Despite the increased emphasis on domestic politics in the study of international law, scholars remain divided about whether and how international law affects domestic institutions. Moreover, while public support is a core ingredient for sustainable, legitimate policies in a democracy, research at the individual level of analysis remains limited. Weighing in on these areas of study, we investigate the use of drone strikes for counterterrorism, a subject of considerable debate. Proponents in the government point to drones as both effective for disrupting terrorist networks and compatible with international law. Critics from groups such as international organizations (IOs) and nongovernmental organizations (NGOs) respond that attacks create more terrorists than they kill and violate legal commitments. The central question we ask in this article is whether these international legal criticisms impact public support for drone strikes, the centerpiece of US counterterrorism policy, or whether individuals are more persuaded by effectiveness-based arguments. Employing a survey experiment of a nationally representative sample of the United States, we find IO and NGO criticisms can shape public attitudes even around an important national security issue like drone strikes, but are most influential when messages center on legal critiques rather than matters of effectiveness. Our findings speak to fundamental questions about the domestic politics of international legal commitments, the role of IOs and NGOs in shaping political debates, and the durability of US counterterrorism policy.