Despite the widespread nature of evasion (bad-faith compliance), this interesting phenomenon is under-studied in International Relations. Even the most sophisticated typologies of compliance and rule following overlook evasion. This is problematic because evasion is essentially a false positive that looks like genuine compliance but can have the effect of violation. Drawing on purposivist legal theory, this article offers an in-depth discussion of evasion. It articulates what evasion is, why it occurs, how it relates to designed flexibility, and how it impacts accountability. Evasion entails intentional compliance with the letter of the law but violation of the purpose of the law in order to minimize inconvenient obligations in an arguably legal fashion. Three original case studies illustrate the empirical purchase and generalizability of evasion in International Relations. Evasion contributes a more nuanced understanding of compliance, cautions that legality sometimes hinders accountability, and offers policy recommendations to counter undesirable evasion. The article concludes with promising directions for a research program on evasion.