Evaluating forensic DNA evidence: Connecting the dots

Technological developments within the field of forensic genetics have enhanced the sensitivity and specificity of DNA testing tremendously and have broadened the applications of biological evidence in criminal investigations. Evaluation and communication of the evidential findings within criminal cases have not maintained the same pace, which has largely stemmed from a failure to adopt a standardized approach within and across the various fields of forensic science. Within forensic biology, this has led to unjustified opinions on the weight of the evidence and occurrences of the association fallacy, when the weight of evidence given propositions at one level of the hierarchy of propositions is inappropriately transposed to a higher level. We further define the association fallacy to include the terms, “source level fallacy” and “activity level fallacy,” to enable the forensic science community to better identify and address issues in biological evidence evaluation. It is important to understand these concepts and their causes, and in doing so, identify potential avenues to avoid these fallacies in forensic science casework. These avenues include training and education of forensic and legal professionals, as well as research into transfer, persistence, prevalence and recovery (TPPR) of DNA and biological evidence in general. This article is categorized under: Forensic Biology > Interpretation of Biological Evidence