Are Control Tests Fit for the Future? The Slippage Problem in Attribution Doctrines

When do subjects of international law bear responsibility for the acts of others? It is often a question of control. Control is an essential element of the doctrine of attribution, defining the legal relationship between states, international organisations (‘IOs’), and individuals. Control is also a factor in determining what is properly within a state or IO’s purview, legally demarcating the public and private spheres. Yet while control tests are intended to operate according to objective standards, they have important normative dimensions because they can determine the outer bounds of state action, define the allocation of responsibility between states and IOs and have feedback effects for state sovereignty. This article argues that control tests under prevailing doctrines of attribution present a ‘slippage’ problem. Slippage is occurring because the essence of the state, as a primary subject of international law, is changing. In response, various techniques have emerged to adapt control thresholds, locating responsibility within omissions, the duty to prevent, or under the due diligence rule and articulating principles of shared responsibility. This development demonstrates great movement within attribution doctrines and the potential scope of state and IO responsibility. One consequence of this movement is that it may foretell the eclipse of general, secondary rules of attribution. Another consequence of this dynamism is the perception that the effective control test as an objective, portable, general concept of law will become increasingly suspect.