The Self-Declared Islamic State and Ius ad Bellum under Islamic International Law

In terms of international law, IS naturally poses questions on the law of insurgency and international humanitarian law (ius in bello). However, IS claims to operate inside a distinct and parallel law, i.e. Islamic (international) law, the primary sources of which are the Qur’an and Sunnah. The support IS enjoys from their recruits and from a significant part of the population over which it is currently exercising power stems directly from this claim. A focus on public international law alone would thus provide only an external claim to their illegitimacy, one which they and their many supporters would disregard as meaningless, since it could never be above divine commands. In light of this and in light of the fact that in most Muslim majority states, secularism has never obtained the respect it enjoys in the West, it is thus important to ask the questions of legitimacy of IS and their actions from within the norms of Islamic international law. This study therefore essentially aims to provide answers to questions already raised by many scholars and international organisations: What are the justifications for waging war on which the self-declared Islamic State relies? Are these justifications valid under Islamic international law? Who can declare jihād and under what conditions? Could IS still rightfully claim to be a caliphate under Shari’a, regardless of a lack of international recognition? The answers to these questions are crucial because IS recruitment and rallying narrative relies on depicting its struggle as a just and noble jihād.