What explains the variation in the interpretation and enforcement of international law by domestic judges? Can independent judiciaries control the enforcement of countries’ commitments to international law? In this paper, we leverage a unique source of data—cases related to the Alien Tort Statute—to investigate how independent judges might be able to enforce international commitments to human rights without concern for whether the state (here the United States) has opted into the commitments in the first place. We show that behavioral factors in judicial decision making, and particularly those related to judicial ideological preferences, are potent predictors of judicial enforcement of international law. This implies that states with highly independent judiciaries are right to be worried about their abilities to control enforcement domestically, although we also find evidence that the U.S. government get a special degree of deference in these cases.