The starting point of this paper is that if we want to understand the way in which international law structures and mediates the deployment of power in international life, then we need to attend to the relationship between law and knowledge - the relationship between international legal processes and the processes by which we collectively come to know, describe, and imagine the world in which we live. My aim is to explore this relationship empirically by looking in detail at one case study, namely the international legal regime governing international trade in services, and specifically, the World Trade Organisation's General Agreement on Trade in Services. Over the last fifteen years, this new body of international law has developed and evolved alongside a corresponding body of social scientific expertise on the nature and dynamics of the global services economy. I tell a story of the co-evolution of these two systems - the legal regime on the one hand, and the body of knowledge on the other - and try to trace in detail the ways in which law and legal processes have been present in processes of knowledge production, shaping the way the global services economy is collectively imagined and its dynamics understood. I offer four axes along which to think about this relationship, corresponding to the concepts of constitution, transmission, objectification and empowerment.