Automatic Matching of Bullet Land Impressions

In 2009, the National Academy of Sciences published a report questioning the scientific validity of many forensic methods including firearm examination. Firearm examination is a forensic tool used to help the court determine whether two bullets were fired from the same gun barrel. During the firing process, rifling, manufacturing defects, and impurities in the barrel create striation marks on the bullet. Identifying these striation markings in an attempt to match two bullets is one of the primary goals of firearm examination. We propose an automated framework for the analysis of the 3D surface measurements of bullet land impressions, which transcribes the individual characteristics into a set of features that quantify their similarities. This makes identification of matches easier and allows for a quantification of both matches and matchability of barrels. The automatic matching routine we propose manages to (a) correctly identify land impressions (the surface between two bullet groove impressions) with too much damage to be suitable for comparison, and (b) correctly identify all 10,384 land-to-land matches of the James Hamby study (Hamby, Brundage and Thorpe [AFTE Journal 41 (2009) 99–110]).

Fingerprint Science

1. What fingerprint analysts do.
2. Fingerprint Uniqueness
a) Biology
b) Empirical
c) Persistence
3. AFIS (Automatic Fingerprint Identification
4. The identification decision
5. Conclusions

“Brief of Amici Curiae Brandon L. Garrett and 35 Scientists, Statisticians, Law and Science Scholars, and Practitioners, People v. Genrich, No. 2016CA651”

In this case, a toolmark “expert” testified against James Genrich by assuring the jury that several of Genrich’s tools made purportedly unique marks on fragments of the bombs recovered from the crime scene, “to the exclusion of any other tool” in the world. That testimony all but assured Genrich’s conviction. But as this brief describes, the scientific community has now recognized that it is not appropriate to express such a conclusion in the area of toolmarks, or in any forensic discipline. “The reality is that uniqueness is impossible to prove, and is not anywhere near as relevant as some may claim[.]”2 Part I.A of this brief describes how the relevant field of toolmark comparisons lacks scientific research support. While firearms comparisons, which are far more commonly conducted, have been the subject of some studies, toolmarks research is nearly nonexistent. Part I.B describes the “theory” used to advance toolmark identifications in court and explains why scientists have found it unsupported. The section also describes criticism of toolmark comparisons in influential scientific reports that have highlighted problems of overstated testimony, error rates, and lack of research. Part I.C describes toolmark identifications in the courts and how, in recent years, courts have excluded or limited testimony like that presented in the Genrich case. Finally, Part II describes how the flaws inherent in toolmark evidence were borne out in this particular case. In light of the unreliable nature of toolmark evidence, Amici respectfully urge this Court to grant a full evidentiary hearing to review the faulty and wholly unscientific forensic testimony that led to Genrich’s conviction.

Constitutional Regulation of Forensic Evidence

In this Essay, I describe how despite decades of missed opportunities to adequately regulate forensics, in recent rulings the Supreme Court and lower courts increasingly focus on sound litigation of forensics. In an era of plea bargaining, the accuracy of forensic analysis depends far less on cross-examination at trial, and far more on sound lab techniques, full disclosure of strengths and limitations of forensic evidence to prosecutors and the defense, and careful litigation. The Sixth Amendment and the Due Process Clauses are emerging as promising constitutional sources for improved regulation of forensics, including through ineffective assistance of counsel and Brady v. Maryland rulings focusing on investigations and plea bargains, as well as the general due process guarantee of a fair trial.

Forensics and Fallibility: Comparing the Views of Lawyers and Judges

Is there a CSI effect for lawyers? Forensic evidence plays an increasingly prominent role in criminal practice, leading some to worry that depictions of forensics in popular media might make jurors over-reliant on forensics-a so called CSI effect. There is little empirical evidence of a CSI effect among jury eligible laypersons, and, even if the effect may afflict some, its influence depends upon a case proceeding to a trial. As the Supreme Court has put it: “criminal justice today is for the most part a system of pleas, not a system of trials.” However, a CSI effect could be more consequential if it affects how criminal lawyers assess forensic evidence when they negotiate pleas or decide what evidence to present at trial. In this Article, we begin to examine how lawyers evaluate forensic evidence.