This article explores conditions under which global norms change. I use a case study in which the original interpretation of an international agreement on intellectual property rights was modified to address demands for improved access to affordable AIDS drugs. Conventional theories that focus on international negotiations cannot fully account for the events in this case. Drawing on the theory of recursivity and insights from the literature on diffusion, I suggest that shifts in global norms occur through reactive diffusion of policies across states. Experiences accumulated in this ongoing process of reinvention eventually lead to a new, globally accepted reinterpretation of the original obligation.