Selbstverteidigungsrecht gegen nichtstaatliche Akteure. Zugleich ein Beitrag zur deutschen Beteiligung am militärischen Vorgehen gegen den Islamischen Staat

Use of force taken in self-defence is lawful if it, among other things, responds to an armed attack. Up until today, the central question remains: armed attack by whom? Prior to the 9/11 terrorist attacks it was widely acknowledged that it had to be an attack by another state, while after the attacks this view was called into question. Since then, it seems that self-defence against non-state actors had been established as the 'new normal'. Reactions to the military intervention against ISIS in Syria clearly evidences, however, that opposition to this view is still strong, particularly among European international lawyers. Interestingly, both views – a restrictive reading of Art. 51 UN-Charta on the one hand and a rather expansive conception of self-defence on the other hand – start from the same assumption: prior to 9/11 the right to self-defence required an armed attack by another state. What is at issue is therefore the question whether 'the law' has changed since then. But instead of following the 'continuity and change' paradigm, in which the 9/11 attacks qualify as a game-changer, this article emphasizes a 'continuity of change' approach. The concept of self-defence as codified in Art. 51 UN-Charter has been subject to constant change for over 70 years. In addition, the international system itself has changed dramatically from an exclusive club of states to a multipolar order. While these changes are not immediately relevant for the issue whether the right to self-defence applies to non-state actors, it allows for a different conceptual approach. Instead of focusing on the prerequisites for legal change, it asks whether compelling legal reasons exist that in then end restrict the right to self-defence to armed attacks by another state. As possible reasons for such a restriction this article discusses the relationship between the prohibition on the use of force and the right to self-defence, the object and purpose of Art. 51 UN-Charter, existing ICJ jurisprudence, and the territorial integrity of the state from which the non-state actors, especially terrorist groups, operate. While none of these reasons necessitate an interpretation of Art. 51 UN-Charter that restricts self-defence to an armed attack by another state, it also illustrates that the use of force in this context is restricted against the non-state actor and may not directly be used against the harbouring or unwilling and unable state. While self-defence is thus in principle permissible against non-state actor, the terrorist attacks in Paris in November 2015 illustrate how difficult it is to apply Art. 51 UN-Charter to such attacks. Since Germany invokes the right to self-defence as a legal basis to support the military intervention in Syria and thereby explicitly refers to the Paris Attacks, this article in its last section addresses some of the legal obstacles, which arise if self-defence is applied to terrorist attacks.