International legal scholars have identified and argued for and against new forms of non-consent-based international law. We study variation in Brazilian public opinion about adherence to international law created in three different ways: through a consent-based multilateral treaty, by the U.N. Security Council with the participation of Brazil, and by the U.N. Security Council without the participation of Brazil. Information that Brazil has participated in creating the international legal obligation through a multilateral treaty or membership on the Security Council yields levels of support for adherence to the legal obligation that are similar to those found when the origins of the legal obligation are generic. Information that the international legal obligation was created without Brazil’s participation, on the other hand, results in reduced support for compliance. This difference, which is particularly concentrated among highly educated respondents, is not driven by reduced concerns about reputational consequences or sanctions. Our results suggest that the increased use of non-consent-based forms of international law might be challenged by a lack of public support for compliance.