Coherence is highly valued in law. It is especially sought after in investor-state dispute settlement, where charges of incoherence in arbitral awards have long been raised by states and scholars. Yet coherence is a largely underexplored notion in international law. Often, it is treated as a mere ideal to strive towards or simply as a different way to describe the legal consistency of judicial outcomes. This book takes a different approach. It sees coherence as an independent concept having two dimensions: a substantive and a methodological one. Both are critically important for legal reasoning by international courts and tribunals, including by investor-state tribunals, and the book illustrates through several case studies some of the ways this conclusion is borne out in practice. A fuller understanding of coherence in international law has implications for our understanding of the concept of law, the practice of legal reasoning, and judicial professional ethics.
