The margin of appreciation doctrine has become a fundamental part of the jurisprudence of the European Court of Human Rights. It has played a central role in most of the cases decided by that Court, including many of its most significant and controversial, and until recently has been the subject of remarkably little analysis. However, there has been a spate of interest in the doctrine in the last year or so.1Most of this debate has concerned the details of how the margin of appreciation operates in the context of particular articles of the European Convention on Human Rights. This article's purpose is to look at the wider picture. After an outline of the essential characteristics of the doctrine, I will examine the nature of the margin and its role in adjudication. I will suggest that there are logical flaws in the margin as currently conceived, and that these undermine the quality and coherence of the Court's judgments.