The ban on war as a form of international order

For many authors, the introduction of law into the decision to go to war marks a dramatic break the management of international affairs, in Europe and beyond. It is often used as evidence that the post-1945 world is fundamentally different from what existed before. For instance, according to Tom Ruys, ‘up until the end of the nineteenth century, the predominant conviction was that every State had a customary right, inherent in sovereignty itself, to embark upon war whenever it pleased.’Footnote ¹² This right was activated when a sovereign claimed to have experienced a harm at the hands of a foreign agent. The pre-1945 discourse of war legitimation emphasised the existence of harm and the legitimacy of the use of force in response.Footnote ¹³ Precipitating harms might include unpaid debts, territorial incursion, dynastic disputes, regional destabilisation, and more; and the actors perpetrating those harms might include other sovereigns, their diplomats and agents, or even firms and individuals.Footnote ¹⁴ Thus, war choices in the eighteenth- and nineteenth-century European system were legitimated in political rather than legal terms.Footnote ¹⁵

By imposing a legal framework upon war, the UN Charter ended this era. In its place, Christine Gray writes the Charter ‘provides a new terminology and the first expression of the basic rules [for war] in their modern form’.Footnote ¹⁶ Michael Byers sees this as ‘a constitutional moment in international affairs: an anarchic world of self-help and temporary alliances was transformed into a nascent system of governance.’Footnote ¹⁷ Thomas Franck believes it launched the modern age, distinguished by the ‘idea that the use of force by a state against another could itself be violative of the legal order’s very foundations’.Footnote ¹⁸

This argument is often derided as ‘world peace through world law’,Footnote ¹⁹ but its central insight has been adopted widely by liberal, realist, and many critical writers across political science, history, and legal theory. For instance, Hedley Bull identified rules on violence as a key component of the existence of society itself, whether domestic or international. Society, for Bull, begins when individuals put aside their natural right to act as they see fit and become both encumbered and liberated by rules that constrain their recourse to violence.Footnote ²⁰ International society is therefore inconceivable without rules that regulate war. International law scholars often arrive at the same conclusion but by starting at a different point – that regulating inter-state war is the paradigmatic, essential task of public international law: it is common among international lawyers to equate international law with the regulation of violence itself. Hersch Lauterpacht said that the ‘primordial duty of the [international] law’ is to enact the rule that ‘there shall be no violence’ by states.Footnote ²¹ Mary Ellen O’Connell says that ‘law is valued for providing an alternative to the use of force in the ordering of human affairs. In this sense, all of international law is law of peace.’Footnote ²² For Lauterpacht, as for O’Connell, the regulation of war is inseparable from the concept of public international law itself,Footnote ²³ and both share with Bull the faith that controlling war with law will allow international society to emerge among nations.

G. John Ikenberry provides a defence of the view that international rules and institutions, the ban on war prominent among them, are the foundation of contemporary order. For Ikenberry, the post-1945 world is characterised by the multilateral commitment to a rules-based international system. In this ‘liberal hegemonic order’, the commitment to international legal institutions creates ‘an order where weaker states participate willingly – rather than resist of balance against the leading power … . Weaker states agree to the order’s rules and institutions, and in return they are assured that the worst excesses of the leading state – manifesting as arbitrary and indiscriminate abuses of power – will be avoided, and they gain institutional opportunities to work and help influence the leading state.’Footnote ²⁴

Ikenberry is expressing the intuition behind liberal internationalism more generally when he says that the rules and institutions that make up the international order increase the security of both strong and weak states. He thinks they will therefore gain the consent of these states. ‘The United States built postwar order within the Western world – and extending outward – on liberal ideas and principles … looking after the overall stability and openness of the system … . In ideal form, liberal international order is sustained through consent rather than balance or command. States voluntarily join the order and operate within it according to mutually agreed-upon rules and arrangements. The rule of law, rather than crude power politics, is the framework of interstate relations.’Footnote ²⁵ In such a system, ‘power is exercised through sponsorship of rules and institutions’, he says.Footnote ²⁶ The progress of ‘liberal’ postwar settlements since 1815 has therefore been ‘based on a set of principles of restraint and accommodation’, anchored by limitations on inter-state violence.Footnote ²⁷

It isn’t only liberals such as Ikenberry who see international rules on war as giving structure to inter-state relations. Henry Nau, promoting what he calls ‘conservative internationalism’, takes a similar view, although he limits its scope to ‘the West’. In that region (or perhaps ‘community’) he sees a unified international identity ‘in which common law and institutions replace the balance of power and anarchy’.Footnote ²⁸ He differentiates his view from that of liberals by explicitly endorsing the use of force as a means to expand the reach of that identity – he says ‘given the continuing range of threats, the use of force to promote a freedom-forward diplomacy persists’.Footnote ²⁹ Nau never accounts for what ‘freedom’ means nor does he show any connection between it and American military operations, and as a consequence his policy prescriptions carry little weight – but he shares with Ikenberry and others the view that international rules take the place of power politics and thus contribute to international order.

A version of this commitment, albeit with a different political valence, appears also in the work of Michael Hardt and Antonio Negri. In identifying global power in late modernity, Hardt and Negri find an emerging ‘imperial sovereignty … an imperial notion of right’ that straddles the conventional divides of domestic/international and public/private power. The ‘juridification’ of global power has reconstituted sovereign authority in a constellation of institutions and practices across these divides, creating ‘a machine that imposes procedures of continual contractualization that lead to systemic equilibria’ – in other words, a codification of states’ and subjects’ legal obligations and the repackaging of their political relations in legal terms.Footnote ³⁰ This is echoed in B. S. Chimni’s account of the ‘emerging global state’, which he sees arising in the form of the interconnected web of international political, legal, and economic institutions.Footnote ³¹

Hardt and Negri identify the ban on war, and the legalisation of war in the UN, as the mid-twentieth-century hallmarks of the ‘juridification’ of politics, both global and local: the reconstitution of war as a specifically legal category produces ‘the right of duty of the dominant subjects of the world order to intervene in the territories of other subjects in the interest of preventing or resolving humanitarian problems, guaranteeing accords, and imposing peace’.Footnote ³² This juridical global power they call ‘Empire’. ‘Empire is not born of its own will but rather it is called into being and constituted on the basis of its capacity to resolve conflicts. Empire is formed and its intervention becomes juridically legitimate only when it is already inserted into the chain of international consensus aimed at resolving existing conflicts.’Footnote ³³ For Hardt and Negri, the turn to law to adjudicate international disputes and to decide when war is permitted constitutes Empire as an emerging form of global sovereignty.

From O’Connell to Nau to Hardt and Negri, there is a widespread commitment to the view that the legalisation of war-decisions in the mid-twentieth century makes a crucial contribution to the contemporary international order. It gives a specifically legal frame to the distinction between legitimate and illegitimate wars, and it organises international political power in ways that would seem alien to the nineteenth-century model of diplomatic accommodation in European power politics.Footnote ³⁴ By setting legal criteria that differentiate legitimate from illegitimate wars, the new system invites competing claims regarding the relevant laws and their application to particular circumstances. This gives rise to familiar debates about how the rules should be interpreted and applied, which I discuss next, but the point of the present section is that these debates take place within a shared commitment to the ideas that in principle states’ uses of force can be divided into ‘legal’ and ‘illegal’, and that the UN Charter and other texts provide the resources for making that distinction.

State practice in the interpretation of the ban on war

How the rules have been used, interpreted, and argued over in past practice is significant for resolving ambiguity and filling lacunae in international law. According to Thomas Franck, state practice gives ‘“live” meaning … to inert words by existential experience and transactional processes’.Footnote ⁴⁴ It is taken as evidence of how governments understand the content of their obligations and therefore of what they consider to be lawful and unlawful.Footnote ⁴⁵ This is implied by the logic of consent and obligation that is at the heart of international law itself: since states are the agents that consent to the obligations in the treaty, their own understanding of the content of those obligations is relevant when resolving controversies around them.

Past practice toward a piece of international law can change the meaning of the obligations that it contains – indeed it must, since unless it can do so then there is no point in consulting practice as a means to understand the text. As illustrations, Thomas Franck notes several areas in which the obligations of state toward the ban on war have changed since 1945 despite no change in the Charter language. Article 51, for instance, establishes that states must cease their ‘self-defence’ operations when the Security Council takes action on the matter. This has not been followed in practice,Footnote ⁴⁶ and international judicial and political institutions have endorsed this failure as legally adequate.Footnote ⁴⁷

More consequential for international politics is the expansion in concept of ‘anticipatory’ self-defence. The Charter clearly outlaws such action: it requires that ‘an armed attack has occurred’ before self-defence is permitted. But the rule has been read almost from the start as if it permitted anticipatory wars and the legality of the practice is in principle widely accepted.Footnote ⁴⁸ The controversy over anticipation comes from disagreements over how to identify the circumstances in which it is legal, and on this the most common formulation invokes the Caroline case from 1837 to find that anticipatory attacks are lawful when the threat of attack is ‘imminent’.Footnote ⁴⁹

Scholars and states have reconciled this practical reading of the law with its more restrictive Charter text in two ways – first, by suggesting that anticipatory self-defence is part of the ‘inherent’ right to self-defence which the Charter ‘shall not impair’, and second, by showing that the practical implications of banning anticipatory war are unworkable and thus the Charter cannot possibly mean what it says. The first is a technical legal argument and the second a consequentialist one, but they lead to the same outcome: the use of force prior to an armed attack is presented as lawful despite the plain text of the Charter as well as its traveaux preparatoires.Footnote ⁵⁰

The ‘adaptability’ of the Charter to new situations is widely accepted by governments and scholars. It presumes that the line separating acceptable from unacceptable behaviour is not clear or fixed, and that past state practice can illuminate where the line lies today. It isn’t particularly controversial.Footnote ⁵¹ Neither is the fact that the practice and desires of the strongest states dominate in legal interpretation with the effect that the law is likely to evolve in ways that the Great Powers find acceptable. Many scholars see this as a desirable feature of international law, including Franck who says that a ‘strictly literal interpretation of the Charter’s collective security system’ became ‘unworkable’ after 1945 and so its interpretive expansion since then has been a good thing.Footnote ⁵² W. Michael Reisman argues against having international rules that are ‘mechanically applied’ – after all, he says, the ‘political [and] technological environment have been changing inexorably since the end of the 19th century’ and our reading of the law must change with it.Footnote ⁵³ To do otherwise he says (in a startling choice of phrase) ‘rapes common sense’.Footnote ⁵⁴ The interpretation of a treaty must keep up with ‘evolutions in the international security environment’Footnote ⁵⁵ and remain ‘in accord with changing circumstances and social values’.Footnote ⁵⁶ Michael Byers says it is ‘a pragmatic response’ of law to the present needs of states.Footnote ⁵⁷ Tom Ruys believes ‘legal rules are not static, but are capable of evolving over time’.Footnote ⁵⁸

The implication of this flexibility is that the legal status of an act may change even if the text of the law has not. What was legal may become illegal, and vice versa, in response to certain changes in the external environment such as in military technology, the nature of threats, and consequent changes in the needs of states for defence against them. Legal interpretations that are ‘not evident from the text’ (in Franck’s words) sometimes come to be accepted as authoritative,Footnote ⁵⁹ at which point legality no longer means being ‘faithful to the language of the treaty’. According to Reisman, ‘one should not seek point-for-point conformity to a rule without constant regard for the policy or principle that animated its prescription’.Footnote ⁶⁰ Jan Klabbers says, ‘many possibly illegal acts have been warmly welcomed by the membership of the organization concerned, ranging from usurpation of powers to debatable use of credentials procedures. In turn, this creates the following situation: if a healthy majority agrees with the activity, then it can hardly be deemed illegal, for, if it were illegal, how could a healthy majority possibly accept it?’Footnote ⁶¹ To the extent that the law is specified by reference to how it has been used in the past, then possibly illegal acts can be reconstituted as legal through depending on how they are received by the society. These ‘uses of history’ ensure that the law is not seriously at odds with the interests of powerful actors.Footnote ⁶² The dynamics of legal development work toward the natural and perpetual coincidence of law and Great Power interests.

The ‘self’ in self-defence

The Charter creates a legal regime in which self-defence is the sole lawful motivation for a state using force outside its borders. This is what Oscar Schachter called ‘defensism’ with respect to the laws on war – where the needs of self-defence define the outer bounds of legality.Footnote ⁶³ As mentioned earlier, this has come to be understood to include the use of force before an armed attack has occurred as long as it responds to an imminent threat of attack. Defensism as a legal justification suggests that states act legally (and rightly) when they respond militarily to the ‘compulsion from fear’ that is produced by an external threat.Footnote ⁶⁴

It is not surprising therefore that self-defence has become the most popular justification for war, often with all sides in the conflict claiming it as their motivation. In debates about the appropriate application of the law and its core concept, most attention has focused on what might be called the ‘genuineness’ of the connection between the use of force and the security needs of the state – for instance, the Nicaragua decision at the International Court of Justice was founded on the Court’s rejection of ‘justification of collective self-defense maintained by the United States in connection with the military and paramilitary activities in and against Nicaragua’.Footnote ⁶⁵ To make a judgment about whether the use of force is ‘necessary’ for a state’s self-defence requires assessing the security needs of the state, as well as the nature, imminence, and other qualities of the external threat, and also the utility and proportionality of military force in remedying the threat.Footnote ⁶⁶ These questions open the space for disagreement and controversy, which characterises the history of claims to ‘self-defence’ under international law. For methodological positivist approaches to international law, resolving these questions is crucial since only by that path can one determine when states are complying with or violating the law. Post-positivist approaches are not committed to finding answers to such questions, and instead see them as reflecting political disagreements about what the rules should be and what conduct should be sanctioned and in what way.

The concept of self-defence also presumes an understanding of what constitutes the ‘self’ which states have a right to defend. On this issue, the direction of state practice since 1945 has been remarkably consistent: the ‘self’ is expanding. The ‘self’ in self-defence has grown beyond the territorial borders of the state and now encompasses a range of state interests abroad. This is despite no change in the underlying formal texts. For instance, citizens abroad are now often invoked as the subjects of ‘self-defence’ – Entebbe being the classic example, but many states have made similar operations and justifications.Footnote ⁶⁷ Similarly, the current American legal justification for its drone policy asserts that self-defence authorises the US to kill people anywhere in the world who are affiliated with ‘al Qaeda and associated forces’ and who cannot be captured.Footnote ⁶⁸ In the Cold War, both the US and the Soviet Union invoked self-defence to justify military operations designed to install or maintain governments that were consistent with their spheres of influence, on the theory that any adverse change of government was likely the result of ‘external aggression’.Footnote ⁶⁹ More recently, NATO has taken on an active military role outside the territory of its members, in Bosnia, Kosovo, Afghanistan, and Libya, with the justification that its defensive philosophy has ‘move[d] from a geographical to a functional understanding of security’.Footnote ⁷⁰ In other words, the ‘self’ that it defends is conceptual rather than territorial – it is the sum of national interests of its members. Threats to the self might therefore emanate from other states (for instance, Kuwait’s response to the Iraq invasion in 1989) and from entities other than states (the US and others in Afghanistan from 2001 onwards).

Many of these uses of the law are highly contentious among legal scholars but they reflect the political power of international legal justification. These are the terms in which states argue for the legitimacy of their wars, and they presume a confidence on the part of the state that the language of self-defence provides political support for war in a way that its absence does not. Just as the concepts of the ‘civilian’ and its opposite are key to defining what is an acceptable target in armed conflict, the concept of self-defence is accepted as the key to differentiating between acceptable and unacceptable uses of force.Footnote ⁷¹ Kinsella shows for the civilian/combatant dichotomy how the distinction is politically powerful even when there is controversy or uncertainty about who resides on which side of the line. For self-defence, the power of the concept to legitimise war is not dependent on there being a consensus over what precisely it means. Claims about self-defence are appeals for political legitimation for war, making use of interpretive resources and understandings already existing in inter-state relations.

The contemporary expansive understanding of self-defence in effect substitutes ‘threat’ as the trigger for military response where the Charter text says ‘armed attack’. Self-defence has come to refer to the defence of the interests of the state not of its physical borders and territory. Operationalised this way, the rule gives states a right to use force to change circumstances abroad that it deems unfavourable to its national security and thus permits a much wider range of uses of force than the literal reading of the Charter would suggest.Footnote ⁷² It makes a ‘threat to the self’ a sufficient provocation to authorise a military response. It also draws a circle back to the nineteenth-century model of war as a response to harm: self-defence in response to a threat to national interests is indistinguishable from a model that legitimates war in response to the harms suffered by the sovereign. The justification is now in legal as opposed to political terms, but its relation to the sovereign and the sovereign’s interests is unchanged.

When grouped with the expansion of self-defence to include acts taken before ‘an armed attack occurs’, the result is that state practice under the UN Charter has loosened the restrictions of war in both time and space. Lawful self-defence can now take place before or long after an ‘armed attack’. This eliminates the limit implied by ratione tempori.Footnote ⁷³ It can also take place against non-state actors or in defence of citizens abroad. This eliminates the state-centric limit on ratione personae. Self-defence has lost both its physical and temporal limits. This widens the possibility for international military conflict that is seen as lawful under the Charter and makes the ban on war look more like an authorisation of force than a constraint on it.Footnote ⁷⁴

To sum up: the ban on war has evolved under the influence of state practice, especially the practice of strong states, and self-defence has come to dominate the process of assessing the legality of the use of force by states. Both developments make it more difficult (especially for strong states) to take actions that constitute violations of the law against war, as their own interests are already incorporated into the meaning of compliance. Compliance is increasingly guaranteed by the mutual implication of law and interests.

This does not suggest that anything states want do can be made lawful just by making a claim to that effect. Claims about legality are deployed by governments and others in the pursuit of legitimation. These claims are often highly contested both by legal specialists who might object to how the law is being characterised and by political actors who object to the actions being legitimated by the claims. For example, the question of whether US bombing against ISIL in Syria in 2016 really is self-defence or not under the UN Charter is not likely to be resolved – the issue rests on controversies over what the law allows and forbids, as well as over how these US actions fit into the law, and on these points it is probably unrealistic to expect convergence on any settled consensus. Regardless of the controversy, however, it is clear that in this instance the US desires to be seen as acting lawfully, and this desire reflects political power that comes from international legal resources. Governments are motivated to fit themselves into the confines of international legality because it brings them political legitimation. This is the heart of the ‘international rule of law’.Footnote ⁷⁵

The permissive power of international law also implies constraints. I have focused on the former here as I think this is frequently overlooked, but constraints from law are important as well. Both a general and a specific form of constraint is worth considering: first, the need for legal justification is a kind of general constraint on governments in that the desire for legal legitimation makes it more difficult to take actions for which legal justifications are hard to find; second, for the ban on war, the Charter clearly outlaws wars that are not motivated by self-defence and so makes it more difficult for states to engage in wars of aggression, profit, humanitarianism, and other motives.

My goal in this article is to highlight the political power of these legal claims. The contestation over the meaning and application of legal resources is itself evidence of the importance of international law and legality in global politics. This leads therefore to the opposite conclusion than that drawn by some ‘IR realists’ who suggest that international law is relatively unimportant in power politics. I show instead that the permissive power of international law is of central importance to governments: legality, when it lines up with state interests, enhances state power and governments strive energetically to use it to their own ends. This perspective connects political power and the international rule of law in a manner that is more ‘realistic’ than that of the self-styled ‘realists’ in IR theory.

What changed as a result of the Charter?

This difference between the pre-1945 world and the world of the UN Charter is frequently specified incorrectly. Those who see the ban on war in 1945 as a ‘transformative moment in international affairs’Footnote ⁷⁷ and ‘a radical departure in the systemic response to violence among states’,Footnote ⁷⁸ see the laws against war as a constraint on state agency. In this view, the Charter is a new external obstacle to states’ pursuit of what they see as their interests with respect to war; it suggests that the power of the rules is manifest when states choose to follow the rules (and refrain from the use of force) rather than follow their independent interests which might be driving them to war. What is new after 1945 in that model is that the illegality of war makes war harder to choose.

The evidence in this article suggests a different interpretation of the change brought about by the Charter. Rather than outlaw war, it is more accurate to say that the Charter changed the terms of political legitimation for states engaging in war. It differentiates among the purposes for war, and makes some purposes more legitimate and others less. Specifically, it gives privileged status to self-defence and forbids all other purposes. This is not a comprehensive ban on war, and its success cannot be measured by a decline in the incidence of war overall. The change is in what Joseph Raz calls the lawful ‘reason for action’.Footnote ⁷⁹ Its significance therefore should be evident in whether and how this new resource is or is not taken up and used by actors. By this test, the Charter rules on war are enormously successful, as self-defence and Article 51 have become ubiquitous in states’ justifications for military action and the pre-1945 justifications have almost disappeared. It is another question altogether whether this is a step forward or backward for the substantive goals of national, international, or human security. In this light, the main challenge to the laws comes from novel claims that there may exist legal justifications for war outside of the framework of Articles 51 and 2(4) – there are several candidates in this category, including humanitarian intervention, Responsibility to Protect, the defence of democracy, and more, though it is telling that the strongest arguments for each of these stop short of suggesting they are lawful in a formal sense in international law.Footnote ⁸⁰

Permissive role of law: as opposed to regulative/restrictive

Action is only possible when the actor has access to reasons and meaning that situate his or her action in its social context. As Charles Taylor and others have examined, a shared understanding of the meaning of certain kinds of acts is a precondition for meaningful action.Footnote ⁸¹ To sign a contract, vote in an election, or walk a picket line, depends on an existing framework of social understandings that makes it possible for the actor to engage in the action, and without such a framework the acts are impossible. One cannot do what one cannot conceive, at least not intentionally. The invention of new social categories therefore makes new kinds of action possible, as with civil unions, ‘stand your ground’, or wars of ‘self-defence’. The addition expands the set of options available for agents to choose.

Martha Finnemore has explored this phenomenon with respect to the invention of ‘humanitarian intervention’ as a kind of military action.Footnote ⁸² Beginning in the 1980s, as humanitarian intervention came to be widely understood as a distinct and potentially legitimate use of force by states, governments could do something that they literally could not do before. Finnemore argues that in the process states gained a policy option that they previously did not have and they become empowered in a way that would not have made sense at the start of the twentieth century. State power increased as a result (at least for some states).

The Charter forbids wars that are not essential for national security, and this outlaws wars of aggression, retaliation, colonialism, honor, and profit. No state today claims these are the motive for their wars. This is persuasive evidence of the success of the law. But the Charter legitimates defensive wars and therefore after the Charter states have in ‘self-defence’ a justification for military action that is endorsed by the political power of international legalisation. It is no surprise that states have been enthusiastic about identifying their wars as defensive. This points to the permissive power of the law on war: to go ahead with a war, states are encouraged to explain how it qualifies as self-defence, which means showing how it serves the essential security interests of the state. Failing to this incentive raises the costs of war for governments, in much the same way that Kenneth Waltz suggested that states are induced to follow other structural incentives in the international system such as self-help.Footnote ⁸³

Infrangible law: Compliance and law that cannot be broken

Scholars may well strive to identify a conceptual core to the idea of self-defence, but few real-world instances where the concept is invoked are so clear-cut – it is likely that all such claims are contested. These dynamics account for the characteristic controversies that accompany claims to self-defence, as when one’s opponent challenges the authenticity of the claim. The typical result is that the parties advance competing interpretations of the facts of the case, the security needs of the actors, and the law itself, in support of their preferred policy positions. Many scholars interpret such disputes as a sign of a problem for the law, perhaps even evidence of desuetude – the collapse of legal obligation in the face of persistent violation: Thomas Franck declared Article 2(4) ‘dead’ in 1970 and Michael Glennon updated that claim in the 2000s.Footnote ⁸⁴ But this conclusion confuses manipulation and disinterest; it treats the law as a regulative rule rather than a resource of legitimation. States work hard to remain within the limits provided by international law, and part of this effort is evident in their provision of explanations about their behaviour and about the congruence between their behaviour and for the law. The utility that actors find in invoking the rules to explain their actions is evidence of both law’s malleability and its continuing, compelling political appeal. These suggest that the law is highly salient to actors, which is the opposite of desuetude.

States’ ability to use the ‘self’ to redefine the law in line with their national security interests leads not to desuetude but rather to infrangibility. An infrangible law is one that cannot be broken, and the ban on war’s internalisation of state interests produces this effect. As long as states are using war only to secure their own selves, then their actions cannot be violations of Articles 51 and 2(4). The Charter is automatically complied with in the course of pursuing the state’s self-understood, national-security self-interest. The appropriateness of claims to self-defence is established when the state is genuinely defending its essential needs in response to an external threat. Thus, to delegitimate a claim to self-defence requires providing an account of the state’s interests that denies that the war was in fact necessary for the country’s security.

The legalisation of self-defence provides a novel institutional home for the old concept of raisons d’état as justification for war. Where in earlier periods these raisons might take the form of the needs the sovereign in relation to harms caused by outsiders, in our current legalised period they are defined in relation to threats to the national security of the state. International legalisation has rewritten ‘just war theory’ as ‘legal war theory’. Niccolò Machiavelli said: ‘that war is just which is necessary’.Footnote ⁸⁵ In light of the Charter, today he could say ‘that war is legal which is necessary’.