Non-state actors and especially organized armed groups are becoming an increasingly important factor on the international stage and on the conduct of current armed hostilities worldwide. Alongside with this swift change, three questions frequently emerge : is there a renunciation from the existing state-centric public international law ? Can (armed) non-state actors obtain a legal personality / are they a subject of international law - and if answered in the positive, to what extent ? And finally, to what extend can these actors be incorporated or can participate in the creation of rules of international law ? This article addresses these questions on the basis of an analysis of current Treaty and Customary international law and identifies the possible influence of organized armed groups on the creation of international law. This will be illustrated with common Article 3 of the 1949 Geneva Conventions and the emerging question of international responsibility for unlawful acts. Although a renunciation from the state-centric international law might not be in sight, the adequate treatment of these ever strengthening actors remains one of the biggest challenges in modern international law.