In the pages that follow I hope the reader finds a clear, yet challenging and controversial characterisation of competition law. The theme that underpins each chapter is that the substantive rules of competition law are best studied by avoiding exclusive reliance on legal method. Rather, other disciplines offer necessary assistance. I draw mostly on economics, but have also tried to incorporate some approaches used by political scientists. In brief, the gist of this book is that whether one looks at competition law doctrine as a whole, or at a single decision, one should ask three questions in order to understand it best: What is the policy behind it? What economic theory (if any) supports this policy? And who enforces the law? I think these questions receive different answers at different moments in the history of the development of competition law, and perhaps even conflicting answers at the same moment. Enforcers have diverging policy preferences, and different economic theories can be used to justify diametrically opposed conclusions as to the legality of a given practice. Asking these three questions, about the politics, the economics and the institution, reveals valuable information about the application of the law, its evolution and direction. The focus is on the competition law of the European Community, in the way it has been developed by the Commission and the European Courts; I hope that the method of analysis can be transplanted and applied to other legal systems and frame an inquiry into other competition laws.