Corruption presents an assurance problem to businesses: all businesses are best off if none act corruptly but in the event that corruption occurs are better off if they act corruptly than if they do not, and because there is no assurance that other actors are not cheating a business does not know how to act. The usual solution to an assurance problem – criminal sanctions imposed on cheaters – does not work in a corrupt system. Integrative Social Contract Theory suggests a solution to the assurance problem. Application of Integrative Social Contract Theory to corruption demonstrates that in the case of corruption it has advantages over international law, and that the theory’s elegance lies in its recognition of norms generated by multiple communities.