Law on the Use of Force and Armed Conflict
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Law on the Use of Force and Armed Conflict

Robert Cryer and Christian Henderson

This comprehensive research review discusses seminal works from leading authors on the use of force and armed conflict, beginning with detailed analysis of the prohibition of forcible intervention, including interpretation of the rule and notable exceptions to it. In addition, the review provides a wealth of important information on the law of armed conflict in connection with its foundations, applicability, sources, substance, practical application, and implementation. This review provides a thorough grounding in the law relating to the initial use of force and subsequent armed conflict, and is an essential source of reference for practitioners, academics and students alike.
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Review Article

Robert Cryer and Christian Henderson

Today it is almost impossible to escape the harsh realities of war. Although the use of force between states has become less prominent than it was previously, armed conflict between state forces and non-state actors has surpassed inter-state conflicts both in frequency and destruction. Conflict between states and non-state actors was traditionally witnessed in the context of struggles for self-determination and freedom from colonisation, but today it is seen more often in the context of terrorism. We have observed an additional change in the nature of armed conflict due to the greater destructive capabilities of states and, in particular, nonstate actors. There has also been a change in modus operandi. Whereas the most sophisticated weaponry might once have been in the form of an F-16 fighter jet, today the prospect of conflicts fought using unmanned aerial vehicles and cyber space has become a reality.

The purpose of this Research Collection is to provide some key academic writings on the international law governing, first, the initial resort to armed force and, second, the law regulating the conduct of ensuing hostilities. Both topics rest under the general umbrella of ‘war’, but some may argue that they are very different in nature and should not in fact be included within the same collection. Admittedly, in many respects the law governing the resort to armed force (the jus ad bellum) needs to be distinguished from the law governing the actual conduct of armed conflict (the jus in bello). Indeed, the former can be said to apply in times of peace, while the latter is concerned with periods of war and the alterations in the relationships between states that result. In addition, the jus in bello applies to all involved in the armed conflict regardless of the legality of the initial use of force.

Yet, there are also many reasons to view these two areas of the law together. Much of the law in existence today emerged after the end of the Second World War, in particular in the form of the 1945 United Nations (UN) Charter and the 1949 Geneva Conventions. There are certain overlaps between the two branches of the law and, as we have seen through the actions of the United States in Afghanistan following the events of 11 September 2001, as well as through its use of drones around the globe, these two branches of law are, or are widely seen to be, in operation at the same time. For example, the principle of proportionality plays a very significant role in both the jus ad bellum and the jus in bello. Yet, its meaning and application are different in each of these branches of the law, with both potentially applying at the same time. Furthermore, the line when a use of force becomes an armed conflict is not always clear, meaning that a use of force and an armed conflict may be observed to exist simultaneously.

Jus ad Bellum

The first two volumes of this Research Collection focus upon legal issues connected with the initial resort to force, otherwise known as the jus ad bellum. The use of force has been a reality in the relations between various entities for centuries. Indeed, decisions regarding the resort to force were once dominated by the writings and teachings of Classical Greek and Roman philosophers, such as Plato, Cicero and Aristotle, where the focus was more upon procedural formalities than substantive morals. Later, decisions concerning the resort to forcible measures were the concern of the Roman Catholic Church. One of the earliest theologians to write about issues concerning the resort to force was St Augustine (AD 354-430), using the concept of the ‘Just War’, which formed a focal point for the writings at this time and continued in one form or another for the next thousand years. Yet, there was an inherent subjectivity connected with the concept in that both warring parties could legitimately claim that their use of force was ‘just’. The opening chapter in this collection by Joachim von Elbe (Chapter 1) highlights well the breadth and scope of this concept.

Following the Peace of Westphalia, and at the height of sovereign state power in the 18th and 19th centuries, states were relatively unrestricted in their ability to resort to forcible measures. However, given the growth of increasingly destructive wars, a self-serving distinction emerged in the practice of states between ‘wars’ and other uses of force. So, for example, a state could justify its forcible actions as ‘self-defence’ in order to protect its vital interests. These justifications were widely viewed as being of a political, as opposed to a legal, nature since there was no general legal prohibition of the use of force in existence at the time. In any case, the identification of what constituted a vital interest was left very much up to each state to determine.

Following the horrific and unprecedented suffering of the Great War, attitudes to the resort to force began to change. War was no longer seen as just an uncomfortable fact of life that had to be endured. Instead, while far from perfect, and not prohibiting the resort to war per se, the Covenant of the League of Nations (1919) placed certain restrictions upon the members of the League in that the preamble contained an ‘acceptance of obligations not to resort to war’. There was also an obligation to submit any dispute likely to lead to a rupture in relations to independent arbitration or for consideration by the Council of the League of Nations (Article 12(1)), an obligation not to go to war with any state that complies with the arbitral award (Article 13(4)) or settlement (or, failing that, recommendations) by the Council (Article 15(6)) and, in any case, an obligation not to resort to war for three months after the arbitral award or the report of the Council (Article 12(1)). Yet, in addition to these and other inherent loopholes that states could draw upon in justifying the resort to forcible measures, the League of Nations was beset by additional impediments that tarnished its credibility, such as the United States not ever becoming a party.

The Treaty Providing for the Renunciation of War as an Instrument of National Policy (1928), also known as the ‘Kellogg-Briand Pact’ or ‘Pact of Paris’, more clearly renounced the resort to war as an ‘instrument of national policy’. It did not, however, expressly renounce war as an instrument of international policy or contain a prohibition on armed measures short of war, and it did not cover situations where full-scale hostilities were occurring but neither party had recognised that a state of ‘war’ was in existence. In any case, neither the League of Nations nor the Pact of Paris prevented the Japanese conquest of Manchuria in 1931, the Italian conquest of Abyssinia in 1935 or, of course, Germany’s invasion of Poland in 1939. While the focus of this Research Collection is on events after 1945, Volume I begins the discussion of the prohibition of forcible intervention with two of the leading pieces, by John Fischer Williams (Chapter 2) and James Brierly (Chapter 3), on the Covenant of the League of Nations and the Pact of Paris, respectively, and how they dealt with the concept of war.

It was towards the end of the Second World War that changes to the law governing the initial resort to force were deliberated and later introduced in the form of the UN Charter. While the two legal instruments noted above attempted to limit war, when states adopted the UN Charter in 1945 they instead expressly obligated themselves to refrain from the ‘threat or use of force’, as opposed to ‘war’, in Article 2(4) of the Charter, which has been widely recognised as the ‘cornerstone’ provision of the Charter. Indeed, this provision, which deserves to be quoted in full in this introduction, states that:

All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.

Seemingly relatively clear, the prohibition as contained within this provision has been the subject of much scrutiny and debate. As such, Volume I of this Research Collection explores the contours of this debate. Part I has selected pieces that address the general prohibition of forcible intervention. While Vaughan Lowe (Chapter 4) sets the prohibition of the use of force in the context of the more general prohibition of intervention, the following two pieces by Thomas M. Franck (Chapter 5) and Louis Henkin (Chapter 6) offer opposing positions on the status of the prohibition of the use of force in the UN Charter. While Franck claims that numerous violations have essentially led to the ‘death’ of the prohibition (a claim he was to later reignite after the 2003 invasion of Iraq), Henkin, by contrast, claims that this overstates the significance of these perceived violations and that if Article 2(4) really is dead, ‘it rules - not mocks - us from the grave’.

Either way, it does open up the question as to the normative status of the prohibition and how easily it could be ‘killed’. Many - perhaps even a majority - hold the view that the norm prohibiting the threat or use of force is of a peremptory, or jus cogens, status. This would mean that not only is a breach particularly serious but that normative change is a particularly onerous process. In this respect, the article by James A. Green (Chapter 7) questions this widely held view as to the prohibition’s normative standing and in doing so leads us to think about what it means to provide a norm with such a lofty status. Taking a step back, another established part of legal doctrine is that during the 19th century international law was indifferent to the use of force. Indeed, as discussed above in this introduction, the widely held view is that states were relatively free to resort to force. The article by Agatha Verdebout (Chapter 8) questions this view and claims that while not entirely clear, it is not entirely accurate to state that force was not regulated during this period.

While the use of force undoubtedly receives the vast majority of attention, and for good reason, it should not be overlooked that Article 2(4) also prohibits the threat of force. Indeed, if one is to accept the contention that the prohibition in general is of peremptory status, it is plausible to claim that threats are prohibited by a peremptory norm of international law. And yet, not only are threats of force made on a regular basis, but their illegality almost always passes without comment. There are various possible reasons for this. It might of course be put down to the fact that the prohibition of threats of force is not, in fact, a peremptory norm. It may even be the case that threats of force are not unlawful, or at least not that unlawful, and can in any case often be a useful diplomatic tool. In his article, Marco Roscini (Chapter 9) explores the contours of contemporary threats of force and their position under international law.

While Part I of Volume I of this Research Collection includes key contributions on the history and development of the prohibition and its present normative status, Part II seeks to provide key writings on the various ways in which the prohibition might be read, and how it might apply in various practical situations. Just as the contributions of Franck and Henkin represent two opposing sides of an important debate, the contributions of W. Michael Reisman (Chapter 10) and Oscar Schachter (Chapter 11) in this part provide another key debate on the lawfulness of using force for politically coercive purposes. In the Nicaragua case the International Court of Justice noted that ‘[t]he element of coercion, which defines, and indeed forms the very essence of, prohibited intervention, is particularly obvious in the case of an intervention which uses force’ (para. 205). The contributions by Reisman and Schachter were published shortly after the forcible intervention by the United States in Granada and, in light of this particular use of force, come to very different conclusions as to the way in which Article 2(4) should be construed.

The prohibition of the threat or use of force contained within Article 2(4) of the UN Charter is arguably concerned primarily with protecting the sovereignty of states. In this respect, interventions that do not appear to violate state sovereignty do not engage the prohibition of the use of force. Much debate has thus taken place as to when a use of force that does not lead to such a violation may be said to occur, with one way being when a state has been invited to use force upon the territory of the territorial state concerned. The question then becomes one of who has extended the invitation. Is it the government, or an opposition force? The International Court of Justice famously proclaimed in the Nicaragua case that intervention by invitation must be limited to the government of the state concerned. Indeed, it noted that ‘it is difficult to see what would remain of the principle of non-intervention in international law if intervention, which is already allowable at the request of the government of a State, were also to be allowed at the request of the opposition’ (para. 246). But this does raise the question as to how one determines whether a particular entity represents the government? Should this be done on the democratic credentials of the particular entity, or upon whether in practice the entity controls the state concerned, or at least large parts of it? The articles by Louise Doswald- Beck (Chapter 12) and Christopher J. Le Mon (Chapter 13) are notable contributions to this debate.

A further important issue in this debate is at which point in an internal disturbance, if at all, the government is no longer legally permitted to invite outside assistance from a third state. While it is generally considered permissible for the legitimate government of a state to invite such assistance from another state in the midst of internal unrest, the position has been taken by some, including Doswald-Beck, that once it can be identified that the civil unrest has morphed into a civil war the government is no longer permitted to invite outside assistance. This is based upon the central premise that providing assistance to one of the parties in a civil war would amount to interfering with state sovereignty, as any assistance would unfairly tilt the balance of the war, and therefore its outcome, in favour of one or another of the parties. The outcome to such unrest is something that the people of the state should be permitted to determine for themselves. However, if intervention does occur on one side in these circumstances, should there then be a right of counter-intervention? The contribution by John A. Perkins (Chapter 14) provides a superb analysis of the issues underlying this very question.

While outside forces might be prohibited from intervening in support of an opposition force at any stage, the question arises as to at what point an unlawful intervention crosses the line to become an unlawful use of force. Indeed, this is potentially an important question if we are to consider the prohibition of the use of force as a peremptory norm. For example, the International Court of Justice in the Nicaragua case postulated that:
while the arming and training of [opposition forces] can certainly be said to involve the threat or use of force against [the state concerned] ... the Court considers that the mere supply of funds to [opposition forces], while undoubtedly an act of intervention in the internal affairs of [the state concerned] ... does not in itself amount to a use of force. (para. 228)
The contribution by Christian Henderson (Chapter 15), in attempting to map out the law on this issue, focuses on the distinctions between intervention and the use of force on the one hand and direct and indirect uses of force on the other, particularly in the context of the provision of ‘non-lethal assistance’ in the Libyan and Syrian conflicts.

While the contribution by Henderson addresses the type of force that is ostensibly prohibited, the remaining contributions in this part of the Research Collection go back to looking at the legality of force for particular purposes. In a seminal piece on the topic, Derek Bowett (Chapter 16) addresses the concept of the legality of peacetime forcible reprisals. The idea that force might be permitted where it seeks to ensure that a state begins to comply with its international legal obligations is not a new one and was famously addressed in the Naulilaa case of 1928. This practice was ostensibly made unlawful with the introduction of Article 2(4) of the UN Charter, and has been condemned by organs of the United Nations as unlawful ever since, but with so many forcible actions of states resembling acts of reprisal, Bowett looks at how this might be reconciled with the contemporary prohibition of the threat or use of force. Similarly, the notion that a state may use force to protect its nationals abroad is well addressed by Tom Ruys (Chapter 17) in a key contribution on this debate.

Perhaps the single most controversial issue in interpreting the prohibition of the use of force has been that of the lawfulness, and legitimacy, of using force for humanitarian purposes. While this debate has been fierce in recent years, and particularly in light of the conflict in Syria, it is easy to forget that it is one that has been on the agenda of scholars for a good deal longer. The first piece in the Research Collection on the topic of humanitarian intervention, by Thomas M. Franck and Nigel S. Rodley (Chapter 18), addresses the issue directly in light of one of the more favourable precedents for a right of humanitarian intervention in the Cold War era, that is, India’s intervention in East Pakistan. While this represents one of the relatively few scholarly contributions on this topic during this era, there has been a plethora of writing on it in the post-Cold War era, particularly following the interventions in Iraq and Kosovo. Included here are two key articles by Bruno Simma (Chapter 19) and Antonio Cassese (Chapter 20) that were published during NATO’s intervention in Kosovo in 1999. While Simma took the view that the intervention was unlawful, but only by a ‘thin red line’, Cassese questioned whether instead this intervention represented a move by the international community towards accepting the legality of humanitarian intervention. Lastly, the chapter by Christine Gray (Chapter 21) provides a sober analysis of where the law stood on the issue as recently as 2013, when the debate at that time was whether intervention in Syria on the basis of humanitarian intervention was permissible.

While the practice and opinio juris of states remain key in identifying the contours of the law governing the use of force, one cannot exclude the influence of other actors in this process. Indeed, Article 38(1)(d) of the statute of the International Court of Justice singles out the importance that judicial decisions and writings of the most highly qualified publicists have in determining the position of international law on a particular issue. This Research Collection itself highlights the impact that scholars have had on how we think about the law in the areas of the use of force and armed conflict. However, arguably the most influential of actors within the epistemic community is the International Court of Justice itself. While only discussing the law on the use of force at any length in three cases (Nicaragua, Oil Platforms and Armed Activities) and two advisory opinions (Nuclear Weapons and the Wall), the pronouncements of the Court have proved influential. It is in this respect that the final piece in Part II of Volume I, again by Christine Gray (Chapter 22), looks at the impact that the Court has had upon, and the relationship it has with, the jus ad bellum.

Article 2(4) of the UN Charter is not explicit as to any exceptions to the prohibition contained within, and Volume I of this Research Collection explores some implicit exceptions that may be argued to exist, such as humanitarian intervention and peacetime armed reprisals. Nonetheless, while there are no direct links back to Article 2(4), the UN Charter regime does elude to exceptions to the general prohibition contained within this provision. In this respect, while Volume I focuses upon the general nature of the prohibition of the use of force and the various interpretations placed upon it, Volume II looks at the two established exceptions to the prohibition: forcible measures taken under the authority of the United Nations and individual and collective self-defence.

The UN Charter is very much a living instrument. It can be, and is, interpreted to meet the circumstances of the day. The significant limitation in this process, however, is that any such interpretations must be accepted by the various member states that are a party to the Charter. Significant (re)interpretations have not often occurred. One example, however, is the reading into Article 27(3) of the Charter of the abstention rule, so that rather than requiring the concurring affirmative votes of the permanent member states of the UN Security Council, if one or more of the permanent members decide to abstain this would not prevent the adoption of a resolution by the Council. Another example is the fact that while the composition of the Council is stated in Article 23(1) as including the ‘Union of Soviet Socialist Republics’, after the dissolution of the Soviet Union at the end of the Cold War this was interpreted so as to mean the Russian Federation.

However, perhaps the most significant interpretation of the UN Charter has been witnessed in the form of the UN Security Council authorising states to use force. It was envisaged in the Charter that the UN collective security system would be in possession of a standing army of troops contributed to by various member states, which could be drawn upon by the Council when necessary. A Military Staff Committee was due to oversee the deployment of these troops. However, the agreements necessary for the realisation of this element of the system were never made, and there is therefore no standing army. Given the relative deadlock in the Council during the Cold War, which prevented the conclusion of these agreements, it would have been unlikely, in any case, that decisions would have been taken to deploy the troops that the Council was to have had at its disposal. Yet, while there were a few notable occasions during the Cold War where force was undertaken under the authority of the Council, it was Iraq’s invasion of Kuwait in 1989 that led the Council to initiate a practice whereby it would ‘authorise’ a state or group of states to use force on specific occasions. As the first piece in Volume II, by Oscar Schachter (Chapter 1), highlights, this was innovative yet not without its problems. However, as Ugo Villani (Chapter 4) discusses in his article, the concept of the Council authorising states to use force was not plucked out of thin air, as Chapter VIII of the Charter already requires that any military force by regional organisations be authorised by the Council. But its application in authorising states or groups of states meant that the Council could become more fully involved in the collective security system. The technique soon became an established part of Council practice, and some initial problems regarding its implementation were gradually ironed out.

The key problem of states auto-interpreting UN Security Council mandates did not dissipate, however. Indeed, while a Security Council ceasefire came into effect following Iraq’s eviction from Kuwait, including an elaborate weapons inspection regime, certain states took it upon themselves to enforce this ceasefire regime as and when they deemed it necessary and appropriate over the course of the following decade. As the contributions here by Jules Lobel and Michael Ratner (Chapter 5) and by Niels Blokker (Chapter 6) demonstrate, this caused much confusion and angst within the international community as to the legality of the various uses of force. By 2003, when the final and most controversial of these forcible interventions in Iraq took place, arguments of legality were faced with widespread opposition not only from within the Security Council but also from across the international community. The acting states advanced an intricate and well thought through legal argument, but one that was not ultimately accepted. The articles in this collection by Dino Kritsiotis (Chapter 7), Sean Murphy (Chapter 8) and Nigel White (Chapter 9) not only assess the specific legal arguments involved, but do so in light of the auto-interpretive nature of the international legal system and the lasting consequences of this intervention and its associated legal justification both for the UN Security Council and the law governing the use of force.

Furthermore, while there has been notable controversy in relation to unilateral humanitarian intervention, this has not been witnessed to the same degree in the case of the UN Security Council acting for humanitarian purposes, providing that it could, in line with Article 39 of the UN Charter, determine a threat to the peace, a breach of the peace or an act of aggression. Indeed, as Ruth Gordon (Chapter 2) discusses in her article, the UN Security Council’s involvement in internal conflicts was initially controversial from some perspectives, given the Council’s responsibility for international peace and security, but quickly became an established part of UN practice. More recently, however, and particularly in light of the conflict in Syria, the Security Council has been blocked. In his piece, Andrew J. Carswell (Chapter 10) argues that the key to unblocking the Council lies in the ageing yet still relevant Uniting for Peace resolution. Indeed, while much focus is placed upon the UN Security Council, the UN General Assembly also has an important, perhaps underplayed, role in the maintenance of international peace and security.

The institution of UN peacekeeping has been around almost since the beginning of the United Nations. During this time the key principle of non-use of force has been constantly challenged in light of the development of the practice of authorisation by the Security Council. Indeed, as Yasushi Akashi (Chapter 3) highlights, UN peacekeeping forces have moved beyond their humble beginnings as observer forces to bearing quite substantial mandates, which have often included the use of force for various purposes. Furthermore, problems have arisen when states and other organisations have been authorised to use force from the skies while peacekeeping forces have operated on the ground.

While the Chapter VII collective security system was undoubtedly the most innovative part of the UN Charter regime, the right of self-defence was consciously recognised by the drafters of the Charter as an ‘inherent’ right in Article 51. Indeed, this provision of the Charter, which was included right at the end of Chapter VII, states that:

Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.

Part II of Volume II of this Research Collection includes articles that provide a comprehensive view of this right, both as it appears in Article 51 and as it exists in customary international law. The articles by Ian Brownlie (Chapter 11) and Derek W. Bowett (Chapter 12) provide a relatively early assessment of this right, with Bowett’s article providing specific treatment of the right of collective self-defence. From Article 51 of the Charter one can see that while rights of both individual and collective self-defence were perceived by the drafters as being somewhat natural, they were still very much tied in with the UN collective security system, with the Security Council in many ways overseeing the exercise of these rights. In his contribution, Donald W. Greig (Chapter 13) provides a comprehensive assessment of this relationship between the inherent right of self-defence and the UN collective security system.

However, and as observed above, what has been relatively clear is that since the Second World War conflicts between states have been overshadowed by those between states and non-state actors. Indeed, terrorism, in its various guises, has been the most significant challenge to the law governing the use of force. While terrorism is by no means novel, the 11 September 2001 attacks opened up new questions and debates, including whether non-state actors could be perpetrators of ‘armed attacks’ for the purposes of Article 51 of the UN Charter; the timing of any response taken; whether, and if so how, measures taken prior to the launching of an attack are necessary and lawful; the proportionality of any actions taken; and whether the actions of non-state actors need to be attributable to a state before action can be taken upon its territory.

Writing shortly after the ‘9/11’ attacks, Michael Byers (Chapter 14) assesses four possible legal justifications for the use of force against Afghanistan, including action under Chapter VII of the Charter, intervention by invitation, humanitarian intervention and, importantly, self-defence. Furthermore, in the post-9/11 environment a group of practitioners and academics convened under the umbrella of Chatham House to discuss the principles of international law governing the use of force in self-defence. The result, included here in Chapter 15 by Elizabeth Wilmshurst, is a significant set of principles that includes coverage of many of the issues raised above.

Of course, terrorists do not reside on the high seas or in outer space, but on the territory of one or more states. In this respect, a particularly interesting debate opened up between scholars in connection with the issue of when a state may use force upon the territory of another state. While the International Court of Justice in the Nicaragua case was widely interpreted as having required attribution of the actions of a non-state actor to a state before a response in self-defence could be launched, the ‘effective control’ standard thereby laid down appeared to be too high and difficult to establish in the context of modern terrorism. As such, Christian J. Tams (Chapter 17), among others, is of the opinion that the standard of attribution should be lowered to take into account the realities of the relationship between terrorists and host states. In her contribution in this collection, Kimberley N. Trapp (Chapter 16), however, takes the view that the customary principle of necessity is sufficient to address this concern, with there being no need to resort to questions of attribution. It was in this respect, and as addressed in the article by Theresa Reinold (Chapter 18), that the ‘unable or unwilling’ doctrine found its way into the discourse of states and scholars. While some used this doctrine to frame the issue as one of attribution, others used it to demonstrate the necessity of any resulting armed force in self-defence.

In addition, although questions of preventative self-defence are not new, and perhaps can be traced back to the Caroline incident of the 19th century, the events of 9/11 led the Bush Administration in the United States to put this form of self-defence firmly on its agenda, so that it was given particular prominence in the 2002 National Security Strategy. Christopher Greenwood (Chapter 20) addresses this particular interpretation of self-defence following 9/11, in particular in the context of Iraq and its suspected possession of weapons of mass destruction. Moreover, and as Michael Bothe (Chapter 19) and Daniel Bethlehem (Chapter 21) demonstrate, the question of pre-emptive self-defence has particular relevance in the controversial context of combating terrorism.

Finally, the issue of cyber security has been on the agenda of the international community for some time, particularly following the Tallinn and Georgia cyber incidents in 2007 and 2008, respectively. This has, consequently, raised questions as to how the law governing the use of force might be applied in the context of a cyber attack, and in particular whether such an attack could give rise to the right of self-defence. A leading writer in this area has been Michael N. Schmitt, who in his seminal piece included here (Chapter 22) provides some thoughts as to the normative framework applicable.

Jus in Bello

The second two volumes in this collection move over to the Jus in Bello. This is the law applicable once an armed conflict has broken out. It used to be the case that international law was split strictly into the Law of Peace and the Law of War. For example, the classic work on International Law by Lassa Oppenheim, which will be familiar to generations of international lawyers, has always had separate volumes on each subject. It is more common nowadays, though, to accept that the two are not entirely separate, but, nonetheless, there are limitations on how armed conflicts are waged. There are various terms used for the Jus in Bello: the Law of War, the Law of Armed Conflict (LOAC), and International Humanitarian Law (IHL). To some extent, the terminology is interchangeable, but sometimes the term chosen is deliberate, so, for example, the International Committee of the Red Cross (ICRC) almost always speaks of IHL, whereas the armed forces tend to use LOAC. For reasons that will become clear, the use of the term Law of War has largely diminished in the post-World War II era.

This choice of terminology, to the extent to which it is true, reflects that the law in this area is based on two, perhaps contradictory, principles. The first of these is the principle of humanity, which accepts, in a Millian sense, that even though states go to war, people are harmed, and that is, prima facie, a wrong done to them, whether they are civilians or fighters. Hence, this ought to be ameliorated as much as possible. The ‘as possible’ is important here, owing to the countervailing principle of military necessity. This principle is reflective of the fact that there is an armed conflict happening, and therefore the military, within constraints, have to engage in activities which would normally amount to crimes. Engaging in armed conflict involves killing and maiming people and damaging property. Whether this is liked or not, the law here has to take this into account, not least because if it did not it would be ignored (i.e. be considered utopian, rather than apologetic, in Martti Koskenniemi’s memorable formulation [Martti Koskenniemi, From Apology to Utopia, Cambridge: CUP, 2005]). If, however, it always accepted military expedience, it would be apologetic, and exercise little normative force (although in the 19th century there was the idea of kriegsraison, which held sway, particularly in Germany, that maintained that military considerations trumped everything else).

The Jus in Bello has a lengthy history, and one which crosses all cultures. The laws have not always been the same, or always respected, but they have remarkable resilience. These volumes are not intended to provide a history lesson (that is done with extraordinary skill by Geoffrey Best in Humanity in Warfare, London: Weidenfeld and Nicholson, 1980). It should be noted at the outset, though, that in the major era of the development of the modern jus in bello (roughly, the period between the start of the 20th century up until 1977) the law was split into what were called its ‘Hague’ and ‘Geneva’ branches, after the places the relevant treaties were negotiated. The former branch dealt with the conduct of hostilities (i.e. what weapons and tactics can be used, and who can be targeted), the latter with the protection of those who were not, or no longer, fighting. The distinction is of less importance now, but is sometimes still relevant.

Volume III begins by dealing with the nature and influences of the jus in bello. It opens with a highly influential piece by one of the leading scholars of the jus in bello, Theodor Meron. Meron (Chapter 1) argues that the jus in bello more generally has, under the influence of the principle of humanity, swung more towards that side of things. This can be witnessed in the forms of implementation, the treatment of Prisoners of War, and the interpretation of numerous other jus in bello concepts. Meron does not consider this to be without its contradictions. As he accepts, all limitations on war still accept that war occurs, with all the suffering it entails. He identifies various influences on this principle, including human rights law, the ministrations of the ICRC and, importantly, the role of international criminal tribunals, which have, although not in an unprecedented manner, engaged in some of the most detailed judicial analysis and application of the jus in bello.

Meron, who was later to become the president of the International Criminal Tribunal for the former Yugoslavia (ICTY), is basically pleased with such developments. Others, in particular from the military side, are less comfortable, on the basis that these applications are undertaken by people they consider inexpert and too willing to ignore military concerns when putting their thumbs on the scale on the side of humanity (for a careful analysis see Michael Schmitt, ‘Military Necessity and Humanity in International Humanitarian Law: Preserving the Delicate Balance’ (2010) 50 Virginia Journal of International Law 795).

The volume continues with a piece that looks to the shadow side of the jus in bello. That is it permits status-based killing (of combatants) which would be clearly unacceptable in any other circumstances. Thus Chris af Jochnick and Roger Normand (Chapter 2) argue that the function of the jus in bello provides technocratic legitimation for behaviour that ought to horrify everyone. This piece was quickly followed up with an application of their ideas to the 1991 Gulf conflict (Chris af Jochnick and Roger Normand, ‘Legitimation of Violence: A Critical History of the Gulf War’ (1994) 35 Harvard International Law Journal 387).

From there we move to the contemporary influences on the jus in bello. It is often said that the jus in bello always lags at least one conflict behind, and to some extent there is truth in this: the 1949 Geneva Conventions were drafted in the aftermath of the Second World War and the 1977 Additional Protocols to those Conventions came after the Vietnam war. Hence there are now claims that the law needs to move more quickly, to keep up with contemporary conflicts. John B. Bellinger III and Vijay M. Padmanabham (Chapter 3) set out what they believe to be the failures of the current law on detention in armed conflicts between states and non-state actors, and how states (not non-state actors) ought to deal with those failings. As a counterpoint, we have also included Frederic Megret s piece (Chapter 4), which argues that, in the end, the jus in bello has always created its own ‘others’ who fall outside its protections but are subjected to the treatment that the law allows the opposing side to implement against them. States are not always above taking a ‘consumerist’ attitude to the jus in bello.

Moving on to Part II, as was discussed above, the jus in bello is the law applicable in armed conflict. It used to be the case that it was only applicable in the case of a fully declared war, with a formal declaration being issued with the intention to bring a state of war into existence. This was obviously open to abuse, as states would try to deny the applicability of the jus in bello by denying the status of war.

In part owing to this, in the era following the adoption of the UN Charter (in which there were also questions about the legality of declaring ‘war’) the jus in bello moved to the factual status of ‘armed conflict’ for its applicability. Whether this has always transcended the problem (especially in non-international armed conflicts (NIACs) might be questioned. The status of war both before and after the Charter, though, is the subject of the masterful study by Christopher Greenwood that begins Part II (Chapter 5). The second piece (Chapter 6) is also by Greenwood, and relates to the relationship between the jus ad bellum and jus in bello. In this piece Judge (as he now is) Greenwood largely restates the traditional view that the two are essentially separate. Alexander Orakhelashvili (Chapter 7), challenges that orthodoxy to show that, in some, limited areas, the two do interact.

Further on the subject of the interaction of different areas of law, and related to some of the pieces in the first part, this part of Volume III contains a piece by Heike Krieger (Chapter 8) which, through the lens of the ICRC’s very important customary law study (to which this volume returns), looks at the interrelationship (not the influence) of human rights and the jus in bello. Krieger’s piece stands out against the background of a large literature on point, as among many excellent arguments, Krieger makes a foundational point that is often overlooked. That is, the relationship between the two areas of law (which as the International Court of Justice has accepted, for example in the Wall advisory opinion, apply simultaneously) cannot be defined in the abstract, but has to be taken down to the more microscopic level of each particular rule of each regime. Sweeping generalisations are unhelpful when dealing with this matter. In addition, Krieger also counsels linguistic caution: although rules in both areas of law use the same word, they may turn out to be ‘false friends’, as they in fact mean very different things (as is the case in the use of the term ‘proportionality’ in the jus ad bellum and jus in bello contexts).

It is important to note that there is a fundamental fissure in the jus in bello, between the law applicable to international (inter-state) armed conflicts and the law applicable to NIACs. The distinction may not make moral sense, but, as Peter Rowe has said, ‘that is what States did’ (Peter Rowe, ‘The International Criminal Tribunal for Yugoslavia: The Decision of the Appeals Chamber on the Interlocutory Appeal on Jurisdiction in the Tadic Case’ (1996) 45 International and Comparative Law Quarterly 691, p.698). Although the ICTY, in particular, has attempted to harmonise the law between the two, certain areas (Prisoners of War status and the law of Belligerent Occupation) are off limits to such an approach, as states have shown that they are hostile to such a development. As such, it is extremely important to understand the nature of each and how to determine which is which (and when one can become the other). Dapo Akande (Chapter 9) provides a modern, comprehensive and sophisticated analysis of all of the types of armed conflict and their relationships. There are those that are of the view that a single definition of armed conflicts would be preferable. There is considerable merit in such an idea, as the law in the area is technical, complex and requires often difficult factual determinations. Owing to this, we have included James G. Stewart’s plea for rationalisation here (Chapter 10). States have yet to be entirely convinced, however.

The existence of NIACs causes some conceptual difficulties for the jus in bello. In international armed conflicts, states become bound by the relevant rules through the traditional processes of becoming subject to those rules (i.e. the sources of international law canvassed in Part III). The same, however, does not apply to armed opposition groups, who do not take part in the traditional processes of making, and becoming subject to, international law. This has, over the years, been the subject of outstanding scholarship by some of the greatest scholars of the jus in bello (e.g. Antonio Cassese, ‘The Status of Rebels under the 1977 Geneva Protocol on Non-International Armed Conflicts’ (1980) 31 International and Comparative Law Quarterly 416). We have chosen, however, to include a piece by Sandesh Sivakumaran (Chapter 11), as it gives the most convincing answer, which is that such groups’ consent is not required by international law, it simply binds them as states have set up a regime that does so. States get the international law they want, armed opposition groups do not.

To round out this part, we have included pieces that relate to modern armed conflicts and the challenges they pose to the jus in bello. The first of these is Nicholas Lamp’s piece on ‘New Wars’ (Chapter 12), that is, polycentric, transnational or other conflicts that do not conform to the traditional ideal, against which the jus in bello was drafted. This piece looks with subtlety at the difficulties this causes for attempting to ensure that non-state actors, who have little commitment to the jus in bello, nonetheless comply with it. Hans-Peter Gasser (Chapter 13) deals with a similar issue, the so-called ‘war on terror’. Responding to challenges that were said to be made to the jus in bello (in particular from the United States) by this purportedly different type of conflict, Gasser shows how the traditional approach both condemns terrorism unequivocally and provides the tools to combat it. Moving away from the physical world, this part concludes with how cyber conflict ought to be characterised, as it is difficult to fit into any of the traditional paradigms. As ever, Michael Schmitt (Chapter 14) was a trailblazer on this.

Part III deals with the sources of the jus in bello. Obviously, treaties play a huge role here, but it was decided that it would be impossible to cover them in any depth, to the extent that it would be deceptive to try: the standard documents collection (Adam Roberts and Richard Guellff, Documents on the Law of War, Oxford: OUP, 3rd ed., 1999) runs to some 750 pages. So it is suggested that readers seeking detail on them go directly to the primary materials (the ICRC also has a very useful treaty database available at, which also has links to the highly influential ICRC commentaries on the 1949 Geneva Conventions and their Protocols).

So, very briefly, there are four major sets of treaties. First, there are various treaties limiting or banning certain forms of weapons, such as ‘dum-dum’ bullets and mines. The extent to which they are customary, or apply to NIACs, differs according to the treaty, but the ICRC tends to treat those that are customary for international armed conflicts to be customary for NIACs. Second, there are the Hague Conventions of 1907, in particular the Regulations Annexed to Hague Convention IV. These are customary, and provide the basis for the conduct of hostilities on land, and are largely accepted to (other than on the law of occupation) reflect the law applicable in both international armed conflicts and NIACs. Third there are the (universally ratified) four Geneva Conventions of 1949 which deal with the law relating to the Wounded and Sick on Land (I), the Wounded, Sick and Shipwrecked at Sea (II), Prisoners of War (III), and Civilians (IV). As Theodor Meron shows in his classic piece, included here (Chapter 15), they are, generally speaking, customary. Many of their provisions are, broadly, customary for NIACs too. In addition to this, they contain a common Article 3, which reads:
In the case of armed conflict not of an international character occurring in the territory of one of the High Contracting Parties, each Party to the conflict shall be bound to apply, as a minimum, the following provisions:
(1) Persons taking no active part in the hostilities, including members of armed forces who have laid down their arms and those placed ‘hors de combat’ by sickness, wounds, detention, or any other cause, shall in all circumstances be treated humanely, without any adverse distinction founded on race, colour, religion or faith, sex, birth or wealth, or any other similar criteria. To this end, the following acts are and shall remain prohibited at any time and in any place whatsoever with respect to the above-mentioned persons:
(a) violence to life and person, in particular murder of all kinds, mutilation, cruel treatment and torture;
(b) taking of hostages;
(c) outrages upon personal dignity, in particular humiliating and degrading treatment;
(d) the passing of sentences and the carrying out of executions without previous judgment pronounced by a regularly constituted court, affording all the judicial guarantees which are recognized as indispensable by civilized peoples.
(2) The wounded and sick shall be collected and cared for. An impartial humanitarian body, such as the International Committee of the Red Cross, may offer its services to the Parties to the conflict ...
This, the first provision in relation to the jus in bello that expressly dealt with NIACs, is undoubtedly customary (Nicaragua case, para. 218), and remains the core of the law on point, as well as having been described as reflecting the ‘elementary considerations of humanity’ (Corfu Channel Case, p.22).

The final main set of treaties comprises the Additional Protocols to the 1949 Geneva Conventions, finalised in 1977. Protocol I applies to International Armed Conflicts, Protocol II to NIACs. As will be seen, their customary status is not simple, and some important states (the United States, India, Israel, Pakistan) are not a party to one or the other.

In the past twenty or so years, largely beginning with the establishment of the ICTY in 1993, customary law has been a significant driver of the development of the jus in bello. In part this is owing to the pronouncements of the ICTY, beginning with its hugely influential Tadic case, which determined that there was customary law in NIACs that was not contained in common Article 3 or Additional Protocol II, and much of which traced, or was very close to, the law applicable in international conflicts. It is not only this though. After a lengthy (ten- year) and wide-ranging programme of research, in 2005 the ICRC released a weighty study of customary law, which determined that large swathes of rules (largely drawn from or inspired by Additional Protocol I) were customary for both international and non-international armed conflicts. It is hugely impressive, and this part contains an explanation of the study by one of its authors, Jean-Marie Henckaerts (Chapter 16). It has not proved uncontroversial, with both academic critique (e.g. George Aldrich, ‘Customary International Humanitarian Law: An Interpretation on Behalf of the International Committee of the Red Cross’ (2006) 76 British Yearbook of International Law 503) and at least one state (the United States) treating it as, in essence, an attempt to impose Additional Protocol I on non-parties. Jean-Marie Henckaerts responded to the United States in the next piece in this part (Chapter 17). The report has proved hugely influential.

One undoubted customary, if not indeed cardinal, (general) principle of the jus in bello is the Martens clause, which reads:

Until a more complete code of the laws of war is issued, the High Contracting Parties think it right to declare that in cases not included in the Regulations adopted by them, populations and belligerents remain under the protection and empire of the principles of international law, as they result from the usages established between civilized nations, from the laws of humanity and the requirements of the public conscience.

This provision first appeared in Hague Convention II of 1899, and is considered a codification of the principle of humanity. There are disagreements about its effect. Antonio Cassese (Chapter 18) argues that its fundamental nature means that it affects the way custom is formed and an absence of state practice can be overcome by its application. Theodor Meron (Chapter 19) takes the more traditional view, that while it may inspire developments, the clause does not alter the sources of the jus in bello. Cassese attempted to apply his idea as a judge in the ICTY (in the Kupreskic case), but this fell on stony ground with states, and was all but overruled by the ICTY later (in the Martic Appeal). The fate of the Kupreskic case ought not to be taken to be the norm for the jurisprudence of the ICTY. As Robert Cryer (Chapter 20) shows, it has had a huge impact on various actors, both directly and indirectly (in part through the ICRC Report). Judicial decisions have played a large role in the development of the jus in bello, as implied above, usually by assertions of customary law.

As previously mentioned, it would simply be impossible to cover the entire corpus of the jus in bello in a work of this nature. Volume IV therefore begins with selected issues that relate to the law here, are controversial and have considerable contemporary relevance. Part I begins with a piece from 1951. This is Major Richard R. Baxter's classic work on those who engage in belligerent activities without being traditional members of the armed forces (Chapter 1). In spite of its vintage, it is relevant to contemporary conflicts, where there are allegations that people are ‘unlawful combatants’ (a term that appears nowhere in any treaty relating to the jus in bello) and this leads to various legal consequences for such fighters. Baxter’s analysis, that international law neither specifically permits nor prohibits such activities, while not providing immunity for domestic legal consequences for those that undertake them, remains persuasive.

On a connected issue, it is often difficult to determine what activities would need to be undertaken by someone who would otherwise not be considered to be a participant in hostilities (i.e. be a civilian immune from attack) to lose that protection, and thus become targetable, and for how long that protection is lost. This has long been a vexatious issue, for both states and others. It is accepted that what is required is direct participation in hostilities (DPH), but what this means is deeply contested. Therefore, the ICRC initiated an analogous study to its customary cousin, to try to provide clarity. This proved difficult. In the end, and without the agreement of many of the experts that were consulted, the ICRC published its guidance on the interpretation of DPH, written by the author of the next piece, Nils Melzer (Chapter 2). The piece explains the Guidance briefly and accurately. The Guidance, as might perhaps be expected given the contested nature of the concept and the genesis of the report, has received some furious critique. Nils Melzer (Chapter 3) has explained, and responded to them. It is for the reader to determine whether he has done so convincingly. Great disagreements remain.

The next piece relates to one of the most contentious areas of the jus in bello. This is the law relating to targeting more generally. The controversy arises because some of the concepts, in particular that of proportionality, are frustratingly vague, and, in certain circumstances, even though civilians are immune from direct attack they may end up being killed as ‘collateral damage’. This is, for obvious reasons, deeply controversial, and to many, immoral. It is certainly an area where many Non-Governmental Organisations (NGOs), who have otherwise largely adopted the jus in bello, feel very uncomfortable. Marco Roscini (Chapter 4) provides a careful, detailed, study of this difficult area, which applies to drones, as much as to any other weapons system. Although much ink has been spilt on the deployment of drones, they do not really raise any novel jus in bello issues. Autonomous weapons, which take the decision to target themselves, to the extent to which they exist, are different on point.

Outside of the situation relating to Israel and Palestine, until the invasion of Iraq, many thought that the law of occupation of territory was old fashioned, and largely in abeyance. This was in part because states have been very unwilling to accept that they are an occupying power. It is therefore very important to understand when such an occupation occurs (and it arises as a matter of law, not when a state accepts the designation). Adam Roberts (Chapter 5) has written the classic study on this point. Iraq raised difficult issues with regard to the law of occupation, which largely requires the occupying power to leave occupied territory as it found it, but the idea of bringing back the Ba’athist regime was not one that many were willing to countenance. David J. Scheffer (Chapter 6) writes about the way in which this was managed by going beyond occupation law. Sadly, as is well known, and for various reasons, Iraq has not prospered since.

One of the most controversial issues in the jus in bello is the law relating to permissible weaponry. Although the basic principle is that weapons that cause unnecessary suffering cannot be employed, outside the specific treaties that ban particular weapons, a balance has to be decided upon between the level of suffering a weapon inflicts and the military benefit it grants. As Judge Higgins said in the Nuclear Weapons Advisory Opinion ‘[the balancing exercise] explains why ... [t]he status of incendiary projectiles, flamethrowers, napalm, high velocity weapons - all especially repugnant means of conducting hostilities - have thus remained contested’ (Dissenting Opinion of Judge Higgins, para. 16). Christopher Greenwood (Chapter 7) provides a typically clear and thoughtful explanation of the law in this area.

Finally, this part has, so far, concentrated on the law insofar as it relates to land (including where attacks are made from the air that affect the ground). There is a wholly separate body of law applicable to armed conflicts at sea. It is an area that has (other than recently, to some extent to the law of blockade) been overlooked. There have been no major treaties relating to the conduct of hostilities for an extremely long period of time. Partially as a result of this, the International Institute of Humanitarian Law decided to provide a statement that was, for the most part (but not entirely), intended as a codification of the law. One of the authors of that Manual, Louise Doswald-Beck, provides a helpful overview of the Manual (Chapter 8), that in spite of its unofficial status, has become the lodestar for discussion of the jus in bello on the ocean waves.

The jus in bello is, like all law, only really understood when it is seen ‘in action’. Therefore, Part II provides some examples of how the law has been applied to contemporary conflicts and issues. The first of these is by Michael Bothe (Chapter 9), and comments on the Report to the ICTY Prosecutor from a group established to advise her whether to investigate the NATO bombing of Yugoslavia (as it then was) in relation to Kosovo. Although the piece is brief, it is pithy and insightful, not least in suggesting that in democracies, the military cannot claim that they are the exclusive interpreters of the jus in bello. This must be right. Law cannot be entirely subject to auto-interpretation by its addressees, or it simply becomes a weak system of self-regulation.

Turning to Afghanistan, Robert Cryer’s piece (Chapter 10) is an early example of an attempt to apply the jus in bello to that conflict. Looking back, with more than a decade of hindsight, it is extraordinary the number of legal issues that arose in that conflict. These include its nature, targeting, weapons, the possibility of interpreting some statements as orders of quarter and, of course, status determinations and detention. These last two issues are taken up in far greater depth in the piece by Diane Marie Amann (Chapter 11), whose title (‘Guantanamo’) would probably have been considered obscure twenty years ago (it being, at the time, a relatively obscure military base that had been used to house refugees). Now it is a name that is notorious. The article is an exceptionally detailed explanation of what was (and sadly, to some extent still is) going wrong there from the point of view of the jus in bello.

This part winds up with a discussion of an issue, rather than one specific conflict. This is Lindsey Cameron’s article (Chapter 12) on private military companies (PMCs). These businesses are already playing a huge role in modern conflicts, particularly, but by no means only, those involving the United States, which has outsourced large parts of, if nothing else, the support work to PMCs. PMCs raise difficult issues for the jus in bello and for the role of the state more generally. Cameron shows a keen legal eye for these difficulties.

The jus in bello needs implementation if it is not simply to be a paper tiger. There are various mechanisms for doing so and these are discussed in the third and final part of this volume. Of course, prevention is better than cure, and, as Peter Rowe (Chapter 13) shows, one of the primary means for ensuring this is through strong command. It is all too easy to forget that the jus in bello is implemented on the ground in times of considerable stress by people often without a huge amount of life experience, simply by dint of their age. Therefore, effective training (which does not have to be in chapter and verse of the treaty provisions, but, rather, strong statements of what is expected) and effective command by those in more senior roles are essential if the rot is not to set in. Steven R. Ratner (Chapter 14) looks to third parties to investigate their role in persuading parties to comply with the jus in bello, in this case, the ICRC, with its well-known diplomatic approach to bringing parties into line. As he shows in his interdisciplinary analysis, this need not be by standing on the letter of the law, but more by getting compliance with it by hook or by crook. Legalism is not always the best approach.

The role of third parties is also the focus of the contribution by Frits Kalshoven (Chapter 15). This time, however, it is states not party to a conflict, pursuant to common Article 1 to the 1949 Geneva Conventions. This provides for the duty on parties to those Conventions to ‘respect and ensure respect’ for the provisions of the Conventions. Some have picked up on the latter part of the quoted phrase to argue that state parties, even where they are not involved in a particular conflict, are required to take considerable actions to oblige parties that are involved in the conflict, to comply with the Conventions. Through a close reading of the travaux preparatoires of common Article 1 and state practice under it, Kalshoven concludes that there is not a broad duty. That said, states may still take all lawful measures to persuade others to live up to their jus in bello responsibilities should they wish to do so.

The role of criminal prosecutions has already been referred to, even if a prosecution is always something of a confession of failure, and will not bring back the dead. In addition, as Rogier Bartels (Chapter 16) shows, there are specific difficulties of both law and fact that render prosecutions for violations of the jus in bello particularly difficult. The practice of the ICTY and International Criminal Court shows that these difficulties are very real, and victims do not understand an acquittal. On a more optimistic note, and one that links back to the earlier discussion of the sources of the jus in bello, Christopher Greenwood (Chapter 17) analyses the interlocutory appeal in the ICTY by its first defendant, Dusko Tadic. Greenwood finds it for the most part persuasive, and it bears mentioning that Tadic was convicted, as many other defendants before international criminal tribunals have been. Where guilt is not proved beyond reasonable doubt, a defendant has a right to an acquittal, so overall not every acquittal is a travesty, even if the victims do not see it that way.

As Judge Cassese said in the Kupreskic case (para. 530), it is better to hold trials than undertake one of the other forms of enforcement of the jus in bello: reprisals. These are violations of the strict law, rendered lawful as they are undertaken in response to a previous violation by the opposing party, are proportionate to that violation, and are intended to bring the enemy into compliance with the law. Suffice it to say, in spite of these, and some other procedural limitations, they are a crude form of ex post facto response to violations of that law. There are specific bans on reprisals against the people and property protected by the 1949 Geneva Conventions. There are also prohibitions on reprisals against civilians not protected by the 1949 Conventions (i.e. those who are not interned or in occupied territory), in Article 51(6) of Additional Protocol I. They were controversial during the drafting of that treaty, and they were almost certainly a progressive development of the law in 1977. Cassese fought hard, in particular as a judge, to eradicate them completely, through the modality of customary law. As Frits Kalshoven (Chapter 18) demonstrates (in Cassese’s Festschrift), the reasoning employed to do so did not pass muster. Therefore, there remains a narrow role (circumscribed by the customary conditions mentioned in the Martic case (paras 263-7)) for this particularly unpleasant form of enforcement to be employed against innocents. The jus in bello is not always above being cruel.

The End of the Beginning

The same can be said about both areas of the law relating to armed conflict. They are not always gentle. So, to end, as we began, with a counsel of caution. The law here is about mitigating, rather than abolishing, the fact of armed conflicts. Sadly, in the same way that the law on homicide cannot prevent every murder, the law we cover in these volumes cannot, in the end in and of itself, bring an end to all violent engagements. Nonetheless, this is not to throw up our hands in despair, just a statement of legalistic humility. The law on point here can (and does) act as a brake on the excesses that often tempt states, and provides an external point of reference from which to appraise state behaviour (and, indeed, on occasion, provide the basis for prosecution of individuals who violate its strictures).

Despite its authoritative nature, it is not always the case that there are institutional means for enforcing the law we cover here. This is a significant issue. Although the UN Security Council has (and has asserted) considerable authority over the areas of conflict and security, it has often fallen short of its responsibilities on point, for reasons of both high and low politics. That said, though, the Security Council is, while very important, not the Alpha or Omega of discussion on the resort to violence. It is a political body that acts, rightly or wrongly, on that basis, rather than on the basis of the relevant law. Even so, on a related point, the law here is not the totality of the standards to which belligerents ought to be held. There are many other influences on the decisions to use force and how to apply it once the use of force has been decided upon. Among other factors, these include moral and political considerations and are, so long as they remain within the bounds of the law, the basis of legitimate decisions.

Belligerents are always entitled to adopt more rigorous standards than the law requires, as, for example, the NGO Geneva Call seeks to bring about for non-state actors. It is also the case that states often adopt Rules of Engagement that are more restrictive than the law renders necessary. This is welcome, although, on the other hand, there are also times when (sometimes tendentious) interpretations of the law are invoked instrumentally. This applies to both the jus ad bellum and the jus in bello.

That said, the relevant law is the shared vocabulary from which a tolerable, albeit imperfect, course may be set. We hope that this Research Collection helps in disseminating the law on point. If nothing less, this law is a foundation from which a shared basis upon which the parties to a conflict (and others) may speak to one another. Debates occur about these issues, and we want them to. What is important, though, is that they are informed by, and about, the law, and we hope that this collection contributes to these discussions.

The world would be a better place without armed conflicts, but they have been a constant feature of human history. Hence, discussions on the law relating to armed conflict are unlikely to be relegated to mere historical significance in even the medium to long term. In the interim, though, the law which is covered in the pages that follow provides some guidance on what should be done. Better this than nothing, and there is much sense in its prescriptions. Even taking into account its limitations, ambiguities and contentious nature, the law here serves as a mediating factor, or common language, in which debates can be framed. Law cannot, in and of itself, end armed conflict. It can, though, make things a little better.