All legal traditions have their own fundamental words. In seeking to trace the origin of the Western rights tradition, one is inevitably confronted with the term ius. Dependent upon context, this may refer to law (or laws), recognised customs having the force of law, or the right outcome required of justice (that is, the iustum). Within modern scholarship, rights have a decidedly personal, subjective – not to say, individualistic – flavour. The origins of prevailing subjective rights theories have, however, been notoriously difficult to plot. For a significant period, Villey asserted that the subjective right had its origins in the work of William of Ockham. More recent writers have highlighted the importance of Hugo Grotius, presenting Grotius as enjoying in the sphere of ethics a comparable status to that enjoyed by Descartes in epistemology. Notably, some authors have pointed to the subjective right as having prevailed throughout the mediaeval canonical tradition, only to be distorted in the hands of enlightenment thinkers. It has also been suggested that the term ius has its origins in the writings of Ulpian and Gratian. However, the common theme of previous studies has been the attempt to locate the foundation of modern rights understanding in iustum or ius.

In contrast, Tierney points to a third dimension of the term ius, one which is capable of being encapsulated in the notion of freedom (libertas) or competence (facultas). For this purpose, Tierney draws upon the ancient understanding of laws as requiring, forbidding or permitting. It is in this latter respect – the law as possessing a permissive sphere – that libertas or facultas find expression and the conceptual foundations of the subjective right is to be found. Such an understanding distils to the principle that what the law does not prohibit, it must permit. In isolation, the principle may be regarded as consistent with the notion that persons enjoy rights and freedoms antecedent to participation in any legal or political community. However, it is equally consistent with the positivist legal perspective that the law has elected to enter into (and regulate for) certain spheres of human interaction, while refraining from doing so in others. Both accommodate a sphere of personal autonomy. How has this residual personal autonomy informed the understanding of the term ius as supportive of a subjective right?

This book is concerned with that question. In formulating a response, Tierney engages with the subject in a masterly fashion. His suggestion that his work is ‘descriptive’ (p xi) does both his labours and the result a disservice. He invites the reader upon a journey along the avenues (and occasional cul-de-sacs) which mark the evolutionary travels of the Western legal tradition. He transports the reader through the authors, primary works and influences, doing so with all of the skill and facility of an expert tour guide and interpreter. This is a remarkable work, not only for its erudition but for its lightness of touch. Like many of the authors with whom Tierney has identified, this book is not directed to definitive statements but to the promotion of continued informed discussion on matters which continue to have a relevance to any jurist.