I. On the search for ‘a small number of big and important things’

Kenneth Waltz’s Theory of International Politics is often described, by its proponents and detractors alike, as an elegant and parsimonious representation of the operation of the international system.^{Footnote 6} Waltz’s objective was not to design a theory that explains every event in international politics. Rather, his intention was to construct a systemic – as opposed to a reductionist – theory that identifies the effects of the structure of the international system on the behaviour of states.^{Footnote 7} According to Waltz, the structure of the international system is composed of three elements. The first is the ordering principle of anarchy that is defined as the ‘absence of agents with system-wide authority’,^{Footnote 8} which means that the units within the international system recognise no authority superior to themselves. The second element is the functional differentiation of those units that make up the system, while the third is the distribution of capabilities among those units.^{Footnote 9} Since the constituent units of the system are states that, in Waltz’s view, perform identical functions, the second element of the structure is irrelevant, which leaves anarchy and the distribution of capabilities as the operative elements of the structure.^{Footnote 10}

This tripartite conceptualisation of the structure of the international system was not intended as an accurate rendition of reality. Rather it is an idealised image of international politics that purges the complexities and richness of political history to isolate and highlight the structural features that influence state behaviour.^{Footnote 11} For Waltz and his progeny of neorealists, the power and potency of this abstract concept of structure, especially the ordering principle of anarchy, is that it explains the recurrent patterns of competition and conflict that pervade international politics across time and space. As long as the system remains anarchic, all states, whatever the identity or ideology of their leaders and regardless of their domestic politics, are subjected to the ‘constraining and disposing force’ of the structure of the international system.^{Footnote 12} The cumulative effect of the structure is that international affairs is a realm of realpolitik in which states selfishly pursue their individual interests, especially ‘preserving and strengthening the state’,^{Footnote 13} even if to the detriment of other states.

Kenneth Waltz’s concept of ‘ordering principles’ and his identification of anarchy as the structural form of the international system are central tenets of international relations theory.^{Footnote 14} Anarchy is ‘unthinkingly accepted as the structural ordering principle of international systems … By the mid-1990s, anarchy had become ‘‘naturalised’’ across much of the discipline; treated as a taken-for-granted foundational assumption.’^{Footnote 15} Similarly, across the academic aisle, international lawyers almost unanimously describe the international legal order as anarchic and decentralised.^{Footnote 16} Contemporary international legal scholarship adopted the assumption of anarchy without engaging in the ‘great debates’ about the operation of the international system that dominated international relations.^{Footnote 17} Instead, international lawyers have focused on describing, criticising, and developing the doctrinal content of the field.^{Footnote 18} This abdication in favour of international relations specialists of theorising about international politics is surprising given the contributions of philosopher-lawyers such as Grotius, Pufendorf, Wolff, Vattel, Oppenheim and Schwarzenberger, to discussions about the nature of the international system. Therefore, in addition to examining what Richard Ashley called ‘the anarchy problématique’ that dominates international relations,^{Footnote 19} this article hopes to highlight to international lawyers the importance of theorising about the international system to generate better understandings of the political context within which international law operates.

This article interrogates the concept of ‘ordering principles’ and challenges the designation of anarchy as the ordering principle of the international system. It also questions established definitions of the term ‘international system’ that are often depicted as anarchic. This article proposes an alternative theoretical construct – the Constitutive Regime of the International System – that functions as the ordering principles of the international system, which determines its structure and establishes the parameters within which the units of the system interact.

An ‘ordering principle’ determines ‘the arrangement of the parts of the system’.^{Footnote 20} It is an ‘organizational concept’ that establishes the pattern according to which the units within a system are juxtaposed and combined.^{Footnote 21} Anarchy, however, does not and cannot perform that function. In fact, anarchy is not a principle at all.^{Footnote 22} Rather, anarchy is a descriptor that denotes the absence of a central authority that monopolises law-making, law enforcement, and dispute resolution in the international system. To Waltz and most scholars of international relations and international law, ‘the parts of international-political systems stand in relations of coordination. Formally, each is the equal of all others.’^{Footnote 23} This means that the parts of the system, i.e., the states inhabiting the system, are juridically equal and, therefore, arranged horizontally. Anarchy, however, cannot be the source of either the equality of states or their horizontal alignment. It is tautological to posit that the origin of the horizontality of the system and the formal equality of states, and thus, the reason that the international system is anarchic, is anarchy itself. The horizontal distribution of authority, which generates the anarchic structure of the system, must, therefore, result from some deeper, broader norm or principle.

Definitions of the ‘international system’ that is described as being anarchic are also fundamentally flawed. International relations scholars from various theoretical traditions have developed strikingly similar and equally inadequate definitions of the international system. To Waltz, ‘international-political systems, like economic markets, are formed by the coaction of self-regarding units … No state intends to participate in the formation of a structure by which it and others will be constrained. International political-systems, like economic markets, are individualist in origin, spontaneously generated, and unintended.’^{Footnote 24} Hedley Bull, a leader of the English School of International Relations and a critic of neorealism,^{Footnote 25} similarly describes the international system as being created when ‘two or more states have sufficient contact between them, and have sufficient impact on one another’s decisions, to cause them to behave – at least in some measure – as parts of a whole’.^{Footnote 26} Recent definitions of the international system that recognise the role of non-state actors also assume that systems are spontaneously created by combining previously separate units: ‘taken collectively, states and non-state actors co-existing and interacting at any point in history form an international system’.^{Footnote 27}

These definitions of the international system are incomplete and intellectually anemic. The existence of the states (and/or non-state actors) that constitute the system is simply assumed; the designation of states (and/or non-state actors) as the constituent units of the system is similarly accepted as a given; there is no explanation for why interactions between states, but not other types of actors, count towards the creation of a system; and the nature and intensity of the interactions that are required to create the system are also undefined.^{Footnote 28} Moreover, describing the system as ‘anarchic’ does not identify the origin of the juridical equality of states, which generates the anarchic nature of the system. This is especially perplexing in light of the differences in the capabilities of states. Why the power differentials between states do not upend the equality of states and overturn the anarchic structure of the system is left unconsidered.^{Footnote 29}

In short, anarchy cannot, as some scholars describe it, be the ‘deep structure’ of the system.^{Footnote 30} Nor can other structural forms, such as hierarchy and heterarchy that scholars have proposed as alternatives to anarchy,^{Footnote 31} serve as the ordering principles of the system. Like anarchy, these terms are descriptive labels that express either the centralisation of authority – i.e. hierarchy, or, the uneven distribution of authority among entities that are neither super- nor sub-ordinate to each other – i.e. heterarchy. In either case, the anarchic, hierarchic, or heterarchic arrangement of the parts of a system must emanate from elsewhere.

The answer, this article posits, is that the international system is predicated on a set of intersubjective assumptions that provide the ordering principles of the system and that constitute its ‘deep structure’. I call these assumptions the Constitutive Regime of the International System. This regime is composed of three elements. The first is the principle of differentiation, which identifies the constituent units of the system – i.e. the actors authorised to engage in international affairs, and determines the distribution of authority between those units. By determining the distribution of authority, the principle of differentiation generates the structure of the system. If authority is decentralised and the units are considered co-equals, the system is anarchic, but if authority is concentrated with some actors that are entitled to dominate other actors, the system becomes hierarchic or imperial, while if authority is shared and multilayered the system becomes heterarchic. The principle of differentiation could also generate systems that exhibit combinations of these patterns of authority. The second component is the theory of world order, which is a world view that prescribes principles and policies that are considered necessary for maintaining order in the system and that determine the parameters governing the interactions of the units operating within the system. The third component is the secondary rules of international law, which are the rules and processes of law-making and law enforcement in the international system. The Constitutive Regime, to borrow Stanley Hoffmann’s phrase, is the ‘law of the political framework’.^{Footnote 32} It is the normative foundation that structures the system and establishes the ground rules for interaction between its members.

Before proceeding, it is necessary to outline the intellectual ambitions of this article. In response to criticism that the Theory of International Politics failed to explain a wide range of events in international affairs, Kenneth Waltz clarified that his objective was to identify ‘a small number of big and important things’ that shape state behaviour.^{Footnote 33} The Constitutive Regime of the International System is not dissimilar. It is not a theory of everything. It does not explain the content of every rule of international law, or the structure of every international institution, or every event in international politics. It is, however, ‘one big thing that explains a small number of important things’. The Constitutive Regime is an heuristic instrument that explains the structure of the international system. It provides an account of how the structure of the international system is determined by intersubjective assumptions the allocate authority between the constituent units of the system. It shows that the structure of the international system is not static, but a historically contingent construct that is determined by deeper intersubjective assumptions.^{Footnote 34} The Constitutive Regime is also an instrument of systematisation. It uncovers the background world view that shapes and justifies the rules, institutions, and practices of international politics. It shows that underlying these rules, institutions, and practices that often appear unrelated and fragmented are coherent (or, at times, competing) world views. The Constitutive Regime, therefore, functions like DNA; it embodies the genetic code of the international system.

The Constitutive Regime is not, however, a normative theory of the international system.^{Footnote 35} It does not espouse specific substantive values nor does it advocate a preferred vision of world order or any particular conception of justice. It is an ethically neutral construct. It is flexible enough to encompass systems as diverse as the hierarchic Sino-centric system of the seventeenth century,^{Footnote 36} Napoleon’s revolutionary, republican, and imperial systems, and the post-Napoleonic reactionary system,^{Footnote 37} and the post-World War II Liberal World Order. The Constitutive Regime identifies and describes the ordering principles of international systems without passing normative judgment on those principles. This is because a morally pernicious system predicated on racialised or colonial principles of differentiation or that operates on the bases of an ethically reprehensible world view is no less ‘systemic’ than a morally laudable system.

II. Of systems, structures and constitutions: Surveying the scholarly terrain

The claim that the international system operates on the bases of foundational or constitutive norms is not entirely novel. Therefore, it is necessary to highlight how this article contributes to, builds on, and differs from scholarship that has investigated the normative foundations of the international system. After all, in proposing the Constitutive Regime of the International System, my intention is not to contribute to the conceptual congestion that often afflicts international law and international relations scholarship, but to offer a theoretical construct that synthesises and simplifies existing scholarship and introduces unexplored elements of the normative substructure of the international system.

This article builds on two core contributions of constructivist scholarship. The first is the claim that the structure within which international affairs occurs is the product of shared meanings and social understandings, while the second is the importance of problematising the constitutive, as opposed to the causal, impact of rules and norms in international affairs.^{Footnote 38} Constructivists, however, generally accept the neorealist presumption of anarchy as the ordering principle of the international system;^{Footnote 39} a proposition that I reject. Where constructivists diverge from realists on anarchy is in their powerful and persuasive critique of the realist claim that ‘international anarchy is the principal force shaping the motives and actions of states’.^{Footnote 40} Instead, Alexander Wendt argues that ‘political culture is the most fundamental fact about the structure of an international system, giving meaning to power and content to interests, and thus the thing we need most to know to explain a “small number of big and important things”’.^{Footnote 41} I disagree. Before identifying the prevalent ‘political culture’ among the units of an anarchic system, it is necessary to determine why those particular units are the principal actors of the system whose culture and preferences matter and to trace how the allocation of authority among those units created an anarchic (or hierarchic or heterarchic, etc.) system in the first place. These are the ‘most fundamental fact(s)s’ about the international system that the Constitutive Regime of the International System embodies.

This article is also influenced by the English School of International Studies which, as Andrew Hurrell explains, generated a large body of scholarship based on the insight that ‘central to the “system” is a historically created, and evolving, structure of common understandings, rules, norms, and mutual expectations’.^{Footnote 42} English School theorists have not, however, contested the neorealist assumption that anarchy is the fundamental structural feature of the system. Indeed, the English School’s canonical tome, Hedley Bull’s magnum opus, is titled The Anarchical Society. Instead, the ‘central motif’ of the English School is the claim that, despite its anarchic structure, order is maintained in the system because its units are organised into what has been alternately called the ‘society of states’, the ‘international society’, or the ‘system of states’.^{Footnote 43} What makes the system a society is, first, that states share ‘common interests in the elementary goals of social life’,^{Footnote 44} and second, the existence of ‘primary institutions’ (war, diplomacy, the Great Powers, balance of power, international law) that facilitate relations between states and contribute to maintaining order.^{Footnote 45}

This article builds on these English School insights by taking a theoretical step-back. It argues that preceding any consensus on elementary goals and underlying the primary institutions of society are a set of constitutive norms, which are embodied in the Constitutive Regime of the International System. These norms are essential for the existence and operation of an international society because they identify the members that constitute the society, determine the distribution of authority amongst those members, and establish the law-making and law-enforcement mechanisms. These constitutive norms, in other words, empower actors to engage in international politics, partake in diplomacy, act as great powers, wage war, and make international law. In a sense, therefore, the Constitutive Regime is, to use English School terminology, the primary institution of international society. This constitutive dimension of the normative architecture of the international system is largely ignored by the English School. Indeed, Hedley Bull merely alludes, virtually en passant, to ‘the complex of rules that states what may be called the fundamental or constitutional normative principle’ which he identified as ‘the idea of a society of states … as the supreme normative principle of the political organisation of mankind’.^{Footnote 46} Neither Bull nor later English School theorists expanded on or elaborated this insight. This article addresses this blind spot by constructing a theoretical account of those constitutive norms.

This article also builds on the work of scholars of both international law and international relations who have theorised that the international system is based on constitutive or foundational norms. Some scholars have hinted at the existence of background principles that constitute the normative foundation of the international system without exploring the matter further. For instance, Jeffrey Dunoff and Joel Trachtman noted that certain norms exist at a ‘meta-constitutional’ level that constitute ‘the basic decisions about the fundamental structure of society [which] precede and determine the structuring of legal constitutions’.^{Footnote 47} Similarly, Jack Donnelly discussed the ‘constitutional structure of an international society’, which is ‘an ensemble of fundamental, society-wide rules, practices, and roles that enable, prohibit, constrain, permit, facilitate, or encourage particular kinds of action and interaction among the participants in international relations’.^{Footnote 48} Writing in this journal, Thomas Müller used terms similar to Donnelly’s to define ‘constitutional structures’ as a ‘set of fundamental and prioritised principles and rules that serves as a framework for the self-ordering of international societies, or more abstractly relations between polities’.^{Footnote 49}

John Ikenberry further contributed to theorising about constitutional foundations of the international system.^{Footnote 50} Writing on the political and historical circumstances in which constitutional norms are formed, Ikenberry categorised constitutional norms as a form of institutional, as opposed to substantive, bargaining. The latter involves bargaining ‘over distributive outcomes, where states struggle over the distribution of benefits in specific relationships’.^{Footnote 51} Constitutional norms, however, are not issue-specific agreements. Rather, they are agreements on ‘the rules of the game – that is the parameters within which states will compete and settle disputes over specific issues’.^{Footnote 52}

These definitions and descriptions of norms that are labelled as ‘constitutional’, ‘meta-constitutional’, or ‘fundamental and prioritised’ are underdeveloped. The existence of these norms is presented as a general theoretical insight without expanding on their nature or content, and their functions are described in broad, generic terms. For example, the ability to ‘enable, prohibit, constrain, permit, facilitate, or encourage particular kinds of action’, which Donnelly attributes to constitutional norms, are functions that apply to all of international law. This fails to distinguish with sufficient precision the distinctive constitutive nature of these norms. In particular, these definitions overlook the principal functions that the Constitutive Regime of the International System performs; namely, the identification of the constituent units of the system, the articulation of their basic rights and competences, the elaboration of a theory of world order that governs interactions between them, and the creation of law-making and law-enforcement rules.

Christian Reus-Smit partially remedied these omissions by arguing that the international system is based on ‘meta-values defining legitimate statehood and rightful state action’.^{Footnote 53} Similarly, Ian Clark suggested that ‘core principles of legitimacy constitute international society … legitimacy defines both rightful membership and rightful conduct, it specifies the key requirements for international society’.^{Footnote 54} Writing separately, Alec Stone and Samantha Besson highlighted another function of constitutional norms in the international system which Reus-Smit and Clark do not discuss. According to Stone, ‘a constitution denotes a body of metanorms, rules that specify how legal norms are to be produced, applied, and interpreted. Metanorms are thus not only higher-order but prior, organic norms – they constitute a polity.’^{Footnote 55} Similarly, Besson defined a ‘thin constitution’ as an ‘ensemble of secondary rules that organize the law-making institutions and processes in a given legal order’.^{Footnote 56}

The Constitutive Regime of the International System proposed in this article refines, develops, and expands on these understandings of the constitutional or foundational norms of the international system.

First, as a semantic matter, referring to these norms, as Reus-Smit does, as determining ‘legitimate statehood’ creates the misimpression that states are the only conceivable constituent unit of international systems. Instead, I prefer the theoretically capacious concept of the principle of differentiation as an instrument that could identify states or any other form of organising human communities as the constituent units of the international system.

Second, one weakness of existing discussions of constitutional or foundational norms is that different types of constitutive norms are examined separately. Reus-Smit and Ian Clark, for instance, focused on the norms of ‘rightful membership’ and ‘rightful conduct’ in the international system, while Stone and Besson explored the law-making rules of the international system. A main contribution of the concept of the Constitutive Regime is that it combines these constitutive functions into a single, holistic theoretical construct. It highlights the connection, symbiotic relationship, and causal priority between identifying the members of the system and elaborating the rules of international law-making and law enforcement. It also clarifies the role of the theory of world order in shaping the rules of international law-making and law enforcement. As discussed below, I argue that the principle of differentiation, which identifies the constituent units of the international system, and the theory of world order, which prescribes the policies and principles necessary for order within the system, ultimately determine the content of the secondary rules of international law.

Third, this article highlights the role of ‘authority’ in determining the composition of the international system and shaping its structure. The composition of an international system and its structure are, in essence, determined by decisions about the allocation and distribution of authority. Any international system is populated by various types of actors and entities that engage, to varying degrees, in international affairs. The principle of differentiation, which is one of three components of the Constitutive Regime of the International System, codifies a social consensus regarding the types of actors or entities that are endowed with the authority to engage in international affairs. The principle of differentiation also determines the structure of the international system by codifying a social consensus about the distribution of authority among the units authorised to engage in international affairs. If it adopts a centralised distribution of authority between the actors or entities entitled to engage in international affairs, the system becomes hierarchic, while if it adopts a decentralised distribution of authority, the system becomes anarchic.

Fourth, Donnelly’s claim that the constitutional norms of the international system ‘enable, prohibit, constrain, permit, facilitate, or encourage particular kinds of action and interaction among the participants in international relations’ and Müller’s argument that ‘constitutional structures’ serve as a ‘framework for the self-ordering of international societies’ are unduly broad. All international law and all international regimes can be described in these terms. Therefore, this article argues that, in addition to a principle of differentiation, the Constitutive Regime of the International System includes a theory of world order. This theory of world order regulates state behaviour, not by prescribing or proscribing policy in specific areas, such as security or trade, but by articulating a coherent world view or an overarching ideological vision that provides a justificatory narrative for policies and practices in the various areas of global governance.

Fifth, the Constitutive Regime of the International System provides a theoretical vocabulary to conceptualise the different forms of change in international systems. This article distinguishes between change within a system and change of a system. The latter occurs when the constituent unit of an international system – which, as discussed below, is the dominant method of organising human societies and controlling territory – is replaced. On the other hand, change within a system occurs when the extant theory of world order is challenged or when new units and actors exercise authority within a system without replacing the established constituent units of an international system. This is particularly relevant given current developments in the contemporary international system. Today’s world is witnessing a confluence of phenomena that challenge the structure and operation of the international system. These include the shifting balance of global power, the appearance of novel law-making processes, and the rise of various actors that exercise different forms of authority within a system that continues to be dominated by territorial states. The Constitutive Regime provides an intellectual tool that conceptualises and explains how these developments affect the structure and operation of the international system.

III. The constitutive regime of the international system

The Constitutive Regime of the International System is a set of intersubjective assumptions that provide the normative foundation of the international system. It is composed of a principle of differentiation, a theory of world order, and the secondary rules of international law.^{Footnote 57} The Constitutive Regime, thus, consists of three components. The first two are the principle of differentiation and the theory of world order, while the third is the secondary rules of international law.

The Constitutive Regime of the International System is analogous to what Mark Tushnet calls ‘constitutional regimes’. These regimes, which govern domestic political systems, are broader than the written Constitution and the corpus of constitutional doctrine and precedent. A constitutional regime consists of ‘a reasonably stable set of institutions through which a nation makes its fundamental decisions over a sustained period, and the principles that guide those decisions’.^{Footnote 58} In other words, constitutional regimes establish the normative parameters of politics. As Tushnet explains, ‘these institutions and principles provide the structure within which ordinary political contention occurs’.^{Footnote 59}

Like a domestic constitutional regime, the Constitutive Regime of the International System provides the normative framework within which international politics is exercised by embodying elementary assumptions about the structure of the international system. Unlike Tushnet, however, I employ the term ‘constitutive’ as opposed to ‘constitutional’ to describe this regime. This terminological choice is driven, first, by a recognition of the difficulty of defining terms like constitution, constitutional, constitutionalism and constitutionalisation with clarity and concision,^{Footnote 60} and second, it reflects an appreciation of the normative-weightiness of these terms. Especially when used in the literature on Global Constitutionalism, these terms express a normative agenda that seeks to promote individual autonomy, human rights, and the rule of law in a globalised, interdependent, and institutionally fragmented international system.^{Footnote 61} The Constitutive Regime of the International System, however, is a theoretical construct that makes no such normative prescriptions. Rather, the term ‘constitutive’ is intended to communicate the ethical neutrality of the Constitutive Regime of the International System.^{Footnote 62}

The term regime should be readily recognisable. It is borrowed from international relations Regime Theory, which explains how certain areas of transnational relations, such as trade, security, or environmental protection, are regulated by a set of rules, principles, and decision-making procedures.^{Footnote 63} A Constitutive Regime functions like a regime. It is a set of principles, norms, and rules that are broadly accepted and that perform a governing function. In this case, however, the function of this regime is constitutive not regulative, and its scope is systemic not issue-specific.^{Footnote 64}

The Constitutive Regime is logically antecedent to the international system.^{Footnote 65} Without background norms that identify the members of the system, determine their rights and competences, and establish the mechanisms of international law-making, any examination of the system would be incomplete and incomprehensible. In other words, underlying the flags, anthems, embassies, and the pomp and pageantry of statehood, is an intersubjective assumption that designates states – as opposed to empires, tribes, the Catholic Church, the Islamic Ummah, or some other form of organising human societies – as the constituent units of the international system. It is the Constitutive Regime of the International System that endows Germany, Gambia, and Georgia, but not Google, Greenpeace or the US State of Georgia, with the authority to establish embassies, issue passports, fly ensigns on airplanes and ships, wage war, make peace, achieve détente and maintain entente, and practice the balance of power. Moreover, the elementary rule that international law emanates from state consent, is merely an expression of the intersubjective assumption that states, and not, for instance, international organisations, NGOs, corporations, or individuals, are the primary lawmakers of the international system and that their consent is necessary for the creation of valid rules of international law.

Constitutive Regimes are creations of Great Powers. Throughout history, every power that succeeded in establishing hegemony over an international system has configured the basic norms that govern that system – i.e. the Constitutive Regime of that system – in a manner that served the values and interests of that hegemonic power.^{Footnote 66} Therefore, while every international system is predicated on a Constitutive Regime, the normative content and ethical orientation of Constitutive Regimes will vary depending on the interests and values of the Great Powers of that particular system. The concept of the Constitutive Regime, therefore, is purely functional.^{Footnote 67} Once its content is articulated by the Great Powers and accepted, either by acquiescence or coercion, by the other actors in the system, it performs the function of constituting the international system and becomes the dominant approach to governing the system.

Constitutive Regimes are not static constructs. As the balance of power shifts and as new participants engage in international affairs, the content of the Constitutive Regime is revisited to reflect new realities in international politics. New actors and new entities periodically emerge and challenge the established configuration of the international system. As these actors and entities acquire more power and exercise more influence, they could gradually be accepted as centres of legitimate authority in the international system thereby reconfiguring its structure. International organisations, corporations, NGOs, actors engaged in ‘private ordering’,^{Footnote 68} global governance networks,^{Footnote 69} and even terrorist organisations like ISIS,^{Footnote 70} all, to varying degrees, challenged the state-centric Constitutive Regime of the twentieth century. Eventually, some of these actors were endowed with different forms and degrees of authority to participate in an international system in which states remain the primary actors.

The next three sections define and discuss the three components of the Constitutive Regime of the International System.

IV. Constitutive moments and constitutive crises

The Constitutive Regime of the International System is a living concept. Its content is articulated by the Great Powers of every historical era, but then those powers and units that inhabit a system are continuously constituted and reconstituted by the Constitutive Regime. As the units within the system continue to operate on the bases of the principle of differentiation, theory of world order, and secondary rules of international law underlying the system, the authoritativeness of the Constitutive Regime of that system is reasserted, which in turn, reconfirms the standing, rights, and competences of those units. Simultaneously, the adherence of the constituent units of an international system to the terms of a Constitutive Regime means that its content is constantly being reproduced by the activities of those units.^{Footnote 142} In other words, as constructivist theorists have insisted, the ordering principles of the international system and its constituent units are locked in a relationship of mutual dependence and constant reconstitution.^{Footnote 143}

The success of a particular conflict group or specific power in dictating the content of the Constitutive Regime of the International System never spells the end of history. Every system includes the disenfranchised, the disenchanted, and the dissatisfied. Every polity includes actors espousing alternative visions and competing world views that challenge the established orthodoxy. At certain historical junctures pressure mounts to revisit the normative foundations of the international system. This pressure may originate from the emergence of a new conflict group that seeks to establish itself as the dominant mode of organising human society. This pressure may also emanate from a shift in the balance of power among existing conflict groups. As the topography of power shifts and as normative winds change, opposition to the dominant Constitutive Regime will gain traction. These are periods of constitutional crises that can lead to change within a system or, if the standing of the constituent unit of the system is challenged, that can cause the total change of an international system. These are periods when global political contestation is not limited to specific issues or particular conflicts. Rather, the normative foundation of the entire international system becomes a site of contestation.

The contemporary international system is experiencing a period of constitutional crisis. The Constitutive Regime of the current international system was designed by the US in the post-Cold War years. The theory of world order of this Constitutive Regime was based on the Liberal Peace Theory. This theory, which is a mainstay of American foreign policy, is predicated on the presumption that democratic states that are economically interdependent are less likely to wage war against each other. Therefore, to preserve order and prevent war, Liberal Peace Theory prescribes promoting the democratisation of states and the liberalisation and integration of their economies.^{Footnote 144} Accordingly, the principle of differentiation of the post-Cold War Constitutive Regime was configured to identify liberal democratic states as the constituent units of the international system. The legitimacy of states increasingly depended on the democratic credentials and human rights record of their governments.^{Footnote 145} States that failed to fulfil this standard of legitimate statehood risked losing the privileges of membership in the international system.^{Footnote 146}

This Constitutive Regime of the post-Cold War years is currently in crisis. It is being challenged by a tectonic shift in the global balance of power the manifestations of which include China’s re-emergence, Russia’s resurgence, India’s growing prosperity, and the economic success of states like Brazil, South Africa, South Korea and Turkey.^{Footnote 147} These non-Western powers do not adhere to the Liberal Peace Theory. These states espouse a traditional state-centric Westphalian image of the international system and reject attempts to adopt a principle of differentiation and a theory of world order that identifies liberal democratic states as the sole legitimate constituent units of the international system.^{Footnote 148} The Constitutive Regime of the post-Cold War order is also being challenged by the rise of nativist, pseudo-nationalist, and populist parties in Western societies. This populist revolt has demonstrated the depth of the discontent towards the ideas and values embodied in the post-Cold War Constitutive Regime, including free trade, environmental protection and combatting climate change, pro-immigration policies and multiculturalism, and multilateralism. The importance of this ongoing populist backlash is that it has afflicted the very heart of the Western world. Many within the societies that articulated the post-Cold War Constitutive Regime appear to be rejecting the normative foundation of the international system they sponsored and led.

Given the current state of world politics, it is reasonable to predict that the international system will experience an extended constitutional crisis. One of the principal arguments of this article is that determining the content of the Constitutive Regime of the International System is an act of elite engineering. Today’s international system, however, is No One’s World. ^{Footnote 149} Power is dispersed to the extent that there is no clear centre of political gravity in the system. In this politically weightless world it is unlikely that any single state or coalition of states will wield sufficient power to wholly determine the content of the Constitutive Regime of the International System. Instead, for the foreseeable future, our world will be governed by a decaying Constitutive Regime that is no longer accepted by either its creators or consumers, but to which no clear constitutive alternative has emerged.