This article provides a general introduction into the concept of accountability and its potential relevance to international and European legal scholarship. It argues that the scale of the shifts in governance and public authority away from the territorial state towards different forms and levels of governance, within and beyond the parameters of the traditional nation state, call for shifts in accountability relationships beyond that applicable within the confines of the territorial state. This, in turn, requires a rethinking of the concept, aims and forms of accountability as that can apply in international and European law. The articles explores five elements of the concept of accountability: the aims of accountability, the actors involved in processes of accountability, the institutions to which accountability must be rendered, the process of accountability, and the levels of accountability. In each of the aspects, the concept of accountability allows to move beyond traditional concepts such as liability and responsibility and to gain a better understanding of proper responses to abuses of power resulting from shifts in authority