Brian Greenhill makes an important contribution to the study of international governmental organizations by considering how the entire network of IGOs to which states belong can impact their human rights behavior. Employing this network perspective, he conceives of a state’s collective IGO memberships as providing forums for diplomats to interact with their peers from other member states, and in so doing to both generate IGOs’ internal norms and socialize one another into those norms. Over time, Greenhill argues, states that share IGO memberships will thus exhibit increasingly isomorphic human rights behavior.

Greenhill presents a cyclical “three-stage model of norm transmission” to specify the logic of his argument (p. 23). In the first stage, an IGO’s member states generate the human rights culture of that IGO. In the second stage, the collective human rights cultures of the IGOs to which a given state belongs create that state’s IGO context. And in the third stage, each state’s IGO context in turn shapes its human rights norms, either because diplomats are able to influence policymaking in their home states or because policymakers themselves enter IGO forums and are exposed to IGOs’ rights cultures. The author argues that the diffusion of human rights norms through these stages is propelled primarily by acculturation, rather than material inducement or persuasion, where states’ representatives are “driven to behave in ways that are similar to their peers . . . because of a desire to maximize their status within the group or perhaps simply because they want to ‘fit in’” (p. 45).

To evaluate this theory Greenhill employs an empirical strategy based on network analysis, conducting large-n statistical tests of the relationship between states’ individual human rights behavior and a network variable capturing each state’s IGO context. Using this strategy, he finds that states’ human rights practices do indeed become increasingly correlated with the human rights practices of their fellow IGO members in the first few years after joining.

The empirical analysis also reveals that not all states and not all IGOs are created equal. Greenhill finds meaningful variation in the states that have the greatest influence on IGO culture, in the IGOs that have the greatest influence on their members, and in the states that are most susceptible to socialization from their IGO networks, and some of the results are surprising. On the subject of variation in IGO influence, one of his more intriguing findings is that the IGO’s specific mandate does not seem to matter; because the acculturation mechanism dominates, membership in IGOs can influence states’ human rights practices even if the IGOs in question are not explicitly focused on human rights.

On the subject of variation in susceptibility to socialization, another somewhat counterintuitive finding is that materially powerful states are in fact more receptive to socialization by their fellow IGO members than are less materially powerful states. While one might anticipate that wealthy states are more independent and thus in a better position to resist pressures to conform, Greenhill suggests that they also have more capacity to implement the norms into which they have been socialized through their international interactions. He additionally identifies democracies, states with a large number of human rights INGOs (international nongovernmental organizations), and states with many IGO memberships as more likely receivers of socialization through IGOs.

Yet Greenhill also finds that materially powerful states and democracies exert the greatest influence on their fellow IGO members. The empirical analysis thus suggests that the most effective norm senders are also the most likely norm receivers, which raises some questions given the cyclical nature of the theory. Indeed, the actual dynamics among IGO member states remain something of a black box: Who is actually being socialized, and how, if the states that do the most to create an IGO’s culture are also the ones most receptive to influence?

There are additional areas in the book where some tension exists between theory and evidence. The theoretical model’s three stages lay out three key variables (states’ human rights norms, IGOs’ human rights cultures, and states’ IGO contexts) and the mechanisms of norm transmission between them in substantial detail. Yet states’ norms, which may be complex and vary across different types of human rights issues, are proxied by the frequency of actual human rights violations. Similarly, IGOs’ human rights cultures are indirectly measured simply as an aggregate of the frequency of human rights violations by their members (meaning that the culture does not actually inhere within the organization, and so IGOs themselves are merely sites rather than actors in the story). Thus, the Stage 1 argument that different IGOs develop different human rights cultures as a result of their members’ distinctive norms cannot be tested. Instead, Stages 1 and 2 are collapsed into the measure of IGO context (constructed by calculating an average of the IGO culture scores for each state in each year), and only Stage 3 is independently evaluated, by regressing states’ individual human rights violations on their IGO context. What Greenhill is then able to show empirically is simply that human rights practices are converging among states linked via IGOs, rather than that norm transmission occurs through the stages described by his theory. The empirics would thus benefit from a clearer sense of process, perhaps through additional qualitative work. (In building his theory, Greenhill references interviews he conducted with diplomats that are indeed suggestive of a transmission mechanism, and more data of this nature would have been valuable.)

Nonetheless, Greenhill’s contributions to the study of IGOs and the politics of human rights are significant. A particularly notable finding, and one with significant real world implications, is that the convergence that occurs within IGO networks can be either positive or negative—while a state whose fellow IGO members exhibit superior human rights performance will tend to improve its own human rights record, a state whose fellow IGO members exhibit inferior human rights performance will tend to see its human rights record deteriorate. This symmetry in the convergence effect means we should not just assume “that the increasing institutionalization of the international system will lead to better human rights standards” (p. 165). And an important policy implication is that IGOs whose members care about human rights should not exclude states with poor human rights practices, because it both prevents them from being socialized upward and leaves them with a disproportionate share of IGO connections that may cause them to be socialized further downward.

The author also deserves substantial credit for being transparent about some of the problems he faces in testing his theory empirically, and for being careful about trying to solve them. In particular, he notes two possible alternative explanations for the empirical pattern he observes: Instead of IGO social networks causing the convergence of states’ human rights practices, it might instead be the case that states self-select into IGOs whose members have similar human rights practices to their own (a homophily effect), or that some third variable is influencing states’ individual human rights practices and the practices of the other states in their IGO network (a case of omitted variable bias). Greenhill convincingly eliminates the former possibility through both longitudinal analysis using lagged independent variables and a careful analysis of the factors driving states’ self-selection into IGOs, and the latter possibility through inclusion of a wide array of potentially confounding variables as controls in his statistical models. He even provides replication files for readers interested in digging more deeply into his statistical analyses, which is unusual and impressive in the context of a book.

Finally, it bears saying that Transmitting Rights is extraordinarily clearly written and effectively organized, making it accessible to a wide range of audiences. This is the sort of thing that is often overlooked in considering the merits of scholarly work, but it should not be. The book was genuinely a pleasure to read.