This book, as the subtitle suggests, takes a critical look at whether the historical divide between the Common Law and the Civil Law traditions is still as real and relevant to the law of criminal evidence today as it may have been in the past. In order to answer this question, the authors look at the ways in which evidence is regulated across both systems. Their method is not primarily comparative. Rather, it is to ‘consider what values the systems share and whether there are commonly accepted principles that can be drawn upon to build a system of evidence that commands consensus across the different legal traditions’ (13). Significantly, the aim is not to come up with a one-size-fits-all model that could be adopted in all jurisdictions. Rather, the stated goal is to ‘promote change and improvements’ within existing systems.

The main argument of the book is that ‘a common set of evidentiary principles’ has developed, based on two fundamental ‘traditions’ that are said to bridge the Common/Civil Law divide. The first, so-called ‘rationalist tradition’, promotes truth-finding by way of ordinary cognitive processes, unfettered by any technical rules. The second is the individual rights (or ‘social contract’) tradition, which in recent times has mainly found expression in human rights.

There is some inevitable tension between the two traditions, as individual rights sometimes require limitations on the unconstrained search for evidence and truth. For example, a suspect's right to remain silent does not sit well with the search for all the relevant information that could lead to the truth. The authors argue that the ‘common evidentiary framework’, which they identify, helps to resolve the tensions between the rationalist and social contract traditions by ‘translating’ the rationalist tradition into a ‘dialectic’ theory of proof and the theory of individual rights into ‘institutional’ rights for the defence.’ (28)

In order to substantiate the claim that Common and Civil Law systems do indeed have a common core which transcends their apparent differences, the book systematically discusses a wide range of issues. In Part I, the authors analyse how the rationalist tradition has developed in both common law, civil law as well as international criminal jurisdictions. Part II traces how specific rights—ie presumption of innocence, privilege against self-incrimination, right to legal assistance and disclosure, right to cross-examination—have evolved into a common conception of fair trial rights.

At the core of the argument about fair trial rights, which constitutes the lion's share of the book, is the claim that there is a nascent ‘theory of positive evidentiary rights around the notion of effective defence participation’ (367), which underpins most, if not all, evidentiary rules. This principle is said to be based upon universally accepted human rights norms, which provide a ‘common grammar’ for discourse about evidentiary rules. This common grammar can be detected in domestic systems, in the decisions of international human rights bodies as well as in procedural decisions of international criminal courts and tribunals.

This is quite a claim, but the authors are careful not to suggest that the principle of effective defence participation has been consciously adopted and applied by national and international courts and tribunals. In fact, it is not always entirely clear whether the putative principle of effective defence participation is primarily an empirical finding, some sort of rationalization after the fact, or whether it is primarily a normative claim by the authors about what should drive domestic and international courts when they consider evidentiary issues. This ambiguity is probably a result of the authors’ scrupulous awareness of the limits of what can be inferred from the—often hopelessly opaque or convoluted—jurisprudence on evidentiary questions, especially by international courts and tribunals.

Regardless of the exact status of the alleged principles of dialectic proof and effective defence participation, they clearly have great theoretical potential, as the authors demonstrate throughout the book. It is well known, as the authors repeatedly point out, that much of the human rights jurisprudence in relation to evidence rules lacks conceptual clarity and specificity. The book proposes a clearer theoretical underpinning for many of the existing decisions and sometimes offers a reconceptualization of certain rights. For example, the right to remain silent is viewed by the authors as a safeguard for institutional values of the criminal process, such as the need for accuracy and the protection of the innocent (284). At other occasions, the authors rely on the principle of effective defence participation to point to areas where the current law falls short of providing the necessary safeguards. For example, the authors make a very strong case for why suspects need stronger protection during the pretrial phase of the criminal proceedings in both Civil and Common law systems.

Despite the strong unifying theoretical potential of the underlying principle, the authors do not claim that this will—or even should—automatically lead to complete harmonization into a single procedural model with uniform evidentiary rules across legal cultures. Indeed, it is one of the great strengths of this book that the authors thoroughly understand the reality of the deep cultural and conceptual differences that divide the legal traditions they discuss and that they do not get carried away in abstract theorizing that bears little connection with the real world. On the contrary, the proposed principle of effective defence participation is sufficiently broad and flexible for it to be capable of being interpreted in different ways and to adapt to different procedural contexts.

However, this flexibility and universality could also be a potential weakness. As all practitioners know, with procedural rules the devil is always in the detail. Although it is certainly important to reflect upon broad underlying principles, the practical relevance thereof for concrete cases is not always immediately clear. This is because fundamental principles can only resolve specific questions through extensive interpretation and this inevitably leaves the adjudicator with a wide margin of discretion. In the end, grand principles may thus just as easily justify the status quo, as each tradition may claim that its implementation of the values protected by the principles is superior or at least equally valid. However, the authors would probably see it as great progress if both traditions were ‘competing’ to implement the same values. Indeed, this could only improve the overall protection of those values and allow meaningful comparison of how different procedural models fare in this regard.

Even if one is not persuaded by the empirical/normative argument of the book, it is a must-read for anyone who wants to understand the big questions in evidence law today. Indeed, one would hope that especially practitioners before international courts and tribunals will study this book carefully as it raises the classic Common Law vs Civil Law debate to a whole new level.

This leads to another observation: The Internationalisation of Criminal Evidence is in fact two books in one. On the one hand, it offers a sophisticated analysis of the fundamental principles underlying modern rules of criminal evidence. On the other hand, it provides a clear, thorough and accessible introduction into the subject. It is thus a book that can be read at different levels and has plenty to offer for both specialists and students who are new to the subject. Nevertheless, a second edition would benefit from a more developed concluding chapter that brings together the wealth of information and ideas which are developed throughout the book. This would certainly help practitioners looking for concrete guidance about how to find solutions to specific problems.

Only time will tell whether The Internationalisation of Criminal Evidence will become one of the classic texts in the field of comparative evidence scholarship that moved the perennial Common Law vs Civil Law debate significantly forward. It certainly has this ambition and possesses the necessary depth and erudition for it. It can therefore only be hoped that it will be widely read and taken into consideration by those who shape the rules of evidence of the future