With increased globalisation, digitisation, cross-border movement of persons and multinational businesses, events and cases have progressively become transnational. Conversely, with the current geopolitical climate, increase of migration and recent pandemics, borders have regained importance. These developments raise questions about the territorial scope of legislation. In this book, 28 mechanisms have been identified which influence the territorial scope of EU law. By using these mechanisms, the territorial scope of any rule of EU law can be determined. The mechanisms relate to decolonisation, overseas countries and territories, disputed borders and territorial claims, Brexit, accession, enhanced cooperation, opt-in and opt-out, the Brussels effect, etc. In addition, this book covers various fields of EU law (free movement rules, migration law, the GDPR, competition law, VAT, sanctions, etc.). The book is unique and stands out from other EU law books, because it encompasses all mechanisms relevant to mapping the territorial scope of the different fields of EU law. It is written for academics, practitioners, policymakers and lawmakers alike.