The article addresses the issue of attribution of conduct in the context of UN peacekeeping operations. In the absence of a Convention, the essential reference is the International Law Commission’s Draft Articles on the Responsibility of International Organizations. Article 7 DARIO (Draft Articles on the Responsibility of International Organizations, Giorgio Gaja special rapporteur) states that responsibility for the conduct of an organ put at the disposal of an International Organization shall be attributed on the basis of the “effective control test”. This criterion has led to considerable difficulties in determining which subject – the Troup Contributing Nation or the UN – should be held legally responsible for an unlawful act committed during a peacekeeping operation. The analysis of the judgments of the European Court of Human Rights in the Behrami and Saramati Cases, the judgments of the Dutch Courts in the HN v Netherlands case and in the Stiching mothers of Srebrenica case shows that the effective control test has been interpreted and applied in different ways. Therefore, it is needed to define an unambiguous interpretation of “effective control” that could be able to reflect the operations’ command and control structure, overcoming the peacekeeping forces’ institutional ambiguity.