Geneviève Cartier introduces cities ‘as both subjects and agents on the international stage’. Traditionally seen as creatures of domestic law alone, cities are increasingly actively engaged in what is sometimes called ‘local foreign policy’. The legal boundary crossings implicated in such local/foreign action require a form of ‘normative mediation’ between the different fields of law involved: local government, constitutional, and international. She develops a double-facing conception of administrative law in which these boundaries do not disappear but are revealed to be ‘more porous than is usually assumed’. The resulting processes of normative travel and transfer, as in several of the other double-facing analyses in this volume, go in two directions. External norms and practices affect the content of domestic understandings of city power, while cities rely on their traditional status in domestic law to shape their actions on the international stage.