2 - Customary International Law

Summary

Have International Investment Agreements (IIAs) generated or changed customary law? (1) Scholarship’s optimistic approach to the status of customary international law fails to distinguish the elements of custom-creation from their proofs. (2) IIAs are not instances of expropriation or non-expropriation, hence they cannot serve as state practice. Verbal acts are not practice of the content of that verbal act. (3) IIAs are not opinio iuris because it is unlikely that treaty parties express preferences regarding customary law by concluding a treaty. (4) If treaties are an opt-out from general international law, then IIAs are likely concluded to counter perceptions of custom and a fortiori not custom-building. Therefore, a customary international law on expropriation is unlikely to be shaped significantly by IIAs and even if they did shape it, the resulting norm would be highly unspecific.