This article analyses elements of the social structure of transnational criminal justice. The main goal of the analysis is to investigate if the terminology crafted around transnational criminal law as a distinct legal system corresponds to the social structuration of this space as it can be observed in the justice practices that drive it. To enable such an analysis, the article contributes both a theoretical discussion of how best to conceptualise the social spaces of transnational criminal justice as well as, more cautiously, an empirical investigation into the workings of these spaces, focusing the fight against drugs, terrorism, corruption and ecological crimes. Building conceptually on Pierre Bourdieu’s field theory, the analytical focal point of the article is the practices of transnational criminal justice and the professionals who are active in this space. This raises crucial questions of how the social practices of transnational criminal justice structures usages and developments of the law. Based on the identification and analysis of four separate but interrelated spaces of practice, the article argues that our theoretical understanding of transnational criminal justice and law needs to be recalibrated to take into account the different ways in which it is mobilised to create either security or good governance.