' - Veerle Heyvaert, London School of Economics, UK This innovative book explores the constitutional compromise between the European Union's legislative competence and member states' regulatory autonomy, and analyses the reconciliation of economic integration and welfare protection within the European internal market. It does so through the original lens of article 114 TFEU, the law-making clause underlying the European harmonisation process. Focusing on a critical provision and the controversial derogation mechanism contained therein, the book discusses contemporary, universally fundamental topics, such as risk assessment and related responsibility allocation within the constraints of complex legal frameworks, the preservation of regional regulatory autonomy against the background of centralised legislative norms, and the interaction of economic integration with policy interests like consumer, environmental and health protection. Highlighting the collaborative rather than adversarial value of national deviations from common European measures, the study not only complements the literature available on 'negative integration' of the internal market, but also challenges traditionally accepted axioms, revealing opportunities for risk prevention and legitimacy enhancement stemming from diverse European and national regulatory standards. This detailed book will be of wide international appeal to academics, practitioners, students, judges, policy-makers and officials working within the European Union and government representatives of individual member states, as well as anyone more generally interested in the dynamics of EU integration. : Foreword Introduction 1. The Harmonisation of the Internal Market 2. EU Competence in the Internal Market 3. Regulatory Differentiation in the Internal Market 4. The Harmonisation Model Under Article 114 TFEU in Practice 5. Appraisal and Reform Proposals Bibliography Index