The Liber decretorum of Bishop Burchard of Worms was one of the most important canon law collections in the eleventh and early twelfth centuries until the compilations associated with Ivo of Chartres came into widespread use. Its popularity is borne out not just by its subsequent use as a formal source but also by its widespread transmission; the Liber decretorum remains extant in more than eighty manuscripts with some twenty fragments including single leaves. Compiled between 1012 and 1022, the Decretum was quickly transmitted, and Burchard himself may have had a role in its early dissemination. The collection – in the form of the Frankfurt manuscript – moved rapidly beyond Worms to southern Germany, to Burgundy and to Italy. This new study by Greta Austin is not only the first full-length work devoted to the Decretum since the study of the collection's sources and manuscripts by Hoffmann and Pokorny in 1991 but also is in fact the only monograph in English devoted to Burchard in many years.

Following the introduction in which Greta Austin sets out her contention that the popularity and success of Burchard's collection derives not only from its usefulness as a practical compendium but also on account of its systematic jurisprudence, the book is divided into three parts: part i, ‘Background’ (chs i–v); part ii, ‘Burchard's editing priorities’ (chs vi–x); and part iii, ‘Implications’ (chs xi–xii). In chapter i, Austin describes her methodology and justifies her case study approach of examining books vi, x, xi and xii of the Decretum. Chapter ii surveys the collection itself, its stages of composition, its manuscripts and audience. Chapter iii, whilst offering some basic definitions on medieval canon law, is devoted to an examination of the earlier and contemporary canonical collections that Burchard had at his disposal as formal sources. Chapter iv focuses upon Burchard himself, his education and ecclesiastical career, and addresses the range of roles that he exercised as an educator, reformer, temporal lord and bishop – all of which had an impact on his canonical collection. Chapter v returns to the principal thesis of the volume by arguing that the Decretum's preface sets out a coherent vision of canon law that is supported by other canons on jurisprudence in the collection, all of which informed the way that Burchard subsequently selected and presented the canons. Part ii contains a very detailed textual assessment of the Decretum with reference to the four books selected as case studies. Chapter vi addresses the practical presentation of the canons and the reorganisation of material from Burchard's principal formal source, Regino of Prüm's Libri duo; here Austin argues for Burchard's clear concern for the collection's structural elements as evinced by the early manuscripts. Chapter vii focuses upon the authority of the Decretum's canons and the extent to which Burchard's preoccupation with legal authority is reflected in his ‘editorial’ decisions, ones that included the alteration (indeed even fabrication) of inscriptions and the exclusion of other acknowledged sources of church law such as secular law. Chapters viii and ix turn to the ways in which Burchard eliminated the discordant canons found in Regino in an effort to provide a consistent body of laws by assessing how he sought to offer both ‘general principles’ of law derived from Scripture as well as specific rulings, again often involving editorial intervention and alteration. Chapter x examines the substantive law in each of the four case study books, exploring both the general principles and specific rulings. In part iii Austin explores the implications of the alterations and the extent to which Burchard should be considered a ‘forger’ in chapter xi, with the final chapter addressing the issue of whether or not it is possible to argue that, despite its practical focus, the Decretum is a collection utilising the tools of theological reasoning. The book ends with a conclusion, a staggering series of appendices and a detailed bibliography.

Despite Austin's concerted efforts to make this a user-friendly volume with attention to basic definitions and introductory material on medieval canon law collections, this is necessarily a difficult book. The seventy-two-page appendix with seven tables detailing the transmission and alteration of Burchard's formal sources, along with the proliferation of other tables throughout the volume and indeed the scale of the annotation, could easily daunt any but the most committed historian of pre-Gratian medieval canon law. (It is important here to compliment Ashgate Press and its editors on their quality of production in these appendices; I noticed very few typographical errors throughout, though some repetition could have been eliminated.)

Whilst acknowledging that the volume is difficult is relatively easy, evaluating its thesis is less so, and involves something of a partisan decision. This is less a book about the contents of Burchard's Decretum and how it was used but rather an investigation of how a compiler worked and the vision of law that animated him. Much depends on how one evaluates Austin's objectives and methods (some will not be convinced by the decidedly quantitative approach), and on the extent to which one is convinced that it is possible to extrapolate a compiler's agenda from the selection and presentation of his formal sources. Intentionality is a fraught issue among historians of canon law, especially pre-Gratian, even in cases such as here where there is an extant preface. There are instances in this book where this intention may be over-stated. Whilst Austin acknowledges that ‘Burchard’ is used to refer to Burchard and his assistants, this does become blurred in the course of the volume; surely Burchard did not oversee the selection of every canon or the recording of its inscription. That said, whilst I have some reservations in accepting Burchard as one of the ‘fathers of systematic legal reasoning’, given Austin's familiarity with the Decretum's early manuscripts and knowledge of Burchard's formal sources, she makes a persuasive case that will fundamentally challenge historians to re-think the construction of collections in the era before Gratian.