The word ‘Byzantine’, alas, all too frequently gets used as a term of abuse, and the study of canon law in the Eastern Roman Empire does little to discourage that use. It is rarely referred to in academic circles and is even more rarely taught (even in faculties of canon law); it is unsystematic, contradictory, disorganised and written in a language that is technical (at best) and downright obfuscating (at worst). While Wagschal's work, based on his 2010 Durham University doctoral dissertation, may not force the reader to come to the opposite conclusions, it will definitely provide a fuller appreciation, and even explanation, of how the subject got that way.

The central argument of this work is that the picture of law that emerges from the Byzantine material is fundamentally at odds with many formalist/positivist expectations of modern Western legal culture. This dissonance had traditionally made it very easy to dismiss Byzantine canon law as ‘primitive’ or ‘decadent’, particularly when compared with the pristine heights of classical Roman law from which it descended, or degenerated. If approached more sympathetically, however, this strange legal world can be read as constituting a surprisingly coherent and rich legal system that is characterised by the centrality of the idea of law (the ‘legality’ of the book's title) as a sacred and relatively inviolable tradition, with a strong orientation towards the realisation of substantive justice, rather than formal consistency. If taken seriously, this picture of law has a number of important implications for contemporary canonical legal theory, the broader history of canon and ecclesiastical law, and the study of late antique and Byzantine law generally. The canons (as Wagschal emphasises) were church laws, but did not create a system of church law.

For the vast majority of readers, this will be an introduction to the canon law of the Eastern churches: there is very little available on this subject, and treatments in English are rare indeed. With extremely few exceptions, almost everything written about Byzantine law, both secular and ecclesiastical, in the past two centuries has been surveys of sources; this work is almost (but only almost) unique in attempting a synthetic, thematic and interpretative presentation of Byzantine canon law. Wagschal sets out clearly how the corpus was built up: the original nucleus consisted of the canons of the First Council of Nicaea (325), the so-called ‘apostolic canons’ (presumed to have the authority of the apostles themselves) and the canons of several fourth-century particular councils. Over the centuries, layers of new canons were gradually added to this base. Wagschal's discussion of the origin and use of the Byzantine nomokanon, a quintessentially Byzantine collection that combines both secular laws (nomoi) and ecclesiastical canons (kanones) is especially illuminating; while the term is widely used by scholars of Byzantine and Eastern law today, this designation did not enjoy widespread currency in the first 500 years of the Byzantine canonical tradition, which Wagschal studies.

Subsequently the decrees of later ecumenical councils were added, and also a body of patristic canons, such as those of St Basil, to a far greater extent than occurred in the contemporary Western canonical writers and sources – who typically augmented their legal collections with papal decisions. Beyond these elements, different collections appended various additional materials, whose authority depended not on official authorisation but on its kinship to the common core: it is here that the development and augmentation of canon law differs most noticeably between East and West during this period. In the East, material was added but not taken away: if an earlier canon disagreed with a later one, it was not deleted. The essential note was not repetition but a common grounding in the patristic inheritance, to which was attributed (in practice) the same authority as that of Scripture. This is most evident in reading synodical condemnations in this period, which typically contain no explicit citation of any legal text, as would certainly have been the case in a Western trial or decision, but rest upon an agreed theological understanding, manifest in the canons and numerous other sources as well.

This book remains a study of the canonical collections precisely as collections. It does not treat the content of individual canons, except occasionally as illustrations; it does not discuss the occasion and purposes of new canons, notably at several of the ecumenical councils. Nor does it treat the actual application of the law in particular cases. But in its consideration of the notion of ‘legality’ and how that is manifest not only in the collections but also in the legal culture of the Byzantine Empire, this book is a milestone in the study of Byzantine canon law and the legal culture of the Byzantine world. Let us hope that there will be many similar works following it.