1. Introduction
When Russia launched its ‘Special Military Operation’ and invaded Ukraine on 24 February 2022, the international community reacted swiftly. Meetings were immediately held at the United Nations (UN) Security Council (UNSC) and the UN General Assembly (UNGA) organised an Emergency Special Session. Speaking before the UNSC, the United States (US) representative characterised Russia’s operation as an aggression against Ukraine that ‘threatens our international system as we know it. We have a solemn obligation to not look away. … In coordination with our allies and partners, we are imposing severe and immediate economic costs on Russia’.Footnote 1 This sentiment was echoed by the delegate of the European Union (EU) Observer Mission during the UNGA’s Emergency Session on 28 February 2022, who referred to Russia’s invasion as the ‘biggest aggression in Europe since the end of the Second World War’.Footnote 2 The EU joined the US in adopting ‘unprecedented’ sanctions.Footnote 3 Shortly after, the UNGA adopted Resolution ES-11/1, which ‘[deplored] in the strongest terms the aggression by the Russian Federation against Ukraine in violation of Article 2(4) of the Charter’, by a majority of 141 Member States.Footnote 4 While the UNGA voting records demonstrate that a large majority of States recognise the wrongfulness of Russia’s aggression, only a minority have imposed sanctions.
As illustrated by their reactions to Russia’s aggression against Ukraine, the EU and US often consider unilateral sanctions to be an appropriate response to breaches of community norms (also known as obligations erga omnes (partes)), such as the prohibition of aggression. Unilateral sanctions are adopted by States pursuant to their national legislation or executive powers, or by international organisations against non-Member States or non-State actors in conformity with their constitutive instruments. These measures often constitute the imposition of a restriction or a withdrawal of a benefit. They come in many forms and there are various terms that represent this diversity: targeted sanctions, sectoral sanctions, unilateral coercive measures, restrictive measures, outcasting,Footnote 5 etc. The US and the EU are the most active sanction senders,Footnote 6 and States such as Canada, the United Kingdom (UK) and Australia often align with their restrictions. Nonetheless, there are stark divisions in States’ views over their legality and these measures are heavily contested.Footnote 7 The result of these disagreements is that under international law unilateral sanctions are largely unregulated and their legality is subject to debate.Footnote 8 While ‘a rule of customary international law against economic sanctions does not exist’,Footnote 9 there is, however, one overarching rule of thumb: a sanction is unlawful if it breaches an obligation owed by the sender to the target.
In short, whether a sanction is legally permissible depends on the applicable legal commitments between the sender and the target. As long as a sanction does not breach an obligation that the sanctioning State owes to the target of the sanction, it is a lawful act of retorsion. If the sanction involves causing the sender to breach an obligation that it owes to the target, it would be considered an internationally wrongful act, and the target could invoke the sender’s responsibility.Footnote 10 It is here that countermeasures become relevant, as a countermeasure is recognised as a circumstance precluding wrongfulness. They are adopted by States, or an organisation, such as the EU, in response to a prior wrongful act, with the aim of inducing the State responsible for the initial wrongful act to comply with its international obligations and provide reparation. Under Articles 49 to 53 of the draft Articles on the Responsibility of States for Internationally Wrongful Acts (ARSIWA), a number of conditions need to be met in order for a sanction to constitute a lawful countermeasure. For example, a countermeasure should be a proportionate response to the injury suffered by the State, and to the extent possible it should be reversible and temporary.
Whereas countermeasures are well established under customary international law, third-party countermeasures are more controversial. These measures are implemented by States or international organisations that are not injured within the meaning of Article 42 ARSIWA. Rather, they are countermeasures adopted in response to breaches of obligations erga omnes (partes), codified by Article 48 ARSIWA, and the actor adopting the measures is not directly (or ‘personally’) harmed by the wrongful act. For instance, the EU considered confiscating Russian Central Bank assets. The rationale behind the confiscation would be to provide reparation to Ukraine for Russia’s wrongful act, but it would arguably constitute a breach of Russia’s State immunity. While the EU eventually opted for a different approach,Footnote 11 the question of confiscating State assets revived the debate over the legality of third-party, or collective, countermeasures. The legality of third-party countermeasures has been a source of disagreement since the International Law Commission (ILC) first considered the matter while drafting ARSIWA.
A legal opinion provided to the EU on the confiscation of Russian State assets to fund Ukraine’s reconstruction advocates in favour of third-party countermeasures, claiming that the view that such measures are unlawful is ‘rigid’.Footnote 12 This position is supported by scholarly works which have found that these measures are permissible under customary international law.Footnote 13 However, the issue is that these studies have acknowledged that opinio juris accepting third-party countermeasures as lawful is lacking.Footnote 14 Moreover, sanctions practice is highly ambiguous.Footnote 15 Actors that adopt unilateral sanctions justify them as policy tools and avoid putting forward legal justifications. Furthermore, it is often unclear whether a unilateral sanction is a retorsion, a wrongful act or a lawful countermeasure. Curiously, actors whose practice (according to some authorsFootnote 16 ) provides evidence that third-party countermeasures are permissible have been relatively silent on the matter, albeit with some exceptions. Finally, as noted above, the legality of unilateral sanctions is heavily disputed by a significant number of States.
Against this backdrop, this article argues that given the inherently political nature of unilateral sanctions and the uncertainty that surrounds their adoption, it is necessary to demonstrate that States and international organisations believe that they are legally permitted to adopt wrongful sanctions in response to a prior breach of an obligation erga omnes (partes). As such, due to the persistent ambiguity in sanctions practice and the absence of clear opinio juris, it is concluded that third-party countermeasures are currently not widely accepted and therefore are not (yet) permitted under customary international law.
To make this argument, Section 2 explains how this article approaches international custom and, in particular, opinio juris. It then returns to the debate that was held over third-party countermeasures during the drafting of ARSIWA. It does so because various analyses find that the final Special Rapporteur on State Responsibility, James Crawford, was wrong to not include third-party countermeasures in the final text.Footnote 17 Following a detailed analysis of the responses received from States to the provision on third-party countermeasures, it is argued that there was not enough support for its inclusion in ARSIWA. The sections thereafter review sanctions practice and the legal positions put forward since ARSIWA’s conclusion in 2001. While there have been some developments, opinio juris is largely absent and overall practice remains too ambiguous for one to conclude with confidence that third-party countermeasures are accepted under customary international law. This is illustrated by the discussion of the confiscation of Russian State assets in Section 4.1.
2. The necessity of opinio juris when practice is ambiguous
In 2018, the ILC adopted the Draft Conclusions on Identification of Customary International Law (Draft Conclusions) which approved of the two-element approach to the identification of customary international law that requires evidence of a general practice (objective element) and opinio juris (subjective or mental element),Footnote 18 and concluded that each element must be ascertained separately.Footnote 19 The ILC’s two-element approach to customary international law is in line with the International Court of Justice’s (ICJ or Court) judgments on the ascertainment of custom,Footnote 20 which is one of the sources of law that the Court may apply, as reflected in Article 38(1)(b) of the Statute of the ICJ. Many scholars have been sceptical of the two-element approach and have questioned whether there exists a uniform method to establish custom.Footnote 21 Monica Hakimi is critical of the ‘rulebook’ approach to custom codified by the ILC, advocating instead for an approach that more accurately captures how States engage with custom in practice. Describing the process as ‘enigmatic and elastic’,Footnote 22 she explains that custom ‘emerges … through an unstructured process in which the participants apply variable criteria to justify their normative positions in [customary international law]’.Footnote 23 While her alternative is rather vague, she is right to point out that whether a given practice will become custom depends ‘on how global actors interact with it over time’.Footnote 24 Actors will issue legal claims, which will become ‘legally entrenched’ depending on whether they support, ignore or challenge the practice in question. The creation and eventual crystallisation of custom is thus an ongoing, interactive process.Footnote 25 It is argued that this does not mean foregoing the two-element, or rulebook, approach altogether, but acknowledging that one must pay attention to how States justify their conduct and consider how it is received by others. This is the function of opinio juris. When actors justify their conduct in legal terms, they are signalling that it should be considered a ‘legal practice’. Whether such practice is, or becomes, custom depends on how it is received by other States, who may accept it or contest it. It also matters how unequivocal the practice itself is, in the sense that it must be clear that the actors believe that they are acting in accordance with a legal obligation or right, or at least that they consider that there should be such an obligation or right.
Maurice Mendelson, who questioned the utility of opinio juris generally, found that this component counts when circumstances suggest that the practice should not be established as law,Footnote 26 such as when the reason for State practice is ambiguous. This occurs when various other factors can explain why a State conducted itself in a certain way and when it ‘is not clearly referable to an existing legal rule’.Footnote 27 This means that, in the absence of opinio juris, one cannot be certain that States are acting on the basis of legal considerations, especially if there are other possible explanations. On the other hand, opinio juris is redundant:
where there is a constant, uniform and unambiguous practice of sufficient generality, clearly taking place in a legal context and unaccompanied by disclaimers, with no evidence of opposition at the time of the rule’s formation by the state which it is sought to burden with the customary obligation, or by another State or group of States sufficiently important to have prevented a general rule coming into existence at all.Footnote 28
The influence of his approach can be found in the International Law Association’s (ILA) ‘Report on the Formation of Customary (General) International Law’, of which Mendelson was Special Rapporteur. The ILA found, inter alia, that the subjective element is useful to distinguish practice that generates new customary rules from practice that does not.Footnote 29 Echoing Mendelson, the report affirms that practice will not count if the conduct does not take place in the context of international legal relations or if there are various other reasons explaining why a State might behave in a certain way; under these circumstances the conduct is too ambiguous.Footnote 30 The ILA also explained that the absence of opinio juris ‘may mean that such a rule has not come into existence’.Footnote 31
Somewhat relatedly, Dahlman argues that opinio juris serves an important function in the creation of customary international law: it acts as a filter to prevent unwanted State practice from becoming custom.Footnote 32 As he writes: ‘There are situations where a certain behaviour is generally practiced among States in spite of the fact that every State would prefer that no State would practice it. The function of opinio juris … is to prevent such practice from becoming customary law’.Footnote 33 Dahlman contends that if a State does not want its own behaviour to become law it will not justify its action in legal terms. Instead, it will say, for instance, ‘that an important national interest is at stake’.Footnote 34 Dahlman’s approach reflects the ICJ’s attitude in the Nicaragua judgment when it assessed whether the principle of non-intervention had evolved to allow for a ‘general right for States to intervene, directly or indirectly, with or without armed force, in support of an internal opposition in another State, whose cause appeared particularly worthy by reason of the political and moral values with which it was identified’.Footnote 35 For such a right to take form in customary international law, there needed to be a settled practice and an accompanying opinio juris. The Court found that ‘States have not justified their conduct by reference to a new right of intervention or a new exception to the principle of its prohibition’.Footnote 36 As for the US Government, the respondant in this case, it had justified its conduct on ‘statements of international policy, and not an assertion of rules of existing international law’,Footnote 37 and thus its conduct was not properly justified in legal terms. Practice was therefore not sufficient to result in the development of a new custom or an evolution of the principle of non-intervention.
Against this backdrop, this article argues that because the practice of prima facie wrongful unilateral sanctions is so ambiguous, it is necessary to identify opinio juris in order to assess whether third-party countermeasures are permitted as a matter of custom. The challenge is that the mental element is predominantly absent. The actors responsible for such practices are reluctant to characterise their measures in legal terms, generally referring to ‘statements of international policy’, and many States contest the adoption of unilateral sanctions and invoke international law when doing so. Each of these issues will be explored further below. It is first useful to situate the starting point of the analysis. It has been argued that the ILC erred when it decided not to recognise that these third-party countermeasures are custom in 2001,Footnote 38 but Section 3 finds that, given the feedback received by the ILC from States, the better option was to include collective countermeasures as a ‘saving clause’ under Article 54 ARSIWA. Sections 4 and 5 thereafter consider the evolutions in State practice and custom that have occurred since ARSIWA was concluded.
3. Third-party countermeasures at the ILC in 2001
3.1. Discussing responses to breaches of obligations in the collective interest
International law has devised various categories for acts of decentralised enforcement, which are reflected in ARSIWA. Depending on the applicable rules, a sanction will either qualify as a retorsion, an internationally wrongful act or a countermeasure. Provided a measure does not violate an obligation that the sending State owes to the target State, sanctions are an act of retorsion, a lawful albeit unfriendly act. Given their inherent lawfulness they do not (presumably) pose a problem under international law and the target of the sanction cannot invoke the sender’s responsibility. Consequently, retorsions fall outside the scope of ARSIWA. This would evidently not be the case if the sanction breaches an obligation that the sender owes to the targeted State, in which case the sanction would constitute an internationally wrongful act. Under such circumstances, the countermeasure argument becomes relevant.
Given that international law aims to secure the respect of international obligations and the promotion of friendly and peaceful relations between States, justifying prima facie violations as self-help because the international system lacks central enforcement was no easy pill to swallow. Nonetheless, during the drafting of ARSIWA the majority of the ILC members preferred to recognise countermeasures as a necessary evil in a decentralised system rather than to leave them in ‘the limbo of lawlessness’.Footnote 39 The ILC therefore incorporated substantive and procedural safeguards to minimise their potentially nefarious side effects.Footnote 40 The ILC could only go as far as codifying bilateral countermeasures, which are adopted by the directly injured State against the allegedly responsible State. This was despite the fact that, while State responsibility was under consideration, the world was shifting from bilateral relationships to ‘communitarian obligations’, which were reflected in the emergence of multilateral obligations, international crimes, peremptory norms and obligations erga omnes (partes). The latter term was introduced by the ICJ in the Barcelona Traction case in its well-known dictum,Footnote 41 which was subsequently incorporated into Article 48 ARSIWA.Footnote 42 According to Crawford, the Court’s introduction of obligations owed to the international community as a whole was a manifestation of Special Rapporteur Ago’s view that there are obligations in the public interest, a concept Ago initially conceived of as international crimes.Footnote 43
With the concept of collective legal interests came the issue of their enforcement. The ILC believed that this shift should be mirrored in reactions to wrongdoing. Discussions revolved around the legal relationships that arise from a wrongful act, whether different types of norm violations trigger different consequences and who has standing to respond to wrongfulness and how. The broadening of actors who have a legal interest in the respect of these norms and who have standing to enforce them was salient throughout the drafting process,Footnote 44 which was often discussed under the auspices of the ‘new legal relationship’ that arises between the (non-)directly injured State and the State responsible for the wrongful act. The traditional view in international law was to focus on the bilateral relationship that emerged as a consequence of an internationally wrongful act.
However, in the aftermath of the Second World War and the developments that had taken place in international law, the question was whether, depending on the importance of the norm breached, different types of internationally wrongful acts gave rise to different regimes of responsibility.Footnote 45 Special Rapporteur Ago proposed a draft article that encompassed different categories of breaches, international crimes and international delicts.Footnote 46 Yet, when Crawford became Special Rapporteur, he decided that Article 19 on international crimes would be replaced by Article 41 on serious breaches of international law and Article 48 on obligations erga omnes (partes). He also decided that international law made no distinction in responsibility based on the type of norm breached.Footnote 47 Instead, he proposed to make a distinction based on States’ standing to respond to a breach; they either had an interest because they were directly affected, or because the breach concerned an obligation owed to the international community. Attention was then turned to collective countermeasures adopted in reaction to breaches of obligations erga omnes (partes).Footnote 48 Although he recognised that it was hard to reach conclusions,Footnote 49 he nonetheless ‘expressed the feelings of many’Footnote 50 when he recommended that ‘international law should offer to States with a legitimate interest in compliance with [collective obligations], some means of securing compliance which does not involve the use of force’.Footnote 51 Reaching this conclusion, he proposed to include third-party countermeasures in draft Article 54 [2000]. However, the clause was eventually removed, notably due to the reactions of States, which are addressed in Section 3.2.
3.2. The reactions from governments to third-party countermeasures during the Sixth Committee debates
In the articles adopted on second reading in 2000, draft Article 54 [2000] provided that non-directly injured States may adopt countermeasures at the request of and on behalf of the injured State and that any State may adopt countermeasures in reaction to serious breaches of obligations erga omnes (partes).Footnote 52 Following the reactions from States, Special Rapporteur Crawford decided that the better view was to include third-party countermeasures in the form of a saving clause, a suggestion made by the UK.Footnote 53
According to Christian Tams, the ILC erred in following the UK’s proposal. He argues that Special Rapporteur Crawford was incorrect to conclude that governments were opposed to draft Article 54 [2000] and submits that the feedback from States during the second reading ‘present a surprisingly nuanced spectre of views’.Footnote 54 Despite the fact that there were criticisms, he finds that ‘an even larger number of governments … expressly or by implication, accepted that in the case of serious breaches of obligations erga omnes, all States could resort to countermeasures’.Footnote 55 He concludes that ‘while article 54 [2000] undoubtedly proved controversial, it was by no means generally rejected … to the majority of States, such a provision would have been acceptable’.Footnote 56
The review below of the comments made by governments during the UNGA Sixth Committee debates reveals that their feedback was indeed very nuanced. It is concluded that, although there were States that expressed support for draft Article 54 [2000], a majority were either against its inclusion or feared the risk of abuse.Footnote 57 The following paragraphs categorise State feedback based on: first, those who called for draft Article 54 [2000]’s deletion (including when it was suggested to change it to a saving clause); second, those who feared its abuse; third, those who questioned how to coordinate third-party countermeasures with UNSC sanctions; and, fourth, those who accepted the draft Article’s inclusion but required further guidelines.
3.2.1. The deletion of draft Article 54 [2000]
The US delegate supported the UK’s suggestion to change draft Article 54 [2000] to a saving clause.Footnote 58 China argued in favour of the deletion of draft Article 54 [2000], which ran counter to the ‘basic principle that countermeasures’ could only be adopted by the injured State.Footnote 59 It maintained that the provision ‘could provide a further pretext for power politics in international relations’ and would be inconsistent with the principle of proportionality.Footnote 60 According to Cuba, draft Article 54(2) [2000] ‘went well beyond the progressive development of international law’ and draft Article 54 [2000] should be deleted.Footnote 61 In its written comments, Mexico rejected the ‘saving clause’ solution and also called for the deletion of draft Article 54 [2000], arguing that it was not supported by international law and that it raised serious difficulties.Footnote 62 Mexico also stated that Chapter VII of the Charter of the UN covered the consequences of serious breaches by a State of an obligation owed to the international community as a whole.Footnote 63 Japan found that the risk of abuse of collective countermeasures outweighed their potential benefits and also called for their removal from the draft Articles.Footnote 64 The Israeli delegate spoke against draft Article 54 [2000] on collective countermeasures, finding that such measures could have a destabilising effect and that the provision ‘went beyond existing law and [was] unwarranted’.Footnote 65
3.2.2. The fear of abuse
Turning to the fears of abusive practice, the Tanzanian delegate was uncomfortable with the general regime of countermeasures, even criticising their adoption by directly injured States. They were described as ‘a threat to small and weak States’.Footnote 66 The Iranian representative articulated Iran’s concern that countermeasures may be used as a tool of economic coercion, referring to resolutions adopted by the UNGA,Footnote 67 and argued that collective countermeasures ‘must be coordinated by the United Nations’.Footnote 68 Botswana found that draft Article 54 [2000] was too wide and open to abuse by powerful States.Footnote 69 The Iraqi delegate also expressed a general concern that countermeasures may be abused by more powerful States and that adequate safeguards were necessary.Footnote 70 The Republic of Korea found that it was necessary to reduce arbitrariness and to ‘alleviate the influence of the more powerful States’.Footnote 71 The Greek representative defined countermeasures as ‘an archaic notion, one which favoured more powerful States and thus had no place in an international community based on the sovereign equality of nations’.Footnote 72 Guatemala made no statement on third-party countermeasures but was troubled by the overall negative effects of countermeasures, especially when they could be equated to economic coercion, thus sharing Iran’s concern.Footnote 73 Hungary,Footnote 74 Slovakia,Footnote 75 and CyprusFootnote 76 were also worried about the potential abuse of countermeasures.
3.2.3. How to coordinate third-party countermeasures with UNSC measures
The issue of coordinating measures unilaterally adopted by States and those adopted by the UNSC was also raised. Algeria expressed its reluctance to include countermeasures and proposed that collective countermeasures should be adopted within an institutional framework.Footnote 77 Greece also suggested that draft Article 54(2) [2000] should be amended to include that ‘countermeasures should not be taken unilaterally by any State if the organized international community was seized of the matter through the Security Council’.Footnote 78 The Russian delegation stated that:
It would be unacceptable for any State to take countermeasures at the request of any injured State, because that would give the big Powers the opportunity to play the role of international policemen. The only exception concerned the acts referred to in Article 41. There were cases where such relations between States might also fall under the jurisdiction of international organizations responsible for security matters.Footnote 79
Recognising that third-party countermeasures could be adopted in cases falling under draft Article 41 [2000] on ‘serious breaches of essential obligations to the international community’, the Russian Federation did seem to accept third-party countermeasures under draft Article 54 [2000] (which in 2025 is ironic) while at the same time raising the issue of coordination with measures adopted by the UNSC. It should be noted, however, that Russia criticised draft Article 41 [2000].Footnote 80 The latter was reiterated in draft Article 54(2) [2000], which provided that ‘In the cases referred to in article 41, any State may take countermeasures, in accordance with the present Chapter in the interest of the beneficiaries of the obligation breached’.Footnote 81 This suggests that, while Russia apparently accepted collective countermeasures it believed their scope should be narrower.
3.2.4. The need for further guidelines
Speaking on behalf of the Nordic States, the Danish delegate did not make any specific comments on the draft provision entitled ‘Countermeasures by States other than the injured States’, but recognised that countermeasures were a sensitive issue that had to be properly regulated by the ILC. He further recalled that ‘it was nevertheless crucial to establish strong safeguards against possible abuses of countermeasures’.Footnote 82 According to Indonesia, the law on countermeasures was still undergoing development. The Indonesian representative also stressed that countermeasures should not be a means to settle disputes between States.Footnote 83 Brazil stated that ‘the right of the third State to take countermeasures on behalf of the injured State’ needed further consideration.Footnote 84 Germany suggested that the options of the State indirectly injured should be more narrow than those of the directly injured StateFootnote 85 and was concerned about the risk of disproportionate unilateral acts, ‘which in reality were not justified by the interest they sought to protect’.Footnote 86 According to Argentina, collective countermeasures should be subjected to more restrictions than bilateral countermeasures.Footnote 87 They considered that draft Article 54 [2000] should be ‘regarded as progressive development’.Footnote 88 Jordan noted that collective countermeasures were a ‘new’ concept introduced by the draft Articles and, although not against its inclusion in the final text, it called for more consideration of the question.Footnote 89 Slovenia stated that such countermeasures could be justified under certain circumstances but that the broad scope of draft Article 54 [2000] could give rise to abuse.Footnote 90
The South African delegation, speaking on behalf of the South African Development Community, seemed to be in favour of draft Article 54 [2000].Footnote 91 France’s written comments suggested improvements that could be made to the provision,Footnote 92 thus indicating that it accepted the draft Article’s inclusion in the final text.Footnote 93 Spain was very clear in stating that draft Article 54 [2000] was ‘correct’.Footnote 94 Italy also seemed to accept the provision and suggested that it should go further.Footnote 95 ChileFootnote 96 and Costa RicaFootnote 97 also accepted that countermeasures could be adopted by non-injured States in cases of violations of obligations erga omnes. In their written comments, the Netherlands spoke of the ‘innovative nature’ of draft Article 54 [2000] but accepted it.Footnote 98 Australia’s comments imply acceptance of the provision while requiring further clarification.Footnote 99 Austria submitted that ‘countermeasures as a means of obtaining compliance for obligations erga omnes presented a thorny problem’.Footnote 100 The questions raised by the Austrian representative are related to the formulation of draft Article 54 [2000], without questioning the general idea of collective countermeasures.Footnote 101 Similar comments were made by the Polish delegation, especially concerning the link between third-party countermeasures and the UNSC.Footnote 102 Although recognising that there was a trend in international law whereby every individual State has recourse to countermeasures in response to serious breaches of obligations erga omnes, Poland also found ‘that this practice has met important opposition within the international community’.Footnote 103 Such practice should therefore be ‘subjected to some form of control by the international community’.Footnote 104
The Indian delegate’s statements on collective countermeasures were rather ambiguous. On the one hand, he stated a preference for the exclusion of countermeasures from ARSIWA altogether, as they could give rise to abuse.Footnote 105 On the other hand, he seemed to suggest that obligations erga omnes and responses to their violation are an area of progressive development, possibly suggesting that India was not against the proposal.Footnote 106 Nonetheless, as he called for the deletion of draft Article 41 [2000], which as mentioned justified the adoption of third-party countermeasures under draft Article 54(2) [2000], it is unclear on what grounds collective countermeasures could be adopted.Footnote 107 Sierra Leone also expressed the concern that countermeasures may be abused. Though making no comment on draft Article 54 [2000], its representative stated that ‘draft Articles 50 to 55 failed to state clearly that countermeasures were only legitimate as between two States in a relative sense’.Footnote 108 This raises questions as to whether or not Sierra Leone agreed that non-directly injured States could adopt countermeasures.
3.2.5. Takeaways from the debate
Based on this analysis, States that were not vehemently against draft Article 54 [2000] were still concerned that these measures may lead to abuse by powerful States and would obstruct multilateral measures adopted by the UNSC. They therefore required further safeguards. States that accepted draft Article 54 [2000] recognised that the provision was a new concept in international law. Although the draft ARSIWA suggested that third-party countermeasures be subjected to the same rules as bilateral countermeasures (draft Article 54(3) [2000]), this was not deemed sufficient. The ILC was required to provide further guidance as the rules governing the adoption of third-party countermeasures were very unclear. Having spent 50 years drafting ARSIWA, this was certainly too much to ask of the ILC. Consequently, even if draft Article 54 [2000] had made it into the final version, it still would have been a provision of progressive development of international law and not codification.
Furthermore, if States presumably adopting countermeasures in response to violations of obligations erga omnes (partes) believed that they were acting lawfully or contributing to international law’s development, then one must wonder why they did not accept the inclusion of third-party countermeasures in the draft ARSIWA. This is the case of the US, the UK and Tanzania. In 1990, 11 years before the adoption of ARSIWA, Sicilianos wrote that Western States’ opposition to third-party countermeasures was problematic in the sense that it appeared to contradict their practice and foreign policy decisions. He explained this inconsistency by the fact that these States were expressing their opposition to these measures because of their link to the concept of ‘international crime’, a concept they were against and which was at the basis of the provision on third-party countermeasures at the time.Footnote 109 In 2000, however, draft Article 41 on ‘serious breaches of essential obligations to the international community’ replaced draft Article 19 on ‘international crimes’. Draft Article 54(2) [2000] expressly referred to Article 41. Even though third-party countermeasures were no longer based on the concept of international crimes, these States still objected to their inclusion in ARSIWA.
Over 20 years after the ILC adopted ARSIWA one could question whether its findings that the customary rules permitting countermeasures by non-directly injured States have yet to emerge are still valid. After all, the frequency at which certain non-directly injured actors respond to violations of obligations erga omnes (partes), such as political and civil human rights violations, through (potentially unlawful) sanctions could suggest that third-party countermeasures are recognised under international custom. Sections 4 and 5 address this question, first focusing on practice and, subsequently, on opinio juris.
4. The ambiguity of sanctions practice
It is argued here that the practice concerning the imposition of unilateral sanctions is ambiguous. While sanctions practice has flourished over the decades, it remains a largely political practice dominated by the US and the EU. It is true that these tools are often justified as a means to uphold international norms, and one could argue that as the EU and the US are claiming to have the authority to enforce international law, they are providing legal claims.Footnote 110 However, as will be seen, they frame their restrictions as a sovereign right to make use of their economic power in pursuance of foreign policy interests, which include supporting the norms that, in their view, form the basis of the international order. Such statements suggest that they view their measures as retorsions. It is unclear if this practice actually constitutes wrongful sanctions that could eventually be justified as third-party countermeasures. This ambiguity is first illustrated by the debate over confiscating Russian State assets, after which Section 4.2 takes a broader view of unilateral sanctions practice.
4.1. Reluctance to seize Russian assets
One of the more severe sanctions that was adopted against Russia after the start of the war in February 2022 was the freezing of Russian Central Bank assets in foreign jurisdictions.Footnote 111 As the war progressed, discussions turned to whether the sanctioning actors should seize or confiscate the assets as a means to guarantee that Ukraine would receive reparation for the harm that it had suffered. Both the freezing and the confiscation of State sovereign assets led to the resurfacing of the debate on third-party countermeasures.
As always when it comes to sanctions, commentators disagreed on the initial question: whether the action was a retorsion or a wrongful act that required justification. According to Franchini, ‘central bank sanctions are likely to violate several international legal principles and rules such as non-intervention, State jurisdiction, immunity, human rights and various international economic law treaties’.Footnote 112 When discussing these types of restrictions, most of the literature has focused on their compatibility with State immunity. Russian assets, such as those of the Central Bank, constitute State property and thus are immune from measures of constraint.Footnote 113 The latter are generally related to judicial proceedings, and the question is whether they also arise following executive and legislative decisions.Footnote 114 Ruys has argued that sovereign immunity only applies to judicial decisions and that an executive decision that orders the freezing of assets is not in violation of State immunity.Footnote 115 One wonders whether such a distinction undermines immunity. As Kamminga comments, ‘it would be rather incongruous if Central Bank immunity could be invoked against intervention by the judicial branch but not against intervention by the executive branch’.Footnote 116 He also notes that some States have objected to the freezing of State assets.Footnote 117 Following an analysis of opinio juris against non-judicial measures of constraint (such as sanctions) directed against State property, Janig concludes that State immunity protects State property from executive and legislative acts.Footnote 118 For others, sovereign immunity applies to the actions of the legislature and the executive where those actions are judicial in nature.Footnote 119 The ICJ may eventually provide insight. At the time of writing, Iran has instituted proceedings against Canada for violating ‘Iran’s jurisdictional immunity and immunity from measures of constraint under customary international law’, which it alleges results from a ‘series of legislative, executive and judicial measures adopted by Canada against Iran and its property since 2012’.Footnote 120
According to Brunk, while freezing Central Bank assets through executive action does not violate immunity, confiscation of such assets would, as it generally involves judicial action.Footnote 121 In her view, whereas States may very much want to confiscate Russian assets, they have not done so. To her, this is demonstrative of opinio juris: ‘countries very much want to confiscate Russian central bank assets, but customary international law governing Central Bank immunity and countermeasures do not permit them to do so’.Footnote 122 She also notes that ‘[t]he absence of State practice of third-party countermeasures against Central Bank immunity suggests, in this context, that such measures are not permissible’.Footnote 123 Some scholars have argued that confiscating State assets would not fulfil the criteria for lawful countermeasures as these measures would not be proportionate as required by Article 51 ARSIWA, would not be temporary or reversible as required by Article 49 ARSIWA and may have broader ramifications that could harm fundamental human rights contrary to Article 50(1)(b) ARSIWA.Footnote 124 As always, these arguments are debated. Kamminga posits that the freezing and confiscation of Russian State assets would be unlawful but that this could be excused as ‘a permissible third-party countermeasure to induce Russia to halt its aggression against Ukraine’.Footnote 125 To support this position, he refers to Canada’s Special Economic Measures Act 1992, which allows Canada to confiscate foreign property, including that of a State, in response to a grave breach of international law.Footnote 126 He does not note that Canada is one of the few States to have expressed opinio juris against the adoption of collective cyber countermeasures.Footnote 127 Furthermore, while the Group of Seven (G7) collectively froze Russia’s assets, Kamminga acknowledges that it ‘did not couch their measure in these terms’.Footnote 128 So far, the language of collective countermeasures has been absent in G7 pronouncements and more generally, but it is clear that a number of legal, policy and financial issues are at stake that are leading States to be very cautious.
Because the majority of Russian State assets that have been frozen are held by Euroclear, a financial market infrastructure group in Belgium, the decision on whether to confiscate the funds lies with the EU. So far it has resisted US and UK pressure to do so. It appears that a legal team advised the European Commission that confiscation would be unlawful, particularly under domestic laws.Footnote 129 On 21 May 2024, the Council of the EU announced that the profits that had accrued from the assets’ interest ‘will be used for further military support to Ukraine, as well as its defence industry capacities and reconstruction’. This outcome would be ‘consistent with applicable contractual obligations and in accordance with applicable laws’.Footnote 130 As always, the question remains whether this includes collective countermeasures. According to Webb, it is unclear whether the use of Russia’s accrued profits in such a manner would comply with international law, as it depends on whether they are considered to be Russian property.Footnote 131
The decision-making process has been difficult, as all EU Member States have to agree and concerns have been raised over the legal and financial fallout. Nonetheless, in June 2024, the G7 countries affirmed the decision ‘to make available approximately USD 50 billion leveraging the extraordinary revenues of the immobilized Russian sovereign assets’.Footnote 132 The EU endorsed the proposalFootnote 133 and further concrete steps were taken when the Council of the EU announced the Ukraine Loan Cooperation Mechanism in October 2024,Footnote 134 which will use the Russian extraordinary revenues to enable Ukraine to repay the loans that it has received from the G7 countries.
Third States expressed opposition to confiscating Russian State assets. According to Politico, China, Saudi Arabia and Indonesia feared that the actions of the EU would set a precedent.Footnote 135 This could suggest that they are not convinced that there is, at present, a legal justification (such as third-party countermeasures) for such an action. Following lawsuits in Russia over Western sanctions, in May 2024, a Russian court ordered that Deutsche Bank assets in Russia which totalled €239 million, as well as those of Commerzbank totalling €93.7 million, should be seized.Footnote 136 It also ruled that assets and property belonging to UniCredit, estimated at €462.7 million, should be seized.Footnote 137 In February 2025, Reuters reported that Russia is set to adopt legislation that would enable it to seize foreign assets in retaliation against the restrictions imposed on it.Footnote 138 At the time of writing it is unclear if this legislation has been adopted, but Russian retaliation against European funds is feared, and there is also concern that investors might become reluctant to do business in the EU.
To conclude, the EU has refrained from confiscating Russian State assets and has opted for mobilising accrued profits instead. It is unclear if it avoided confiscation because it fears the political ramifications or if it considers that the measures would be difficult to justify legally, either because third-party countermeasures would not be permissible or because the criteria for their imposition would not be met in this case. Of course, it is likely that a combination of both legal and political considerations influences decision-making. Section 4.2 delves further into the ambiguity of sanctions, which are often justified as policy tools and whose legality is often unclear.
4.2. Unilateral sanctions as political practice, which may or may not require legal justification
When it comes to unilateral sanctions, State practice is hardly new but has increased since 2001. While it is not required that a general practice be universal or unanimous, it should be widespread and supported by a majority of States or international organisations,Footnote 139 particularly those whose interests are most affected.Footnote 140 All States are arguably affected by the adoption of collective countermeasures; they have the potential to be the adoptee or the target. State practice is dominated by a limited number of (mainly Western) States and the EU and therefore does not meet the requirements of a general practice that is needed to form customary law. Non-Western States engage in adopting unilateral sanctions, but less frequently than the US, the EU and those who align with them. Additionally, whereas practice should be consistent,Footnote 141 sanctions’ adoption is selective and stained with double standards. States and international organisations are relatively consistent in the types of violations to which they respond, but they do not always react when similar violations of international law are at stake. Though there is no obligation to adopt sanctions, this inconsistency is also the source of objections to the imposition of unilateral sanctions.Footnote 142 While it is not surprising that a target State objects to unilateral coercive measures, it should be noted that they are frequently supported by an important number of (developing) States that object to the use of these measures as a foreign policy instrument.Footnote 143
The US is very clear in stating that unilateral coercive measures are an essential foreign policy tool and an acceptable response to violations of international norms. Speaking before the UNGA Third Committee in 2021, the US delegate explained their vote against the UNGA Resolution 53/141 on Human Rights and Unilateral Coercive Measures in the following manner:
The text inappropriately challenged the sovereign right of States to determine their economic relations and protect legitimate national interests. It also attempted to undermine the ability of the international community to respond to offences that were contrary to international norms. Economic sanctions were a legitimate means of achieving foreign policy and other objectives, and the United States was not alone in that view or practice.Footnote 144
In this case, sanctions are justified on both political grounds and to protect and promote international norms. Unilateral measures are described as a ‘sovereign right’ and as ‘legitimate’, suggesting that they would be acts of retorsion as opposed to wrongful acts in need of justification or countermeasures where restrictions would apply. Comparable reasoning was given in the US explanation of the vote against UNGA Resolution 58/198 on Unilateral Economic Measures as a Means of Political and Economic Coercion against Developing Countries:
Sanctions were an appropriate, effective, peaceful and legitimate tool for addressing threats to peace and security. … In cases where the United States had applied sanctions, it had done so with specific objectives, including the promotion of democratic systems, the rule of law and respect for human rights and fundamental freedoms, or to respond to security threats.Footnote 145
Although the EU abstained during the vote on this resolution, it was explained that:
Sanctions should respect the principles of international law, including the international contractual obligations of the State applying them and the rules of the World Trade Organization. The European Union imposed restrictive measures in full conformity with its obligations under international law … .Footnote 146
While the EU often reiterates that ‘[a]ll restrictive measures adopted by the EU are fully compliant with obligations under international law, including those pertaining to human rights and fundamental freedoms’,Footnote 147 this is a rather broad claim. It is unclear if it understands ‘international law’ to include third-party countermeasures or if it believes that its restrictive measures are acts of retorsion.Footnote 148 In Venezuela v Council, the European Court of Justice (ECJ) had the opportunity to situate restrictive measures within international law but instead framed EU restrictive measures as an ‘autonomous’ foreign policy. As Kassoti writes, the General Court ‘proclaimed that the EU’s external sanctioning power stems from its internal mandate to observe international law and to advance democracy, the rule of law and human rights’.Footnote 149 While the judgment can be criticised on a number of grounds,Footnote 150 the point here is that that ECJ did not engage with the debate under international law and therefore did not provide legal clarity. Rather, it seems to have supported the stance that unilateral sanctions are foreign policy tools that are somehow independent from international law.
In sum, actors that adopt unilateral sanctions reiterate that they have the sovereign right to implement coercive measures to protect their interests and the interests of the international community. Though States will justify sanctions as a response to a breach of international law, they are usually considered a foreign policy instrument. According to Dawidowicz, this would imply that they believe they can adopt third-party countermeasures:
Even if States have not explicitly invoked the concept of third-party countermeasures … they have relied on it in substance. In other words, States have adopted prima facie unlawful unilateral coercive measures based on an explicit legal rationale; namely, the enforcement of obligations erga omnes (partes). This rationale neatly corresponds to third-party countermeasures as a legal category.Footnote 151
It is difficult to follow this reasoning. While sanctioning entities clearly believe that they are entitled to use their economic power to enforce community norms, the key question is whether they can adopt third-party countermeasures to uphold these norms or if such enforcement measures must be acts of retorsion. To the extent that the sanctions would constitute acts of retorsion, this would not be problematic under the law of State responsibility. However, difficulties arise when the measures constitute wrongful acts that require justification. The responsibility of the sending entity could be invoked unless the sender is able to raise a circumstance precluding wrongfulness. This is not an element that is addressed by the senders. It is perfectly plausible that they believe their sanctions are acts of retorsion that do not require justification,Footnote 152 which seems to be the approach adopted in Venezuela v Council, or they wish to preserve the argument that their measures are retorsions.
Sanctions are a grey area of international law. As it is not a straightforward task to identify an unlawful sanction, actors may prefer to leave the issue open and unregulated by international law. They may also not want to justify themselves unless they are required to, for instance before a judicial body, and even in these circumstances they have not invoked third-party countermeasures. Sanctioning countries have been called upon to justify their measures before the ICJ and the ECJ, with the sanctions being justified as measures that fell within a treaty’s security exception, thus suggesting that they were acts of retorsion.
Before the ICJ, in Alleged Violations of the 1955 Treaty of Amity, Economic Relations, and Consular Rights (Iran v US) Iran has accused the US of violating the 1955 Treaty of Amity, Economic Rights and Consular Relations. However, the US claims that its sanctions fall within the treaty’s security exception, Article XX(1).Footnote 153 In the case before the ECJ, PJSC Rosneft Oil Company v Her Majesty’s Treasury and Others, Rosneft, a Russian-owned company that had been targeted by the EU, challenged the legality of the EU’s restrictive measures under the EU-Russia Partnership and Cooperation Agreement (Agreement). The ECJ ruled that these measures were compatible with the Agreement as they constituted security measures under Article 99(1) Agreement.Footnote 154 Even in other fora, sanctioning States do not raise the third-party countermeasures argument. For example, Qatar contested the legality of the sanctions adopted against it by Saudi Arabia, the United Arab Emirates, Bahrain and Egypt, who justified their measures under the framework of collective security,Footnote 155 as security exceptions under the Agreement on Trade-Related Aspects of Intellectual Property RightsFootnote 156 and then eventually as countermeasures under Article 49 ARSIWA, but not as collective countermeasures.Footnote 157 As already mentioned, the ECJ did not engage with this question in Venezuela v Council, preferring to frame restrictive measures as a form of autonomous sanctions.
Having argued that State practice is ambiguous due to the political nature of sanctions and because it is difficult to establish when unilateral sanctions are wrongful acts that require justification, Section 5 turns to the question of opinio juris.
5. The missing subjective element
An important issue that has not received sufficient attention in the literature is the fact that neither the EU nor the States that have adopted sanctions have indicated their belief as to the law to demonstrate the opinio juris needed to support the recognition of third-party countermeasures under customary international law. Section 5.1 reviews how doctrine has assessed opinio juris and to what extent States have provided evidence of the subjective element since ARSIWA’s conclusion in 2001, and then Section 5.2 argues why opinio juris cannot be inferred from practice and needs to be assessed separately.
5.1. Doctrine’s assessment of opinio juris and the views expressed by States
The most in-depth analyses on collective countermeasures, conducted by Tams, Katselli Proukaki and Dawidowicz, recognise that the subjective element is lacking but nonetheless conclude that they are accepted as a norm of customary international law and that the ILC erred in not including them in ARSIWA.Footnote 158 Relying on these works, BillsFootnote 159 and BogdanovaFootnote 160 both find that collective countermeasures should be considered permissible. Referencing Katselli Proukaki and Dawidowicz, Kamminga also notes that ‘State practice appears to be moving to a situation in which the entitlement to take countermeasures no longer distinguishes between directly and indirectly injured States’.Footnote 161 A report prepared by Webb cites Dawidowicz to argue that practice supporting third-party countermeasures is now ‘virtually uniform’, yet recognises that States may not label their own practice in this manner.Footnote 162
Lim and Mitchell (who mainly reference Dawidowicz) note that the legality of third-party countermeasures, or collective countermeasures, is contested but appear to accept them in their analysis on how States have responded to Russia’s aggression against Ukraine. In their view, the response of Western States to Russia ‘constitutes the development of third-party collective countermeasures outside of UN authorisation’.Footnote 163 Their assessment of the UNGA Sixth Committee debates on the matter of third-party countermeasures equally finds that only a minority of States were against Crawford’s initial proposal to include them in the final version of ARSIWA,Footnote 164 which is disputed above.
Hathaway, Mills and Poston’s analysis also affirms that both elements of custom are met.Footnote 165 Their article includes some instances of State practice, including sanctions adopted by non-Western States (such as those adopted against South Africa for its apartheid regime, or the League of Arab States’ sanctions against Syria). The examples are not supported by opinio juris, which, according to the authors, can be tacit. To give two final examples, Moiseienko argues in favour of third-party countermeasures as an appropriate policy in response to grave breaches but acknowledges their debated legality,Footnote 166 and Schmitt and Watts reach a balanced conclusion that ‘the legality of collective countermeasures is that the matter is unsettled, with no clear obstacle standing in the way of either view’.Footnote 167
Other commentators have disagreed on the legality of third-party countermeasures. Reviewing Dawidowicz’s monograph, Lanovoy notes that State practice is unclear and that little is said on opinio juris.Footnote 168 Questions relating to methodology are also raised by Focarelli, who is ultimately not convinced that third-party countermeasures are established custom.Footnote 169 Brunk also appears sceptical, noting that ‘[t]hird party countermeasures … are generally contested and their legality is unclear in all circumstances’.Footnote 170 Finally, Jackson and Paddeu’s detailed assessment on the legality of countermeasures in the general interest concludes that, even if one adopts a flexible approach to custom, ‘the best that can be said is that the law remains uncertain’.Footnote 171
Interesting developments regarding opinio juris have occurred over the last few years. In 2019, the Estonian president publicly endorsed third-party countermeasures: ‘Estonia is furthering the position that States which are not directly injured may apply countermeasures to support the State directly affected by the malicious cyber operation’.Footnote 172 In 2023, Poland expressed ‘the view that the evolution of customary international law over the last two decades provides grounds for recognising that a State may take countermeasures in pursuit of general interest as well’, adding that States may adopt these measures in response to aggression.Footnote 173 Ireland, Costa Rica and Italy have also expressed support for their permissibility.Footnote 174 New Zealand has been cautiously open to the idea but non-committal.Footnote 175
In contrast, the French Government has asserted that ‘[c]ollective counter-measures are not authorised’,Footnote 176 and the US appears reluctant to endorse third-party countermeasures. As noted by Jackson and Paddeu, while the US has ardently supported Ukraine and condemned Russia’s aggression, it has adopted the rather unique position of claiming that it is an injured State under Article 42 ARSIWA, stating it is affected by Russia’s aggression by being one of Ukraine’s allies ‘who have bankrolled its economy and military during the war’.Footnote 177 This sleight of hand purportedly allows the US to adopt countermeasures under Article 49 ARSIWA, and avoid the debate on countermeasures adopted by States other than the directly injured State. Canada has rejected third-party countermeasures, stating that it ‘has considered the concept of “collective cyber countermeasures” but does not, to date, see sufficient State practice or opinio juris to conclude that these are permitted under international law’.Footnote 178 This position is rather unclear: is it disputing third-party countermeasures in general or only in the context of cybersecurity (as suggested by the statement)? The same question could also be raised in relation to Estonia’s statement quoted in the previous paragraph. China has stated that there is disagreement over whether ‘measures taken by States other than an injured State’ are lawful.Footnote 179 Jackson and Paddeu also note that Algeria, Denmark, Russia, the UK and the Netherlands have expressed uncertainty, noting that the question remains unsettled.Footnote 180 The position of the Netherlands however appears to have evolved since Russia’s aggression. The Dutch Advisory Committee on Questions of International Law recommended that the Netherlands may adopt third-party countermeasures in response to serious breaches of international law,Footnote 181 which the Dutch Government endorsed in April 2024.Footnote 182 In essence, while it remains difficult to come to a clear conclusion, there have been some shifts in favour of third-party countermeasures in recent years.
Some may suggest that it is time to move on and simply accept third-party countermeasures. However, this is a rather one-sided perspective that favours the policy of a minority of States and serves to legitimise a practice that is still hotly contested by a large number of States.Footnote 183 The response to the wars in Ukraine and Gaza illustrates that States do not agree on how third parties should respond to disputes, even when a peremptory norm is at stake. For example, Brazil and China have preferred to remain neutral and have abstained from adopting sanctions, arguing that dialogue between Russia and Ukraine should be promoted to reach a peace agreement.Footnote 184 In February 2022, while the US and the EU announced the adoption of sanctions against Russia, Brazil, Bolivia, Kenya and Syria expressed reservations and called for caution.Footnote 185 A few months later, during another Emergency Special Session before the UNGA, Bangladesh stated: ‘we believe that antagonism, like war, economic sanctions or countermeasures cannot bring good to any nation. Dialogue, discussion and mediation are the best ways to resolve disputes’.Footnote 186 This is not to say they do not consider Russia’s behaviour unlawful, but that they find the dispute should be resolved by other methods. That said, States that contest unilateral sanctions are also inconsistent. While the most ardent sanction senders have withheld from sanctioning Israel, Malaysia, which has reportedly stated that it does not recognise unilateral sanctions,Footnote 187 banned ships under the Israeli flag from entering its ports in response to ‘the ongoing massacre and brutality against Palestinians’.Footnote 188 Under the law of the sea, this would be considered a retorsion, but it could also raise questions under the prohibition of discrimination.Footnote 189
Finally, the argument could be made that there are instances of implicit opinio juris because sanctioning States have arguably adopted prima facia wrongful restrictions. Section 5.2 argues that opinio juris should not be inferred from State practice and should be assessed separately.
5.2. Assessing opinio juris separately from practice
It could be argued that as there are instances of prima facie unlawful sanctions adopted in response to breaches of obligations erga omnes (partes), there is implicit opinio juris that third-party countermeasures are permitted. An example of this is the EU’s airspace ban against Russian air carriers and a series of other aviation restrictions against Russia.Footnote 190 In response, Russia adopted a series of counter-sanctionsFootnote 191 and filed a complaint over the restrictions before the International Civil Aviation Organization (ICAO), arguing that they breach the Chicago Convention on International Civil Aviation (Chicago Convention).Footnote 192 A plausible argument could be made that the restrictions against Russia constitute a form of discrimination in violation the of Chicago Convention. While Article 9 Chicago Convention permits States to ‘restrict or prohibit uniformly the aircraft of other States from flying over certain areas of its territory’ in cases of military necessity, public safety or an international emergency, such measures cannot single out one State in particular. It remains to be seen if EU Member States will invoke the third-party countermeasure argument before the ICAO Council, which, as noted above, they have thus far refrained from doing. It is also clear from the above that there are differences of opinion among EU Member States on the legality of collective countermeasures.
Studies that have found that third-party countermeasures are accepted under customary international law while acknowledging that opinio juris is lacking have argued that the mental element can be inferred from practice.Footnote 193 The sending States believe that their sanctions constitute third-party countermeasures without stating so explicitly. Tams’ analysis is based ‘on the assumption that in absence of specific indications to the contrary, the conduct of States will be based on the accompanying legal conviction; opinio juris can thus usually be inferred from State practice’.Footnote 194 Tams and Dawidowicz find that there is no evidence suggesting that States do not believe that their conduct cannot be legally justified, or that they only base their action on moral or political grounds.Footnote 195 It is also argued that politically motivated conduct does not mean that opinio juris is lacking: ‘While [the] decision to resort to countermeasures (as opposed to other forms of response) might have been influenced by political considerations, their assessment of the underlying dispute was legally relevant’.Footnote 196 Dawidowicz references Ian Brownlie’s ‘burden of proof argument’Footnote 197 to justify that opinio juris can be inferred from State practice: ‘in absence of any antecedents to the contrary, the [ICJ] has presumed that a uniform conduct of States is accompanied by the relevant opinio juris’.Footnote 198 This is slightly ironic if Brownlie’s reaction to draft Article 54 [2000] during the ILC debates is considered:
In reality, Article 54 constituted neither the law nor its potential progressive development. Progressive development related to some existing foundations, but practice was inconsistent in the extreme. … In addition to that inconsistent practice, there was no evidence of an opinio juris in the material. … In reality, Article 54 was not about countermeasures: it was about sanctions, it was incompatible with the Charter and it was neither lex lata nor lex ferenda. Perhaps a new category would need to be invented for it: lex horrenda.Footnote 199
This article argues that, as one of the constituent elements of customary international law, opinio juris needs to be treated separately from State practice. To assume that a general and established State practice necessarily means that the States responsible for the conduct believe that they are acting legally would mean that the mental element is superfluous. While this approach has been advocated by legal scholars,Footnote 200 to simply infer opinio juris from State practice would amount to double countingFootnote 201 and mean that the same weight would not be given to each constitutive element, an approach that was rejected by the ILC in draft Conclusion 3(2) of its ‘Report on Identification of Customary International Law’, which provides that: ‘Each of the two constituent elements is to be separately ascertained.’Footnote 202 This may be considered a formalistic or unrealistic approach to custom, but as discussed throughout, opinio juris can assist in preventing unwanted State practice from becoming custom,Footnote 203 which makes it especially useful when practice is ambiguous. In Nicaragua v Colombia, the ICJ inferred State opinio juris from practice: ‘The Court considers that the practice of States … is indicative of opinio juris, even if such practice may have been motivated in part by considerations other than a sense of legal obligation’.Footnote 204 In that case, the Court found that practice was sufficiently widespread and uniform, and had taken place over a long period of time so as to justify proceeding by induction.Footnote 205 While the approach taken was not without controversy,Footnote 206 if it were applied in assessing whether third-party countermeasures are custom, it would not assist as sanctions practice is neither widespread, consistent nor uniform. Furthermore, States’ reluctance to confiscate Russian State assets shows that there are instances of States refraining from adopting potentially unlawful restrictions, which could indicate they do not believe third-party countermeasures are permitted.
As has also been seen, most actors have refrained from explicitly justifying their sanctions as third-party countermeasures when given the opportunity. It is true that ‘it is a general feature of practice that States reacting to a violation of international law will “only reluctantly” officially qualify their reaction as a countermeasure or “reprisal”’.Footnote 207 Nonetheless, States have been given the opportunity to qualify their reactions during debates before the UNGA Sixth Committee and other international fora, as discussed above. States whose own practice gave rise to the ILC’s inclusion of draft Article 54 [2000] suggested that the provision be changed to a saving clause. Doctrine should be critical of the fact that these States were unwilling to formally express support for the adoption of third-party countermeasures in response to violations of obligations erga omnes (partes). Their attitudes could be interpreted as a ‘deliberate withholding of consent’ that their own practice be recognised as law.Footnote 208 This ‘withholding of consent’ brings to mind the ICJ’s judgment in North Sea Continental Shelf. Denmark and the Netherlands alleged that the Federal Republic of Germany’s conduct amounted to acceptance of the equidistance method, yet it had not ratified the Geneva Convention on the Continental Shelf of 1958. This element was of importance to the Court, which indicated that:
[I]f there had been a real intention to manifest acceptance or recognition of the applicability of the conventional régime then it must be asked why it was that the Federal Republic did not take the obvious step of giving expression to this readiness by simply ratifying the Convention.Footnote 209
Under these circumstances, the fact that opinio juris is absent is all the more significant. In conclusion, practice is too ambiguous to forego the assessment of States’ ‘legal beliefs’ when assessing whether third-party countermeasures are considered custom.
6. Concluding remarks
James Crawford once wrote: ‘nowadays it seems that international law develops more rapidly than international society does’.Footnote 210 This aptly captures the disconnect between the development of obligations in the collective interest and the lack of means available to States to respond to their breach. The question of enforcement has always been subject to discussion and led to questions of international law’s effectiveness, but its lack becomes even more glaring when it comes to responding to breaches of obligations in the collective interest. State practice (especially that of the EU and the US) is clear that unilateral sanctions can be considered a tool of enforcement, yet they are unclear about where their own measures lie under international law and reactions from other States illustrate that the matter is contested.
Although unilateral sanctions have flourished and doctrine has suggested that third-party countermeasures are permitted under customary international law, this article has argued that practice is too ambiguous and opinio juris too absent to reach this conclusion with confidence. In order to substantiate this argument, the analysis returned to the origins of the debate that occurred while the ILC was drafting ARSIWA. Focusing on the reactions of States to the inclusion of third-party countermeasures in ARSIWA, it argued that Special Rapporteur James Crawford was correct to opt for a saving clause in the final text. Many States were concerned that collective countermeasures would lead to abuse and raised questions over how unilateral reactions could be reconciled with UNSC sanctions. Even States that were in favour of including collective countermeasures wondered how they should be regulated. Many of the issues surrounding the adoption of third-party countermeasures remain valid today. Since the ILC wrapped up the codification of State responsibility, sanctions practice has proliferated and so too have legal ambiguities.
To conclude, the present author considers that third-party countermeasures are currently not permitted under customary international law, due to issues in establishing the two constitutive elements of customary international law. As Paddeu notes, ‘most analyses of customary law will be subject to varied methodological critiques’,Footnote 211 and the reader may object that the approach advocated here is too rigid, or that expectations may be unrealistic. Nonetheless, it is the author’s view that it is not the responsibility of doctrine to justify State conduct. If actors are genuinely committed to enforcing obligations erga omnes (partes) through third-party countermeasures, they should engage with international law and provide legal clarity. That being said, it is acknowledged that a gradual shift may be underway. In the wake of Russia’s aggression against Ukraine and in the context of ongoing deliberations on cyberattacks, States are tentatively accepting collective countermeasures. Considering that political positions can lead to legal developments, it remains to be seen which view will prevail.
Acknowledgments
Part of this research was conducted at UGent (Ghent, Belgium) when the author was completing their PhD. The manuscript was then finalised at Utrecht University. The author wishes to thank the anonymous reviewers for their feedback, which improved the piece greatly. All errors remain the author’s own.
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