The Concept of Law is one of the most influential texts in English-language jurisprudence. 50 years after its first publication its relevance has not diminished and in this third edition, Leslie Green adds an introduction that places the book in a contemporary context, highlighting key questions about Hart's arguments and outlining the main debates it has prompted in the field. The complete text of the second edition is replicated here, including Hart's Postscript, with fully updated notes to include modern references (...) and further reading. (shrink)

The paper consists of three parts. In the first part five kinds of defeasibility are distinguished that is ontological, conceptual, epistemic, justification and logical defeasibility. In the second part it is argued that from these, justification defeat is the phenomenon that plays a role in legal reasoning. In the third part, the view is defended that non-monotonic logics are not necessary to model justification defeat, but that they are so to speak the natural way to model this phenomenon.

In this paper we will analyse the issue of defeasibility in the law, taking into account research carried out in philosophy, artificial intelligence and legal theory. We will adopt a very general idea of legal defeasibility, in which we will include all different ways in which certain legal conclusions may need to be abandoned, though no mistake was made in deriving them. We will argue that defeasibility in the law involves three different aspects, which we will call inference‐based defeasibility, process‐based (...) defeasibility, and theory‐based defeasibility. Only the integration of these three perspectives allows us to provide a satisfactory account of the role of defeasibility in legal reasoning. (shrink)

Inspired by legal reasoning, this paper presents a formal framework for assessing conflicting arguments. Its use is illustrated with applications to realistic legal examples, and the potential for implementation is discussed. The framework has the form of a logical system for defeasible argumentation. Its language, which is of a logic-programming-like nature, has both weak and explicit negation, and conflicts between arguments are decided with the help of priorities on the rules. An important feature of the system is that these priorities (...) are not fixed, but are themselves defeasibly derived as conclusions within the system. Thus debates on the choice between conflicting arguments can also be modelled.The proof theory of the system is stated in dialectical style, where a proof takes the form of a dialogue between a proponent and an opponent of an argument. An argument is shown to be justified if the proponent can make the opponent run out of moves in whatever way the opponent attacks. Despite this dialectical form, the system reflects a declarative, or relational approach to modelling legal argument. A basic assumption of this paper is that this approach complements two other lines of research in AI and Law, investigations of precedent-based reasoning and the development of procedural, or dialectical models of legal argument. (shrink)

New to English law? Need to know how rules are made, interpreted and applied? This popular and well-established textbook will show you how. It simplifies legal method by combining examples with an account of rules in general: the who, what, why and how of interpretation. Starting with standpoint and context, it identifies factors that give rise to doubts about the interpretation of a rule and recommends a systematic approach to analysing those factors. Questions and exercises integrated in the text and (...) on the accompanying website will help you to develop skills in reading, interpreting and arguing about legal and other rules. The text is fully updated on developments in the legislative process and the judicial interpretation of statutes and precedent. It includes a new chapter on 'The European Dimension' reflecting the changes brought about by the Human Rights Act 1998. (shrink)