Between Power and principle impact of the over 50,000 international treaties now in force, covering nearly every aspect of international relations and nearly every facet of state authority. This Article offers a theory of international treaty law that helps fill this gap. I call the theory an "integrated"theory of international law because it brings together and builds upon two cross-cutting facets of existing scholarship on international law and politics. First, the theory draws on both political science and legal scholarship, using them together to construct a broader and deeper understanding than is possible working solely within either discipline alone. Second, it operates at the intersection of two distinct theoretical approaches regarding the role of international law-what I term the interest-based and norm-based approaches--that cut across the disciplinary divide between political science and international legal scholarship The theory--and this Article--is integrated in yet another sense as well. It accepts and seeks to respond to the challenge mounted by the critics of international law. B integrating their insights into an analysis of how international law affects what states actually do. Rather than reject altogether the arguments of international law skeptics-as international lawyers and scholars are sometimes want to do-I seek to show when and why their claims have power and when and why they do not. I begin by confronting the root auses of doubt about the power of international law. I focus attention on the voluntary nature of international treaty law(the fact that countries often choose whether to be bound by it) and on the frequent absence of any central it powe to show how despite and at times because of these distinctive features, international treaty law can profoundly shape state behavior. The central goal of this Article is to explain the impact of international treaty law on state behavior(that is, on countries' decisions to comply or not with treaty law). The integrated theory I develop herein begins with the claim that understanding the political interplay between countries' decisions to commit and to comply is essential to a complet picture of the influence of international treaty law. I thus argue that we must pay attention to he interaction of the domestic and transnational levels at each stage of a country's entry into an international legal framework: its decision to commit (or not) to international legal rules; and its decision to comply (or not) with them. When we do so, we find that compliance not only depends upon the decision to commit, but commitment also depends upon the decision tO comp Beginning with this interactive mode of thinking about state decisionmaking, the transnational level. Legal enforcement occulr: terms or bays in which treaties shape what Article proceeds to describe and elaborate the two central countries do: through legal enforcement of the the treaty and by bringing about collateral consequences for state interests. Both operate at the domestic as well use the country's own legal system to enforce the terms of international legal agreements. At the transnational level, legal enforcement occurs when international bodies or other states The United Nations Treaty Series currently contains over 50,000 treaties. United Treaty Overview online http://untreaty.un.org/english/overView.asp(visitedNov24,2004) This Article adopts the definition of"transnational"used by Philip Jessup: he wrote that "transnational law" includes " all law which regulates actions or events that transcendBetween Power and Principle 4 impact of the over 50,000 international treaties now in force, covering nearly every aspect of international relations and nearly every facet of state authority.8 This Article offers a theory of international treaty law that helps fill this gap. I call the theory an “integrated” theory of international law because it brings together and builds upon two cross-cutting facets of existing scholarship on international law and politics. First, the theory draws on both political science and legal scholarship, using them together to construct a broader and deeper understanding than is possible working solely within either discipline alone. Second, it operates at the intersection of two distinct theoretical approaches regarding the role of international law—what I term the interest-based and norm-based approaches—that cut across the disciplinary divide between political science and international legal scholarship. The theory—and this Article—is integrated in yet another sense as well. It accepts and seeks to respond to the challenge mounted by the critics of international law. By integrating their insights into an analysis of how international law affects what states actually do. Rather than reject altogether the arguments of international law skeptics—as international lawyers and scholars are sometimes want to do—I seek to show when and why their claims have power and when and why they do not. I begin by confronting the root causes of doubt about the power of international law. I focus attention on the voluntary nature of international treaty law (the fact that countries often choose whether to be bound by it) and on the frequent absence of any central enforcement power. I go on to show how, despite and at times because of these distinctive features, international treaty law can profoundly shape state behavior. The central goal of this Article is to explain the impact of international treaty law on state behavior (that is, on countries’ decisions to comply or not with treaty law). The integrated theory I develop herein begins with the claim that understanding the political interplay between countries’ decisions to commit and to comply is essential to a complete picture of the influence of international treaty law. I thus argue that we must pay attention to the interaction of the domestic and transnational levels at each stage of a country’s entry into an international legal framework: its decision to commit (or not) to international legal rules; and its decision to comply (or not) with them. When we do so, we find that compliance not only depends upon the decision to commit, but commitment also depends upon the decision to comply. Beginning with this interactive mode of thinking about state decisionmaking, the Article proceeds to describe and elaborate the two central ways in which treaties shape what countries do: through legal enforcement of the terms of the treaty and by bringing about collateral consequences for state interests. Both operate at the domestic as well as transnational level. Legal enforcement occurs at the domestic level when domestic actors use the country’s own legal system to enforce the terms of international legal agreements. At the transnational level,9 legal enforcement occurs when international bodies or other states 8 The United Nations Treaty Series currently contains over 50,000 treaties. United Nations Treaty Series Overview (2003), online at http://untreaty.un.org/English/overview.asp (visited Nov 24, 2004). 9 This Article adopts the definition of “transnational” used by Philip Jessup: he wrote that “transnational law” includes “all law which regulates actions or events that transcend