This Letter to the Editor proposes a procedure for the forensic analysis of evidence that will reduce the likelihood that the forensic analyst will make subjective errors in judgement.
A variety of tools are available for addressing evidence examiners’ cognitive bias. These are called context management tools. The proposed context management tool is called “Linear Sequential Unmasking” (LSU). LSU requires examiners to first analyze the trace evidence in isolation from the reference material and provides a balanced restriction on the changes that are permitted after exposure to the reference material. The LSU approach requires examiners to specify their confidence in their conclusions. Expressions of confidence could take many forms, from indicating confidence scores or ratings to developing verbal expressions of confidence. A balanced restriction in changing the initial analysis depends on the confidence in the initial analysis. If an examiner can show that the initial judgment was tentative and uncertain, subsequent revisions are reasonably justified; however, if the initial judgment was rated with high confidence and certainty, special attention may be warranted when examiners revise their judgment. In such cases, additional quality assurance measures are appropriate, such as blind review by another examiner. Another alternative is to prohibit alteration of high-confidence judgments. A recent FBI study found that erroneous identifications of suspects often contained substantive revisions to an examiner’s initial analysis of the trace evidence following exposure to reference materials. 7 references
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