The point of departure of this paper is the link between ius positivum and ius voluntarium and the perception of international law as a unified system of rules that emanates from states’ own free will. The 'old', 'classical' approach to legal positivism considered that international law is a body of law which has been created by states as opposed to natural law theories. It was expressed, for example, in the famous dictum of the Permanent Court of International Justice in 1927 in the Lotus case: 'The rules of law binding upon States…emanate from their own free will…Restrictions upon the independence of States cannot therefore be presumed'. This approach has often been criticised on several grounds, including for being overly deferential to state sovereignty. International legal positivism has evolved significantly since the 19th century and has been greatly informed by its critics. Nonetheless the will of states still remains an important (although of course far from exclusive) explanatory factor in the process of international law-making. The Lotus dictum however, must be read correctly today. It should not be considered as implying the 'absolute power' of the will of states or the concept that they are bound only to what they have explicitly consented to. Instead the Lotus dictum should be scrutinised and understood in the negative sense: states should not be bound against their will, by what they have not explicitly or implicitly consented to. This chapter 'tests' this 'voluntarist' approach in a particularly 'tough' case study. There are few other areas of international law where the 'voluntarist paradigm' of legal positivism is challenged as much as in the area of human rights. The bustling activity of the human rights treaty bodies gives the impression of a complete departure from voluntarist values. The first part of this chapter discusses developments in this respect which seem to challenge the 'voluntarist paradigm'. These practices include: the constant recourse by human courts and bodies to evolutive interpretation as a tool in order to 'adapt' HR treaties in a rapidly changing world; the introduction of the whole range of 'positive obligations' which was not guaranteed on the basis of textualism; the theory of 'autonomous concepts' which could be seen as a distrust of domestic legal orders; the use of ius cogens as a tool to crush state resistance; et al. The second part of the chapter undertakes the 'mission impossible' of reconciliation between human rights and the will of States. It argues that the nature of human rights treaties requires dynamic and evolutive interpretation. Indeed, it would be completely absurd to argue that drafting states 'had 'intentions' regarding the almost infinite number of cases which may arise under the different convention rights' (Letsas). They have decided, for obvious reasons, to entrust the mission of 'adapting' these treaties to new realities to courts and monitoring bodies. These bodies understand that there are limits to the dynamic interpretation of human rights treaties and often exercise self-control and self-restraint. Evolutive interpretation is also often balanced by 'consensual interpretation' while deference to the sovereignty of states is also expressed by the use of the doctrines of 'national margin of appreciation' and 'subsidiarity'. The reactions of states to the methods used by human right treaty bodies could nonetheless indicate that judicial activism has crossed the Rubicon. The Chapter ends by discussing these possible reactions and notes some recent strains and tensions between states and monitoring bodies.