In the past decade and a half, political scientists have increasingly applied their theoretical and empirical tool kits to the analysis of international law. This has come in part as a response to new developments, such as the creation of the International Criminal Court (ICC) and the World Trade Organization. Yet theoretical puzzles have also fueled this surge in interest. Why do states vary so much in their legal commitments? What, if any, meaningful consequences do such commitments have?
While much of the early theoretical work within the liberal paradigm gave expressly functionalist answers to these questions, a more recent literature by scholars such as Xinyuan Dai, Andrew Moravcsik, and Beth Simmons has emphasized the domestic political incentives leaders may have to make and comply with international legal commitments. Sarah Mitchell and Emilia Powell's clearly written and illuminating book fits within this latter strand of research. The twist is that these authors emphasize not domestic politics but domestic legal traditions as an important source of variation in the interactions states have with the international legal system.
Mitchell and Powell accept the basic functionalist insight that international courts provide focal-point solutions that help states resolve coordination dilemmas. Yet as they rightly argue, such solutions create winners and losers. It is not always clear ex ante who will fall into what category. In order to minimize uncertainty, states will prefer international courts that mimic the rules and procedures that they are comfortable with domestically. Thus, contestation over the design of international legal institutions often shapes up as a battle between common law and civil law (and, to a lesser extent, Islamic law) countries. States are more likely to accept the compulsory jurisdiction of courts that more closely resemble their legal tradition. Moreover, states are better able to use legal commitments as credible signals of intent when the international courts overseeing these commitments more closely match their domestic legal systems.
The empirical chapters test these theoretical predictions. Conflicts between civil law and common law countries shaped disputes about the design of the ICC and left Islamic law countries largely on the sidelines. The court eventually adopted a hybrid structure. Consequentially, civil law and common law countries are equally likely to ratify the Rome Treaty that established the ICC. However, civil law states are much more likely to accept the compulsory jurisdiction of the International Court of Justice (ICJ), which resembles a civil law court. In Chapter 6, which is the strongest empirical chapter, the authors disentangle the various nuanced ways that common law, civil law, and Islamic law countries define their contractual relationship with the ICJ through reservations and compromissory clauses.
Chapter 7 deals with the effects of legal commitments. The authors show that ICC ratification is correlated with observed reductions in some human rights outcomes. This analysis is somewhat puzzling in that the theory makes no strong prediction on this front. Moreover, the analysis fails to deal with the obvious concern (recognized by the authors) that governments that expect to commit few future crimes against humanity may be more likely to ratify the Rome Treaty. The analysis of the ICJ's effectiveness is more interesting. Here, they show that pairs of civil law states that accept the ICJ's compulsory jurisdiction are better able to resolve their disputes peacefully due to the credible threat of trusted third-party dispute resolution. This outcome does not necessarily hold for pairs of common law states (who may distrust the ICJ), pairs of states with mixed legal systems, or pairs of civil law states that do not accept the ICJ.
The authors are careful not to exaggerate the differences between legal traditions. They are well aware of arguments that convergence is taking place. Throughout, the book is nuanced and measured in its characterization of legal traditions, although more attention to diversity within legal traditions would have been useful.
The authors could have been more careful in disentangling the precise theoretical mechanism through which legal tradition influences behavior. The emphasis is on the argument that familiarity with rules and procedures reduces the uncertainty and enhances the legitimacy of international court rulings. Yet there is also an alternative strain of reasoning, which focuses on the domestic legal consequences of international legal commitments. For example, common law states may be more suspicious toward international legal commitments because courts in common law countries tend to be more independent and have a wider degree of discretion than their civil law counterparts. Thus, the sovereignty cost of making legal commitments may be higher for common law states.
Mitchell and Powell acknowledge this argument (p. 62) but do not see it as contrary to the familiarity claim. Nevertheless, the implications can be quite different. They argue that international treaties are quintessential civil law constructs that may be viewed as foreign by common law states because they do not derive from judge-made law (p. 62). By this logic (and contrary to the sovereignty cost argument), common law states should be more comfortable with international law if it looks more like judge-made law. I would posit that there is little evidence for this proposition, perhaps exemplified most clearly by the current resistance in the United Kingdom over rulings by the European Court of Human Rights.
Domestic Law Goes Global is agenda setting. Mitchell and Powell are surely correct that greater attention to domestic legal characteristics, and not just politics, can enlighten our understanding of the way in which international law works and does not work. Their book is clear, well written, and meticulously researched. At the same time, they have taken the argument about legal traditions about as far it can go. Legal tradition is clearly a rough proxy for more specific features of legal systems that the authors believe are important. Detailed information about the incorporation of international law into domestic constitutions, the rise of judicial review, judicial independence, the enforcement of contracts, and other characteristics of domestic legal systems is becoming increasingly available. Emphasis on these specific institutional features, rather than broad categories of legal systems, would help us identify the causal mechanisms in a more precise way. This book sets a very high standard against which future attempts to incorporate such domestic legal characteristics will be measured.
