Emer de Vattel’s argument that states should be understood as free and independent bodies operating as moral persons in the international sphere is credited with launching a doctrine of sovereignty that hardened national borders against external interference or obligation. It also helped launch one of the world’s first modern states through its influence on the American founding. Vattel’s theory rests upon the critical role of judgment, specifically, the judgment of interests. That doctrine requires that states must always think for themselves, but not only about themselves. Offering some justification for international action, even in the midst of disagreement or war, is what separates civilized from villainous nations for Vattel, and this grounds interests in the communicative habits of an international community. Because the judgment of interests incorporates a communicative element, Vattelian internationalism cannot become exclusively self-regarding, and state interests cannot be entirely contained within national borders. Instead, Vattel’s distinctive combination of independence and interests is set within a global community that makes the fate of outsiders the business of every state.