Underlying the protection of human rights in Europe is a complex network of overlapping legal systems - domestic, EU, and ECHR. This book focuses on the potential for conflict to emerge between the systems where rights overlap and interpretations in different courts begin to diverge. From the perspective of EU law, where the interpretation of rights differs national courts are asked to renounce the constitutional scope of protection in favour of the scope defined by the European Court of Justice. This work presents a theory of supranational judicial authority to confront this problem, grounded in an ideal of judicial dialogue. It represents the first attempt to provide a thorough theoretical account of the value of judicial dialogue, and its potential for legitimating judicial decision-making at a supranational level. Combining theoretical rigour with attention to the practicalities of European human rights law, the book will be accessible to a broad readership of legal theorists, EU lawyers and judges involved in building inter-judicial dialogue.