Europe’s legal and regulatory landscape is changing.Historically, regulation through litigation was unheard of in European democracies. The United States was the land of “adversarial legalism,” famous—or perhaps infamous—for its activist courts, rapacious lawyers, class action lawsuits, massive damage awards, and more generally litigious, adversarial relations between government, industry and interest groups. In west European democracies, by contrast, approaches to regulation were much more informal, cooperative and opaque, as closed, insider networks of bureaucrats and regulated interests developed regulatory policy in concert, with little influence from courts and private litigants.Eurolegalism explores how and why the process of European integration is transforming traditional patterns of law and regulation across Europe.While we are certainly not witnessing a convergence of the two systems, it is clear that patterns of law and regulation in the European Union (EU) are shifting toward a distinctive European variant of American legal style—what I call “Eurolegalism.”European integration plays a central role in driving this transformation. The EU’s fragmented political structure and its project of market integration encourage policy makers to enact more and more detailed, judicially enforceable rules—often framed as individual rights—and to back them with the threat of enforcement litigation by public authorities or private actors.