The Law Against War

The Prohibition on the Use of Force in Contemporary International Law

Olivier Corten

• Publisher: Hart Publishing
• Year: 2021
• ISBN:
  9781509949007
• Edition: 1
• Topic: Law
• Subtopic: International Law
• Index: Law

Praise for previous edition:
"...a comprehensive, meticulously-researched study of contemporary international law governing the use of armed force in international relations…'
Andrew Garwood-Gowers, Queensland University of Technology Law Review, Volume 12(2) When this first English language edition of The Law Against War published it quickly established itself as a classic. Detailed, analytically rigorous and comprehensive, it provided an indispensable guide to the legal framework regulating the use of force. Now a decade on the much anticipated new edition brings the work up to date. It looks at new precedents arising from the Arab Spring; the struggle against the "Islamic State" in Iraq and Syria; and the conflicts in Ukraine and Yemen. It also reflects the new doctrinal debates surrounding recent state practice. Previous positions are reconsidered and in some cases revised, notably the question of consensual intervention and the very definition of force, particularly, to accommodate targeted extrajudicial executions and cyber-operations. Finally, the new edition provides detailed coverage of the concept of self-defense, reflecting recent interpretations of the International Court of Justice and the ongoing controversies surrounding its definition and interpretation.

1

A Choice of Method

At a conference on ‘the right of humanitarian intervention in contemporary international law’, two speakers clash. The first claims that the right of humanitarian intervention arose in the 1990s as a result of the advancement of humanistic values typical of the ‘new world order’. The second retorts that the United Nations Charter has not been amended and does not recognise the existence of any such right in the positive international legal order. The first speaker then points out that international law can and must evolve informally so as to keep pace with the needs of life in society. The second answers that law cannot admit any informal evolution of the sort unless it is materialised by a treaty revision or, at the very least, by the emergence of a customary rule accepted by the international community of States as a whole.

This schematised debate clearly shows that, in the area of the non-use of force perhaps more than in others, legal controversies are often inseparable from deeper issues about the methods, or even the theory, of international law.¹ In the example just set out, the proponent and the opponent of the right of humanitarian intervention plainly do not share the same methodological options. For their discussion to be meaningful, it must therefore extend beyond the analysis of this or that particular source of law (article 2(4) of the United Nations Charter, the major resolutions of the UN General Assembly on the use of force, such and such a precedent at the time the rule was invoked, and so on) and address the way such sources are apprehended and interpreted. So, and this was borne out by precedents like Kosovo, Iraq or Syria, it seems that such controversies cannot be understood without some grasp of the methodological debates and options underpinning them.

The purpose of this first chapter is not to come down on one side or other of the fence by trying to show that one or other option is scientifically valid. In introducing a particularly thorough study, one author argues ‘there is an objectively correct interpretation of the rules of the use of force which can be discovered by the proper application of the tools of interpretation and methodology in international law’.² Regrettable as it may be, it is not certain that there is one and only one method or approach universally recognised as objective by all international lawyers, or that the common choice of a method implies agreement on the substance of the questions addressed.³ Accordingly I shall first emphasise the width of the methodological divide by identifying two extremes between which commentators can usually be situated (section I). Only after setting out the terms of the debate shall we be in a position to ascertain the methodological options to be followed in the remainder of this book (section II). These options are the result of a choice; and while no claim is made that it is the only possible choice – although while not ‘objective’ it is probably the choice that most closely matches the approach followed by a substantial part of legal opinion (including the International Law Commission) as well as case law (especially that of the International court of Justice)⁴ – it is important to be clear about it from the outset if we are to understand properly the scope of the substantive arguments to be developed in the ensuing chapters.

I.THE TERMS OF THE METHODOLOGICAL DEBATE ON THE NON-USE OF FORCE: THE EXTENSIVE VERSUS THE RESTRICTIVE APPROACH

The prohibition of the use of force is first and foremost a treaty-based rule, enshrined in the Charter of the United Nations and in numerous other treaties of regional scope. However, it is at the same time a rule of customary law, the evolution of which has been at the centre of lively debates, particularly in the last few years. On one side of those debates is the extensive approach; it consists in interpreting the rule in the most flexible manner possible. By this approach, doctrines such as ‘preventive self-defence’, self-defence against non-State actors, ‘ex-post authorisation’ of the Security Council, or the right of ‘humanitarian intervention’ can be accepted as conforming to the rules. On the other side is what can be categorised as the restrictive approach; it advocates a much stricter interpretation of the prohibition so making it generally much less likely that new exceptions or new interpretations tending to make the rule more flexible or even to set it aside will be viewed as acceptable.⁵ Beyond the validity of the basic arguments advanced by both sides, a review of scholarship reveals that the debate is also, and perhaps above all, about method.⁶ The most profound divergences arise over the status and interpretation of the customary prohibition of the use of force. The extensive approach, unlike the restrictive one, tends to favour a highly flexible method when it comes to ascertaining the status and content of the customary rule. Individual authors will tend to develop their arguments by siding (more or less) with one or other of these perspectives and will propose their version or even their narrative of jus ad bellum (an expression characteristic of an extensive approach) or jus contra bellum (denoting a more restrictive approach).⁷ This right thus appears to be the stomping ground of what has been termed Lawfare, meaning the use of law to ensure one’s positions prevail, and it is in this context that the opposition between approaches tending to make the prohibition of the use of force more flexible or more stringent should be resituated. In any event, it is this working hypothesis that will be tested in this section. The questions of the status and the constitutive elements of custom will be dealt with in turn in order to illustrate the methodological differences between the two approaches.

Before addressing those points, it should be noted that, while the arguments that will be presented here are articulated in terms of the two opposing extremes, the diversity of doctrinal opinions that have currency is considerably more complex and nuanced than this might suggest. This, however, shall not prevent us from illustrating the two theoretical extremes by using commentators whose work cannot be reduced to either position, the objective being to present types of argumentation rather than to classify any given author as belonging to one or the other category. It is in this spirit that a sample of works on the use of force has been selected, ranging from the war in Kosovo to that in Syria, by way of the wars in Afghanistan, Iraq and Libya.

Although it is impossible to be anything like exhaustive in this regard, an attempt has nonetheless been made here to cover as wide a range of viewpoints as possible, in particular by integrating ‘US’ and ‘European’ works into the analysis alongside those from Third World countries so far as can be done. It may be possible to advance the hypothesis of a schism opposing US scholars to those from the rest of the world, with the former espousing the extensive approach and the latter the restrictive one.⁸ Next it should be emphasised that, theoretically a restrictive approach may tend, in substance, to a broad interpretation of the possibilities of the use of force⁹ while in parallel a rather flexible approach may be used in support of a strict interpretation of the Charter.¹⁰ In practice, though, and as shall be observed, the tendency will be to place extensive interpretations on one side and restrictive interpretations on the other in terms of both method and substance.

Moreover, and since the first edition of this book came out, other publications have taken up this two-way methodological divide, albeit under other names: Matthew Waxman speaks of ‘Balancers’ and ‘Bright-Liners’,¹¹ Tom Farer of ‘Purists’ and ‘Eclectics’,¹² while others make a distinction between ‘Expansionists’ and ‘Restrictivists’¹³ or, from a slightly different perspective, an ‘institutional code’ and a ‘state code’.¹⁴ I shall clarify the meaning and implications of this divide in the following lines (subsection A) before pondering a possible development of doctrine in favour of the extensive approach, portrayed by some as having developed spectacularly in recent years (subsection B).

A.The Extensive and Restrictive Approaches to the Interpretation of the Rule Prohibiting the Use of Force

The following Table 1, which will be explained in more detail below, provides us with an overall picture of the debate.

	Extensive approach	Restrictive approach
Status of custom	Privileged source Formal and material source Policy-oriented or objectivist tendencies	Equality between sources Formal source Voluntarist or formalist tendencies
Understanding of the constitutive elements of custom	Practice as the dominant element; the role of political organs ‘Instant’ or rapidly evolving custom Dominant role of major States	Opinio juris as the dominant element; the role of legal discourse Custom evolves gradually Equality between States

It is on the basis of this table, then, that I shall try to describe the extensive approach (subsection i), and then the restrictive approach (subsection ii), it being understood that I can obviously not claim to be absolutely objective in this area insofar as I situate myself very m...

Table of contents

• Cover
• Title Page
• Foreword by Bruno Simma
• Series Editor’s Preface
• Preface
• Acknowledgements
• Contents
• Introduction
• 1. A Choice of Method
• 2. What Do ‘Use of Force’ and ‘Threat of Force’ Mean?
• 3. Do the Prohibition of the Use of Force and Self-Defence Apply to Non-State Actors?
• 4. Can Circumstances Precluding Wrongfulness be Invoked to Justify a Use of Force?
• 5. Intervention by Invitation
• 6. Intervention Authorised by the UN Security Council
• 7. Self-Defence
• 8. A Right of Humanitarian Intervention?
• Conclusion
• Selected Reading
• Index
• Copyright Page