Firearm-Mark Evidence: Looking Back and Looking Ahead

26 Pages Posted: 15 Feb 2018 Last revised: 15 Jun 2018

See all articles by David H. Kaye

David H. Kaye

PSU - Penn State Law (University Park); ASU - College of Law & School of Life Sciences

Date Written: February 3, 2018


This article, written as a contribution to a festschrift for Paul Giannelli, surveys the development of the law on one type of feature-matching evidence that repeatedly attracted Professor Giannelli’s attention — “firearm-mark evidence.” By inspecting toolmarks on bullets or spent cartridge cases, firearms examiners can supply valuable information on whether a particular gun fired the ammunition in question. But the limits on this information have not always been respected in court, and a growing number of opinions have tried to address this fact.

The article explains how the courts have moved from a position of skepticism of the ability of examiners to link bullets and other ammunition components to a particular gun to full-blown acceptance of identification “to the exclusion of all other firearms.” From that apogee, challenges to firearm-mark evidence over the past decade or so, have generated occasional restrictions on the degree of confidence that firearms experts can express in court, but they have not altered the paradigm of making source attributions and exclusions instead of statements about the degree to which the evidence supports these conclusions. After reviewing the stages in the judicial reception of firearm-mark evidence (including reactions to reports from the National Academy of Sciences and the President's Council of Advisors on Science and Technology), the article concludes by describing a more scientific, quantitative, evidence-based form of testimony that should supplant or augment the current experience-based decisions of skilled witnesses.

Keywords: evidence, criminalistics, forensic science, firearms, toolmarks, bullets

Suggested Citation

Kaye, David H., Firearm-Mark Evidence: Looking Back and Looking Ahead (February 3, 2018). Case Western Reserve Law Review, Vol. 68, Issue 3, 2018, Forthcoming, Penn State Law Research Paper No. 4-2018, Available at SSRN:

David H. Kaye (Contact Author)

PSU - Penn State Law (University Park)

Lewis Katz Building
University Park, PA 16802
United States


ASU - College of Law & School of Life Sciences ( email )

111 E Taylor St.
Phoenix, AZ 85004
United States


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