David Skarbek’s volume, The Puzzle of Prison Order, belongs to the category of academic books that you would talk about with your partner over lunch at the kitchen table. The reason is that the examples Skarbek uses to describe comparatively the inner workings of global prison governance often sound incredible: How could one, for instance, imagine that within the Bolivian San Pedro prison convicts often live with their families and operate grocery stores, barber shops, and a copy center? And can it be really true that prisoners sell and buy their homes in some sort of a real estate market and create self-governing institutions to regulate the market as well as political and societal issues? In exploring these questions, Skarbek’s book is to be praised for taking us on a journey that includes prisons in Latin America, Scandinavia, England, and the United States and for providing a rich and thorough account of how life behind bars is organized.

In addition to describing prison life in these empirical examples very thoroughly, the book contributes in several other respects to the scientific state of the art on penal policy and prison systems. Most importantly, it delivers on its basic promise, namely “to understand the diversity that exists in a wide-ranging sample of prisons around the world and through time” (p. 2). The two core arguments Skarbek proposes to understand the variance in prison governance are presented in the two main parts of the book.

In Part I, “Who Governs?” Skarbek explores cases where official governance is provided by the state and cases where such governance is absent. With this setup, Skarbek intends to show that the less state officials meet prisoners’ governance needs, the more extralegal institutions will flourish behind bars. Empirically, this expectation is supported by the data: extralegal governance is absent in Nordic states where officials provide “high-quality official governance institutions” (p. 49). In contrast the cases from Latin America show that, indeed, extralegal governance mechanisms are developed by the prisoners and provide either self-governance or co-governance together with state actors. Moreover, exploring the historical example of the Andersonville prisoner-of-war camp in the US Civil War, the analysis also includes an extreme case where neither officials nor prisoners themselves provided governance due to the very special circumstances of significant overcrowding and no relationships to the outside world.

The second part of the book— “How Do Prisoners Govern?”—deals with the question of what such extralegal governance looks like. To study these cases, Skarbek develops a convincing theoretical argument according to which smaller prisons, dense social networks, or low social distance between prisoners will lead to decentralized mechanisms (for example, in English prisons), whereas in the opposite case, extralegal governance will use centralized mechanisms, such as a hierarchical system of representatives who engage in rule setting and conflict resolution in the Bolivian case. Again, the case studies provide empirical evidence suggesting that the basic arguments are supported by the data.

In addition to delivering on its promise, Skarbek’s book contributes in two other ways to the literature. First, the setup of the study allows for a very broad comparative perspective and therefore goes beyond the literature on penal systems, which has been dominated by case studies on single nations, especially the United States (e.g., Gottschalk, Caught: The Prison State and the Lockdown of American Politics, 2016) or Latin America (e.g., the special issue by Hathazy and Müller, “The Rebirth of the Prison in Latin America: Determinants, Regimes and Social Effects,“ Crime, Law and Social Change 65, 2016). Similarly, broadly comparative work has focused heretofore mainly on the Western industrialized nations (Cavadino and Dignan, Penal Systems—A Comparative Approach, 2006; Lacey, The Prisoners’ Dilemma, 2008; Lappi‐Seppälä, "Trust, Welfare, and Political Culture: Explaining Differences in National Penal Policies," Crime and Justice, 37, 2008; Tonry, Sentencing Policies and Practices in Western Countries: Comparative and Cross-National Perspectives, 2017). The variation between the case studies helps accentuate the crucial differences between the systems when it comes to the governance mechanisms—an aspect that has not yet been discussed strongly in the comparative literature.

Second, the study provides an innovative contribution in describing how individuals develop extralegal governance institutions when official governance is absent or only rudimentarily present. The book’s findings, according to which the degree of centralization of extralegal governance seems to be affected by the size of the prison population, social networks within the population, and the social distance between prisoners, may well travel to other settings where official governance is weak or nonexistent and where extralegal governance emerges, such as in slums, favelas, or suburbs of big metropolitan areas.

However, the setup of the empirical analysis, based on a sample with a medium number of cases (N = 16) from all over the world, also comes as a price—which has to be weighed against the comparative merits just outlined. Limitations in the empirical analysis are palpable especially in the first part of the book (“Who Governs”). Comparing very different cases such as prisons in Scandinavia and Latin America provides only limited analytical leverage, because the examples essentially seem to illustrate two sides of the same coin: cases with the absence of state governance and the presence of extralegal institutions (Y = 1), and cases where the state provides high-quality governance, which is why prisoners do not engage in extralegal activities (Y = 0). The Andersonville case, which would be an example of neither extralegal nor official governance, strikes the reader as quite different from all the other cases studied, given the totally inhumane conditions and the context of a civil war. Hence, from my reading, the first part of the book is more an interesting description of different degrees of governance on the continuum between official governance and extralegal governance than a test of a theoretical claim. In contrast, the second part of the book provides far more analytical leverage, because the different ways of extralegal governance are explored while holding the basic governance setup almost constant.

Another problematic consequence of studying a medium number of cases from around the world has to do with the difficulty of actually making causal claims. Although the book rightly acknowledges that the research design does not allow for theory testing in a strict sense, the author nevertheless claims to “put the causal mechanism, rather than the causal effect, at the heart of the analysis” (p. 162). After reading the cases studies, I am unsure about how deeply such causal mechanisms have been carved out. Even though the empirical illustrations provide good and profound descriptions of the cases, causal mechanisms—as discussed in qualitative methodology (Blatter and Haverland, "Case Studies and (Causal-) Process Tracing," in Comparative Policy Studies: Conceptual and Methodological Challenges, 2014; George and Bennett, Case Studies and Theory Development in the Social Sciences, 2005)—could have been identified more clearly by teasing out the causal chain that links explanatory variables (e.g., low social distance) to the outcome (decentralized mechanisms of governance). Although some traces of such causal evidence can indeed be found in some of the case studies—the interview data from Bolivian San Pedro and the Wellingborough case—the fact that the author uses several cases combined to make his point prevents him from zeroing in on causal mechanisms in the individual cases. Clearly, this can be explained by the fact that Skarbek primarily draws on secondary literature, mostly from in-depth ethnographic studies, and that many empirical cases are used to sustain the theoretical claims. Nevertheless, restricting the number of cases somewhat might have allowed him to unearth the causal mechanism more convincingly.

In a way, the book’s weaknesses are therefore almost inevitable given the setup of the study, but they are minor given the comparative merit of the endeavor. Although the great variety of cases reduces the analytical leverage, at least with regard to the basic question of whether official governance is provided, the idea of sampling very different cases allows the author to highlight the important differences that would have remained hidden in a traditional most-similar-cases design. And even though the methodological choice to draw on existing ethnographic work reduces the ability of the author to elaborate more on the causal mechanisms, only this methodological strategy allows him to cover a medium-size sample of cases. Finally—and this is the grand merit of the book—Skarbek’s analysis succeeds in bringing different academic fields together that are often mainly concerned with themselves and usually work with much more limited country samples, such as Western Europe, Latin America, or the United States only. Despite the weaknesses discussed earlier, one can learn much from such an audacious study that involves very different cases, because it makes aspects of the world appear that would not have been visible on a lower level of abstraction (Sartori, "Concept Misformation in Comparative Politics," American Political Science Review, 64, 1970).