Law and force

This danger is intensified when leaders speak of the ‘war on terror’ as one against a single enemy.7 Moreover, it is open to doubt whether the use of force is an appropriate and effective response to terrorism. The experience of Afghanistan and Iraq, Lebanon and Somalia does not suggest that the use of force has proved effective in securing stability. And the UN Secretary-General has expressed concern that the war against terrorism will detract from other equally, if not more, pressing dangers—sometimes categorized as ‘soft threats’—such as threats of extreme poverty, unsafe drinking water, the disparity of income between and within society, the spread of infectious diseases or climate change and environmental degradation.8

Nevertheless, the rhetoric of the ‘war on terror’ has some significance for the law on the use of force in that it has been used to justify a wide right of self-defence against non-state actors, and to threaten pre-emptive action to prevent certain states, accused of state sponsorship of terrorism, from developing nuclear weapons. There are significant differences between states, and between commentators, on these issues. In pursuit of those responsible for the terrorist attacks of 9/11, and on the basis of a right of self-defence against terrorist attacks, the USA initiated Operation Enduring Freedom in Afghanistan, an operation which continues today. But President Bush then widened the focus of the war against terrorism beyond Afghanistan. In his famous State of the Union Address of January 2002 he singled out the states of the ‘Axis of Evil’—Iran, Iraq and North Korea—as posing a threat to the USA. He argued that there was a danger that such ‘rogue’ states would develop chemical, biological and nuclear weapons of mass destruction for use against US targets or for supply to terrorists hostile to the USA. In response to its perception of a fundamentally changed international situation, the USA put forward a new 2002 National Security Strategy, including the controversial doctrine of pre-emptive self-defence. The 2006 National Security Strategy reaffirmed US commitment to pre-emptive self-defence.

In contrast to the broad acceptance by states of the legality of Operation Enduring Freedom, the right to take military action against Iraq was bitterly contested. The USA and the UK argued that Iraq was developing weapons of mass destruction, and undertook Operation Iraqi Freedom in March 2003, leading to the overthrow of President Saddam Hussein and the occupation of Iraq. This use of force was extremely divisive and its legality was challenged not only by Russia and China, but also by close allies such as France and Germany. Even the UN Secretary-General spoke out to deny the legality of this use of force, in a departure from his normal practice. The Security Council was deeply split. Some states saw its refusal to authorize force against Iraq as a failure on the part of the Council to act in enforcement of the disarmament regime imposed on Iraq; others regarded this as the normal and successful working of the Charter system.9 President Bush in a 2002 speech to the UN General Assembly issued a famous challenge: ‘The conduct of the Iraqi regime is a threat to the authority of the United Nations, and a threat to peace. Iraq has answered a decade of UN demands with a decade of defiance. All the world now faces a test, and the United Nations a difficult and defining moment. Are Security Council resolutions to be honored and enforced, or cast aside without consequence? Will the United Nations serve the purpose of its founding, or will it be irrelevant?’10

After the invasion of Iraq the UN Secretary-General spoke of ‘a fork in the road’; he declared dramatically that ‘this may be a moment no less decisive than 1945 itself, when the UN was founded’.11 Since then states had generally sought to deal with threats to the peace through containment and deterrence, by a system based on collective security and the UN Charter. It had been understood that when states went beyond self-defence and decided to use force to deal with broader threats to international peace and security, they needed the unique legitimacy provided by the UN. Now some said that this understanding was no longer tenable since an armed attack with weapons of mass destruction could be launched at any time, without warning; rather than wait for that to happen states have the right to use force pre-emptively, even on the territory of other states and even while weapons systems that might be used against them are still being developed. ‘According to this argument, States are not obliged to wait until there is agreement in the Security Council. Instead they reserve the right to act unilaterally, or in ad hoc coalitions. This logic represents a fundamental challenge to the principles on which, however imperfectly, world peace and stability have rested for the last fifty-eight years.’

Accordingly the Secretary-General set up a High-level Panel on Threats, Challenges and Change, mandated to make a broad examination of global peace and security issues, to identify the contributions of collective action in addressing major challenges and threats, and to recommend changes necessary to ensure effective collective action. In 2004 it issued its report A More Secure World;12 the following year the Secretary-General issued his own report, In Larger Freedom,13 in preparation for the 2005 World Summit which produced an Outcome document.14 The consensus of all these instruments was that no change in the UN Charter provisions on the use of force was necessary. The fundamental prohibition on the use of force in Article 2(4), the right of self-defence in Article 51, and Chapter VII on collective action were all adequate to meet the new threats.15

Nevertheless international law on the use of force, its content and effectiveness, is now the object of more speculation than ever before. Some commentators use apocalyptic language and mourn the death of Article 2(4), the prohibition of the use of force in the UN Charter.16 In contrast others welcome the end of the Charter system and of any international law constraint on the USA.17 Yet others argue that international law is evolving to meet new threats, and welcome the changes they identify in the law on self-defence, intervention and regime change.18 It remains to be seen how far the USA is deliberately posing a challenge to the whole UN system and to the existing international legal order, or whether it is operating within the system, even if manipulating the rules for its own ends. The apparently cynical manipulation of legal rules is nothing new; disingenuous rhetoric is certainly not unique to the international legal system. Thus the question arises whether US lip service to international law on the use of force is meaningless or to be welcomed as indicating continued adherence to the Charter system? Are its assertions that it is acting multilaterally and in the interests of the international community of any value? Or is the USA actually claiming special rights exercisable exclusively by it as the only remaining superpower.19 The impact of 9/11 and of Operation Iraqi Freedom on international law on the use of force will be examined in detail in Chapters 6 and 8 below.

Even those who challenged the role of the UN Security Council with regard to the use of force against Afghanistan and Iraq subsequently turned to it for legitimacy and support in the attempts at reconstruction of those states. There is greater demand than ever before for UN peacekeeping and post-conflict peacebuilding. The problems of East Timor, Haiti and of many African states have increased awareness of the need to prevent the resurgence of conflict after the conclusion of a peace agreement or political settlement, and after the withdrawal of UN peacekeeping forces. The UN has established a new Peace-Building Commission. In 2007 the UN maintained peacekeeping forces in Africa, the Americas, Asia, Europe, and the Middle East. This major surge in peacekeeping brought with it serious difficulties in securing troops and equipment, and also calls for increased cooperation with regional organizations and for a reappraisal of peacekeeping doctrine.

Several long-lasting conflicts continue, some dating back to the establishment of the UN. Among the first conflicts ever considered by the Security Council were those between India and Pakistan and between Israel and Arab states. These disputes have continued off and on for the last fifty years and are to a large extent still unresolved. Long-lasting civil wars and separatist struggles also continue in Burma, Colombia, Georgia (Abkhazia), Indonesia, Kashmir, the Philippines and Thailand; conflict was resurgent in Sri Lanka after the government proclaimed an end to the 2002 ceasefire which had long existed in name only. The violent struggle for self-determination continued in the occupied territories of the West Bank and Gaza.

On the positive side, in 2007 the UN played a major role in ending other serious conflicts, especially in Africa where it has increasingly acted in cooperation with regional organizations. The prospects for the settlement of the complex and often interrelated conflicts in the Democratic Republic of Congo (DRC), Burundi, Uganda, Sierra Leone, Liberia, and Côte d’Ivoire were encouraging, but the situation in many of these states is far from stable. In many of these conflicts the UN played an important role in seeking a solution or in running a peacekeeping operation. But serious challenges still faced the UN in its attempts to bring peace in the interconnected conflicts in Sudan, Chad and the Central African Republic. Although the twenty-five year civil war between north and south Sudan finally ended in 2005 and a UN peacekeeping force was established, the UN had less success with regard to the humanitarian crisis in Darfur. In 2007 the government of Sudan finally agreed to the deployment of a new type of hybrid UN/AU force, marking a new era of cooperation between UN and regional organizations. The UN also cooperated with the EU in the creation of a joint peacekeeping operation in Chad and the CAR, to prevent the overspill of conflict between Darfur, Chad and the CAR, but many problems faced these two operations at the start of 2008. Again in the interconnected conflicts in the Horn of Africa the UN could make little progress in peacekeeping; the bad relations between Eritrea and Ethiopia following their 1998–2000 conflict, manifest also in the 2006 conflict in Somalia, and the serious unrest in Kenya make the region dangerously unstable. Although a small AU force was sent to Somalia after the Ethiopian invasion, the situation was too precarious for UN peacekeeping.

The rest of this chapter has two main interrelated themes: first, the problems with the identification of international law on the use of force in the light of the fundamental disagreements between states and between commentators, and second, the role of international law in this area and the complexities of any inquiry into its effectiveness.


The starting point for any examination of the law is the prohibition of the use of force in Article 2(4) of the UN Charter.20 Irrespective of whether the UN Charter is seen as a revolutionary departure from existing customary international law on the use of force or as a codification of rules that had already undergone a major shift in the twentieth century,21 the Charter system was a marked departure from that of the League of Nations, and the language of Articles 2(4) and 5122 provides a new terminology and the first expression of the basic rules in their modern form. States may still use the rhetoric of ‘war’, in the language of the Covenant of the League of Nations, as was apparent in the language used by Ethiopia in its recent conflict, but the drafters of the UN Charter deliberately chose to use the wider term ‘use of force’ in the prohibition in Article 2(4).23 This book will examine the use of force since the Charter; the focus will be on state and UN practice under the Charter.24 The aim is to identify the areas of agreement and disagreement, to examine through practice the application and development of the law in the light of the Charter framework, and to provide enough primary material to enable the reader to decide between the sometimes radically opposed interpretations of the same practice.

The rules of the Charter on the use of force are brief and cannot constitute a comprehensive code. The provisions in Articles 2(4) and 51 are very much a response to the Second World War and are accordingly directed to inter-state conflict. It is now a commonplace that such conflict, or at any rate large scale inter-state conflicts, have proved to be the exception in the years since 1945; and that civil wars, with or without outside intervention, have outnumbered traditional inter-state wars.25 Cross-border guerrilla incursions and limited inter-state fighting in border areas have been the norm rather than all-out wars between states. The struggles of national liberation movements for independence during the decolonization process also did not fit easily into the framework of Articles 2(4) and 51. The evolution of rules to cover these conflicts has been a complex process. Even in inter-state conflicts the apparently simple words of the Charter have given rise to fundamental differences between states.

This is one of the most controversial areas of international law; even from the early days of the UN many disagreements between states (between developed and developing, between East and West) as to the law were apparent. The prohibition of the use of force led to fundamental divisions as to whether the prohibition of the ‘use of force’ included economic coercion, the scope of the right of self-defence, the right to use force to further self-determination and to intervene in civil wars. These differences emerged in the context of the Cold War and the decolonization process. The end of the Cold War, the dominance of the USA as the one remaining superpower, and the virtual end of decolonization now call for a reappraisal of international law on the use of force by states and by UN forces. How far should the Charter be interpreted to allow the use of force to restore or further democracy, to restore order in a state without an effective government, to further the right to self-determination outside the decolonization context and to respond to terrorist attacks? How far should the UN Security Council exercise centralized control over these and other uses of force? How, if at all, can these controversies, old and new, be resolved? A central question is whether it is possible to use state practice to arrive at an authoritative interpretation of the Charter or to supplement its brief provisions. Is it possible to find standards by which to assess the legality of states’ actions and which advisers can use to give guidance to states? Given that state practice includes the actual use of force, the justification offered by states for it, the response of other states inside and outside the UN and other organizations, and their public positions in debates on general resolutions of the General Assembly on the use of force, as well as an extensive treaty practice including friendship treaties, non-aggression pacts, border treaties, mutual defence agreements and regional arrangements, how are universal rules to be extracted?26 Questions also arise as to who speaks for a state: is it to be the US President or the more cautious US State Department Legal Adviser, the UK Prime Minister or the Attorney-General? Should the Charter be seen as open to dynamic and changing interpretation on the basis of subsequent state practice or should the prohibition of the use of force in Article 2(4) rather be seen as having a fixed meaning, established in 1945 on the basis of the meaning of the words at that date in the light of the preparatory works and the aims of the founders?27

The International Court of Justice in the Nicaragua case apparently regarded the Charter provisions as dynamic rather than fixed, and thus as capable of change over time through state practice. It said that ‘The UN Charter . . . by no means covers the whole area of the regulation of the use of force in international relations’, and went on to explain how the Charter provisions on self-defence needed to be interpreted in the light of customary international law.28 On the fundamental principles as to the use of force contained in Article 2(4) the parties agreed that the Charter provisions represented customary law and the Court accepted this without going into the question of how far the meaning of Article 2(4) was fixed or how far it had evolved over time. The Court did, however, go into the question of what amounted to a use of force under Article 2(4) not amounting to an armed attack under Article 51.29 It also accepted the possibility of the development of new law on forcible intervention allowing a new exception to the prohibition of the use of force in Article 2(4). That is, it seems to have accepted the possibility of a dynamic interpretation of Articles 51 and 2(4) based on the development of state practice.30

Almost from the time of the creation of the UN the states parties have worked to elaborate on the provisions of the UN Charter on the use of force in General Assembly resolutions. Western states have often evinced some unease about this process; thus the USA has asserted that there is no lack of understanding of Article 2(4). During the Cold War the UK and the USA tended to argue that Article 2(4) should be treated as the last word, for fear that any modification would be to the advantage of the Soviet Union.31 But the western states have come to accept the legal significance and customary international law status of certain of these resolutions. This process of elaboration on the UN Charter began with the 1949 Resolution on the Essentials of Peace. The ICJ in the Nicaragua case in 1986 singled out the 1974 Definition of Aggression32 and the 1970 Declaration on Friendly Relations33 to help it to identify customary international law on the non-use of force. These resolutions have since been supplemented by the 1987 Declaration on the Non-Use of Force.34 But even though these resolutions adopted unanimously or by consensus may be seen as authoritative interpretations of the UN Charter or as contributing to the formation of customary international law,35 they often leave controversial issues unresolved.

Typically the price of consensus has been ambiguity on the crucial issues that divide states. The drafting history of the resolutions reveals more about the views of states than the resolutions themselves do.36 Thus the central question of the scope of the right of self-defence is not dealt with in the General Assembly resolutions. This issue divides states which take a wide view, such as the USA, Israel, and in the past South Africa and, to a lesser extent, the UK and France, from the vast majority of other states. These states claim a right to use force to protect nationals abroad, to take anticipatory self-defence, and to respond to terrorism as part of self-defence. The vast majority of states rejected such claims before the events of 9/11. But it seems that states preferred to avoid any substantial provision on this question of self-defence and this enabled them to maintain their opposing positions. During the debates on the 1987 Declaration on the Non-Use of Force only the USA and Australia spoke out expressly in favour of anticipatory self-defence; the other states were able to maintain their positions simply through the omission of any provision on self-defence apart from the general formula that ‘States have the inherent right of individual or collective self-defence if an armed attack occurs, as set forth in the Charter of the UN’.37

Also the General Assembly resolutions could not settle the controversies that divided developed and developing states as to the meaning of ‘force’, as to the right to use force in the furtherance of self-determination for colonial peoples or to recover territory illegally seized by another state. Nor did the resolutions resolve the dispute as to the legality of use of nuclear weapons.38 These differences manifested themselves during the debates on the Declaration on Friendly Relations from 1962; the same differences continued to divide states during the ten years’ drafting of the Declaration on the Non-Use of Force and the end product did not constitute any real advance on the Declaration on Friendly Relations.39

And if we turn to other actions and statements of states to interpret or supplement the Charter and the General Assembly resolutions, how is the legal significance of such practice to be assessed? 40 Can state practice be used to resolve the differences between states or is it impossible to find universal standards in this context? It is important not to exaggerate these differences and to keep them in perspective, even after Operation Iraqi Freedom. For the vast mass of actual use of force reveals that states almost always agree on the content of the applicable law; it is on the application of the law to the particular facts or on the facts themselves that the states disagree. Of course it may be difficult to keep these three categories entirely separate, as is clear from the rather repetitive judgment of the International Court of Justice in the Nicaragua case. The Court made the distinction between the facts, the law and the application of the law to the facts, but it found itself unable to maintain a strict distinction, especially between the last two categories.