This book aims to provide a clear understanding of the effects of norm contestationNorm contestation on EU foreign policy. The motivation for this research stems from the fact that the EU is often regarded as the poster child of the post-national liberal order. It follows that if the international orderInternational order or its normsNorm are challenged, the EU will also be a locus and focus of that contestation. To this end, the research is situated at the intersection of two bodies of literature: normsNorm research in International Relations (IR) and EU studies that focus on the concept of the EU as a normative power (Manners, Journal of Common Market Studies 40:235–258, 2002). This intersection underscores the primary contribution of this book, which conceptualises the EU as a normNorm community. Within this framework, contestation can take the form of both applicatory and validity contestationValidity contestation (Deitelhoff, N., and Zimmermann, L. 2020. Things We Lost in the Fire: How Different Types of Contestation Affect the Robustness of International Norms. iInternational Studies Review 22 (1): 51–79.).