In a landmark decision issued in March 2025, the EC ruled that the €101 million ICSID arbitration award granted to Antin Infrastructure for changes to Spain’s renewable energy subsidies constitutes unlawful state aid under EU law. The EC concluded that the award—resulting from intra-EU arbitration under the ECT—violates the autonomy of the EU legal order, and that any implementation or payment by Spain would breach Articles 107 and 108 Treaty on the Functioning of the EU (TFEU). The ruling aligns with prior the CJEU judgments rejecting intra-EU investment arbitration and marks a development regarding the enforcement of intra-EU awards, obliging Spain to neither pay nor facilitate enforcement of the award and to recover any payment already made. This development is also notable, as it underscores the Commission’s stance against using investor-State arbitration to uphold fossil-friendly subsidies and could reinforce broader calls for withdrawal from the ECT and neutralization of the treaty’s sunset clause.