or comparisons of ridge skin features in the world population.

“Inconclusive” is the conclusion an examiner reaches when there is insufficient quantity or clarity in the samples compared. The basis for the conclusion is that there is insufficient information from either of the two impressions.

“Source exclusions” is the conclusion that the two impressions did not originate from the same source. The basis for the conclusion is the examiner’s decision that there exist sufficient “features in disagreement” to conclude the two impressions originated from different sources.

Examiners must not assert that the “impressions originated from the same source to the exclusion of all other sources” and must avoid use of the terms “individualize” and “individualization.” Examiners must not assert a 100% level of certainty to the conclusion, must not assert that the examination “is infallible or has a zero error rate”; the examiner “shall not cite the number of latent print comparisons performed in his or her career as a measure for the accuracy of a conclusion offered in the instant case” and “shall not use the expressions ‘reasonable degree of scientific certainty,’ ‘reasonable scientific certainty,’ or similar assertions of reasonable certainty as a description of the confidence held in his or her conclusion in either reports or testimony unless required to do so by a judge or applicable law.”

Sources: “DOJ Approved Uniform Language for Latent Fingerprint Comparisons,” forensicsforum.net, February 25, 2018:
Department of Justice, “Approved Uniform Language for Testimony and Reports for the Forensic Latent Print Discipline,” released February 21, 2018:

A Look at Implicit Bias

A recent article in Scientific American suggests that the idea of implicit bias – a “tendency for stereotype-confirming thought to pass spontaneously through our minds” – has moved from academia into sometimes “heated” debates in the popular press. The article suggests that those on the far right may discount the idea of implicit bias as just another claim “of progressives seeing injustice under every bush” and those on the far left may have concerns that the idea of implicit bias detracts from more explicit bigotry in society.

The authors looked at two common misunderstandings about the subject. They said that a famous implicit bias test that is in use, the Implicit Association Test (“IAT”), has low stability and is a limited measure, and, while the majority of people taking the test show evidence of implicit bias, there is little correlation between a person’s test score and discriminatory behavior. The second misunderstanding, according to the authors, relates to the usefulness of a test score to predict behavior; that is, some scientists will say the testing cannot predict whether a person will actually discriminate on a particular occasion.

The article points out that most measures used in psychology for predictive purposes are valuable for predicting average outcomes of large group (e.g., cities, counties, and states) behaviors, and not behaviors of individuals. The authors state that the IAT is valuable at predicting average outcomes in larger populations; for example, in metro-areas with greater average implicit bias there are larger racial disparities in police shootings, infant health problems, medical treatment (physicians tend to recommend less pain medication for a black patient than is recommended for a white patient with the same injury), and employment opportunities.

The authors conclude the article by stating that “many of us are more biased than we realize.  And that is an important cause of injustice – whether you know it or not.”

Source: Keith Payne, Laura Niemi, and John M. Doris, “How to Think About ‘Implicit Bias,’” scientificamerican.com, March 27, 2018:

by Neil Leithauser
Associate Editor