Research & publications In the spotlight

Luca Ferro
Killing Qasem Soleimani: International Lawyers Divided and Conquered

Case Western Reserve Journal of International Law, volume 53(1)

This article first sets out the facts surrounding the killing of Iranian Major-General Qasem Soleimani by U.S. drone strikes on 3 January 2020 as reported by media outlets and widely relied upon by international legal experts. It then delves into the analysis by no less than 15 of them who co-authored 11 legal briefs of varying depth, all tackling (to some extent) the same question: Was Soleimani’s killing in conformity with the relevant requirements of international law, consisting of the jus ad bellum (“JAB”), jus in bello (“JIB”) and international human rights law (“IHRL”)? However, there was little consensus among the experts – if any.

The article hopes to better understand why international lawyers disagree so spectacularly by comparing and contrasting the variety of views in the Soleimani-case and stripping down the supporting argumentation to uncover the underlying (theoretical and methodological) approach. This is then followed by some final reflections. More generally, it hopes to spark a much-needed debate by identifying a worrying trend in international legal scholarship that seemingly allows each controversial interpretation to stand, and taking a swing at offering preliminary explanations rather than present a definitive solution to a perennial concern in international law.

After all, if the “invisible college of international lawyers” cannot even decide on the disputed legality of a State unapologetically taking out the military brass of its arch-enemy on the territory of a neutral country, it is difficult to see what remains of the prohibition on the use of force – the cornerstone of the Charter of the United Nations and international law more broadly.

Tom Ruys Luca Ferro
Divergent Views on the Content and Relevance of the Jus ad Bellum in Europe and the United States?

in Chiara Georgetti and Giuglielmo Verdirame (eds), Whither the West? International Law in Europe and the United States (Cambridge University Press 2021)

This chapter studies the idea that Americans and Europeans hold different views on global security. Generally, it is considered that the EU side demonstrates a stronger adherence to positivism in international law, while the US adopts policy-oriented methodologies. This translates into different views of the actual content of the UN Charter rules on the use of force, for example of the permissibility of self-defense against attacks by non-State actors, calls for new exceptions to the prohibition of the use of force and in relation to controversial issues, such as the legality of the anticipatory self-defense. The chapter offers a critical look at the alleged difference by studying the US-led military coalition fighting against the so-called Islamic State (IS) in Iraq and Syria. This reveals a gradual acceptance of the more expansionist interpretation put forward by the US. Indeed, the case of the US-led military coalition against IS is one where European States - and several other western States - originally steered clear from murky legal grounds only to find themselves ultimately embracing an extensive reading of the right of self-defense, and relying for the first time, whether explicitly or implicitly, on the controversial “unable and unwilling” doctrine to justify military operations abroad.

Klaas Willaert
Deep sea mining partnerships with developing states: favorable collaborations or opportunistic endeavours?

Klaas Willaert and Pradeep Singh

In order to engage in deep sea mining activities on the international seabed (otherwise known as “the Area”), non-state actors must be sponsored by a state, which bears the responsibility to ensure that the sponsored entity complies with the applicable rules. Not only the state of nationality, but also the state which exercises “effective control” might be required to serve as a sponsoring state, depending on the circumstances. However, it is not completely clear how “effective control” should be interpreted. Forum shopping seems a realistic possibility and the recent trend of partnerships between private deep sea mining companies and developing states can produce similar effects. These collaborations might be beneficial to both parties, but given the privileges awarded to developing states, it should be scrutinized whether such partnerships do not undermine the principle of the common heritage of mankind and the objective to realize benefits for mankind as a whole.

Klaas Willaert
Traditional dimensions of seabed resource management in the context of Deep Sea Mining in the Pacific: Learning from the socio-ecological interconnectivity between island communities and the ocean realm

Virginie Tilot, Klaas Willaert, Bleuenn Guilloux, Wenting Chen, Clement Yow Mulalap, François Gaulme, Tamatoa Bambridge, Kimberley Peters and Arthur Dahl

In many of the Pacific Islands, local communities have long-held cultural and spiritual attachments to the sea, in particular to species and specific marine areas, processes, habitats, islands, and natural seabed formations. Traditional knowledge, customary marine management approaches and integrated relationships between biodiversity, ecosystems and local communities promote conservation and ensure that marine benefits are reaped in a holistic, sustainable and equitable manner. However, the interaction between local traditional knowledge, contemporary scientific approaches to marine resource management and specific regulatory frameworks has often been challenging. To some extent, the value of community practices and customary law, which have provided an incentive for regional cooperation and coordination around ocean governance, is acknowledged in several legal systems in the Pacific and a number of regional and international instruments, but this important connection can be further enhanced. In this article we present a science-based overview of the marine habitats that would be affected by deep seabed mining (DSM) along with an analysis of some traditional dimensions and cultural/societal aspects of marine resource management. We then assess whether the applicable legal frameworks at different levels attach sufficient importance to these traditional dimensions and to the human and societal aspects of seabed (mineral) resource management in the region. On basis of this analysis, we identify best practices and formulate recommendations with regard to the current regulatory frameworks and seabed resource management approaches. Indeed, the policies and practices developed in the Pacific could well serve as a suitable model elsewhere to reconcile commercial, ecological, cultural and social values within the context of deep sea mineral exploitation in addition to sustaining the Human Well-being and Sustainable Livelihoods (HWSL) of the Pacific communities and the health of the Global Ocean.

Klaas Willaert
Payment regimes for the exploitation of mineral resources in the Area and on the extended continental shelf: deep sea mining at a discount?


Given the significant commercial interests and huge investments in deep sea mining, it comes as no surprise that states and private enterprises are not only pursuing exploration and exploitation activities in the Area, but are also targeting mineral-rich patches on the continental shelf. Indeed, it must be noted that the same mineral resources that deep sea mining actors are keen to exploit in the Area, are also available within zones falling under national jurisdiction. However, crossing this legal border results in a different legal regime, as activities on the continental shelf are governed by the national legislation of the coastal state and are, therefore, not subject to the comprehensive international regime applicable to the Area. Nevertheless, a similar duty to provide financial contributions to the International Seabed Authority exists in case of exploitation activities on the continental shelf beyond 200 nautical miles. Taking into account that this payment system was already established by the Law of the Sea Convention back in 1982, it is necessary to assess to what extent the modalities and tariffs relate to the ones that are now being considered for its counterpart in the Area. Can we discern a logical balance or is deep sea mining on the extended continental shelf subject to discount rates and advantageous provisions? In order to clear this up, this article thoroughly analyzes the existing legal framework and the proposals which are currently being discussed at the International Seabed Authority, followed by a general comparison and several useful considerations.

Luca Ferro
The Doctrine of 'Negative Equality' and the Silent Majority of States

Journal on the Use of Force and International Law, volume 8(1)

Critics of the so-called negative equality doctrine, which prohibits third-state military intervention upon invitation by a government embroiled in civil war, point to recent contravening practice together with a generally passive or politically supportive attitude by states to substantiate their views. If, however, a prohibition indeed remains the starting point under the lex lata, that critical view largely depends on the legal transformation of state silence into acquiescence.

This article contests such a transformation based on the accepted conditions for acquiescence to arise, concerns which are confirmed by two case studies on interventions in the Libyan and Yemeni civil wars. As a result, states’ inaction to controversial military operations rarely qualifies as ‘negative opinio juris’. Indeed, the erosion of customary international norms, especially those that regulate sending troops to war, surely requires more than a few deviant states and a regrettable but legally inconsequential apathy by the international community.

Luca Ferro
No Interference, No Problem: Voter Influence Operations and International Law

(2020/1) Revue belge de droit international 323 

The 2016 US Presidential Election was marred by (cyber-)meddling allegedly directed by Russia and aimed at sowing discord in the political system, boost Donald Trump’s election chances, and steal voter data and other sensitive information. Using that alleged Russian involvement in the 2016 election as a case study, this article examines its legality under public international law. Numerous books, articles and blog posts have since dealt with this issue, focusing on (all or some of) such primary international legal norms as the principle of sovereign equality of States, the principle of non-intervention, the right to self-determination, the duty of due diligence and the human right to privacy. Almost without exception, although expressed with varying degrees of confidence, commentators concluded that one or more of these norms were violated leading up to the 2016 election, resulting in a fragile yet broad academic consensus on the illegality of the Russian operation and, by extension, voter influence operations (or VIOPS).

This article aims to revisit and challenge that consensus. It starts with an overview of case facts as well as the domestic and international reactions to which they gave rise in Section 2. Section 3 then zooms in on three key (and interrelated) international legal norms: sovereignty, non-intervention and self-determination. It applies these legal standards (as interpreted) to the facts (as assumed). Finally, Section 4 wraps up the legal analysis and concludes.

Tom Ruys Felipe Rodriguez Silvestre
Military Action to Recover Occupied Land: Lawful Self-defense or Prohibited Use of Force? The 2020 Nagorno-Karabakh Conflict Revisited

(2021) 97 International Law Studies, pp. 665-738

In September 2020, heavy fighting erupted between Armenia and Azerbaijan in and around Nagorno-Karabakh, a region of Azerbaijan long controlled by Armenia. After two months of military confrontations, a tripartite ceasefire was concluded, drastically altering the pre-existing territorial status quo.

The "Second Nagorno-Karabakh War" brings to light a fundamental question for international law on the use of force—and one that has received limited attention in legal doctrine. The question is this: when part of a State’s territory is occupied by another State for an extended period of time, can the former still invoke the right of self-defense to justify military action aimed at recovering its land?

The present article provides a broad appraisal of this question, examining the arguments for and against. In particular, it examines the conditions of self-defense—and whether occupation might be construed as a “continuing” armed attack. It subsequently addresses the relevance of the principle of the non-use of force to settle territorial disputes as well as the role of armistice and ceasefire agreements, before turning to relevant State practice. Ultimately, the authors agree with the Ethiopia Eritrea Claims Commission that “any exception to the prohibition of the threat or use of force for territory that is allegedly occupied unlawfully would create a large and dangerous hole in a fundamental rule of international law.”

Tom Ruys Luca Ferro
The Enemy of My Enemy: Dutch Non-Lethal Assistance for 'Moderate' Syrian Rebels and the Multilevel Violation of International Law

Netherlands Yearbook of International Law, 2019

Between 2015 and 2018, the Dutch government has supported Syrian rebels fighting the regime of President Bashar al-Assad through a ‘non-lethal assistance’ (NLA) program. Pertinent questions have been raised regarding the program’s compatibility with international law and a joint commission was tasked with developing criteria to evaluate the legality and political expediency of future programs. This commentary looks in retrospect at the legality of the NLA program. The substantive analysis is divided into three sections: First, it provides an overview of hard-and-fast facts about the program that have come to light following an admirable amount of journalistic scrutiny and parliamentary debate. Second, it takes a helicopter view of the legal landscape, touching upon the relevant primary norms of international law. Third, it applies that legal framework to the Dutch NLA program, tackling a threefold question: (1) Is the type of assistance legally relevant? (2) Is the type of beneficiary non-State armed group legally relevant? (3) Is the aim or purpose of the assistance programme legally relevant? While the authors recognize that the program was limited in scope and explicitly designed to stay within (or as close as possible to) the parameters of the international legal framework, they nevertheless conclude that it violated the principle of non-intervention, the prohibition on the use of force and the duty to ensure respect for international humanitarian law. Moreover, it may have led to secondary State responsibility for serious breaches of international law committed by the beneficiary armed groups. This conclusion puts in doubt the legality as a matter of lex lata of any such future program, be it lethal or not.

Tom Ruys Cedric Ryngaert
Secondary Sanctions: A Weapon out of Control? The International Legality of, and European Responses to, US Secondary Sanctions

(2020) British Yearbook of International Law, 116 p.

The US is increasingly weaponizing economic sanctions to push through its
foreign policy agenda. Making use of the centrality of the US in the global
economy, it has imposed ‘secondary sanctions’ on foreign firms, which are
forced to choose between trading with US sanctions targets or forfeiting access to the lucrative US market. In addition, the US has penalized foreign
firms for breaching US sanctions legislation. In this contribution, it is argued
that the international lawfulness of at least some secondary sanctions is
doubtful in light of the customary international law of jurisdiction, as well as
conventional international law (eg, WTO law). The lawfulness of these sanctions could be contested before various domestic and international judicial
mechanisms, although each mechanism comes with its own limitations. To
counter the adverse effects of secondary sanctions, third states and the EU
can also make use of, and have already made use of, various non-judicial
mechanisms, such as blocking statutes, special purpose vehicles to circumvent
the reach of sanctions, or even countermeasures. The effectiveness of such
mechanisms is, however, uncertain.

Tom Ruys (editor) Nicolas Angelet (editor) Luca Ferro (assistant editor)
The Cambridge Handbook of Immunities and International Law

Few topics of international law speak to the imagination as much as international immunities. Questions pertaining to immunity from jurisdiction or execution under international law surface on a frequent basis before national courts, including at the highest levels of the judicial branch and...

The volume comprises 34 chapters including contributions by GRILI members Tom Ruys and Luca Ferro

Full list of authors: Tom Ruys, Nicolas Angelet, Luca Ferro, Hazel Fox, Lori Fisler Damrosch, Wenhua Shan, Peng Wang, Alexander Orakhelashvili, Yas Banifatemi, Sally El Sawah, Catherine Amirfar, Niels Blokker, Kristen E. Boon, Ramses A. Wessel, Jean-Marc Thouvenin, Victor Grandaubert, Ingrid Wuerth, Cedric Ryngaert, Matthew Happold, Eric De Brabandere, Mark A. Cymrot, Mathias Audit, Maria-Clara Van Den Bossche, Frédéric Dopagne, Sanderijn Duquet, Eileen Denza, Andrew Sanger, Michael Wood, Muriel Ubéda-Saillard, Rosanne Van Alebeek, Chimène I. Keitner, Christian Walter, Fabian Preger, Aurel Sari, Rosa Freedman, Nicolas Lemay-Hébert, Harmen Van Der Wilt, Pierre D'argent, Pauline Lesaffre, Phillipa Webb and David P. Stewart.

Jan Wouters Cedric Ryngaert Tom Ruys Geert De Baere
International Law: a European Perspective

This textbook offers for the first time a comprehensive analysis of the classic doctrines and main areas of international law from a European perspective, meeting the needs of the many European law schools teaching public international law in English. Special attention is devoted to the practice of the European Union, the Council of Europe and European States – both civil law and common law countries – with regard to international law. In particular the book analyses the interplay between international law, EU law and national law in the case law of the Court of Justice of the EU, the European Court of Human Rights and national jurisdictions in Europe. It provides the reader with insights into how the international legal practice of the EU and its Member States impacts the development of international law, both in terms of doctrines such as treaty-making and customary law, the exercise of (extraterritorial) jurisdiction, state responsibility and the settlement of disputes, as well as particular sub-fields of international law, such as human rights law and international economic law. In addition the book covers other important areas such as the use of force and collective security, the law of armed conflict, and global and regional international organisations. It provides European perspectives on all these issues and will be of great value to students, scholars and practitioners.

Tom Ruys (editor) Olivier Corten (editor) Alexandra Hofer (assistant editor)
The Use of Force in International Law: a Case-based Approach

The international law on the use of force is one of the oldest branches of international law. It is an area twinned with the emergence of international law as a concept in itself, and which sees law and politics collide. The number of armed conflicts is equal only to the number of methodological...

The volume comprises 66 chapters including contributions by GRILI members Tom Ruys, Alexandra Hofer and Luca Ferro.

Full list of authors: Constantine Antonopoulos, Karine Bannelier, Janina Barkholdt, Susan Breau, Wenke Brückner, Michael Byers, Enzo Cannizzaro, Kenneth Chan, Théodore Christakis, Olivier Corten, Fanny Declercq, Ashley Deeks, Oliver Dörr, François Dubuisson, Luca Ferro, Mathias Forteau, Gregory H. Fox, Daniel Franchini, Tarcisio Gazzini, Terry D. Gill, Christine Gray, James A. Green, Douglas Guilfoyle, Andrea de Guttry, Gerhard Hafner, Nabil Hajjami, Wolff Heintschel von Heinegg, Mohamed S. Helal, Christian Henderson, Etienne Henry, Alexandra Hofer, Jörg Kammerhofer, Maurice Kamto, Pierre Klein, Robert Kolb, Marcos Kotlik, Vaios Koutroulis, Claus Kreß, David Kretzmer, Dino Kristiotis, Jean-Christophe Martin, Lindsay Moir, Sean D. Murphy, Anne Lagerwall, Eliav Lieblich, Georg Nolte, Benjamin K. Nußberger, Mary Ellen O'Connell, Alexander Orakhelashvili, Ki-Gab Park, Mónica Pinto, Erin Pobjie, John Quigley, Aurora Rasi, Theresa Reinold, Natalino Ronzitti, Tom Ruys, Alison See, Ying Xiu, Paulina Starski, Raphaël Van Steenberghe, Christian J. Tams, Kinga Tibori-Szabó, Dire Tladi, Kimberley N. Trapp, Nicholas Tsagourias, Antonios Tzanakopoulos, Agatha Verdebout, Ugo Villani, Christian Walter, Marc Weller, Erika de Wet, Nigel White, Myra Williamson, Sir Michael Wood

Eva Brems Ellen Desmet
Integrated Human Rights in Practice Rewriting Human Rights Decisions

This book aims to introduce concrete and innovative proposals for a holistic approach to supranational human rights justice through a hands-on legal exercise: the rewriting of decisions of supranational human rights monitoring bodies. The contributing scholars have thus redrafted crucial passages of landmark human rights judgments and decisions, ‘as if human rights law were really one’, borrowing or taking inspiration from developments and interpretations throughout the whole multi-layered human rights protection system. In addition to the rewriting exercise, the contributors have outlined the methodology and/or theoretical framework that guided their approaches and explain how human rights monitoring bodies may adopt an integrated approach to human rights law.

Eva Brems Ellen Desmet Wouter Vandenhole
Children’s Rights Law in the Global Human Rights Landscape

Children’s rights law is often studied and perceived in isolation from the broader field of human rights law. This volume explores the inter-relationship between children’s rights law and more general human rights law in order to see whether elements from each could successfully inform the other. Children’s rights law has a number of distinctive characteristics, such as the emphasis on the ‘best interests of the child’, the use of general principles, and the inclusion of ‘third parties’ (e.g. parents and other care-takers) in treaty provisions. The first part of this book questions whether these features could be a source of inspiration for general human rights law. In part two, the reverse question is asked: could children’s rights law draw inspiration from developments in other branches of human rights law that focus on other specific categories of rights holders, such as women, persons with disabilities, indigenous peoples, or older persons? Finally, the interaction between children’s rights law and human rights law – and the potential for their isolation, inspiration or integration – may be coloured or determined by the thematic issue under consideration. Therefore the third part of the book studies the interplay between children’s rights law and human rights law in the context of specific topics: intra-family relations, LGBTQI marginalization, migration, media, the environment and transnational human rights obligations.