The exercise of legal powers is the most concrete way by which international organizations make their presence felt. For this reason the question of powers is also often a source of disagreement. In international institutional law powers of organizations are commonly constructed through the attributed powers and implied powers doctrines. Even a discussion on constitutionalism in organizations has become increasingly popular. This study explores the function of the doctrines of attributed powers, implied powers, and constitutionalism in a debate on powers of organizations. A separate part is also devoted to discussing the doctorines in the context of the Human Rights Committee.