24 Legal Resilience: Just a Warm and Fuzzy Concept?

In modern usage, the term ‘resilience’ refers to the ‘action or an act of rebounding or springing back’ or ‘the power of resuming an original shape or position after compression, bending’ and the like.¹ In its literal meaning, the term describes the property of an object or material to resume its initial shape once certain forces it has been subjected to are relaxed. The resilience of a blade of grass, for example, refers to its ability to bend in the wind and return to an upright position without breaking. Figuratively, the term is often applied to individuals, groups, and social relationships to refer to their capacity to recover from the ‘effects of a misfortune, shock or illness’² or to describe their robustness and adaptability under duress.³

Resilience has become a popular idea across many disciplines.⁴ No doubt it owes part of its success to the fact that it is a ‘stretchy and a pervasive concept’.⁵ The term is capable of carrying diverse meanings and it is used differently from one context to another.⁶ Another reason for its popularity is the fact that the notion comes with positive connotations: clearly, resilience is a good thing to have. Whatever its exact meaning, it is surely better to be resilient than not to be. In short, resilience is a warm and fuzzy concept: a notion that lacks a single definition, but one that is widely understood to refer to a goal or quality worth pursuing.⁷

The purpose of this chapter is to explore the utility of resilience thinking at the intersection between international law and contemporary security threats. Specifically, it asks what benefits, if any, the notion of resilience may offer for addressing the legal challenges associated with grey zone conflict and hybrid threats.

This turn to resilience has not escaped criticism. Helmut Aust, for example, has suggested that appeals to resilience ‘entail a tendency to securitize responses to hybrid threats’ and that this risks giving up what defines ‘free and open societies’.⁸ Aust is of course right to note that the language of resilience places legal questions within the broader strategic context and in this sense securitizes the law. However, the close relationship between law and security—or law and politics more generally—is not the product of resilience thinking, but the fact that law is both an instrument of and a constraint on politics. The real issue, therefore, is not whether appeals to resilience securitize the law, but what kind of political values and security objectives they promote. Here, Aust is correct to warn about the dangers of over-reach: the risk that open societies may curtail some of the very freedoms that they seek to protect against malign interference. However, such over-reach is not inevitable, as long as we guard against it. Nor does the risk of over-reach diminish the reality of authoritarian interference and the need to protect liberal values and institutions against it.

With these points in mind, section 2 of the chapter reviews the key features of resilience thinking and its reception in legal doctrine to formulate a definition of ‘legal resilience’. Section 3 explores the utility of legal resilience in the context of grey zone conflict and hybrid threats, suggesting that the notion offers certain analytical and normative benefits that are worth pursuing. To realize these benefits, section 4 calls on open societies and institutions to develop ‘legal resilience strategies’ to serve as conceptual and policy frameworks to resist, recover from, and adapt to disturbances in the legal domain in a more comprehensive and systematic fashion. Section 5 offers some concluding thoughts.

The origins of contemporary resilience thinking are often traced to the field of ecology, in particular to the work that Canadian ecologist Crawford Holling published in the early 1970s.⁹ In fact, Holling was not the first to use the term. Understood generically as the capacity to bounce back from adversity, the concept has cropped up in other disciplines long before it became popular in the field of ecology.¹⁰ Nevertheless, Holling’s work has been particularly influential and offers a convenient point of departure for our purposes.

Traditional models of ecological systems were based on the assumption that natural systems exposed to external disturbances, such as human intervention, would return to a pre-existing stable equilibrium once the disruption had passed.¹¹ Holling questioned these assumptions in a seminal paper published in 1973.¹² In his view, the traditional equilibrium-centred view was too static and led to inappropriate and even counter-productive practices in natural resource management. Holling distinguished between stability, defined as the ‘ability of a system to return to an equilibrium state after a temporary disturbance’, and resilience, the ‘measure of the persistence of systems and of their ability to absorb change and disturbance and still maintain the same relationships between populations or state variables’.¹³ Ecological systems could thus display low stability, for instance, by experiencing wild fluctuations in their population size, but nevertheless be highly resilient. Conversely, other ecosystems could be stable over time but enjoy low resilience and thus suffer a sudden and potentially catastrophic collapse due to their inability to tolerate even a limited degree of further disturbance.¹⁴

Other authors often employed resilience in a narrow sense to describe the speed at which natural systems return to their original equilibrium following a perturbation.¹⁵ In response, Holling distinguished between two definitions of resilience which emphasize different aspects of stability.¹⁶  Engineering resilience focuses on a system’s efficiency, constancy, and predictability.¹⁷ These are attributes encountered primarily in the physical sciences and engineering—hence the name. They represent the more traditional definition of resilience concerned with stability near an equilibrium state. In essence, engineering resilience is about elasticity. It describes a system’s ability to resist disturbance and its capacity to return to its state of origin. Ecological resilience, by contrast, focuses on persistence, change, and unpredictability.¹⁸ These attributes reflect the preoccupations of biologists and recognize that external disturbances may be uneven and erratic. Ecological resilience is concerned with conditions far removed from a system’s original equilibrium, which may lead that system to flip into a different regime or stable state, rather than return to its original position. Here, resilience describes the amount of disturbance that a system can absorb before changing its essential functions and other core features.

Holling argued that it is important to distinguish between these two forms of resilience because they encourage different strategies for managing complexity, disturbance, and change.¹⁹ Whereas engineering resilience emphasizes maintaining efficiency of function and thus seeks to guarantee that a system continues to perform its essential tasks without a drop in performance, ecological resilience focuses on maintaining existence of function by seeking to ensure that a system retains its essential characteristics.²⁰ Put differently, engineering resilience resists change, whereas ecological resilience mitigates its effects. Unlike engineering resilience, ecological resilience thus emphasizes a system’s ability to adapt.²¹

Inspired by Holling’s distinction, adaptability has emerged as a prominent theme in the literature on socio-ecological resilience.²² Whereas classic ecological models viewed human action as an external driver of change, socio-ecological approaches treat humans and nature as interdependent systems.²³ Since human societies typically benefit from the capacity to reorganize themselves and modify their environment in response to outside pressure, proponents of a socio-ecological perspective put adaptability at the heart of resilience. Adaptability has been defined for these purposes as ‘the capacity of actors in a system to influence resilience’.²⁴ The adaptive capacity of a system refers to its own ability ‘to learn, combine experience and knowledge, adjust its responses to changing external drivers and internal processes, and continue developing within the current stability domain’;²⁵ in short, its ability to grow more resilient. This emphasis on adaptability has been incorporated into more recent definitions of resilience. Authors working in this area thus define resilience as ‘the capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity, and feedbacks’.²⁶

The notion of socio-ecological resilience has also initiated a growing interest in adapting institutions. Applying a resilience perspective to institutions—understood broadly as ‘rules of the game’ that arise from formal and informal norms and rules and organizational structures²⁷—directs our attention to the qualities and features that enable institutions to adapt, so as to be better prepared for dealing with surprises and uncertain futures. The quest for adapting institutions is concerned with the ‘capacity of people, as part of social–ecological systems, from local groups and private actors to the State, to international organizations, to deal with complexity, uncertainty and the interplay between gradual and rapid change’.²⁸

The work on adapting institutions creates a bridge between socio-ecological understandings of resilience and its use in the social sciences.²⁹ In the field of international relations,³⁰ regime theorists have equated resilience with regime robustness to refer ‘to the “staying power” of international institutions in the face of exogenous challenges and to the extent to which prior institutional choices constrain collective decisions and behaviour in later periods’.³¹ Institutions that give way under external pressure, either by suffering a fundamental shift in their normative content or by experiencing a dramatic drop in norm compliance among their members, are thought to lack resilience.³² Change is thus portrayed as a negative development, whilst resilience is understood positively as resistance to change. This essentially reflects the values associated with what Holling called engineering resilience. Others have taken a broader approach, borrowing insights from socio-ecological notions of resilience. Philippe Bourbeau, for example, has defined resilience as ‘the process of patterned adjustments adopted by a society or an individual in the face of endogenous or exogenous shocks’.³³ This definition emphasizes adaptation, viewing it as a dynamic process. In doing so, it avoids assumptions about the existence of social equilibria and instead suggests that disturbances and adaptation are context-dependent and socially construed.

Resilience thinking has also made inroads into legal scholarship. An in-depth review of the legal literature published in the period between 1985 and 2013 suggests that growing numbers of scholars are relying on the concept.³⁴ Even a passing glance at more recent publications confirms that this trend continues. In legal writing, the meaning and usage of resilience is inspired mostly by ecological understandings of the term. Accordingly, the distinction drawn between engineering and ecological resilience is widely accepted and repeated.³⁵ Similarly, resilience is discussed mostly in connection with uncertainty, complexity, and change.³⁶ However, despite its growing popularity, the reception of resilience thinking in legal scholarship has been uneven. In some fields, resilience has become a popular idea, whereas in others it has not made much of an impression at all. Broadly speaking, legal scholarship on resilience falls into three groups.

First, resilience has proven fashionable with legal experts working on environmental matters. This should not come as a surprise, given the thematic overlap between environmental law and ecology. A substantial part of this literature explores how more adaptive regulatory mechanisms may promote ecological resilience,³⁷ including in areas such as energy policy,³⁸ water management,³⁹ climate change,⁴⁰ and the conservation of biodiversity.⁴¹ Other authors have explored the extent to which the existing rules of international environmental law have absorbed resilience as a normative principle.⁴² One prominent concern in this field, often voiced by authors from the United States, is that old-fashioned views of nature still dominate the law. Instead of encouraging adaptive and flexible natural resource governance, environmental and administrative law thus promote rigid conservation practices which are widely regarded as sub-optimal and as an obstacle to enhancing ecosystem resilience.⁴³

A second strand of legal scholarship has explored how law may contribute to the resilience of systems other than the natural environment. As in the literature on environmental matters,⁴⁴ this body of writing treats legal rules and regimes as instruments which may enhance the resilience of other social systems. For example, law has been identified as a critical component of disaster management.⁴⁵ Law confers binding force on disaster management plans, distributes risk across society, allocates resources, provides a framework for monitoring performance, and sustains specialized decision-making mechanisms. Law therefore plays a vital role in enabling effective disaster management, from risk assessment to emergency intervention and recovery. Other studies have focused on the contribution that regulatory action makes to enhancing the resilience of the banking sector,⁴⁶ the electricity grid,⁴⁷ data privacy,⁴⁸ international financial systems,⁴⁹ and critical infrastructure.⁵⁰ Some of this work suggests that resilience principles extend to the law itself, for example, requiring adaptive forms of regulation in fields such as information and communication technology.⁵¹

The third strand of legal scholarship is concerned with the resilience of the law itself. Save for a handful of exceptions,⁵² most of the writing falling into this category invokes the notion of resilience in an uncritical way, seemingly unaware of the debates that are raging over its meaning in other disciplines. It thus ends up employing the term in its narrow, engineering sense to describe the resistance of specific legal rules and regimes to internal or external shocks. Examples include publications invoking resilience with reference to the common law as a regulatory framework for policing powers,⁵³ the constitutional foundations of the European Union,⁵⁴ governance based on political conventions,⁵⁵ the Paris Agreement on climate change,⁵⁶ national constitutions,⁵⁷ and the legal basis of European banking agencies.⁵⁸

Only a small number of authors have explored how resilience theory, as developed in the socio-ecological literature, maps onto the law more generally. Among these, J. B. Ruhl has set out to identify what design principles make legal systems more resilient and adaptive,⁵⁹ leading him to formulate several key insights. First, according to Ruhl, the resilience of a legal system says nothing about the desirability of its substantive content.⁶⁰ Bad law may be resilient just as much as good law. Resilience therefore should not be treated as a self-evident value in the field of law. Second, the use of law as an instrument to render other social systems more resilient must be distinguished from the resilience of the legal system itself.⁶¹ Accordingly, there are two sides to legal resilience: resilience through law and resilience of law. Third, Ruhl suggests that any legal system has many potential equilibrium states at many different scales.⁶² In other words, different components and layers of a legal system may display different degrees of resilience. Fourth, no agreed method exists for quantifying and measuring the resilience of a legal system.⁶³ Finally, the adaptive capacity of a legal system, that is, its ability to reorganize in response to external drivers, includes the ability to switch between different resilience strategies (e.g. between engineering and ecological forms of resilience).⁶⁴

Other work in this field suggests that the design features which render law more resilient and adaptable are not uniform across different legal systems. The objectives, content, procedures, institutions, and vulnerabilities of legal regimes are simply too diverse for there to be a single, universally applicable recipe to enhance their resilience and adaptability. For example, Craig Anthony Arnold and Lance H. Gunderson suggest that environmental law could increase its adaptive capacity by adopting a polycentric and multimodal structure, favouring flexible standards and discretionary decision-making and embracing iterative processes with feedback loops among multiple participants.⁶⁵ These features may well enhance environmental law’s ability to foster ecological resilience, but it would be a stretch to assume that the same mix of features would necessarily render other legal regimes, for instance, international human rights law, more resilient and adaptive.

Based on the foregoing, we may define legal resilience as the capacity of a legal system, first, to resist, recover from, and adapt to internal and external disturbances whilst maintaining its key features and, second, to contribute to the resilience of other natural or social systems. This dual definition reflects the distinction drawn between the two aspects of legal resilience identified earlier—resilience of the law itself and resilience mediated through law. The definition describes legal resilience as a capacity rather than a process. Law may be more or less resilient. Resilience is therefore a property of legal systems, whilst efforts to maintain or increase this property are best seen as an ongoing process.

For the purposes of this definition, legal systems are understood in a broad sense as a set of functionally, thematically, or hierarchically related rules, procedures, and institutions. The notion of a legal system thus may refer to a specific legal regime or branch of law, the legal order of a State, the internal law of an international organization, or the international legal system as a whole. Alternatively, it may also refer to rules, procedures, and institutions that are connected more loosely by functional or thematic ties, but without forming a distinct legal regime or branch of law, such as the law of disaster management or the law of military operations. Finally, the definition recognizes that engineering and ecological resilience entail different coping strategies. It therefore describes legal resilience as the capacity to resist, recover from, and adapt to disturbance, whether that disturbance originates from within the law or stems from extra-legal sources. Such disturbances will have exceeded a legal system’s capacity to cope if the system is unable to sustain the core features that make up its identity (e.g. its substantive content, structure, or function). These features are referred to as a legal system’s persistence criteria.⁶⁶

It is important to underline that legal resilience so defined merely describes a property that legal systems may possess to varying degrees. Legal resilience is not a theory of the relationship between law and other social systems, a blueprint for strengthening the rule of law or an off-the-shelf strategy for countering contemporary security threats, including those posed by grey zone conflict, hybrid threats, and hybrid warfare. Instead, legal resilience is best understood as a perspective—a conceptual framework and mindset—for thinking about the law’s ability to withstand shocks and to deal with pressure for change in a diverse range of contexts.⁶⁷

What, then, does legal resilience offer in the present context? The first benefit of adopting a legal resilience perspective is analytical. Legal resilience shines a spotlight on the capacity of the law to cope with the disturbances caused by grey zone and hybrid threats. This focuses our attention, first, on the law’s vulnerabilities and coping mechanisms and, second, on what support law may lend to other systems in addressing their own vulnerabilities and strengthening their respective coping mechanisms. However, some care is required, as adopting a legal resilience perspective raises methodological dilemmas.⁶⁸

Resilience is a theory about systems. The identity of the system is therefore critical to any resilience analysis.⁶⁹ However, in the field of law, system boundaries are not always easy to demarcate. Law is predominantly structured along functional, thematic, and hierarchical lines and operates on multiple scales, including the individual, communal, regional, national, transnational, and global.⁷⁰ Most functional regimes, such as consumer law, span several jurisdictions and have national, regional, and international dimensions.⁷¹ To complicate matters, legal questions often cut across multiple legal regimes and orders. This was recognized by the Parliamentary Assembly of the Council of Europe when it suggested that the use of non-forcible measures by hybrid adversaries ‘should be examined in the light of domestic criminal law and, if necessary and depending on the situation, relevant international legal instruments covering specific policy areas (such as the law of the sea or norms on combating cybercrime, terrorism, hate speech or money laundering)’.⁷²

Due to the multiscale and cross-cutting nature of law, it is easy to end up with a framework of analysis that is either over- or under-inclusive. The analytical framework will be over-inclusive if the disturbance caused by a hybrid act manifests itself on a significantly lower scale or in a significantly narrower thematic area than the legal system studied. For example, international law has relatively little to say about non-coercive interference by one State in the public discourse of another State. Hence international law would not constitute a sufficient reference point in this instance. By contrast, the analytical framework will be under-inclusive if the disturbance occurs at a significantly higher scale or in a wholly different thematic area than the legal system selected. For example, the use of chemical weapons may have no impact on the resilience of Dutch election law, but obviously this is the wrong framework for analysis. These points suggest that a disturbance-driven, rather than a system-driven, analysis often may be more appropriate. This involves relying on the grey zone activity or hybrid threat to define the boundaries of the legal system to be assessed: if the threat engages multiple jurisdictions and legal regimes, then legal resilience is a matter of their collective capacity to resist, recover from, and adapt to that threat.

The notion of an original stable state constitutes another source of difficulty. One of the core principles of ecological resilience is that natural systems may have more than one equilibrium and therefore may flip between different stable states.⁷³ Ruhl suggests that legal systems may have multiple equilibrium states too.⁷⁴ However, the idea of a legal equilibrium is problematic. Examples can be found where a legal system may be said to have flipped from one stable configuration to another as a result of shocks. In the past, the absolute doctrine of State immunity comprehensively barred national courts from exercising their jurisdiction over foreign States.⁷⁵ This doctrine came under increasing pressure during the twentieth century as governments began to engage in commercial transactions on a wide scale. A growing number of States abandoned the old rule, thereby paving the way for the emergence of a more restrictive doctrine of State immunity.⁷⁶ This episode in the development of the law of State immunity may be re-told as a legal system losing its resilience in the face of sustained disturbance, eventually flipping over into a new stable state.⁷⁷

However, the idea of an equilibrium becomes less compelling when legal change is gradual and evolutionary in nature, rather than abrupt and radical. For example, there can be no doubt that the growth of human rights law has weakened the State-centric features of international law,⁷⁸ but this has not involved any obvious ‘flip’ from one equilibrium to another. Indeed, it is more credible to describe the impact of human rights on general international law as a process of gradual adaptation rather than as a sudden switch into a new configuration brought about by disturbances that exceeded the State-centric model’s resilience. Yet even where change is abrupt, the historical reference point is critical. The post-1989 transition of former communist societies into open-market economies exposed their legal systems to immense shocks. The transformation of socialist legal systems therefore may be interpreted as a sign of their insufficient resilience. However, to the extent that this transformation involved a return to earlier legal traditions, it may also be interpreted as proof of pre-socialist law’s resilience.⁷⁹

Selecting a legal system’s persistence criteria has significant methodological implications too. In her analysis of Russian law, Tatiana Borisova argues that the traditional equilibrium of the Russian legal system rested on the relationship between the sovereign, the people and a class of legal intermediaries.⁸⁰ Although the 1905 and 1917 revolutions upset this equilibrium, Borisova suggests that Russian law nevertheless proved highly resilient, as the Soviet authorities quickly rediscovered its value as an instrument of State power. This argument locates the Russian legal system’s resilience in its continuing utility as an instrument of social control, despite the fact that its substantive content, processes, and institutions proved far less resilient to the dramatic changes set in motion by the October Revolution.⁸¹

What these examples and caveats demonstrate is that legal resilience is very much in the eye of the beholder. It is far from obvious how key elements of the concept—including the notion of a legal system, stable equilibria, disturbance, and persistence criteria—should be applied in concrete cases. Adopting a legal resilience perspective thus involves a series of methodological choices. These choices not only frame the analysis, but also shape its outcome, depending on whether changes in the law are seen as transitions from one stable state to another or as successful adaptations. This is not to suggest that legal resilience analysis is erratic, but to stress that it is contingent on the observer’s vantage point. For example, seen from a Soviet perspective, the post-communist transformation of socialist legal systems illustrates their lack of resilience, whereas from a post-Soviet perspective, the same transformation may demonstrate the long-term resilience of alternative legal traditions. The Soviet and post-Soviet perspectives are clearly incompatible, but their respective assessments of the law’s resilience may both be correct within the confines of their own methodological horizons. It is not that resilience theory leads to inconsistent results, but that it tells multiple stories, depending on the analytical reference points chosen by the narrator.

The message to take away in the present context is that the methodological choices which inform the legal resilience perspective involve the exercise of political judgement. The hostile instrumentalization of the law by grey zone and hybrid adversaries, as described throughout this volume, poses a challenge to the national interests of the targeted States. However, whether or not the instrumentalization of law is hostile is a matter of perception: measures that one State may regard as valuable acts of statecraft another State may deem to be detrimental to its interests. The same holds true for legal resilience: whether legal stability is celebrated as a sign of law’s resilience or condemned as its failure to adapt, and conversely, whether legal change is hailed as a legal system’s successful adaptation or lamented as its lack of resilience, depends on whether stability and change are perceived as positive or as negative developments.⁸²

Legal resilience therefore is not solely an analytical concept, but also a normative one.⁸³ As David Alexander has observed, one person’s resilience may be another’s vulnerability.⁸⁴ Entering into judgements about the value of legal resilience seems unavoidable.⁸⁵ As we noted earlier, ecologists criticize environmental law as maladaptive because it has been slow to incorporate socio-ecological insights. Yet environmental law’s failure to adapt is a sign of its remarkable resistance to change, in other words its resilience. Accordingly, when ecologists denounce the law as maladaptive, they do so on the basis of a value judgement as to what aims the law should pursue. This, in turn, leads them to see legal change as desirable and legal stability as unappealing.

This normative dimension represents the second benefit of adopting a legal resilience perspective. In essence, legal resilience is a status quo strategy. For States that seek to safeguard the current configuration of the international legal order and their own position within it, legal resilience is a goal worth pursuing. A legal resilience perspective encourages such States to reinforce the capacity of relevant domestic and international rules, processes, and institutions to withstand the challenges posed by grey zone and hybrid adversaries and to make systematic use of relevant legal instruments as a means to strengthen their national resilience against such threats. Adopting a legal resilience perspective thus provides national authorities and international organizations with a framework for setting and pursuing legal policy goals.

More specifically, for liberal democracies, legal resilience essentially entails a program of defending liberal values in international law against encroachments and subversion by illiberal forces, including by authoritarian regimes.⁸⁶ The distinction drawn between different modalities of resilience, in particular between resistance and adaptation strategies, harbours some useful lessons in this regard. Clearly, there is a need to resist serious threats to the international rule of law both by reaffirming basic norms and by imposing costs on those who transgress them. Liberal democracies have thus rightly spearheaded the international response to Russia’s war of aggression against Ukraine.⁸⁷ However, doing so under the banner of upholding the ‘rules-based international order’ against the forces of revisionism is at best misleading and at worst counter-productive.⁸⁸ It is misleading because it glosses over the fact that the political West can hardly be described as the defender of the legal status quo without qualifications, given that it has pushed and at times overstepped the boundaries of international law in areas such as the rules governing the use of force. Nor is it credible to suggest that the machinations of authoritarian States, serious though they are, threaten the very existence of the international legal system. Indeed, framing the response to Russia’s war of aggression as a fight for the survival of the rules-based international order as a whole is potentially counter-productive precisely because the hyperbole and selectiveness of this framing lends credence to the charges of hypocrisy that Russian diplomats and their allies so frequently hurl against the West,⁸⁹ and because the implicit assumption that liberal and democratic values enjoy universal validity does not resonate with governments that in fact are not fully committed to these values. A more nuanced approach is needed to uphold international law in general and liberal gains in particular: in addition to resistance, there is also a place for adaptation and, at times, accommodation in the interest of building broad coalitions against the most severe threats. Framing this endeavour as a Manichean struggle of status quo powers against revisionists, a struggle between rule-followers and rule-breakers, suggests that what is at issue is a choice between stasis and change, whereas in reality it is about the direction of change and adaptation.

While a legal resilience perspective can be applied to individual rules and institutions, its main benefit lies at the level of systems, where it provides a conceptual framework to help think through the modalities for resisting, recovering from, and adapting to disturbances in the legal domain in a more comprehensive and systematic fashion. To realize this benefit, liberal democracies should develop legal resilience strategies. Inspired by national security strategies adopted by many States, the purpose of legal resilience strategies is to formulate a comprehensive and forward-looking policy to counter the challenges arising in the legal domain, including those associated with grey zone conflict and hybrid threats. Whilst they may vary in length and detail, typically, legal resilience strategies should identify the legal concerns posed by grey zone and hybrid threats, offer a vision for countering them, set specific policy objectives, and establish appropriate ways and means for achieving these. Due to the cross-cutting nature of their subject matter, legal resilience strategies should be designed as top-level policy documents and developed through inter-departmental processes at the senior level. They should be treated as an opportunity to engage diverse expert communities and stakeholders in the formulation of legal policy and to integrate the latter into other strategic planning processes and policies, as an integral part of a nation’s grand strategy.

By definition, individual legal resilience strategies will be shaped by the position and interests of the nations and institutions developing them. Nevertheless, certain elements and guidelines are of general applicability.

Hostile actors exploit legal vulnerabilities. The first task in developing a legal resilience strategy, therefore, is to identify the relevant legal vulnerabilities.⁹⁰ This involves three steps. First, it calls for ascertaining the objectives that hostile actors seek to achieve through the use of legal means, together with their intent, legal capabilities, and the legal tactics they employ to achieve those objectives. The goal is to build up as clear and detailed a picture as possible about the way in which adversaries utilize the law and legal arguments to their advantage. The second step involves determining which legal systems should be covered by the legal resilience strategy. It is advisable to select relevant legal orders and to combine this with a disturbance-driven approach, as suggested earlier. For States, legal orders of interest will include their own domestic legal system, the internal law of any international organizations of which they are members, the domestic legal system of allies, as well as the international legal order. Further relevant legal systems should be selected with reference to relevant grey zone and hybrid threats. Although the exposure of States and international organizations to such threats will vary, tactics of interest are likely to include hostile information operations and strategic communication; election interference; support for organized protest movements, separatists, and extremist groups; strategic leaks; economic leverage; the exercise of influence through cultural and social organizations; industrial espionage; foreign aid and humanitarian assistance; energy dependence; and cyber operations. A legal resilience strategy should map the legal questions and systems engaged by these activities and identify how adversaries utilize and exploit the law to carry them out. The final step is to assess the risks that the vulnerabilities so identified present and to prioritize them based on their gravity. This may be done with the help of a matrix that groups legal vulnerabilities into different categories. The outcome could be recorded in a separate document, a legal vulnerabilities register, that is kept under continuous review in the light of the evolution of the threat landscape.

Legal preparedness is concerned with mitigating known legal vulnerabilities and building capacity to deal with unexpected ones. Some of the vulnerabilities identified as part of a legal resilience strategy may be addressed through domestic legislation. For example, the law of the United Kingdom prohibits any person from carrying on the business of ‘consultant lobbying’ unless they are registered for that purpose.⁹¹ However, consultant lobbying is defined as a commercial activity and therefore does not cover the conduct of foreign officials or government employees.⁹² Calls have been made for the law to be changed so as to compel such persons to register their activities.⁹³ Similar rules exist elsewhere. The Foreign Agents Registration Act of the United States requires persons acting on behalf of foreign powers in a political or quasi-political capacity to disclose their relationship and information about their activities.⁹⁴ Adopting similar legislation in the United Kingdom would subject political activities carried out on behalf of foreign entities to greater transparency and thus remedy a potential legal vulnerability. As this case illustrates, many grey zone and hybrid threats are best addressed through domestic law. This is so because a wide range of unfriendly and hostile measures, such as support for political extremists, acts of industrial espionage, or strategic leaks, do not infringe international law, or at least do not do so manifestly. National legislation therefore offers a more appropriate regulatory and enforcement framework to counter these threats.⁹⁵

However, other known vulnerabilities may not be addressed quite so easily. For example, as long as hostile State and non-State actors employ a comprehensive array of violent and non-violent tactics, the legal thresholds governing the use of force will remain a critical flashpoint. States subject to hybrid campaigns cannot revise these thresholds unilaterally by legislative fiat to reduce their exposure to hostile manipulation. Instead, the competent authorities must be prepared to continuously monitor acts of hybrid warfare, such as unconventional military operations,⁹⁶ to determine whether they have crossed the relevant thresholds and to be ready to respond accordingly. This demands a detailed understanding of the legal environment, but it also requires appropriate mechanisms and resources to gather, assess, and act upon relevant information. Similarly, adversaries should be expected to mask their own illicit operations by donning the mantel of ‘plausible deniability’.⁹⁷ Accordingly, before covert malign activities can be countered through legal action, they must be attributed to the adversary behind them. This is a matter of compelling intelligence, evidence, and public presentation and thus calls for close collaboration among different branches of government.

The dynamic nature of grey zone and hybrid threats further underscores the need for building capacity. Not all legal vulnerabilities are known or identified as such in advance. In fact, experience demonstrates that competition in the legal sphere can be fast-paced and unpredictable. Before the Salisbury poisoning incident,⁹⁸ few would have anticipated that the Chemical Weapons Convention would become the subject of a legal scuffle between the United Kingdom and Russia. Even where legal flashpoints can be predicted, the exact circumstances that may trigger a standoff in the legal sphere can seldom be foretold with absolute certainty. For instance, bearing in mind Crimea’s geographical position, it should not have come as a surprise that Russia and Ukraine became engaged in a dispute involving the law of the sea. Yet neither the timing of the Kerch Strait incident nor the way it has played out could have been forecast by most observers.⁹⁹

Faced with such uncertainty regarding the nature and timing of the legal challenges posed by hybrid threats, any legal resilience strategy must make provision for dealing with legal contingencies, understood for these purposes as unforeseen developments requiring a critical legal input or posing a challenge to core legal interests. In doing so, inspiration may be drawn from the principles of civil emergency management.¹⁰⁰ The response to legal contingencies may be divided into three phases: a preparation phase which involves the establishment of appropriate response mechanisms, the allocation of responsibilities between stakeholders, the preparation of contingency plans, and regular training and exercising; a response phase which involves coordinated action to mitigate the immediate risks and prevent further damage or escalation; and a recovery phase which involves longer-term measures to restore the status quo ante, reduce vulnerabilities, adapt in the light of lessons learned, and take other appropriate measures to limit an adversary’s capacity to gain an advantage from the instrumentalization of the law.

Legal preparedness is also concerned with the role that law plays in enabling and supporting policy action in other fields. Law provides a basis for a wide range of diplomatic, economic, military, financial, and other activities aimed at countering hybrid threats and hybrid actors.¹⁰¹ For law-abiding States and rules-based organizations, it is critical that executive action is underpinned by appropriate legal authorizations. However, law also enables competent authorities to set policy goals and impose obligations on third parties with a binding effect. For example, in 2008, the Council of the European Union adopted a directive on the identification and designation of European critical infrastructures.¹⁰² It directs each member State to identify European critical infrastructures and to ensure that their operators have suitable security plans in place to ensure their protection against major threats. In 2016, the European Parliament and the Council adopted Directive (EU) 2016/1148 aimed at achieving a high common level of security of network and information systems within the European Union.¹⁰³ Amongst other things, the Directive requires all member States to adopt a national strategy on the security of network and information systems and to ensure that operators of essential services take appropriate and proportionate technical and organizational measures to manage the risks posed to the security of such systems. To give effect to their obligations, the member States have adopted national implementing legislation.¹⁰⁴ While the imposition of higher standards has been welcomed, concerns remain that the resulting regulatory landscape remains too fragmented.¹⁰⁵ Indeed, similar fears have been expressed in other sectors.¹⁰⁶

Adopting a legal resilience perspective should encourage relevant authorities to consider the role that law plays in this area in a more systematic and holistic manner. Accordingly, legal resilience strategies may serve as a tool for assessing law’s contribution to resilience across different social sectors. This involves mapping how existing regulatory frameworks support the resilience objectives pursued in key policy areas, assessing the performance of these legal frameworks against common criteria, such as their comprehensiveness, effectiveness, and robustness, and identifying shortcomings in the law. NATO, for example, has identified seven baseline requirements for civil preparedness: assured continuity of government and critical government services; resilient energy supplies; ability to deal effectively with uncontrolled movement of people; resilient food and water resources; ability to deal with mass casualties; resilient civil communications systems; and resilient civil transportation systems.¹⁰⁷ For NATO and its member States, an Allied legal resilience strategy could serve as a useful tool through which to map and assess the legal dimension of these seven baseline requirements. In addition to this analytical benefit, adopting a legal resilience perspective may inform the design and reform of relevant regulatory frameworks so as to improve their ability to promote societal resilience.¹⁰⁸

Legal resilience strategies should articulate an overall vision and roadmap for countering the legal challenges posed by grey zone and hybrid threats. This requires the competent authorities to consider what forms of resilience to promote. As noted earlier, engineering resilience focuses on static responses to disturbance, emphasizing the capacity to resist and recover from shocks. By contrast, ecological resilience favours dynamic responses which mitigate the effects of disturbance through adaptation. Both forms of resilience have a role to play in the legal sphere.

The resilience of legal systems turns in no small measure on their ability to command continued compliance with their rules. Amongst other things, resilience is about resistance to violations of the law. A legal resilience strategy must therefore address how hostile actors may be encouraged or compelled to honour their obligations and deterred from violating them. At the same time, legal resilience strategies must also consider how to respond to breaches of the law and to recover from their effects. Collective self-defence and sanctions mechanisms, such as Article 5 of the North Atlantic Treaty and Article 215 of the Treaty on the Functioning of the European Union, offer examples of arrangements for responding to third-party violations. From a legal resilience perspective, the question to ask is whether these frameworks are efficient and whether dedicated arrangements should be adopted in other areas, for instance in the cyber or information domain. However, increasing the capacity for resistance and recovery is not sufficient. As James Crawford warns, any legal system will only survive ‘if it has the capacity to change and develop over time’.¹⁰⁹ Compliance is difficult to secure if the law is perceived as illegitimate or unworkable. This brings into play ecological notions of resilience and the need for adaptation. To the extent that powers wedded to the status quo are unable to resist demands for change, they will need to accommodate revisionist actors by showing a willingness to adapt the international system. This requires careful thought about the right combination of resistance and adaptation. Russia’s war of aggression against Ukraine illustrates the dilemma: at what point, if any, should Kyiv and its allies switch from a strategy of resistance to a strategy of adaptation and in relation to which specific questions?

These considerations point to the value of more detailed studies on the evolutionary trends of the international legal order.¹¹⁰ Some years ago, the Hague Institute for the Internationalisation of Law suggested that the international legal system may evolve in four possible directions, depending on how the two main drivers of change, the progressive internationalization of law and the growth of private governance regimes, were to interact.¹¹¹ States and international organizations should engage with such forecasts as part of their legal resilience strategies, as this would assist them in formulating what future legal order they wish to promote and what legal future(s) they seek to avoid. In fact, at this level of generalization, it may well be appropriate and useful to apply the notion of legal equilibrium states and consider what factors may induce a legal order to flip from one stable state, such as a more centralized international order, into a different one, for example, a more fragmented, chaotic and pluralist world.¹¹²

Due to the multilayered and cross-cutting nature of the law, the cause of legal resilience can seldom be advanced through unilateral measures. In most cases, countering the legal challenges posed by grey zone and hybrid threats demands concerted action by several actors at multiple levels. This is obvious in the case of collective measures taken at the international level, such as economic sanctions. However, even at the domestic level, effective resistance, recovery from, and adaptation to grey zone and hybrid threats typically requires coordination and cooperation among various stakeholders. The protection of critical infrastructure illustrates the point. Legal resilience strategies must therefore provide the impetus for cooperation among relevant public and private actors across different sectors and throughout the local, regional, national, and international levels.

In fact, since legal resilience is not a purely legal endeavour, it is imperative that legal resilience strategies foster closer cooperation among relevant expert communities, for example, between legal experts and strategic communication specialists. Proponents of resilience thinking often underline its inter-disciplinary nature and its potential to serve as a bridging concept that can stimulate dialogue and collaboration among disciplines.¹¹³ Simply put, adopting a legal resilience perspective highlights—for the benefit of policymakers—that societal resilience has a legal dimension and that law has a resilience aspect. Legal resilience strategies should therefore seek to complement resilience thinking and strategies in other fields, for example, the resilience policies developed within the European Union¹¹⁴ and NATO,¹¹⁵ and vice versa.

As J. B. Ruhl has cautioned, resilience theory offers ‘nothing in the way of strategies legal scholars have not already covered’.¹¹⁶ Indeed, it would be a mistake to turn to resilience and expect a ready-made master plan for countering the legal effects of grey zone conflict and hybrid threats. In the present context, the benefits of adopting a resilience perspective lie elsewhere.

Legal resilience offers a framework for assessing and enhancing the capacity of legal systems to manage the challenges posed by adversaries resorting to grey zone and hybrid tactics. It is both an analytical tool and a policy agenda. A legal resilience perspective helps to better understand the legal dimension of grey zone and hybrid threats, in particular, the vulnerabilities of affected legal systems, their respective coping mechanisms, and the dual role that law plays in this area both as an object and as a medium of resilience. At the same time, a legal resilience perspective also contributes to greater legal preparedness in countering the hostile instrumentalization of the law and in addressing the vulnerabilities of other social systems exposed to such threats. Perhaps most importantly, a legal resilience perspective provides an opportunity to develop and implement more robust legal policies by integrating legal considerations into other policy planning processes and give more concrete and nuanced meaning to broad strategic objectives such as upholding the rules-based international order. Nor should the deterrent effect of legal resilience be overlooked: not only do tackling legal vulnerabilities deny their utility to adversaries, but greater legal preparedness also imposes additional costs on hostile actors. As this chapter has suggested, States and international organizations may realize these benefits by developing individual and collective legal resilience strategies, a new type of policy instrument setting out a detailed program for countering the legal challenges posed by grey zone and hybrid threats.