Conclusion

Abstract The main argument of this book is that, to reconstruct the development of custom as a source of law, it is necessary to think of the law of nations (ius gentium) as a historical discipline. Its analysis shows that the ‘turn to history’ is not just a recent trend in international legal scholarship; ius gentium itself was deeply dependent on the use of historical methods (and on the different temporalities they relied upon) to create legal arguments and techniques. The study of custom makes no exception to this. Authors of the natural law tradition invented customary rules of ius gentium within an open a dialogue with the past, a repository of principles and legal arguments that only needed to be unearthed and appropriated in the present. Thus, to think of custom as a process of historical invention might also offer a significant contribution to contemporary understandings of customary international law. The analysis of the different strategies through which jurists of the past invented custom unravels its fictional nature as a legal concept, and it exposes the belief-system based on which such jurists imagined it.