This dissertation examines the way in which the English public in the nineteenth century engaged with criminal toxicology, through the medium of the newspapers. It aims to fill a gap in the historiography of toxicology, by combining the approaches of single-case analysis and statistical analysis to assess public opinion and action. This dissertation argues that the public’s engagement with criminal toxicology occurred through the context in which they encountered it, namely the judicial system. In addition to this, public engagement was built upon an informed understanding of the role of toxicology in the courtroom and was capable of producing tangible change. Through examining four sensational cases of criminal poisoning over the nineteenth century, this dissertation traces the development of the general public’s understanding of toxicology and resulting reactions to it. Throughout the century, the newspapers gradually disseminated more information about trials and the toxicology involved in them to the public, which they were able to act upon, by means of placing pressure on the authorities to reconsider the outcomes of contentious trials and the laws that had contributed to them. Overall, the public engaged increasingly with toxicology through the judicial system, agitating for and successfully creating change, in the interests of ensuring justice was done in individual cases and in the future.