The Debate section of the Review aims to contribute to reflection on contemporary questions of humanitarian law, policy or action. In this issue of the Review, we invited two experts in international humanitarian law (IHL) – Claus Kreβ and Frédéric Mégret – to debate on how IHL applicable in non-international armed conflict (NIAC) should develop. In the two pieces that follow, Professor Kreβ submits for debate a new norm of international law outlawing NIACs – a jus contra bellum internum – with a corresponding set of rules applicable in NIACs – a jus in bello interno. The jus in bello interno would give the “privilege of belligerency” – akin to combatants' privilege in international armed conflicts – to non-State actors in NIACs, providing an incentive for them to comply with these new rules of civil war. Frédéric Mégret critically examines the proposed privilege of belligerency, pointing out its problematic aspects and positing that the creation of such a privilege is, in fact, not desirable.