The right of injured states to take countermeasures is subject to several substantive and procedural conditions that seek to limit abuse. These same conditions apply in cyberspace.
Background
Countermeasures are responses to a prior breach of international law. As a defence, they preclude the wrongfulness of acts that would otherwise violate international law. Their aim is to induce a state that has breached international law – ‘the responsible state’ – back into compliance with its obligations to stop the breach, if it is still ongoing, and/or repair any damage caused.
There is little debate that states injured by a breach of international law are entitled to take countermeasures against the responsible state under customary international law. This practice dates back to the 1800s, though the term ‘countermeasures’ only gained popularity in the late 1970s to early 1980s. The right of injured states to take countermeasures has been reaffirmed in recent international judgments and arbitral awards. Notably, in the Air Services Agreement case between France and the US, the arbitral tribunal held that:
The International Court of Justice (ICJ) also confronted the issue in the 1997 Gabčikovo-Nagymaros Project case. The court had to determine whether the wrongfulness of the river Danube’s diversion by what was then Czechoslovakia had been ‘precluded on the ground that the measure […] was in response to Hungary’s prior failure to comply with its obligations under international law’. While, on the facts, the court ruled that ‘the diversion of the Danube carried out by Czechoslovakia was not a lawful countermeasure because it was not proportionate’, it did not question the right of injured states to take such measures. Likewise, in the Tehran Hostages case, the ICJ took note of the US’s right to resort to countermeasures against Iran’s wrongful acts. Iran had endorsed the actions of militants who took over the US embassy in Tehran and held American and other foreign citizens hostage for 444 days from 4 November 1979 to 20 January 1981.
The International Law Commission (ILC) – a UN General Assembly (UNGA) subsidiary body of 34 experts set up to make recommendations on the progressive development and codification of international law – has since 1953 examined the topic of countermeasures as part of its work on state responsibility. The right of injured states to take countermeasures is recognized in Article 49(1) of the Articles on State Responsibility for Internationally Wrongful Acts (‘the Articles’, ‘ILC Articles’), which is generally considered to reflect customary international law:
Between the mid-1990s and early 2000s, some developing countries ‘voiced their opposition to countermeasures and to their inclusion in the draft articles’. However, with a few exceptions, such as Brazil and Uruguay, state objections were grounded on reasons of policy rather than law. For example, some of the concerns expressed against countermeasures were that they were ‘archaic’, ‘favouring more powerful States’ to the detriment of ‘small and weak States’. Most states that commented on the Articles on State Responsibility during their drafting accepted that countermeasures were part of customary international law. The same level of support has been voiced at the UNGA’s Sixth Committee, which has been considering the topic of state responsibility triennially since 2004. The ILC Articles are now the primary point of reference for the customary international law rules on countermeasures.
However, there is some debate about the extent to which the substantive and procedural conditions for taking countermeasures set out in Articles 49 to 53 of the Articles reflect customary international law and are thus binding on all states. These conditions reflect a difficult compromise between the need to ensure a sufficiently strict regime (to prevent abuse and conflict escalation) and the injured state’s right to bring internationally wrongful acts to an end.
During the drafting of the Articles, many states questioned or opposed some of the conditions proposed by the ILC. For example, as early as 1992, Bahrain noted that ‘there was a lack of consensus among members of the ILC on several of the conditions stipulated in [the draft]’. Comments by the Czech Republic and Ireland on the 1997 draft took note of the controversies surrounding countermeasures at the ILC, suggesting that at least some of the procedural conditions were a progressive development. Singapore made similar comments, arguing that some of the conditions should not have been included in the Articles. Similarly, for the US, beyond necessity and proportionality, the conditions for the taking of countermeasures were ‘far from clear’ and ‘not supported under customary international law’.
International courts and tribunals have identified several conditions to which countermeasures are subject. Examples include the existence of a prior breach of international law, a requirement of prior demand to stop and/or repair the breach, a notification, including a protest and an offer to settle the dispute, proportionality, necessity, reversibility, and temporariness. However, these have not been sufficiently fleshed out in the practice of states or subsequent case law. Recent academic works on the topic are also scarce, especially in the English language.
While most would agree that the general rules on countermeasures apply in cyberspace, debates about the conditions applicable under customary international law have resurfaced in the cyber context. On the one hand, some have cautioned that recourse to countermeasures in cyberspace may increase the risk of confrontation, therefore calling for strict compliance with those conditions. Others have argued that countermeasures can actually reduce the risk of an arms race in cyberspace and that their conditions should be interpreted more flexibly to accommodate certain operational considerations arising in the cyber context. These include the need to maintain the confidentiality of cyber capabilities and to respond rapidly and efficiently against cyberthreats. The key question is then how the conditions for taking countermeasures apply in the cyber context. To answer this question, one ought to consider not only whether the customary international law on countermeasures can be read in light of cyber-specific considerations but also whether the law has evolved generally or specifically for cyberspace.
Against this backdrop, the aim of this chapter is to ascertain the substantive and procedural requirements for the taking of countermeasures in general and discuss how they apply in the cyber context. This includes consideration of whether the conditions proposed by the ILC in Articles 49 to 53 of the Articles on State Responsibility reflect customary international law, taking into account the available evidence of state practice and opinio juris, the documents produced by the ILC, international jurisprudence and legal scholarship. The views of different states on the applicability of countermeasures in cyberspace are also relevant and will thus be considered.
Substantive conditions
Proper purpose
Before and during the drafting of the ILC Articles, there was some debate about the purpose of countermeasures. Most ILC members and state representatives agreed that they were simply aimed at reinstating compliance with international law. There have been suggestions that, like reprisals, countermeasures also have a punitive purpose. But there is now general agreement that the purpose of countermeasures is not to punish the wrongdoing state, even if, in practice, it may be difficult to distinguish between retaliatory and restorative measures. Thus, Article 49(1) of the ILC Articles stipulates that:
The ‘obligations under part two’ of the ILC Articles arise for the responsible state as a result of carrying out an internationally wrongful act. These obligations are: i) to cease the act, if it is continuing (‘cessation’), ii) to offer assurances and guarantees of non-repetition, if the circumstances so require, and iii) to make full reparation for the injury caused by the internationally wrongful act, including by providing restitution, compensation or satisfaction (such as an expression of regret or acknowledgment of the breach). Given the subsidiary role of assurances and guarantees of non-repetition as well as satisfaction in the spectrum of reparation, questions have been raised as to whether those remedies can be enforced by means of countermeasures. According to the ILC, this depends on whether the countermeasures taken to induce the responsible state to offer assurances and guarantees of non-repetition or satisfaction are proportionate with the injury suffered, as discussed below. In any event, cessation and/or reparation are the primary remedies sought by countermeasures and this paper will focus on them.
An important question is whether the purpose of countermeasures is strictly limited to inducing or procuring compliance by the responsible state or also extends to the direct implementation of the obligations of cessation and/or reparation by the injured state itself, in substitution for the responsible state. In the past, reprisals ordinarily involved such direct action, including the use of force. However, since reprisals are now generally prohibited except in limited circumstances during armed conflict, there has been some debate about whether countermeasures can involve direct non-forcible action.
This debate has gained traction because new technologies, including ICTs, have enabled injured states to take direct action to stop and/or repair a breach of international law remotely, that is, without having to engage in kinetic or physical action in the territory of the responsible state. An example is that of defensive cyber operations carried out remotely to disable the computer systems or networks from which an unlawful ICT operation originates – known as a ‘hack back’. A state may also take direct action by failing to make payments otherwise due to the responsible state.
The text of Article 49 of the ILC Articles does speak of countermeasures as measures taken by the injured state ‘only […] in order to induce’ the responsible state to comply with its obligations of cessation and reparation. However, it is not a stretch of language to interpret ‘to induce’ as including ‘to obtain’ or ‘to secure’ compliance with international law. This language was used by several states in their comments on the Articles at the ILC or the Sixth Committee.
Direct action can be a form of inducement and, sometimes, the only way to get another state to comply with international law. Countermeasures are inherently coercive and there is little difference between coercing a state to do something by direct or indirect action. In some cases, it can be difficult if not impossible to draw a line between both types of action. For example, the injured state may want to direct restrictive measures against foreign assets as a form of inducement or to stop those assets from being used to commit the wrongful act.
ILC reports have also treated direct and indirect countermeasures as equivalent in nature. For some states, this is why the proposed distinction between countermeasures and so-called ‘interim measures of protection’ (i.e. urgent countermeasures taken without prior notice or an offer to negotiate) had to be dropped from the final version of the Articles.
For those reasons, countermeasures may arguably take the form of direct or indirect action, provided that they seek to induce compliance with international law and fulfil all the other conditions for the taking of countermeasures under customary international law, discussed below.
Prior internationally wrongful act by a state
The commission of an internationally wrongful act by a state is an unequivocal condition for the taking of countermeasures. Countermeasures are, by definition, a response to a prior breach of international law attributable to another state. There is some debate as to whether this should be assessed by objective or subjective criteria. The question is whether it suffices that the state taking countermeasures reasonably believes that it is responding to an internationally wrongful act or whether such an act must have objectively occurred. The ILC makes it clear that, like the other conditions for taking countermeasures, the existence of a prior internationally wrongful act must be assessed objectively. A state decides to take countermeasures at its own risk and may be responsible for a breach of international law if it turns out that the act to which it responded was not unlawful. There are suggestions that, if a state acted in good faith, this might be a mitigating factor in assessing its responsibility.
Whether a cyber operation constitutes a breach of international law will depend on i) the attribution of the conduct to a state; and ii) how the primary rules of international law governing state conduct apply to the facts in question. Attribution raises distinct legal, technical and political challenges in cyberspace, especially because many cyber operations are covert and difficult to trace. International law does not dictate the types of evidence required nor does it impose on states a duty to disclose their evidence. But caution is warranted to avoid misattribution and spillover effects on innocent parties, which are particularly common in cyberspace.
The high speed and large scale at which cyber operations can occur might mean that a careful attribution assessment will not always be possible. On this basis, Finland has posited that ‘it may be possible to attribute a hostile cyber operation only afterward whereas countermeasures normally should be taken while the wrongful act is ongoing.’ Although the policy concerns behind this statement might resonate with many, prior attribution remains an indispensable requirement for the taking of countermeasures – online and offline.
This also means that countermeasures may not be taken in anticipation of an internationally wrongful act – the act must have objectively occurred. Nevertheless, certain cyber operations are so instant and so interconnected that they may be seen collectively as a part of a single internationally wrongful act. An example might be a distributed denial-of-service (DDoS) attack, which is a composite cyber operation made up of different, smaller attacks against an IT system, such as a database or a website. In those instances, a forthcoming unlawful cyber operation might be considered as part of a continuing wrongful act and, depending on the circumstances, a state might be entitled to respond to such an operation by resorting to countermeasures of a cyber or non-cyber nature. Relevant factors include whether the unlawful operations are carried out by the same state, as well as their temporal and causal proximity.
Directed at the responsible state
As a reactive mechanism seeking to induce compliance by a state in breach of international law, countermeasures must by definition be directed against the responsible state – not third parties, whether states or non-state actors. This is so even if the actions of private entities would amount to an internationally wrongful act if committed by a state. This means that, when taking countermeasures, the injured state may only breach obligations it owes to the responsible state: the wrongfulness of the measure is only precluded in the relationship between the injured and the responsible state. The injured state will be responsible for any breaches of the obligations it owes to third parties when taking countermeasures against the responsible state.
It is possible that the effects on third parties are unforeseeable or otherwise too remote from the action taken by the injured state. In this case, there may be no causal link between the conduct of the injured state and the result, such that the obligation owed to the third party might not even be breached. This will depend on the facts and applicable standards of causation, where relevant.
It may also be that the internationally wrongful act was in fact carried out by a private entity whose conduct can be attributed to a state. In this case, the injured state may direct its countermeasures against the private entity’s activities or property, which, by application of the customary international law rules on attribution, will be considered as those of the responsible state.
It is a separate question whether countermeasures incidentally affect the position or the interests of other states or non-state actors, without violating their rights. An example is when foreign trade restrictions affect businesses and individuals based in the responsible or a third state. Such collateral or indirect effects are very common. This is especially so in cyberspace, given the interconnectedness of ICTs and the prominent role of private actors, which own or operate the majority of cyber technologies and infrastructure – including hardware, software and data. For instance, if the responsible state is using private property (such as a server or computer device) to commit a wrongful cyber operation, the injured state’s countermeasures may affect those devices or other privately-owned infrastructure in order to induce the responsible state to stop and/or repair the wrong. As long as the countermeasures do not violate the prohibitions laid down in Article 50 of the ILC Articles, assessed below, the injured state cannot be held responsible for incidental effects on third parties.
Temporary nature
According to Article 49(1) of the ILC Articles, ‘[c]ountermeasures are limited to the non-performance for the time being of international obligations of the State taking the measures towards the responsible State’. Countermeasures are a means to induce the state in breach of an international obligation to stop and/or repair that breach. Their aim is to restore the status quo ante – the state of affairs or ‘condition of legality’ – between the injured and the responsible state that had been in place before the breach. To do so, the injured state violates an obligation owed to the responsible state. Once compliance is achieved, this is no longer necessary. As such, countermeasures are temporary or provisional in character. Even though their duration may vary significantly as may be necessary to achieve their purpose, countermeasures must not be permanent.
Reversibility as far as possible
According to Article 49(3) of the ILC Articles, ‘[c]ountermeasures shall, as far as possible, be taken in such a way as to permit the resumption of performance of the obligations in question’. As seen earlier, countermeasures must be temporary in nature, i.e. they must be withdrawn as soon as the responsible state complies with international law. However, their effects need only be reversible as far as possible. This is because it may be impossible to reverse some of the effects of countermeasures. For example, the suspension of aviation or investment obligations may cause irreparable loss of revenue or reputational harm. Furthermore, measures with easily reversible effects are not always available to states.
States are only required to take countermeasures with reversible effects if these are available to them in the first place. This means that, if the injured state has a choice between a number of effective measures one of which produces reversible effects, it must select the latter. But this does not require injured states to select the measure with the most reversible effects among those available.
The argument has been made that, because asset seizure or confiscation may have a ‘more definite impact’ or irreversible consequences, it is not a lawful countermeasure, including in response to Russia’s full-scale invasion of Ukraine. Similar claims might be made with respect to cyber countermeasures that cause permanent destruction of property belonging to or otherwise used by the responsible state. However, the ILC Articles do not require absolute reversibility of the effects of countermeasures but only reversibility ‘as far as possible’. In any event, asset seizure is not necessarily permanent nor irreversible in its effects, as is usually the case of other financial measures. This will depend on the facts, including the domestic legal system in question. At least in theory, the state taking the countermeasure may revoke the asset seizure and return the goods or repay the cash seized upon compliance by the responsible state.
Measures that are difficult or impossible to reverse, such as asset seizure, can be more coercive and thus more effective than easily reversible ones, such as asset freezing. This is true in the context of the war in Ukraine, where confiscation, in the view of many, would allow for the immediate use of the funds to repair, mitigate and prevent the harms arising from Russia’s wrongful actions. But irreversible measures may be less conducive to restoring the status quo ante between the injured and the responsible state, and could easily amount to punishment. Therefore, caution is needed when assessing whether, in each case, confiscation meets the proper purpose of countermeasures and is proportionate to the prior wrong.
Necessity?
The fact that countermeasures are coercive has prompted suggestions that they are an exceptional course of action or a measure of last resort. Similarly, an argument has been made that countermeasures are subject to a self-standing requirement of necessity. For some, this would mean that countermeasures are only lawful if other, less serious, means of securing compliance with international law, such as dispute settlement mechanisms, are unavailable.
Some states also seem to have treated necessity as a separate requirement for countermeasures in the cyber context, though it is unclear what they mean by that. For example, the US has argued that ‘countermeasures […] must meet the requirements of necessity and proportionality’. Similarly, Denmark has stated that ‘[c]ountermeasures must be necessary and proportionate’.
Countermeasures are a circumstance precluding wrongfulness and, in this sense, the exception rather than the rule. Furthermore, given their inherently coercive nature, they do carry a risk of jeopardizing friendly relations between states and worsening a dispute. Nonetheless, countermeasures are also a right of the injured state, allowing it to protect the rights that have been violated by the responsible state.
There is no indication in the ILC Articles that ‘necessity’ is a separate requirement for the taking of countermeasures under customary international law. Rather, necessity is an expression of the need for countermeasures to comply with their purpose of inducing compliance with international law. If a countermeasure cannot achieve this aim – either because it is no longer possible to stop the breach or because the relevant measure cannot induce the responsible state to offer reparation for the injury caused – then it is not necessary and, on this basis, unlawful.
Necessity is also an expression of the principle of peaceful settlement of disputes, which binds all states under customary international law and limits recourse to countermeasures. This principle requires states to attempt to resolve their disputes peacefully. Whether countermeasures might endanger international peace and security and are thus necessary in this sense can only be assessed on a case-by-case basis.
Proportionality
The requirement that countermeasures be proportionate to the injury suffered is firmly grounded in customary international law and set out in Article 51 of the ILC Articles. Proportionality means that countermeasures must be commensurate with or somewhat equivalent to the injury suffered. While this does not require reciprocity, countermeasures are more likely to meet their purpose and be proportionate if taken in relation to the obligation breached or a closely related one.
Thus, the injured state may respond by engaging in the non-performance of one or more obligations owed to the responsible state that are different or unrelated to the original breach. For example, a state may decide to take countermeasures of an economic nature in response to a breach of an environmental obligation. Similarly, it may take cyber countermeasures in response to non-cyber wrongs and vice versa.
When assessing the proportionality of a countermeasure, states must consider the gravity of the internationally wrongful act and the importance of the rights at stake, including the rights of the injured and the responsible state(s). The rights or position of third states affected by the measures in question may also be taken into account.
The assessment of the proportionality of countermeasures is thus flexible. It calls for both a quantitative evaluation of the effects of the breach on the injured state (i.e. the extent of the injury) as well as a qualitative weighing of the importance of the various rights in question and the gravity of the breach. The qualitative component is particularly significant in cyberspace. This is because it is often difficult to compare and quantify harms caused to or through ICTs, especially non-physical harms such as data breaches.
While there is agreement that assessing the proportionality of countermeasures can only be made ‘by approximation’, there has been some debate about how much leeway injured states enjoy. One view is that proportionate countermeasures are those that are not excessively disproportionate to the breach. Another approach, now reflected in Article 51 of the ILC Articles, is that proportionality requires greater equivalence between the countermeasures and the prior wrong. Under this approach, injured states have less latitude in their choice of measures that could be deemed proportionate.
Either way, proportionality is not an exact science and includes both subjective and objective elements. Because countermeasures are measures of self-help, it is for the injured state, in the first place, to evaluate the proportionality of its measures. At the same time, the injured state is responsible for any consequences of disproportionate countermeasures. Whether this has been the case must be assessed by the affected state(s) or a dispute settlement body on the basis of the facts at hand, taking into account the circumstances of the injured state at the time the measures were taken.
ICTs are pervasive and interconnected, which means that assessing the proportionality of cyber countermeasures can be particularly challenging. Cyber operations may easily spill over into unintended targets, causing significant collateral effects on third parties, including states and non-state actors. For example, malware can ‘spread uncontrollably’. This means that, in the cyber context, there is a significant risk of unforeseen consequences. Accordingly, assessing both the quantitative and qualitative components of proportionality in cyberspace should demand a higher degree of precaution. This includes thinking way ahead in terms of possible consequences of the cyber operation deployed as a countermeasure.
Some states, such as the US, Ireland and Japan, have taken the view that the necessity or purpose of a countermeasure (i.e. to induce compliance with international law) should be taken into account as part of the proportionality assessment. In this view, countermeasures need not be commensurate with and might be more serious than the original breach if acting in such a way is necessary to induce the responsible state to stop and/or repair the wrong. In the cyber context, this approach seems to have been endorsed by the experts involved in the drafting of the Tallinn Manual 2.0 and by Denmark in its position paper on the application of international law in cyberspace. Austria has gone even further by suggesting that necessity rather than proportionality should be the ‘true criterion’ to ensure that countermeasures are not punitive. However, other states have rejected this view. It is also contrary to the position taken by the ILC, according to which:
Necessity and proportionality are not unrelated. Disproportionate countermeasures are unlikely to be necessary. Moreover, the necessity of taking a countermeasure will inevitably affect the choice of means employed by the injured state. But necessity and proportionality should not be conflated in this context. Necessity is not about the extent of a particular countermeasure (i.e. what actions are necessary to achieve a countermeasure’s purpose). It is about whether the very taking of countermeasures is needed in the circumstances, i.e. whether resorting to countermeasures achieves the purpose of inducing compliance with international law. Making proportionality dependent on necessity would not only distort the meaning of both necessity and proportionality; it could also legitimize excessive or punitive countermeasures and in turn increase the risk of conflict escalation, contrary to the principle of peaceful settlement of disputes.
Obligations not affected or prejudiced by countermeasures
Article 50 of the ILC Articles lists several obligations that must not be ‘affected’ by countermeasures (paragraph 1) as well as obligations that states are ‘not relieved from’ when taking countermeasures (paragraph 2). The obligations listed in Article 50(1) are of a fundamental nature and therefore have primacy over a state’s right to take countermeasures. Those listed in Article 50(2) have the important function of keeping channels of communication open between states.
The prohibition on the use of force
The first rule that may not be affected by countermeasures under Article 50(1)(a) of the ILC Articles is the prohibition on the use of force. This means that countermeasures must not be forceful. The prohibition on the use of force is a rule of jus cogens, i.e. a peremptory rule of international law from which no derogation is permitted. It applies both to threats and actual uses of military force, including minimal ones. Thus, cyber operations that amount not only to an armed attack but also lower-level uses of force cannot be used as a countermeasure.
Fundamental human rights
Article 50(1)(b) stipulates that ‘countermeasures shall not affect […] obligations for the protection of fundamental human rights’. This provision seeks to avert the consequential effects of countermeasures on ‘fundamental human rights’, such as in the case of economic blockades affecting the most vulnerable groups within the responsible state’s population.
There is controversy about the meaning and scope of ‘fundamental human rights’, as articulated by the ILC. It is generally accepted that countermeasures cannot affect human rights that are i) jus cogens (e.g. the prohibitions of slavery and racial discrimination), ii) absolute (e.g. the prohibition of torture), or iii) non-derogable (e.g. the right to life). The disagreement is about whether (and, if so, which) other human rights are ‘fundamental’. The concept was borrowed from Article 1(3) of the UN Charter, but the ILC commentary to the Articles does not explain what it means.
Nevertheless, the ILC did seem to accept that ‘fundamental rights’ are not limited to civil and political rights but could also encompass economic, social and cultural rights, at least in some circumstances. This, coupled with the origin of the term (the UN Charter), might suggest that all human rights recognized in international or regional instruments are, in principle, fundamental. They are fundamental for the full realization of human dignity, for example.
A related question is the extent to which fundamental human rights are protected from the effects of countermeasures. While there have been suggestions that states must refrain from countermeasures that would affect individuals or cause incidental harm beyond their existing human rights obligations, this view remains contested. At the same time, it would be inconsistent with the purpose of Article 50(1)(b) of the Articles and the very definition of countermeasures if states were allowed to take countermeasures that would breach their existing human rights obligations, irrespective of the characterization of the rights in question.
To be sure, states cannot target individuals or their human rights when taking countermeasures – as seen earlier, countermeasures must be directed at the responsible state. But even when countermeasures are aimed at the responsible state, this does not preclude the wrongfulness of incidental breaches of human rights obligations. The effect of countermeasures is relative: they only preclude the wrongfulness of breaches of obligations owed to the responsible state, not third states or non-state actors. Importantly, human rights obligations are owed not just to individuals or the responsible state but to all states parties to the relevant treaty, or the international community as a whole in the case of human rights obligations under customary international law. As noted by former ILC special rapporteur James Crawford, this is the very rationale for protecting non-derogable human rights from the effects of countermeasures. This reasoning applies equally to other human rights that states are bound to respect, protect and ensure, and that could be breached in the course of taking countermeasures. Furthermore, human rights obligations already accommodate different types of exceptions, including lawful derogations and limitations. Thus, countermeasures can be taken consistently with human rights even when they indirectly affect individuals at home or abroad.
In this light, it is arguable that the concept of ‘fundamental human rights’ limits the effects of countermeasures insofar as human rights obligations i) bind the injured state; ii) fall within its jurisdiction; and iii) would be violated by the state taking the countermeasures. A violation of human rights obligations would occur, for example, when the injured state applies human rights exceptions or limitations inconsistently with the requirements laid out for each human right in treaties or customary international law. Limitations on human rights could be unlawful if they are not grounded in law or are otherwise arbitrary, such as when they are unnecessary or disproportionate.
Therefore, what seems to matter is not so much which human rights are characterized as fundamental. The key question is whether, in the circumstances, the effects of countermeasures would amount to a breach of the injured state’s binding obligations to respect, protect or ensure the enjoyment of particular human rights. If a state cannot justify the taking of countermeasures as a lawful derogation or limitation to its human rights obligations, then its actions will likely be unlawful.
States must respect, protect and ensure human rights online and offline. In the cyber context, the human rights most likely affected by countermeasures are the rights to privacy and to freedom of expression. Countermeasures involving electronic surveillance of private data or restrictions on online content must be justified under the terms of the relevant human rights obligations if they are to be lawful. The rights to life and health are also increasingly dependent on ICTs for their full realization and may be affected by cyber operations targeting hospitals and other healthcare providers.
The prohibition of belligerent reprisals
Article 50(1)(c) of the ILC Articles also limits recourse to countermeasures when they would involve belligerent reprisals against individuals. Such measures are prohibited under international humanitarian law.
Other rules of jus cogens
Article 50(1)(d) also prohibits recourse to countermeasures that would affect other rules of jus cogens, which include the prohibition of genocide, slavery, apartheid and racial discrimination.
Dispute settlement obligations
Under Article 50(2)(a) of the ILC Articles, the taking of countermeasures is also limited when the injured state is bound by a specific obligation to submit the dispute with the responsible state to a dispute settlement procedure. This is justified by the principle of lex specialis, i.e. more specific obligations prevail over more general ones. One example of a provision requiring injured states to submit disputes to a specific dispute settlement mechanism is found in the World Trade Organization (WTO) agreements.
Consular and diplomatic inviolability
According to Article 50(2)(b) of the ILC Articles, when resorting to countermeasures, states must respect the inviolability of consular and diplomatic agents, premises, archives and documents. This limitation is justified by the self-contained nature of the diplomatic and consular law regimes, which provide for their own remedies against wrongdoing. It also seeks to guarantee the physical safety and inviolability of protected persons and objects as well as to ensure that open channels of communication remain open between states.
Procedural conditions
Prior demand
Article 52(1)(a) of the ILC Articles states that, before taking countermeasures, ‘an injured State shall […] call upon the responsible State, in accordance with article 43, to fulfil its obligations’ of cessation and/or reparation. Known as ‘prior demand’, ‘intimation’ or ‘sommation’, this procedural condition has been widely accepted, at least as a matter of principle, in the practice of states, decisions of international courts and tribunals, and scholarly writings. For example, the arbitral tribunal in the Naulilaa case held that reprisals were not lawful unless they were preceded by an ‘unfruitful sommation’. Likewise, in the Gabčíkovo-Nagymaros Project case, the ICJ held that, for countermeasures to be lawful, ‘the injured state must have called upon the state committing the wrongful act to discontinue its wrongful conduct or to make reparation for it.’
According to former ILC special rapporteur James Crawford, the requirement of prior demand is a logical corollary of the purpose of countermeasures, i.e. that they must be necessary to induce compliance by the responsible state. Sometimes, the responsible state may not even be aware that it is not complying with international law. Without prior demand, that state may lack the opportunity to stop and/or repair the wrongdoing, such that countermeasures may not be necessary in the circumstances.
Some states and scholars have questioned whether prior demand is required for direct and/or urgent countermeasures. After all, urgency might dictate the need for prompt and direct action to stop an ongoing wrongdoing, safeguard the rights of the injured state, and prevent further injury.
Writing in 1992, former ILC special rapporteur Gaetano Arangio-Ruiz noted that, in exceptional cases requiring urgent action, states had resorted to direct countermeasures, such as asset freezing, without prior demand. Nevertheless, this ‘may be explained, inter alia, by the fact that the measures in question were resorted to within the context of an actual, open dispute in the course of which the states involved had already exchanged charges and arguments’, such that any intimation was rendered ‘superfluous’. In the overwhelming majority of incidents recorded, including before and after the adoption of the UN Charter and even in situations involving forcible action or urgency, states resorted to countermeasures only after having previously called upon the responsible state to comply with its obligations. For Arangio-Ruiz, this meant that prior demand was a requirement for taking countermeasures under customary international law, even in urgent cases.
The controversy around prior demand has resurfaced in the cyber context. One view is that the requirement of prior demand, as laid down in Article 52 of the Articles, reflects customary international law and applies strictly in cyberspace as elsewhere. But some states and scholars have expressed doubt and concern over an absolute requirement of prior demand in cyberspace. They have pointed to the need to take urgent or immediate countermeasures to effectively stop certain unlawful cyber operations, such as by disabling malware or computer systems at their origin. In those cases, it is argued, a requirement of prior demand would defeat the purpose and effectiveness of a cyber countermeasure – as with other types of urgent countermeasures. There is also concern that a prior demand might compromise covert cyber capabilities or allow the responsible state to evade cyber countermeasures that seek to secure cessation and/or reparation.
At least five states seem to have endorsed a flexible approach to prior demand in cyberspace: the US, UK, Switzerland, Italy and Costa Rica have all taken the view that prior demand may not be required in exceptional cases when urgent or immediate countermeasures are necessary. The position of other states is less clear: they only refer explicitly to the non-applicability of the requirement of prior notification – not prior demand – in urgent cases.
However, the requirement of prior demand is not particularly cumbersome for the injured state. As different ILC special rapporteurs have pointed out, prior demand need not follow a special form or procedure, nor is it subject to a strict timeline. Bilateral communication, such as diplomatic correspondence, might be one way to make this demand. However, even a very general condemnation of the internationally wrongful act might suffice to put the responsible state on notice. So long as the demand encompasses the internationally wrongful act with respect to which the countermeasures are taken, it can fulfil the requirement of prior demand. For example, the injured state may rely on an earlier condemnation of a continuous or recurring violation of international law by the responsible state. It may also take advantage of a collective protest made previously against the responsible state, such as in the form of a UN Security Council or General Assembly resolution. An example is the condemnation of Russia’s aggression against Ukraine by the UNGA in 2022. As an earlier draft of Article 52 of the ILC Articles suggests, in urgent cases, the victim state could even resort to countermeasures immediately after making a prior demand of cessation and/or reparation. This should prevent the responsible state from frustrating the purpose of those measures.
Therefore, prior demand continues to be a condition for the taking of countermeasures generally and in the cyber context, despite some contrary views. For the law to be changed in this respect, more state practice and opinio juris would be necessary.
Notice of the decision to take countermeasures and offer to negotiate
Article 52(1)(b) of the ILC Articles stipulates that ‘[b]efore taking countermeasures, an injured State shall […] notify the responsible State of any decision to take countermeasures and offer to negotiate with that State’. However, during the drafting of the ILC Articles, there was some controversy over whether this condition entirely reflects customary international law. Objections were raised because, in some circumstances, states need to respond promptly and covertly to stop the wrongful act or secure reparation for the injury caused. These concerns also arise in cyberspace. A point was also made that a strict requirement of a prior offer to negotiate would force states to have recourse to particular means of dispute settlement and curtail their choice of means to settle disputes peacefully.
Article 52 of the Articles tried to accommodate these concerns. As a general rule, paragraph 1(b) requires the injured state to give the responsible state i) notice of its intention to take countermeasures and ii) an opportunity to negotiate the dispute. However, in exceptional cases, paragraph 2 allows the injured state to take ‘such urgent countermeasures as are necessary to preserve its rights’. But the question remains whether, beyond urgent countermeasures, i.e. in non-urgent situations, a state may resort to countermeasures without first notifying or offering to negotiate with the state in breach.
In the Air Services case, the arbitral tribunal suggested that countermeasures should be ‘accompanied by a genuine effort at resolving the dispute’, in line with the principle of peaceful settlement of disputes. However, there is nothing to suggest in this or other cases that the notice and offer to negotiate must temporally precede the taking of countermeasures except in urgent cases.
To be sure, recourse to countermeasures, especially without prior notice or negotiation, may carry a risk of conflict escalation. However, the dispute may still be peacefully settled if the injured state notifies and offers to negotiate with the responsible state after taking countermeasures. After all, countermeasures will have been preceded by an unfulfilled demand for cessation and/or reparation, which might indicate an unwillingness on the part of the responsible state to negotiate straightaway. Relatedly, as noted by some states, countermeasures may have an important role in prompting states to agree to settle the dispute peacefully.
In some circumstances, taking countermeasures before notifying and offering to negotiate with the responsible state might better serve international peace and security, irrespective of the urgency of the situation. For example, countermeasures may be necessary to seek reparation for serious wrongs, like genocide or environmental harm, even when the damage is already done and there is no urgency to act, but where negotiations are not forthcoming. On this basis, several states have consistently rejected the existence of a strict obligation of prior notification and offer to negotiate under customary international law.
For these reasons, it is not clear whether Article 52(1)(b) of the ILC Articles entirely reflects customary international law.
It is submitted that, as a general rule, the injured state must give prior notice of its intention to take countermeasures and offer to negotiate with the responsible state. But those requirements might be dispensed with when, irrespective of the urgency of the situation, i) prior notice and offer to negotiate would defeat the purpose of a countermeasure, and ii) the opportunity to settle the dispute peacefully is not lost. This approach is in line with the proper purpose of countermeasures and the principle of peaceful settlement of disputes, as reflected in Articles 2(3) and 33 of the UN Charter.
States also retain their right to take countermeasures while negotiations are ongoing, as this could likewise induce the responsible state to stop and/or repair the wrong and settle the dispute amicably.
Suspension upon cessation and pending a dispute settlement procedure
Article 52(3) of the ILC Articles stipulates that ‘[c]ountermeasures may not be taken, and if already taken must be suspended without undue delay if (a) the internationally wrongful act has ceased; and (b) the dispute is pending before a court or tribunal which has the authority to make decisions binding on the parties.’ Article 52(4) then adds that ‘[p]aragraph 3 [of Article 52] does not apply if the responsible state fails to implement the dispute settlement procedures in good faith’. According to the ILC, these provisions were justified because a tribunal or another third-party dispute settlement mechanism may be able to order provisional measures that perform the same function as countermeasures. But this does not apply where the dispute is submitted to a political organ, such as the UN Security Council, or is the object of private arbitration between the responsible state and a non-state actor affected by the breach.
With few exceptions, most states and scholars agree that states must suspend countermeasures when the internationally wrongful act has ceased and the dispute is pending before a competent third-party dispute settlement body. However, where the internationally wrongful act is still ongoing, the injured state retains its right to take countermeasures, even when a dispute settlement process is pending. Whether or not recourse to countermeasures remains available in those circumstances can only be assessed on a case-by-case basis, in light of the proper purpose of countermeasures and the principle of peaceful settlement of disputes. Relevant considerations include i) the relationship between the parties; ii) the surrounding political context; iii) whether delays in resolving the dispute could be abused by the responsible state; iv) and whether compulsory dispute settlement would aggravate the dispute.
Termination upon compliance
Article 53 of the Articles stipulates that ‘countermeasures shall be terminated as soon as the responsible State has complied with its obligations under part two in relation to the internationally wrongful act.’ In line with Articles 30 and 31 of the ILC Articles, these obligations comprise cessation, assurances and guarantees of non-repetition and reparation. It is uncontroversial that this requirement reflects customary international law. It flows from the purpose of countermeasures to induce compliance with those obligations as well as their temporary nature.
