2. ‘Full Protection and Security’ in Historical Perspective: The Challenge of the Sources

Historical arguments are essential to the identification and elucidation of customary norms of international law. Historical sources about the customary FPS standard pose significant challenges. Analyzing the evolution of FPS involves dealing with diverse intellectual and political agendas. Relevant decisions were rendered under the most varied jurisdictional frameworks, and referred to overlapping causes of action. A study of FPS and its connection to the notion of due diligence must additionally consider the shortcomings of the present-day distinction between primary and secondary norms of international law. Despite these obstacles it is possible to develop a plausible historical narrative about the FPS standard. This narrative is an essential ingredient of the legal argument.