Consuetudine: un’analisi concettuale

In civil law systems, statutes and other legal texts sometimes refer to ‘custom’. In international law, it is undisputed that ‘custom’, alongside with treaties or conventions, is one of the main legal sources. The bulk of this paper is devoted to an attempt at answering a single, simple question: what is custom? What is it that statutes and other legal materials refer to, when they refer to ‘custom’? In answering this question the beginning of wisdom is to realize that there is no single, unique concept custom. ‘Custom’ designates different phenomena, which should be carefully distinguished. It is, then, possible to mould several concepts of custom, and customary rule. In the first, longer section of the paper I provide a series of definitions, of increasing complexity, identifying different (families of) concepts: custom as a mere behavioural regularity, social rules, causal and normative conceptions of custom, customs as strategic interaction phenomena (Lewisian conventions and fair play norms belong to this latter family). In the second, shorter section I argue that, given deep doctrinal disagreements about the features of custom as a source of the law, and the lack of relevant legal provisions, all one can do, in trying to understand what statutes and other legal texts refer to when they speak of ‘custom’, is to list several diffrrent possible meanings of the word – what is done in the first section -, giving up the project of selecting one of them as the right relevant meaning. In the concluding subsection of the paper I show that, Hart’s own remarks (in his Postscript to The Concept of Law) notwithstanding, Hartian rules of recognition are best understood as customary, not as conventional, rules.