Forensic bitemark identification: weak foundations, exaggerated claims.

Several forensic sciences, especially of the pattern-matching kind, are increasingly seen to lack the scientific foundation needed to justify continuing admission as trial evidence. Indeed, several have been abolished in the recent past. A likely next candidate for elimination is bitemark identification. A number of DNA exonerations have occurred in recent years for individuals convicted based on erroneous bitemark identifications. Intense scientific and legal scrutiny has resulted. An important National Academies review found little scientific support for the field. The Texas Forensic Science Commission recently recommended a moratorium on the admission of bitemark expert testimony. The California Supreme Court has a case before it that could start a national dismantling of forensic odontology. This article describes the (legal) basis for the rise of bitemark identification and the (scientific) basis for its impending fall. The article explains the general logic of forensic identification, the claims of bitemark identification, and reviews relevant empirical research on bitemark identification-highlighting both the lack of research and the lack of support provided by what research does exist. The rise and possible fall of bitemark identification evidence has broader implications-highlighting the weak scientific culture of forensic science and the law's difficulty in evaluating and responding to unreliable and unscientific evidence.

Effect of forensic evidence on criminal justice case processing.

This study examined the role and impact of forensic evidence on case-processing outcomes in a sample of 4205 criminal cases drawn from five U.S. jurisdictions. Regression analyses demonstrated that forensic evidence played a consistent and robust role in case-processing decisions. Still, the influence of forensic evidence is time- and examination-dependent: the collection of crime scene evidence was predictive of arrest, and the examination of evidence was predictive of referral for charges, as well as of charges being filed, conviction at trial, and sentence length. The only decision outcome in which forensic evidence did not have a general effect was with regard to guilty plea arrangements. More studies are needed on the filtering of forensic evidence in different crime categories, from the crime scene to its use by investigators, prosecutors, and fact-finders, and to identify factors that shape decisions to collect evidence, submit it to laboratories, and request examinations.

Dr. Walter McCrone's contributions to microscopy workshops and the certification of criminalists.

Walter McCrone was not only a remarkable forensic microscopist, but also a skilled grants man and devoted scientific professional. This article briefly recounts his activities in the 1970s and 80s where he played a major role in securing grant funds to sponsor microscopy training around the country, and in using his considerable professional influence to advance the cause of certification.

The feasibility of external blind DNA proficiency testing. I. Background and findings.

We describe the origins, purposes, and findings of a national study to determine whether a large-scale program of blind proficiency testing in U.S. DNA laboratories is feasible and/or practical. Proficiency testing in clinical laboratories is reviewed, particularly as mandated by the Clinical Laboratory Improvement Acts and its role in the regulation of those laboratories. Proficiency testing in forensic urine drug testing labs is also briefly reviewed. Studies involving comparisons between open and blind proficiency testing are discussed. The clinical laboratory proficiency testing and regulation landscape provides the background for the DNA Act of 1994, and the congressional mandate to investigate blind proficiency testing in forensic DNA laboratories. Four models of blind proficiency testing are defined and discussed, along with the advantages and disadvantages of each and estimates of the costs of a large-scale program. The purposes of proficiency testing in a quality-assurance context are likewise discussed and related to the models and the arguments generally proffered for and against blind vs. open proficiency testing.

The feasibility of external blind DNA proficiency testing. II. Experience with actual blind tests.

The background and goals of a national study to determine the feasibility of blind proficiency testing in U.S. forensic DNA laboratories are discussed. Part of the project involved designing and executing a series of fifteen blind proficiency tests. Execution included biological specimen donor recruitment and case evidence manufacturing. Simulated cases were submitted to DNA laboratories by law enforcement agencies and in some cases by other forensic-science laboratories. Replicate-manufactured evidence was submitted to reference laboratories to simulate the workings of a larger-scale program. Ten tests were straightforward, and essentially tested analytical ability. Five tests involved selecting on the basis of case facts appropriate bloodstains for typing from a bloodstain pattern. We describe in detail our experience in designing and conducting these blind proficiency test trials, and relate those experiences to the overall issue of blind proficiency testing as a quality-assurance tool in forensic DNA laboratories. In this feasibility test series, one blind test was detected by a laboratory, a second one was shown to the lab by law enforcement, and a third was never completed because of lapses in communication. Turnaround times were relatively fast in the independent/commercial labs and relatively slow in the larger public laboratories. Two cross-state case-to-case CODIS "hits" were "planted" among the first series of ten blind tests. One pair was detected. One member of the second pair went to a lab that was not CODIS-ready.