Introduction

This issue of the Journal on the Use of Force and International Law (JUFIL) begins with an editorial by James A Green, in which he considers the right of collective self-defence, and particularly the criteria for the operation of that right. James questions whether the two ‘additional’ requirements of ‘declaration’ and ‘request’ set out in the International Court of Justice (ICJ)’s famous 1986 Nicaragua merits decision – which are commonly repeated uncritically in the literature – are in fact reflected in customary international law. This issue then features four major articles. In the first of these, Paulina Starski examines, through a focus on coalition action against ISIS, whether the mere silence of states in relation to state actions that challenge the established readings of jus ad bellum rules might induce and consolidate a process of normative change (and, if so, under what conditions). She concludes that mere passivity in light of the legal claims made with regard to coalition airstrikes against ISIL positions in Syria does not amount to ‘acquiescence’. In the next article, Gina Heathcote examines the use of force described as ‘robust peacekeeping’. Through a review of innovation in Security Council practice, Heathcote argues that feminists and others who have agitated for inclusion within the work of the Security Council are counselled against pursuing projects that expand the powers of the institution while there remains a lack of checks on how force is mobilised, and that the reluctance of feminist and/or critical engagement to address the structural aspects of the Security Council risks a legitimation of the institution without significant gains in terms of gender equality. In his article contribution, Nader Iskandar Diab assesses the various legal issues that arise as a result of the creation and mandate of League of Arab States’ Joint Arab Forces (JAF) under the relevant rules of international law (predominantly focusing on Article 2(4) and Article 53(1) of the UN Charter). He also discusses the consequences for the founding treaty of the JAF should it violate those international rules. Diab concludes that the gap between such practices by regional organisations and international law is not as wide as it would appear to be at first glance. Finally, the articles section concludes with a contribution by Benjamin Nußberger, who considers Operation Decisive Storm (the Saudi-led military intervention in Yemen in 2015). Against the background of the all-inclusive Yemeni transition heralded by the international community as a ‘model