The decision of the arbitral tribunal in the Vattenfall case holds that investment arbitration based on the Energy Charter Treaty is compatible with EU law, as interpreted by the Court of Justice in the Achmea case. The arbitral tribunal found that the Achmea judgment does not apply to the Energy Charter Treaty (or similar international agreements) and, moreover, that neither the principles of treaty interpretation nor conflict of laws rules give EU law primacy over the Treaty. Even though this ruling is correct from the point of view of international law, it seems to infringe EU law as interpreted in the subsequent opinion in the CETA case.