Behavioural sciences help refine our understanding of human decision-making. Their insights are immensely relevant for policy-making since public intervention works much better when it targets real people rather than imaginary beings assumed to be perfectly rational. Increasingly, governments around the world are keen to rely on those insights for reshaping public interventions in a wide range of policy areas such as energy, health, financial services and data protection. When policy-making meets behavioural sciences, effective and low-cost regulations can emerge in the form of default rules, smart disclosure and simplification requirements. While behaviourally-informed intervention has a huge potential for policymaking, it also attracts legitimacy and practicability concerns. Nudge and the Law takes a European perspective on those issues and explores the legal implications of the emergent phenomenon of behavioural regulation by focusing on the challenges and opportunities it may offer to EU policy-making and beyond.