C. Michael Bowers

Expert Disagreement in Bitemark Casework

Abstract:  Bitemark cases continue to raise controversy due to the degree of expert disagreement which is frequently seen. Using a case mix of 49 bitemark cases from 2000 to 2007 each injury was independently assessed for its forensic significance using a previously described bitemark severity scale. Following the assessment, the mean value for the bites was categorized according to the crime type, the degree of expert agreement, and the judicial outcome. Results suggest that bitemarks found in child abuse cases have statistically significantly lower forensic value than those in other crime types, that bites where there is mutual agreement between experts will have higher forensic value than those where there is disagreement at trial, and that cases in which DNA has provided an exoneration will demonstrate similar quality to those where a conviction was secured. Forensic odontologists should carefully assess bitemark evidence and ensure that it meets certain minimums in relation to the presence of class and unique features before undertaking an analysis.

Forensic bitemark identification: weak foundations, exaggerated claims

Abstract 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 laws difficulty in evaluating and responding to unreliable and unscientific evidence.

Positive dental identification using tooth anatomy and digital superimposition.

Dental identification of unknown human remains continues to be a relevant and reliable adjunct to forensic investigations. The advent of genomic and mitochondrial DNA procedures has not displaced the practical use of dental and related osseous structures remaining after destructive incidents that can render human remains unrecognizable, severely burned, and fragmented. The ability to conclusively identify victims of accident and homicide is based on the availability of antemortem records containing substantial and unambiguous proof of dental and related osseous characteristics. This case report documents the use of digital comparative analysis of antemortem dental models and postmortem dentition, to determine a dental identification. Images of dental models were digitally analyzed using Adobe PhotoshopTM software. Individual tooth anatomy was compared between the antemortem and postmortem images. Digital superimposition techniques were also used for the comparison. With the absence of antemortem radiographs, this method proved useful to reach a positive identification in this case.

Radiographic reconstruction of root morphology in skeletonized remains: a case study.

This is a case study in the application of a laboratory technique first described by Dr. Brion C. Smith in the Journal of Forensic Sciences in January 1992. Our study evaluated a human skull that showed perimortem and/or postmortem tooth loss. It was discovered in 1991 and deemed to have no usable dental information due to severe alveolar bone destruction. In 1994, using minor modifications of Dr. Smiths technique, we sealed off the open tooth sockets and injected a radiopaque material which, after radiographic analysis, revealed previously unobserved dental information. This report demonstrates that root morphology can be reconstructed. This yields radiographic information that may be useful in the identification of unknown human remains.

Chapter 6 – Character Traits of Expert Witnesses: The Good and the Bad

“Impressing” a jury (or a judge) is a relative term. Impressing someone may not be the same as convincing them to believe you, but the oft-referenced list of behaviors and choice of language that aid in creating a good impression are always part of the discussion about expert witnessing “success.” Witness credibility in the legal arena is a multi-factored assemblage of behaviors that the witness must possess in order to be effective. Often, the truth of statements is determined by whether the jury is comfortable with the personality traits discussed in this chapter.

Chapter 11 – Forensic Expert Ethics: Cases and Concepts about Ethical Forensic Practice and Testimony in Court

This chapter explores the moral and ethical demands that are expected of experts testifying in court. It focuses on the independent variables of scientific outcomes, poor forensic methods and the expectations courts have on what experts bring to and say while in court.This chapter explores the moral and ethical demands that are expected of experts testifying in court. It focuses on the independent variables of scientific outcomes, poor forensic methods and the expectations courts have on what experts bring to and say while in court.

Chapter 8 – Cross-examination: The Expert’s Challenge and the Lawyers’ Strategies

The media presents numerous examples of the courtroom process involving cross-examination of witnesses, both layman and expert. Most of the scenes are overly dramatic and void of a basis in factual law and practice; but they are very entertaining. An expert in the real world needs to know the facts and myths regarding what can and cannot happen during cross-examination. Rules of evidence have little to do with “cross ex,” as most questioning from opposing counsel is allowed with few exceptions. There is some case law that touches on some aspects of questioning, but in a courtroom phase where the expert has no control over the subject matter. This is partially why cross-examination seems so scary and stressful for some participants. The fear of the unknown may tend to explain their wariness on the matter. It actually is a result of inadequate study and practice by the expert. It is important for the forensic expert to understand the legal goals lawyers have, how they research and the finite strategies lawyers use to perform their interrogation of the expert trial witness. Experts with broader training will learn to anticipate what will usually happen before even sitting in the witness stand.

Chapter 1 – The History of Experts in English Common Law, with Practice Advice for Beginning Experts

The first chapter provides a brief history of the use of special witnesses in courtrooms. The early expert customs and rules in English Common Law show striking similarity to current rationales. Today the scrutiny of review for expert testimony is much more science based but not devoid of concern in certain areas. The remainder of the chapter develops cases and events involving some forensic disciplines and individual groups that represent examples of forensic challenges, inconsistencies and deficiencies.

Chapter 7 – Voir Dire and Direct Examination of the Expert

The culmination of a forensic examination is when it is brought forward at trial. The evidence brings the forensic analyst along with it. The necessitity for expert preparation is paramount. Practice and understanding the multi-layered sequence of judicial proceedings requires professional commitment to understanding the legal nuances. This chapter presents a framework for that preparation and performance that is expected. The forensic expert must understand that each case is different and high standards of ethics and scientific rigor is the only foundation for testimony that will stand the test of both the courts and future scrutiny of the expert herself.

Chapter 5 – Managing Your Forensic Case from Beginning to End: It’s All about Communication

The complexity of forensic casework requires organizational skills, the ability to properly record and then communicate procedures and findings. This chapter outlines and explains the step by step process with suggestions for proper outcomes during trial.