The EU has been an advocate for stricter regulations on ship-source pollution, adopting its own legislation, where international efforts have been deemed insufficient. This book explores the implications of the single largest regional organisation regulating a field as inherently global as international shipping, while diverging from internationally agreed standards. Three case studies that blend academic analysis and practical insights show that EU legislation on ship-source pollution challenges the boundaries of international law. Avoiding to address their compatibility and possible conflicts with international law adequately reflects on the EU’s credibility as a global player and the legitimacy of its rule-making.