Heterogeneous Non-State Actors, Incoherent Causal Inquiries and Vague Obligations

It has been a great pleasure for our blog to hold the present symposium and present to its readers part of the discussions that were held at a workshop hosted by the University of Bristol in spring 2026, on the question of whether the law of state responsibility can still function as a meaningful framework of accountability in a globalised, multilateral order, or whether it is facing a crisis. Through a series of blogposts, the symposium contributors sought to reply to this question from multiple perspectives.

Some contributors zoomed in on various vaguely formulated primary rules setting out States’ obligations and brought to the forefront the importance of further legislative and scholarly engagement with these rules for the “demystification” of the content and scope of these obligations. Others focused on the vagueness surrounding the role of causation in the law of international responsibility, while others centred on the role of Non-State Actors (NSAs) and the failure of the law of international responsibility to address them. Through these contributions, some authors adopted a more optimistic outlook, whereas others provided a more sceptical perspective on the current state of the law of international responsibility. All of them can, however, help synthesise a better understanding of what role scholars and jurisprudence can play in this transformative stage for international law.

Addressing the Vagueness of Primary Obligations

Antal Berkens, for instance, focused on Article 41(2) of the Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA), which provides for the obligation not to recognize as lawful a situation created by the serious breach of an obligation arising under a peremptory norm of general international law, nor render aid or assistance in maintaining that situation. The author underlined that an often-raised criticism against Article 41(2) ARSIWA is that the obligations of non-recognition and non-assistance are difficult to apply to jus cogens violations that do not give rise to a clearly identifiable territorial unlawful situation, such as the prohibition of forced labour. Upon noting this limitation of the law of international responsibility, he drew attention to the European Union’s ‘Forced Labour Regulation on prohibiting products made with forced labour on the Union market’. This Regulation can be seen as implementing Article 41(2) ARSIWA into EU law, by giving practical effect to these general international law obligations in the context of situations of modern slavery and by requiring Member States to adopt measures that substantially replicate the duties of non-recognition and non-assistance. In this way, the Regulation – and similar EU, international or domestic measures – can contribute to fulfilling these obligations and to preventing wrongdoers and private actors from benefiting from an economy based on modern slavery.

Of course, one can observe that given the States’ selective compliance with their international obligations, despite the easier identification of jus cogens violations that give rise to a clearly identifiable territorial unlawful situation, Article 41(2) ARSIWA remains a somewhat dead letter in instances where the international community chooses to stay silent in the face of explicit and systematic jus cogens violations. This, however, further reinforces the author’s argument that regional, international or even domestic measures can contribute to the States’ compliance with Article 41(2) ARSIWA, and highlights the importance of the adoption of measures similar to the EU’s Forced Labour Regulation with regard to other forms of jus cogens violations as well.

Enenu Okwori has put the emphasis on the States’ obligation to prevent their territories from knowingly being used for acts that are contrary to the rights of other states, namely the international obligation to prevent transboundary harm. The author problematised the application of this obligation in the context of preventing cyber harm, particularly in light of the involvement of Non-State Actors (NSAs). Thus, she proposed a re-assessment of this obligation and specifically of the level of diligence that States need to exercise in order to uphold it. The author stressed that monitoring a State’s cyber infrastructure is of primary importance as it allows the State to handle any relevant challenge in real-time and to prevent its cyber networks and infrastructures from being used in a way that will cause harm to other states. However, as this is an obligation of conduct, States will have complied with this obligation as long as they exhaust all reasonable measures at their disposal to prevent said harm, even if that harm eventually materialises. Since state capacities with regard to monitoring differ, the author ultimately concludes that incorporating a minimum standard of monitoring cyber infrastructures into this obligation would, at the very least, make prevention easier.

This would offer much needed foreseeability as to the circumstances under which the primary obligation at issue would be breached. In this sense, this contribution seems to be also confirming the conclusions of the aforementioned one, whereby additional regulatory and legislative measures could help elucidate the content of the obligation enshrined in a primary norm, thereby assisting in its implementation by States.

Continuing the discussion on primary obligations, Michael Oghenetega Abu analysed the preventive obligations that States facing the risk of climate change-related displacement, as well as States hosting displaced children, bear. As the author underlined, what is relevant in this context is whether timely mitigation, adaptation, or protective measures could reasonably have interrupted the foreseeable pathway from climate risk to the children’s displacement and subsequent rights violations. Of course, the author acknowledged the complexity of examining and establishing causation between an omission and a harm or when harm results from multiple interacting conditions, because it is harder to isolate the legal significance of any single act or omission. Thus, she eventually stressed the importance of a sufficiently concrete causal link between the State’s failure and the harm the child experiences being provided for already in the rule setting out the preventive obligation.

In this way, the analysis addressed an important question, i.e. the role of causation in establishing responsibility for the violation of the preventive obligations that are linked to children’s displacement and subsequent rights violations, by reference to the primary obligation. It highlights how the absence of concrete causal tests provided for in the primary obligations exacerbates the vagueness surrounding causation and creates confusion as to the test that should be applied by adjudicating fora. In this sense, the analysis underlines the importance of additional regulation and legislative measures that could provide more concrete guidance on the causation exercise envisaged by the primary obligation and could lead to a coherent application of the primary norm in jurisprudence. With this symposium contribution, attention already shifted to causation. Other symposium contributions delved further into causation, shifting the attention from its importance when already included in the primary rule to its role in the determination of the content of responsibility.

Constructing Causation

Indeed, Tamás Molnár criticised the minimal guidance provided by the ARSIWA with regard to causation and underlined that absent any meaningful guidance, adjudicators are not called upon to ‘reveal’ which causal test should be applied in each particular case but are rather called upon to choose between multiple tests of causation, and, thus, to construct the very causal reality they claim only to be identifying. Focusing on reparation cases concerning unlawful expulsion of non-nationals, the author observed that if the adjudicators employ indiscriminately a strict directness standard, they will restrict both the restorative and the deterrent function of state responsibility, making it unlikely for the wrongfully expelled individual to receive any form of compensation. If, on the other hand, they set the bar too low, they may render the compensation afforded a punitive measure for the wrongdoing state, a result that international law disavows. Thus, the author seems to be arguing for a causal inquiry that is influenced by the primary rule breached in the case of the unlawful expulsion.

This argument has been raised with regard to the determination of (shared) international responsibility in cases of overdetermined refoulements as well (see here, pp. 81-92). That analysis pointed to foreseeability as the appropriate test of causation for the determination of shared responsibility for refoulement. In the symposium contribution, however, the author identifies as “[a] more conceptually defensible middle path” a causal inquiry in which “the wrongful act may be a conditio sine qua non of a given harm”, but whereby the State bears no duty to repair that harm “if it could not reasonably have been anticipated by the wrongdoer”. This proposed causal test is thus stricter than the test of foreseeability; it does not only assess the foreseeability of the harm caused by the wrongful conduct, but it also requires that the act is a conditio sine qua non of the harm. Overall, this blogpost creates a great opportunity for further engagement with and discussion on the question of which causal link the primary rules prohibiting the expulsion of non-nationals point to.

Abdulkadir Gülçür, then, focused on the issue of contributory fault and its role in the determination of the damages that the host State may be required to pay in investment arbitration. As the author underlined, international investment tribunals have addressed this question incoherently, while also failing to openly explain their approach to the matter. In fact, to justify this approach, tribunals have invoked the breadth of their discretionary powers, as well as the absence of a fault-based structure in Article 39 ARSIWA or of detailed provisions in BITs. According to the author, however, this approach should be replaced by a systemic shift toward rigorous judicial reasoning, which could be realized if tribunals substantiate the reduction in the damage to be paid by the host-State due to contributory fault with concrete economic evidence; if Annulment Committees enforce detailed reasoning standards, treating awards entailing unreasoned or speculative apportionment of fault as unjustified; and/or if institutional bodies issue technical guidelines on causation and contributory fault to standardize the tribunals’ methodologies. Against this background, this author seems to view the ongoing incoherent approach of the tribunals as an opportunity for future standardization and the use of arbitral fora’s discretion as an occasion for reasoned causal assessment. This appears to be not only an optimistic view of the current stage of international responsibility law, but also a call for reasoned creativity to the members of the tribunals, who are essentially shaping the future of the causal inquiry in this field.

From a State-Centric to a Heterogenous Law of International Responsibility

Another broader theme that is traceable in the symposium concerns the heterogeneity of the actors involved in the contemporary practice of international law. Precisely, Scarlett McArdle underlined the particularly high level of complex and distinctive actors that may be observed in the area of global health and drew attention to a growing gap arising from the high number of authoritative non-state actors that fall outside the regulatory scope of the law of international responsibility. As the primary focus in the law of international responsibility has remained on states and international organisations, key actors like the ‘World Health Organisation’ or the ‘Global Alliance on Vaccines and Immunisations’ completely escape its attention. The author further underlined that, particularly, in the area of global health law some of these actors are sui generis, and may even take the form of collectives, through which different global actors (including states, but also foundations funded by investment rounds) act under the radar of the law of international responsibility. Therefore, the analysis underlines that the broad category of “NSAs”, which encompasses many heterogenous actors, calls for sub-categorisation. This, together with academic arguments against relying on ‘subjecthood’ and instead focusing on a concept of legal “participants” are well versed. Engaging with the discussion of participants does not necessarily help with how to determine the legal obligations possessed by these actors. This, in combination with the rejection of the equation of subjectivity with the capacity to bear international obligations and responsibility, could be a meaningful start for more in-depth engagement with NSAs in the field of international law.

Elisa Ruozzi drew attention to the Houthis, a private group with multifaceted features, which seriously challenges the categories of “pirates” and “insurgents”, as well as the application of the law of international responsibility. At the same time, as the author stressed, such lacunae are inconsistent with the legal consequences that such actors often endure (such as multinational naval missions undertaken against them by some States), whose legal justification is debatable. In this vein, she underlined the pressing need to identify legal tools to regulate the conduct of NSAs such as the Houthis, as well as the consequences that may be imposed upon them in instances of unlawful conduct.

Daisy Peterson’s contribution pointed to another form of NSAs that test the capacity of the law of international responsibility, i.e. that of state-owned investment vehicles that hold stakes in, control, or enter into strategic partnerships with companies linked to human rights abuses. The author claimed that the customary rules on the attribution of conduct to States are capable, in principle, of being applied to the conduct of such actors. At the same time, however, it is also clear that depending on how the fund is constituted and governed, the existing rules on attribution may leave gaps, which may even be exploited by States. In this way, the author stressed the importance of attributing NSAs’ conduct to States given international law’s prioritization to the determination of the international responsibility of States and international organizations.  Nevertheless, she also hinted at the gaps that remain open when the international responsibility of NSAs continues to be left unaddressed. In this sense, the symposium contributions that engaged with the role of NSAs in contemporary international law highlight the need for further engagement with their obligations and with the conditions under which international responsibility may be attributed to them.

Concluding Remarks

Taken together, the symposium contributions reveal significant gaps and inconsistencies in the law of international responsibility but also identify avenues for its further development. Felix Butz’s symposium contribution drew on Johan Galtung’s concept of structural violence as avoidable harm built into social structures and Achille Mbembe’s understanding of necropolitics as sovereign power’s capacity to expose people to conditions of premature death, to develop “necropolitical structural violence” and describe severe and diffuse harm that is produced through a social structure that an actor can significantly influence and knows to be deadly. Although necropolitical structural violence appears to lie beyond the law of international responsibility, it offers us a vocabulary to think anew about established doctrine and to conceptualise in novel ways legal solutions to persisting social problems. And it seems that the time is ripe precisely for that.

As Abdulkadir Gülçür noted , treaty renegotiations or formal amendment of the ARSIWA “remain[…] practically unfeasible”. According to him, the current jurisprudential practice is shaping the law of international responsibility in a manner that can address its current deficiencies.

Similarly, it is scholarship that can assist in this process and constructively criticize unreasoned causal inquiries or vaguely phrased primary obligations, while these are being considered for adoption. It is also scholars that can continue discussions and creative engagements with the topic of NSAs and their obligations under international law. Such scholarly engagement allows us to rethink established doctrine and explore how the law of international responsibility might better address severe and diffuse harm produced through social structures.