Lawrence Friedman begins his new book, Impact, by suggesting that we may be able to sum up the project all of law and society scholarship in two questions. The first asks where laws come from and to what degree they are the product of social forces or autonomous creations of law itself? It is however the second question—the impact of these laws—that is the topic of this book. This division of the scholarship into two camps is a sweeping generalization, but an insightful one. At first Friedman says, he thought that law and society scholarship seemed more concerned with where law comes from, but he quickly realized that the impact of the law is equally important in socio-legal scholarship. Indeed the central observation of law and society scholarship that there is a difference between the law in the books and the law in action is an observation about impact, albeit not labeled as such. Criminology, regulatory compliance studies, and the rich literature on the influence and reach of U.S. Constitutional court decisions are all examples of impact studies. So is any exploration of the living law, how law actually works in practice.

Friedman proceeds to summarise the law and society research on impact in a way that is highly accessible yet also comprehensive and rigorous. An important underlying motive for this book is Friedman's concluding observation that

Friedman proceeds to try to impose some order on this “volcanic eruption”. The book begins with the prerequisites for impact—the way that legal action communicates its “messages” (Chapter 2). Friedman discusses studies that investigate which audiences know what about the law, and how they come to learn it? What role do the media play in explaining or distorting the message of the law? What about the impact of the structure or drafting of the rule or decision itself? Is what people think they know about what the law requires really in fact what it requires? As Friedman points out, communication in some form is necessary, but not sufficient, for law to have impact. Chapter 3, “An Anatomy of Compliance” goes on to pull apart the concept of impact itself. While legal studies are concerned with the “internal” impact of the law on itself, socio-legal studies are concerned with the law's impact on the world. The chapter distinguishes helpfully between direct and indirect impact, immediate influence on compliance and ripple effects. It also makes a useful distinction between evaluations of law's impact and evaluations of whether it achieves its purpose, a more complex undertaking. Friedman is skeptical of the tendency in some socio-legal studies to find that legal reforms have had “symbolic” impacts even when no direct impact can be identified, especially where the direction of causation may be the other way around. For example one study found no direct impact of (relatively weak) rape law reform on rape complaints and prosecutions yet suggests that law reform had a symbolic impact. Friedman wonders aloud whether “symbolic” impact means anything in the absence of measureable impact on anything and whether causation might in fact be the other way around with rape law reform following on from changing attitudes (pp. 65–66). Chapter 4 goes on to pull apart “A Typology of Responses” to the law, unpacking the many different ways in which people might respond or adjust to law.

The rest of the book explains what happens in between the communication of the message and the law and people's responses to the law. What are the motivations or mechanisms that explain how people respond to the law and what impact it has? As Friedman shows, research in every sphere of socio-legal investigation suggests three main clusters of factors: rewards and punishments (Chapters 5 and 6); immediate social context or peer pressure (Chapter 7); and the inner voice of conscience, morality, legitimacy, and illegitimacy (Chapter 8). Chapter 9 examines how these three clusters of motivation interact. Friedman summarises vast swathes of this research picking out great anecdotes and examples to illustrate consistent truths that emerge. He also points out consistent problems in policy and study design. In particular he reminds readers of what he calls the “deterrence curve”, that is the idea that at some point deterrence reaches an optimum level and greater and greater deterrence will not achieve a greater impact because all those who are amenable to deterrence have already been deterred.

This is a very readable and thought-provoking book. It provides a nice overview of the area for students and novices and covers the major studies and main researchers from the United States with a good representation of the rest of the world too. Friedman's supportive yet mildly skeptical commentary on the studies will spur readers to think critically about research conclusions and constantly improve study design and analysis. Nevertheless there is something unsatisfying about the book. The high level model represented by the book's structure—the message, the responses and the three sets of factors—is very helpful. It is simple and elegant, yet sophisticated and flexible enough to accommodate many detailed studies and findings, and there are many tantalising insights in these pages. Yet the conversational style of the book tends to perpetuate the sense of feeling overwhelmed by the overflowing of individual research in this area. The focus on telling stories about empirical studies tends to downplay previous attempts to build more comprehensive and plural theoretical models in this area. Nevertheless Friedman surely makes the case that socio-legal impact studies need to pay more attention to theory building and consistency in use of concepts and evidence. We need more ambitious multi-site, multi-method, multi-investigator studies that can help us gain more fine-grained understanding of the three clusters of mechanisms by which law has an impact and where and how they apply.