The precautionary principle provides a justification to act where scientific uncertainty about the nature and extent of detected indications of harm would otherwise possibly impede regulatory interventions. The highly controversial and often misunderstood principle plays a central role in European risk regulation. The present volume should allow readers to gain an overview of all essential points linked with the role of the principle in the risk regulation framework of the European Union. Based on an outline of the precautionary principle's main characteristics and its conception by the European Commission, common allegations brought against the principle are illuminated and critically assessed. The second part of the book is then devoted to the actual implementation of the principle in the EU - from early applications to ongoing disputes. Three case studies from the agrochemical, pharmaceutical and food packaging sector reflect current applications as well as the relevant institutional and procedural framework. Insights from the theoretical part and the case studies are melted in the final discussion section that also includes recommendations for EU risk regulators.