The European Neighbourhood Policy (ENP) is a recent example of an external EU policy drawn up explicitly with the objective of achieving coherence in the external policies of the EU and its Member States. Positioning the ENP in the legal-historical context of political union, this book explains why coherence has become a substantive issue in EU external relations, and why law is integral to attaining the ever-enigmatic single voice of the European Union. The text examines the role of EU externa ...