Why are some politicians guided by a sense of obligation toward international law but others are not? Why do some politicians have a social as opposed to an egoistic preference over compliance with international legal rules? Existing approaches largely assume that the structural features of the compliance environment shape preferences. As a result, they neglect the heterogeneity across decision makers' subjective beliefs in the legitimacy of international law, which is critical for explaining

more »

... o exhibits a sense of obligation and has a non-egoistic preference for compliance. Drawing upon a large body of psychological research on social identity and influence, I argue that obligation toward international law has a behavioral foundation shaped by cosmopolitan social identity. Using data from an original survey of German politicians that includes two compliance experiments, I show that politicians with a high degree of cosmopolitanism are driven by a sense of legal obligation that results in a social preference for compliance while those low on cosmopolitanism lack the same sense of normative respect. Replicated in a second experimental study conducted with a convenience sample, my results indicate that strategic rationality in compliance applies, but only to a particular set of actors. By illuminating the psychological underpinnings of obligation toward international law, this study contributes to a richer understanding of compliance preferences and builds a bridge between instrumental and normative models.