The Making of Evident Expertise: Transforming Chemical Analytical Methods into Judicial Evidence

This article investigates the question of how forensic toxicologists established the credibility of chemical analytical methods in poisoning lawsuits in the nineteenth century. After encountering the problem of laypersons in court, forensic toxicologists attempted to find strategies to make their evidence compelling to an untrained audience. Three of these strategies are discussed here: redundancy, standard methods, and intuitive comprehensibility. Whereas redundancy was not very practical and legally prescribed standard methods were not very popular with most forensic toxicologists, intuitive comprehensibility proved effective and popular. This strategy relied on employing methods which did not require chemical knowledge to be understandable. The methods aimed to generate a visual aid and to be obvious in their results. Two forms of this strategy are discussed here: the presentation of the actual material and explicit comparison. I argue that this shift towards presenting forensic toxicology expertise as evident represents an important step in the history of forensic expertise.