This document summarizes the West Tankers case, which involved an anti-suit injunction issued by an English court to prevent litigation in an Italian court. The ECJ ultimately ruled that such an injunction was incompatible with the Brussels I Regulation, which requires mutual trust between EU member state courts. While the English court viewed the injunction as relating to arbitration excluded from the regulation, the ECJ found it undermined the Italian court's ability to determine its own jurisdiction under the regulation. The ruling affirms that no EU court can prevent another from assessing its own jurisdiction over a dispute.