Substantive Obligations Influence of ICJ PCIJ Judgments on Investor State Arbitration

Substantive Obligations Influence of ICJ PCIJ Judgments on Investor State Arbitration Moderator: Professor Eric de Brabandere ( Grotius Centre, Leiden University) Presenter: Professor José Antonio Rivas ( Georgetown Law / WAU / Xtrategy) Panelists: Dr. Daniel Peat (Grotius Centre, Leiden University) Dr. Cameron Miles (3VB Chambers) Dr. Reza Eftekhar (IUSCT) Ms Bojana Risitc (PhD candidate, Leiden University) At the heart of every international investment agreements lie its substantive obligations — the promises States make to protect foreign investors. From fair and equitable treatment to protection against unlawful expropriation, these standards shape the rights investors can claim and the responsibilities States must uphold. But as global priorities shift, so too does the meaning of these protections. This panel will explore how core standards are being redefined through both cutting-edge treaty- drafting and evolving arbitral decisions. How are tribunals navigting the fine line between investor rights and a State’s right to regulate, especially in critical areas like climate action, public health, and human rights? Can customary international law and past rulings bring clarity to a landscape marked by inconsistency? How influential should the judgments of the ICJ be for investment tribunals, for example on substantives issues such as fair and equitable treatment and whether there is a customary obligation to respect the investor’s reasonable expectations?