Experts and expertise

The term ‘expert witness’ has a long history, and is today defined much as it was at the end of the eighteenth century, when it first came into use. An expert witness is one who, in a court of law, is permitted to give evidence of both facts and opinion, to help judges and juries come to accurate decisions. This is very different from other witnesses, who give evidence solely about the facts of which they have direct knowledge. Furthermore, the term is associated for the most part with science, medicine and technology,1 so that ‘expertise’ is considered largely in relation to these fields. This chapter surveys the history of the role and influence of medico-legal experts and expertise before using six national case studies to explain how states supported the professional development of forensic medicine by formalizing the connections between medical education and legal procedures for investigating deaths and criminal offences, thereby helping to create a cadre of expert witnesses in the modern sense. The final section considers the expert witness in action, taking as its subject toxicology and trials for criminal poisoning, for it was the toxicologist ‘who emerged as the leading representative of the growing field of nineteenth-century medico-legal expertise’.2 The subsequent development of various fields of medico-legal expertise will be addressed in Chapter 6. In its focus on the period before the twentieth century, the chapter is

concerned to show what it was that enabled medical practitioners to offer testimony in particular circumstances, to what degree they could be considered experts, and how this changed over time. In other words, how did forensic medicine come to be ‘a body of knowledge or experience which is sufficiently organized or recognized to be accepted as reliable by a court’?3