On the heels of protracted legal battles, the European Court of Justice (ECJ)—the highest court in the European Union—issued a landmark judgment in 2024, affirming that Ireland's tax rulings granted to Apple constituted illegal State aid. This decision effectively reinstates the European Commission's original 2016 findings and has significant ramifications for multinational enterprises (MNEs) operating in the EU. While the dispute centers on alleged selective tax advantages, transfer pricing practitioners should note the Court's pronounced focus on the arm's length principle, cost-sharing arrangements, and the broader interplay between EU competition law and national tax policies.