How does the EU legal structure impact on its relationship with third countries within its proximity? This original book explores this question, following three related lines of inquiry. Firstly, it examines similarities and differences between EU internal and external integration, looking at both EU membership and neighbourhood law. Secondly, it looks at the legal techniques relied upon to extend the EU's legal space. And thirdly, it sheds light on the different political covenants underlying legal relations in the wider European legal space. The book explains how EU neighbourhood law entails a reconfiguration of how sovereignty is exercised both in the EU and in third countries participating in the extended EU legal space.