This thesis addresses “complex disputes”, which are disputes that crosscut the boundaries of a particular treaty or regime, as opposed to non-complex disputes which arise and are settled under one particular treaty or regime. Complex disputes have arisen in various forms before almost all international courts and tribunals. They all raise the same question of regime interaction before international courts and tribunals. They also raise the same problem, which is that while complex disputes relate to more than one instrument or regime, the jurisdiction of international courts and tribunals, in most cases, is limited to settling disputes that arise under one particular instrument or regime. Thus, the question is whether, and to what extent, international courts and tribunals may address relevant aspects of the dispute under external instruments or regimes. International courts and tribunals have been hesitant and inconsistent. This thesis proposes addressing complex disputes by system-wide tools and policies. This systemic framework does not seek to achieve strict uniformity in the decisions of all courts and tribunals in dealing with complex disputes. It rather seeks to ensure that international courts and tribunals address these inter-regime disputes based on uniform and persuasive legal reasoning, guided by the laws and logics of the broader universe of international law.
