Some Reflections on the Proof-based Theory of Legal Exceptions

In his 1949 essay, ‘The Ascription of Responsibility and Rights’, H. L. A. Hart first introduced the concept of defeasibility. Hart tried to characterise the role of exceptions in legal reasoning. In a nutshell, he considered that the conditions for the application of a legal concept, such as ‘contract’, ‘although necessary are not always sufficient’ for justifying a certain legal conclusion. The debate over defeasibility reached its peak in the 1990s, when the approach of standard deontic logic to dealing with defeasibility was challenged by those who used non-monotonic logics. In recent years, the debate between these rival approaches to defeasibility seemed to have reached an impasse. Now, more than sixty years after the publication of Hart’s seminal paper, the monograph Allowing for Exceptions: A Theory of Defences and Defeasibility in Law tries to find novel solutions for the conceptual analysis of defeasibility. Luís Duarte d’Almeida attempts to develop a third theory of defeasibility, which ‘seeks to reconcile the seemingly conflicting intuitions that we have about exceptions’, and to overtake the opposition between monotonic and non-monotonic logics, which characterises the current debate. The author’s proposal is to make a fresh start, and, so to speak, to go back to the basics (namely, Hart’s theory of defeasibility), in order to investigate if the original understanding of defeasibility might still be useful in legal theory. In this essay, I will first provide the reader with a brief overview of the most important theoretical achievements of this book; after that, I will offer a critical analysis of several themes, or questions raised by Duarte d’Almeida, and finally I will draw some concluding remarks.