This article investigates how superpower rivalry affects public perceptions of international organization (IO) legitimacy in the hegemon. We argue that the representation of a superpower rival state at an IO in the form of its key decision maker's nationality can dampen the IO's perceived legitimacy within the rival power. We test this argument using a survey experiment in the United States under President Trump, where we manipulate the nationality of the International Court of Justice (ICJ) judge who casts a tie-breaking vote against the United States. Our results show that when the judge is Chinese, there is a strong and robust dampening of Americans’ perceptions of the ICJ's legitimacy, with no comparable effect arising when the judge is from other countries, including Russia. Replication of the experiment in the United States under President Biden offers external validity for our findings, which may have important implications for the future of the liberal international order.
