The Science and Culture of Forensic Pathology

6 The Science and Culture of Forensic Pathology The cases we examined at the Inquiry and from which many of our systemic les - sons were drawn all involved the criminal justice system in some way. In a few, there was a criminal investigation but no criminal charge. Others proceeded to a criminal charge and some beyond that, to a preliminary hearing or trial. In each case, there had been the death of a young child and an autopsy done by a pathologist under a coroner’s warrant. To allow a proper understanding of what happened in these cases, and what must be learned from them, I think it essential to provide at least a general overview of the relevant science: forensic pathology, and its subset, pediatric forensic pathology. Forensic pathology is a branch of the field of medicine called pathology. Broadly speaking, pathology is the study of disease – of its causes and the ways in which disease processes affect the body. A well-known medical textbook, Robbins Basic Pathology , describes pathology this way: [I]t involves the investigation of the causes ( etiology ) of disease as well as the underlying mechanisms ( pathogenesis ) that result in the presenting signs and symptoms of the patient. Pathologists use a variety of molecular, microbiologic, and immunologic techniques to understand the biochemical, structural, and functional changes that occur in cells, tissues, and organs. To render diagnoses and guide therapy, pathologists identify changes in the gross or microscopic appearance ( morphology ) of cells and tissues, and biochemical alterations in body fluids (such as blood and urine). 1 1 Vinay Kumar et al ., Robbins Basic Pathology , 8th ed. (Philadelphia: Saunders Elsevier, 2007), 1. THE SCIENCE AND CULTURE OF FORENSIC PATHOLOGY | 67 As this quotation suggests, the objective of much of pathology is to serve patients by providing an important diagnostic step along the way to treatment and cure or control. In colloquial terms, this is often described as clinical pathology. The route to forensic pathology is through one of two kinds of pathology: general or anatomical. General pathology is, as its name implies, concerned with all aspects of the laboratory investigation of disease. It incorporates techniques from the other laboratory sciences and pathology specialties, such as anatomical and hematological pathology. Anatomical pathology is more specific. It involves one particular kind of investigation: the study and diagnosis of disease based on the gross, microscopic, and molecular examination of organs, tissues, and whole bodies (as in an autopsy). Although considered a subspecialty of both general and anatomical pathology, forensic pathology operates on an entirely different paradigm from clinical pathology. Its purpose is to assist the state in finding out why its citizens die. It is concerned with the examination of the dead body for forensic purposes. In foren - sic pathology, there is no patient. Rather, the medical dimension of forensic pathology involves the study of disease and injury in a deceased person using the basic principles and methodologies of pathology to determine, if possible, the cause of death, and to address the timing of injuries or other medical issues that help explain the death. Its legal dimension is to assist the state’s legal systems, most importantly, the criminal justice system, to understand how the death occurred by explaining the relevant pathology. To put this in practical terms, forensic pathology typically involves the per - formance of a post-mortem examination, also called an autopsy, which entails the dissection of the body, an examination of organs and tissues, and ancillary inves - tigations including X-rays, laboratory examinations and toxicology testing. Forensic pathologists do more than just perform the post-mortem examination, however. They are called on to meet with other members of the death investiga - tion team to discuss their work. And they must be able to communicate their findings effectively to various participants in the criminal justice system, includ - ing police, prosecutors, defence counsel, juries, and the court. In summary, the forensic pathologist focuses on interpreting the post-mortem findings to assist in the end point of the death investigation required by the state, which may include a criminal trial, an inquest, or a coroner’s finding of cause and manner of death made without an inquest. As noted above, the distinctiveness of forensic pathology can be seen by comparing it to clinical pathology. Although the fundamental scientific princi - ples of pathology apply equally to forensic pathology and clinical pathology, 68 | INQUIRY INTO PEDIATRIC FORENSIC PATHOLOGY IN ONTARIO : VOLUME 2 their analytical frameworks are very different. The clinical pathologist focuses on providing diagnostically useful advice to a clinician to assist in the medical management of a patient. The forensic pathologist focuses on providing diagnostically useful conclusions for the death investigation team and the judicial process. It follows that, although every forensic pathologist needs to be a competent clinical pathologist, the opposite is not true. Many competent clinical patholo - gists will never have an interest in forensic work and will never need to obtain the requisite knowledge and expertise in forensic work. However, a forensic patholo - gist must be trained in, and develop an aptitude for, the requirements of the legal process. This requires an emphasis in the conduct of the post-mortem examina - tion on identifying forensically significant findings such as injury, collecting potentially relevant evidence, and maintaining its continuity, all of which do not arise in clinical pathology. It requires that post-mortem documentation serve the needs of the participants in the justice system, including the coroner, police, Crown, defence, and court, which also do not arise in clinical pathology. And it is essential that forensic pathologists be able to testify fairly, objectively, and in lan - guage that clearly communicates their findings. Few medical practitioners have, or require, any detailed understanding of the legal system and the legal investiga - tive method. Becoming proficient in these areas is thus one of the features distin - guishing forensic pathologists from their clinical counterparts. Today, the normal route to becoming a properly qualified forensic pathologist begins with completion of an undergraduate medical program. That is followed by a four- or five-year residency in one of the two main specialties within pathol - ogy, general pathology or anatomical pathology. Having completed either of these, a pathologist needs a further year or two of specialized training, not yet offered in Canada, to be accredited the subspecialty of forensic pathology. Pediatric pathology is also a subspecialty of anatomical pathology. The addi - tional training required for the subspecialty focuses on the study of disease in infants and children, which can differ substantially from disease in adults. Its objective is to assist in the treatment of living patients. The training and experi - ence of a pediatric pathologist concentrates on natural, congenital development, and genetic disease processes. There is little focus on death investigation or on participation in the criminal justice system. Pediatric forensic pathology encompasses the subset of cases within forensic pathology that involves the deaths of infants, children, and adolescents. Although training and experience in pediatric pathology can add great value to the forensic investigation of a pediatric death, forensic pathology remains the core discipline for death investigations in pediatric forensic cases. THE SCIENCE AND CULTURE OF FORENSIC PATHOLOGY | 69 Three aspects of forensic pathology should be highlighted at this stage. The first is that forensic pathology is an evolving science. Second, within the science, there are issues of significant controversy. Third, it is an interpretive science, often subject to limitations on the conclusions it can offer. These aspects assist us in understanding not only what went wrong in the cases we examined, but also the relationship between forensic pathology and the needs of the justice system. FORENSIC PATHOLOGY AS AN EVOLVING SCIENCE Like other sciences, forensic pathology was evolving in the 1980s and 1990s, and it continues to evolve today. Time, research, and advances in technology yield new discoveries and knowledge grows. As a result of this progress, theories and diagnoses that were once thought correct or reasonable may be questioned or even rejected. Two examples help to illustrate how the evolution of forensic pathology through time and research can affect a diagnosis. Traditionally, pathologists con - sidered certain findings diagnostic of “asphyxia” (a deprivation of oxygen). These diagnostic criteria included petechial hemorrhages in the thoracic viscera, con - gestion and edema of the lungs, cyanosis of the fingernails, and cerebral edema. 2 For many years, pathologists diagnosed asphyxia based on these findings at autopsy. However, researchers eventually discovered that all of these findings are properly regarded as “non-specific.” In other words, they are not diagnostic of asphyxia. Indeed, in the 1970s, forensic pathology textbooks began to call these criteria obsolete or, as Lester Adelson described it in his seminal text, The Pathology of Homicide , the obsolete diagnostic quintet of asphyxia. A second example is the evolution of the science and

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