This dissertation argues that the physical bodies of the dead and injured were an overlooked grounds of political contestation in the era of high imperialism. When Siamese (Thai) subjects were injured or killed under accidental or unnatural circumstances, their bodies became concrete demonstrations of both the disadvantaged status of Siamese subjects under extraterritorial law, and the nature of the state's constrained sovereignty. Officials in the Siamese state appealed to and appropriated new forms of medical and legal expertise in response to these events. In contrast to state-centric historical narratives of medicalization or the adoption of western forms of legal cultural and institutions, however, I argue that the actions of Siamese officials were overwhelmingly pragmatic and ad hoc. Moreover, I argue that law and medicine were themselves agentive, responding to and altering the sociohistorical conditions of life in fin de siècle Bangkok. To that end, I introduce a host of previously overlooked social actors and forms of agency that helped to transform the dead and injured into politicized bodies. These actors include the practitioners and advocates of these new forms of medico-legal expertise, including lawyers, physicians, and the semi-subaltern bureaucrats in the Siamese state who helped to mediate foreign forms of expertise, as well as new forms of urban mobility such as streetcars, which inflicted injury and death on the uninitiated. Finally, I argue that the dead and injured were themselves agents in this transitional period, though in the end the authoritative forms of medico-legal knowledge that spoke on their behalf favored authoritarian and absolutist trends in Thai political life.