On 9 July 2002, the African Union (AU) officially replaced the Organisation of African Unity (OAU), whose limited capacities were no longer sufficient to meet the new political aspirations of the African States and, more particularly, their desire to create an integrated political union. The establishment of an African Common Security and Defence Policy was one of the key steps in the realisation of such a project. The African States therefore very quickly provided the AU with a collective security mechanism, by adopting the Protocol on the establishment of the AU Peace and Security Council (2002) and a common defence mechanism by concluding the AU’s Common Non-Aggression and Defence Pact (2005). The Pact, which is the subject of this study, differs in many respects from other collective defence treaties and therefore raises specific legal questions. The first arises from the express reference to the obligation of non-aggression in the actual title of the Pact and raises the issue of the legal scope of such a reference. The second relates to the legal basis of the Covenant, which does not refer to any specific provision of the Charter of the United Nations and contains certain provisions which may lead to confusion between apparently distinct concepts of collective defence and regional security. The third, finally, concerns the compliance of the Pact with the Charter of the United Nations and the legal consequences of the possible lack of such compliance; this question is all the more pressing here as certain provisions of the Pact seem to enshrine the currently highly controversial right to use self-defence in the event of terrorist attacks or mere threats of aggression. Finally, more generally, although it has not yet been applied by the States Parties and it is premature to rule on the precise meaning of its provisions, the AU Compact seems to substantially relax the conditions under which the use of force is generally permitted under international law. The dangers to which such a relaxation may give rise are, however, mitigated, in the present case, by the multilateral — regional — nature of the context in which the use of ‘extended’ force is supposed to take place.