This paper sets out to explore the impact of multi-level decision-making on accountability machinery through a case study of asset-freezing decisions taken in response to UN resolutions ordering ‘smart sanctions’ against persons and bodies suspected of involvement in terrorism. A wide literature already surrounds UN counter-terrorism measures and their implementation. This attacks the issue from two main standpoints: first, the concern of lawyers with the hierarchy of legal norms and the question of the ‘primacy’ of international law as posed in the Kadi decisions of the Luxembourg Courts; secondly, the due process rights of individuals, with the consequential intervention of courts, again notably the Luxembourg Courts, to redress this omission. This article adopts a different standpoint. Using asset-freezing as a paradigm of multi-level or composite decision-making, it explores the effectiveness of traditional accountability machinery in dealing with this phenomenon, concluding that cooperative ‘accountability networks’ or networks of entities specialising in accountability such as courts, parliaments and ombudsmen, should be developed to fill the serious accountability gaps that have emerged. The article has three parts. Part 1 deals at a theoretical level with the evolution of composite decision-making and with theories of accountability aimed at the consequential problems. Part II deals with the structure of asset-freezing decision-making at UN, EU and UK levels and the operation of accountability machinery at these levels. Part III evaluates existing accountability machinery, suggesting that change is necessary to redress shortcomings.