The regulae iuris (hereafter RI) have long fascinated scholars of Roman law. Collected in a title towards the end of the Digest (Dig. 50.17), they are presented as a series of terse statements of law, often with little context. Owing to this lack of context, their true nature and purpose have remained a matter of contention. The same issue has also significantly shaped how jurists have used them in later epochs of the Roman legal tradition. In this book the authors address these questions squarely. Before proceeding to the details, a vademecum is provided to readers. Across twelve chapters of irregular length, the authors unpack a rather elegant argument, supported by ample textual evidence. Casual readers wishing to get an overview of this argument are advised to read the introduction, Chapter 4 and Chapter 12 in this order. These three parts give a good overview of the argument and the evidence upon which it relies. Readers may then delve into the remaining chapters where needed to form a deeper understanding of specific parts of the broader argument. This argument is as follows: RI are not contextless legal maxims. Instead, they represent summaries of topical arguments, generally framed, arising from specific cases, many of which have been preserved in the Digest. Thus, by reading RI together with the case out of which they arose, the authors demonstrate a close relationship between law and rhetoric. This method also forces readers to re-evaluate the nature of RI as settled legal maxims.

The argument presented in the book largely unfolds in chronological order. In the introduction, followed by Chapters 1 to 3, the authors revisit the relationship between law and rhetoric in Republican Roman Law, linking it to Cicero while also presenting earlier evidence. These three chapters are foundational and lead into Chapter 4, the book’s scientific engine. It is in this chapter that the authors set out their stall: RI are not settled juristic maxims; they are topical arguments, presented in a slightly generalised manner (as theses). It is also in this chapter that the authors outline the structure of the remaining chapters (5–10). These chapters are arranged according to different types of argumentative structure (status), in which examples of topical reasoning using the RI are presented: coniectura (Chapter 5), definitio (Chapters 6–8), qualitas (Chapter 9) and ambiguitas (Chapter 10). The chapters vary in length, with some devoted to a single example and others containing an accumulation of four, or sometimes five, examples. The final substantive chapter (Chapter 11) is devoted to the first text of Dig. 50.17, which contains the celebrated ‘definition’ of the RI and its relationship to the Regula Catoniana, one of the earliest RI from Republican Roman Law.

A book such as this stands or falls by the quality of its analysis. The case studies offered are detailed, and the authors’ integration of existing Roman law scholarship on points of contention is a welcome addition. One cannot help but wonder, though, what kind of reception it will receive from some sections of the Roman Law community. Despite the persuasive nature of the evidence presented, I fear that the case set out in this book might not persuade those. This is not because the argument is unconvincing – quite the opposite –, but because it is so novel. It would be easy to offer a counterargument, especially for those who champion the civilian tradition over Roman law, that it is the subsequent interpretation of RI as settled legal maxims that has had the most profound impact on the Roman legal tradition rather than the original Roman sense of the term. This is a mistake, but as recent controversies surrounding the publication of Das Handbuch des Römischen Privatrechts (2023) have shown, complex positions, informed by historical notions of ‘science’, can be difficult to abandon (see M. Schermaier’s review in forum historiae iuris, https://forhistiur.net/2024-05-schermaier/, 22 May 2024). For those of us who view Roman law not as a system of settled legal rules, but as a body of competing legal arguments, the implications of the Tellegens’ broader argument are nothing short of revolutionary.