The book makes three arguments. First, it argues that frontier consuls played a key role in creating forms of transfrontier legal authority. Second, it demonstrates that the impetus behind these legal adaptations was the perceived challenges brought by the movement of British subjects and goods across frontiers. Local and transfrontier mobility therefore defined and shaped British jurisdiction across the frontier. Finally, British authority in the frontiers embraced and worked alongside other local norms and legal structures. This book is therefore the story of British consuls at the edge of the British and Chinese Empires and the nature of their legal powers.