Analysis of Experiments in Forensic Firearms/Toolmarks Practice Offered as Support for Low Rates of Practice Error and Claims of Inferential Certainty

Abstract

This paper critically evaluates experiments used to justify inferences of specific source attribution (‘individualization’) to “100% certainty” and “near-zero” rates of error claimed by firearm toolmark examiners in court testimonies, and suggests approaches for establishing statistical foundations for firearm toolmarks practice that two recent National Academy of Science reports confirm do not currently exist. Issues that should be considered in the earliest stages of statistical foundational development for firearm toolmarks are discussed.

Keywords: firearms identification, forensic certainty, validation studies, ballistics, forensic error rate, forensic testimony