Customary international law and human rights law : an impossible relationship? : exploring customary international law’s 'vitality paradox'

Abstract

Custom remains a widely discussed source of international law even if its unwritten nature has raised more questions than it has provided answers. At the same time, rarely do discussions regarding customary international law (CIL) transcend the more traditional boundaries of public international law into its newer branches, such as international human rights law (IHRL). When discussions do transcend such boundaries, IHRL is often discarded as unsuited to be informed through custom. The aim of the present work is to address this divide by exploring more closely the possible intersection of CIL and IHRL. In this context the thesis identifies and zooms onto what it calls custom’s “vitality paradox” — its persistence in the practice of international law despite the multiple challenges raised in the scholarship. To see whether this paradox also manifests itself in the field of IHRL, the thesis addresses the case law of judicial bodies that apply international human rights law. It demonstrates that the sceptical discourse on CIL in general, as well as in respect of IHRL in particular, has not played out in practice. To better locate and understand this vitality paradox and explore its implications for the theory and the practice of CIL identification, the thesis traces the specificities of custom and its identification by drawing analogies with custom’s operation in Roman law, civil law before its codification, and common law. As a result, a necessary link between custom and dispute settlement and the multiple-participant process of identification centred around the latter is uncovered. This view of custom identification offers intrinsic safeguards against the feared degeneration of custom into (judicial) wishful thinking and is equally applicable to the field of human rights law. Building on these findings, the thesis concludes with exploring the specificities of IHRL to determine how it should be informed by means of custom without unduly stretching its scope.