Extraterritoriality – the extension of jurisdiction upon national subjects beyond the territorial limits of the metropolitan state – was a central part of the British presence in China from the arrival of larger numbers of British traders after 1757 through to 1943. This thesis explores the development of extraterritoriality and the exercise of jurisdiction in its criminal justice capacity. It asks: how can we understand the development of extraterritoriality as a system, as a set of practices and as a set of ideas? What were the main functions of consular jurisdiction? What challenges did extraterritorial jurisdiction face and how can we understand its demise? It demonstrates how extraterritoriality was constituted in the local, regional and global context, as well as putting it in comparative perspective. It shows how law was embedded in social and political processes, leading to its development, adaption and demise in the nineteenth and twentieth centuries, ending with its abolition in 1943. Through doing so it develops a number of themes that enrich the fields of legal history, colonialism and imperialism studies as well as treaty port China history.