Chapter 5 is dedicated to the analysis of the amended EU Trade Enforcement Regulation 654/2014 to allow the imposition of unilateral countermeasures in case of appeals into the void in the WTO context or of an FTA party blocking panel proceedings. The chapter introduces the original Regulation, recent amendments, and their legislative history. It then appraises the legality of the amendments in light of WTO and FTA rules and whether general public international law on state responsibility could serve as the necessary legal basis for unilateral countermeasures. Assuming that the imposition of unilateral countermeasures under the amended Trade Enforcement Regulation would be in line with EU’s obligations, Chapter 5 also considers their compliance with the conditions established by general public international law. Finally, the amendments’ possible influence on and consequences for the multilateral trading system are explored in light of EU’s commitment to multilateralism and international law.