When considering ways for preventing Member States from hiding behind the institutional veil of the organization, two distinct approaches can be identified. The first focuses on the position of the Member State as a subject endowed with its own distinct personality and holder of its own rights and obligations. According to this approach, when the State acts as a member within or on behalf of the organization, it continues to be bound by its obligations and may be held individually responsible for their breach. The second approach focuses on the position of the State qua member of the organization. It relies on the institutional link binding together the organization and its members to affirm that, under certain circumstances, all members should be called upon to bear the consequences of the wrongful acts of the organization in a collective way. While much of the debate on the risk of abuse of the organization’s institutional veil tends to focus on the question of collective responsibility of members, the chapter argues that in practice it is through different forms of individual responsibility that the organization’s institutional veil has been pierced or circumvented.