International investment protection is based on treaty obligations between sovereign states. State parties to those treaties enter into international obligations with one another for the protection of foreign investors and their investments. However, the European Commission and Court of Justice of the European Union (CJEU) consider EU law as “supreme”. As such, both the Commission and CJEU have found it difficult to accept international law obligations of Member States insofar as these conflict with EU rules—and as a result have sought to limit or in effect undermine such international law obligations. The latest manifestation of this trend is the Commission’s recent decision to open proceedings against Spain with respect to the arbitral award in Antin v. Spain, the payment of which the Commission says constitutes illegal State aid - even though such award imposes an unambiguous and final legal obligation on Spain to pay that award pursuant to the investment treaty to which it willingly agreed.