CHICAGO WORKING PAPER IN LAW AND ECONOMICS that controls the behavior of states; it is a label people attach to behavior that is generated endogenously from the interactions of states pursuing their self-interest. In addition, our theory rejects the traditional claim that the behaviors associated with cil reflect a single unitary logic. These behaviors instead reflect various and importantly different logical structures played out in discrete, historically contingent contexts. Finally, the theory is skeptical of the existence of law-like, multilateral behavioral regularities that are typically thought to constitute CIL. It holds that multinational regularities will invariably reflect coincidence of interest or coercion (and thus not be law-like), and that regularities that reflect cooperation or coordination arise only in bilateral contexts Section III tests the theory using case studies from four traditional areas of CIL: neutrality, diplomatic immunity, prize, and maritime jurisdiction. We chose to study these areas of the law because they represent a broad spectrum of CIL norms, and becaus these CIL norms are, according to conventional accounts, among the most robust that exist. The case studies teach several lessons The nain lesson is that cil as traditionally understood has little explanatory power. The international behaviors said to constitute CIL are actually disparate and changing practices that follow different logics depending on the interaction of state interests in rticular contexts. The case studies suggest that the behaviors associated with Cil do not reflect a unitary underlying logic, and hat Cil understood as a normative force does no independent work in guiding national behavior. The case studies als so reveal how commentators and courts commit errors of induction in moving from the observation of a behavioral regularity to the conclusion that a CiL rule exists. In addition, in analyzing CIL courts and commentators rely too heavily on what nations say at the expense of what they do and why they do it, and they tend to limit cil to behavioral regularities that are good"from their normative perspective to be CIL, denigrating regularities that are bad as comity"or a violation or an exception to the CIL rule. Finally, the case studies confirm that cil does not reflect multilateral, law-like behavioral regularities Section IV considers several extensions of the analysis. It unpacks the artificial assumption of a unitary state interest that liesCHICAGO WORKING PAPER IN LAW AND ECONOMICS 4 that controls the behavior of states; it is a label people attach to behavior that is generated endogenously from the interactions of states pursuing their self-interest. In addition, our theory rejects the traditional claim that the behaviors associated with CIL reflect a single, unitary logic. These behaviors instead reflect various and importantly different logical structures played out in discrete, historically contingent contexts. Finally, the theory is skeptical of the existence of law-like, multilateral behavioral regularities that are typically thought to constitute CIL. It holds that multinational regularities will invariably reflect coincidence of interest or coercion (and thus not be law-like), and that regularities that reflect cooperation or coordination arise only in bilateral contexts. Section III tests the theory using case studies from four traditional areas of CIL: neutrality, diplomatic immunity, prize, and maritime jurisdiction. We chose to study these areas of the law because they represent a broad spectrum of CIL norms, and because these CIL norms are, according to conventional accounts, among the most robust that exist. The case studies teach several lessons. The main lesson is that CIL as traditionally understood has little explanatory power. The international behaviors said to constitute CIL are actually disparate and changing practices that follow different logics depending on the interaction of state interests in particular contexts. The case studies suggest that the behaviors associated with CIL do not reflect a unitary underlying logic, and that CIL understood as a normative force does no independent work in guiding national behavior. The case studies also reveal how commentators and courts commit errors of induction in moving from the observation of a behavioral regularity to the conclusion that a CIL rule exists. In addition, in analyzing CIL courts and commentators rely too heavily on what nations say at the expense of what they do and why they do it, and they tend to limit CIL to behavioral regularities that are “good” from their normative perspective to be CIL, denigrating regularities that are bad as “comity” or a violation or an exception to the CIL rule. Finally, the case studies confirm that CIL does not reflect multilateral, law-like behavioral regularities. Section IV considers several extensions of the analysis. It unpacks the artificial assumption of a unitary state interest that lies