This book deals with a central problem throughout the legal profession -a solution to the problem is sought and reached in some basic form. At the centre of this prob lematic is the question indicated by the title: What is the nature of discovery in legal decision-making? In the final chapter that problem and the solution reached will be seen to have ramifications throughout the entire field of legal practice and theory. However, the focus of the argument is maintained first to specify adequately the particular manifestation of the problem in a variety of legal fields and secondly to arrive at a precise basic solution to this range of problems. The presentation of the solution is not dictated by the norms of clarity and coherence, but by the dynam ics of the struggle to reach the solution and by aspects of the problem available to various sub-groups within the legal profession -theorists, judges, arbitrators. So, I begin from a relatively familiar zone, discussions of discovery in legal theory before moving to more unfamiliar territory. This book is not a thorough survey of problems and writings on discovery. Rather, the strategic selection of problems and assessment of solutions across the first four chapters represents four aspects of the problem. Those chapters invite the reader to rise to the sense of occurrence of a single problem in a variety of contexts.