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The Oxford Handbook of the Use of Force in International Law edited by Weller, Marc (1st January 2015)

Part VII General Problems, Ch.54 Jus Cogens and the Use of Armed Force

AndrÉ De Hoogh

From: The Oxford Handbook of the Use of Force in International Law

Edited By: Marc Weller

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved. Subscriber: null; date: 19 November 2019

Subject(s):
Peremptory norms / ius cogens — Opinio juris — Vienna Convention on the Law of Treaties — UN Charter — Armed forces — Countermeasures — Necessity — Military necessity — Self-defence — Humanitarian intervention — Aggression — International peace and security — Genocide — Freedom from torture and cruel, inhuman, or degrading treatment — Torture — Crimes against humanity — War crimes — Ethnic cleansing

(p. 1161) Chapter 54  Jus Cogens and the Use of Armed Force

I.  Introduction

The concept of jus cogens, introduced into positive international law by articles 53 and 64 of the Vienna Convention on the Law of Treaties (VCLT),1 has captured the imagination of many an international lawyer. Nevertheless, publications focusing on jus cogens and the use of armed force tend to be rare.2 And yet, there are more (p. 1162) than sufficient reasons to discuss the various legal issues resulting from the claim that the prohibition of the use of armed force in international relations, embodied in Article 2(4) of the UN Charter,3 constitutes a peremptory norm of general international law.4

This chapter will first of all discuss whether or not the prohibition pertaining to the use of armed force can be considered to possess the status of a peremptory norm (Section II). Next, Section III will inquire into the restrictions flowing from the peremptory prohibition of the use of armed force or of aggression and its relationship to accepted or claimed exceptions. It will consider whether the circumstances precluding wrongfulness, namely countermeasures, consent, and necessity allow for use of armed force, and how these relate to the peremptory prohibition. This section will continue to reflect on how specific exceptions to the prohibition, such as the right of self-defence laid down in Article 51 of the Charter, may be accommodated to the peremptory prohibition.

Finally, Section IV will proceed to reflect on demands for forcible action resulting from peremptory norms, such as an armed intervention to stop genocide. First, it will be discussed whether it is admissible to deduce legal effects or consequences directly from the characterization of jus cogens norms as hierarchically higher than ‘ordinary’ norms. Secondly, this section will explore whether the implementation or enforcement of peremptory norms might entail a disregard for the prohibition of the use of armed force in the absence of an accepted conventional or customary justification.

II.  The Peremptory Norm(s) Pertaining to the Use of Armed Force

Article 53 VCLT, headed jus cogens, stipulates:

A treaty is void if, at the time of its conclusion, it conflicts with a peremptory norm of general international law. For purposes of the present Convention, a peremptory norm of general international law is a norm accepted and recognized by the international community of States as a whole as a norm from which no derogation is permitted and which can be modified only by a subsequent norm of general international law having the same character.

(p. 1163) Though the concept of jus cogens now appears fully accepted in international law,5 various issues have engendered debate. One of those concerns the status of the underlying norm of general international law and the way in which such a norm is elevated to peremptory status.

Where Article 53 VCLT stipulates that a norm ought to be accepted and recognized by states as one from which no derogation is permitted, this suggests that a peremptory norm is based on an existing norm. The status of that underlying norm remains unclear, in that Article 53 claims it must be one pertaining to ‘general international law’. Some authors have pointed out that it could not singularly refer to multilateral treaties, since those are by nature relative in character, that is, they do not bind states that have refrained from becoming a party to them (Art 34 VCLT).6 Hence, a sensible construction is that such a norm ought to be based on a universal rule of customary international law.7

The determination of the existence of a peremptory norm thus involves a two-stage process: (1) the establishment of a norm of general international law, that is, a universal rule of customary international law; and (2) acceptance and recognition of such a norm as one from which no derogation is permitted.8 However, this second stage should not be seen to embody simply the criterion of non-derogation, (p. 1164) but rather that states accept and recognize that a certain norm cannot be derogated from precisely because it is a norm of jus cogens. In other words, non-derogability is an attribute, not the defining character, of jus cogens in international law.9

Certainly, when it comes to the first stage, it can be easily affirmed that the prohibition of the use of armed force in international relations embodied in Article 2(4) of the Charter is also established under customary international law. This was already decided by the International Court of Justice (ICJ) in 1986 in the Nicaragua case,10 and this appears to have been confirmed in the Armed Activities case of 2006.11

With respect to the second stage, the waters become somewhat muddy. In 1966, the International Law Commission (ILC) in its commentary held that12 ‘the law of the Charter concerning the prohibition of the use of force in itself constitutes a conspicuous example of a rule in international law having the character of jus cogens.’ Some authors examining a variety of sources and documents have indeed come to the conclusion that the prohibition of the use of armed force is a peremptory norm.13

More recently Green has attempted to cast doubt on the prohibition’s peremptory status by pointing to various complicating aspects.14 Moreover, he points to a certain shortage of practice actually showing that states have held the view that the prohibition of the use of armed force is a rule of jus cogens.15 This last feature constitutes a rather problematic aspect in view of the requirement imposed by Article 53 VCLT that a norm must be accepted and recognized as peremptory by the international community of states as a whole.16 However, Corten recently investigated the matter and came to the conclusion that the prohibition of the threat or use of force, as embodied in Article 2(4), constitutes a peremptory norm.17

Be that as it may, for the purposes of this chapter it will be assumed that a peremptory norm exists in relation to the use of armed force. Nevertheless, various questions arise as to the scope of this peremptory norm. Primary among those is how to position existing and possible future exceptions.

(p. 1165) III.  Jus Cogens Restrictions on the Use of Armed Force

With respect to the prohibition on the use of armed force a particular problem exists in that it allows for exceptions and this poses some difficulties. Other peremptory norms appear to be based on prohibitions that are absolute in character and these do not raise the same issues.18 First, the possibility of invoking generally available circumstances precluding wrongfulness will be investigated (Section III.A). Secondly, to accommodate specific exceptions to the prohibition on the use of armed force as a rule of jus cogens, three possible avenues of reasoning are feasible: a restrictive interpretation of the word derogation (Section III.B); exceptions as jus cogens (Section III.C); and a restrictive scope of the jus cogens prohibition (Section III.D).

A.  Circumstances Precluding Wrongfulness as General Exceptions

One area where the jus cogens status of the prohibition does make a difference relates to the generally accepted circumstances precluding wrongfulness. In this respect Article 26 of the Draft Articles on State Responsibility stipulates that19 ‘Nothing in this chapter precludes the wrongfulness of any act of a State which is not in conformity with an obligation arising under a peremptory norm of general international law.’ Among the circumstances precluding wrongfulness adopted by the ILC particularly countermeasures, consent, and necessity, leaving aside self-defence as a specific exception, are particularly relevant to the present inquiry.

In Article 22 of its Draft Articles on State Responsibility, the ILC provided for the enforcement of the responsibility of states through countermeasures: ‘The wrongfulness of an act of a State not in conformity with an international obligation towards another State is precluded if and to the extent that the act constitutes a countermeasure taken against the latter State in accordance with chapter II of Part Three.’ As such, a state may adopt countermeasures to induce another state to comply with its obligations of continued performance, cessation, (p. 1166) reparation, and assurances or guarantees of non-repetition.20 However, whether such option is open to states other than injured states is unclear considering the savings clause of Article 54 of the Draft, reserving the matter of ‘lawful’ measures.21

Countermeasures or lawful measures appear to be limited to economic or other ‘peaceful’ measures.22 As both countermeasures and lawful measures are set out in the chapter on countermeasures, this could hardly be otherwise since Article 50 requires that countermeasures shall not affect ‘the obligation to refrain from the threat or use of force as embodied in the Charter of the United Nations’.23 The commentary bases this norm directly on Article 2(4) of the Charter and various reaffirmations that armed or forcible reprisals are prohibited.24 Whether this would follow also from the reference in Article 50(1)(d) to ‘other’ obligations under peremptory norms is unclear, since the Commission does not specify in its commentary whether the prohibition of the threat or use of force in general constitutes a peremptory norm.25 If the prohibition in general rather than the prohibition of aggression is a peremptory norm,26 countermeasures or lawful measures involving the use of armed force would be barred under such norm. This would be different only if the use of armed force were dictated by another peremptory norm, since Article 53 VCLT stipulates that a peremptory norm can only be modified by a norm having the same character (see Section IV.B).

Continuing the discussion of generally available exceptions, the Draft Articles on State Responsibility provide in Article 20:27 ‘Valid consent by a State to the commission of a given act by another State precludes the wrongfulness of that act in relation to the former State to the extent that the act remains within the limits of that consent.’ The reference to ‘valid’ consent may be taken to also express the idea that it is invalid if the act consented to were to conflict with an obligation under a (p. 1167) peremptory norm.28 Otherwise, the conduct of a state undertaken pursuant to consent by another state must remain within the limits of the permission given.29

With respect to consent and its relation to the prohibition on the use of armed force, it is generally accepted that a state may invite foreign troops onto its territory.30 Equally, the prohibitions of the use of armed force and (armed) intervention do not stand in the way of such troops engaging in the use of armed force on a state’s territory with a government’s consent.31 Such foreign armed activities are not, however, admissible when based on a request to that effect by the (armed) opposition within a state.32

Issues have arisen in relation to the use of armed force for certain purposes, such as the protection of nationals abroad and humanitarian intervention, and in relation to treaties establishing a permanent right of armed intervention. The examination of various situations by Ronzitti and Hannikainen shows that (ex post facto) consent will only be invalidated for conflict with obligations under the peremptory prohibition in rather limited circumstances: the purported acquisition of territory, overthrow of a government and consequent installation of another government (in particular when combined with the continued presence of foreign troops on, or outright occupation of, the territory of a state).33

Abass has argued that the Economic Community of West African States Protocol and the Constitutive Act of the African Union, establishing legal powers of armed intervention, are not caught by Article 26 of the Draft Articles on State Responsibility.34 However, his argument in support that these constitute consensual (p. 1168) rights of intervention and would not result in coercive use of force may be questioned. The problem with such an argument is that consent is not given in concrete circumstances and intervention can be resorted to against a state rather than at its invitation.35

Turning to necessity, this was put forward by the ILC as a circumstance precluding wrongfulness in 1980. The original provision (Art 33) required the existence of a grave and imminent peril to an essential interest of the state, but invoking a state of necessity was barred if this would seriously impair an essential interest of another state.36 In 2001, the Commission changed the text (Art 25), no longer requiring the essential interest to relate to the state exclusively, stated in the commentary that the essential interest at stake could also relate to the people of a state or to the international community as a whole, and made clear that necessity could not be invoked if it seriously impaired an essential interest of the international community as a whole.37

In changing the text of the provision as it did, the Commission therefore appeared to provide more room for the claim that the use of armed force might be resorted to in order to safeguard the essential interests of the international community as a whole.38 Yet that impression turns out to be false. In its 2001 commentary, the Commission in fact made a volte-face as to whether or not the use of armed force might be claimed under the heading of necessity.

In 1980, the Commission noted in its commentary on necessity that the wrongfulness of conduct could not be precluded if it involved the use of armed force constituting aggression.39 Referring to attacks on ‘the very existence of another State or on the integrity of its territory or the independent exercise of its sovereignty’, the Commission claimed that:40

any use by a State of armed force for an assault of the kind mentioned against the sovereignty of another State, indisputably comes within the meaning of the term ‘aggression’ and, as such, is subject to a prohibition of jus cogens—the most typical and incontrovertible prohibition of jus cogens.

It proceeded to investigate whether certain armed actions infringing the territorial sovereignty of a state could be considered not to amount to acts of aggression or to (p. 1169) breaches of a jus cogens obligation.41 The situations the Commission had in mind concerned incursions into foreign territory in response to a ‘danger to the State, to some of its nationals or simply to human beings’, and it continued by pointing out the limited character of such cross-border armed actions in terms of duration and means employed.42 At that point the Commission expressed doubts whether all obligations to respect the territorial sovereignty of states constituted jus cogens.43 It consequently appeared to envisage the possibility, without committing itself,44 that necessity might be invoked to allow for preclusion of wrongfulness of conduct otherwise in violation of the prohibition of the use of armed force.

In 2001, the Commission expressed its view on which rules constituted clearly accepted and recognized peremptory norms and included the prohibition of aggression.45 However, with respect to the possibility of invoking necessity to justify the use of armed force it now claimed:46

the plea of necessity is not intended to cover conduct which is in principle regulated by the primary obligations. This has a particular importance in relation to the rules relating to the use of force in international relations and to the question of ‘military necessity’. It is true that in a few cases, the plea of necessity has been invoked to excuse military action abroad, in particular in the context of claims to humanitarian intervention. The question whether measures of forcible humanitarian intervention, not sanctioned pursuant to Chapters VII or VIII of the Charter of the United Nations, may be lawful under modern international law is not covered by article 25.

Thus the Commission backtracked and by its references to ‘primary obligations’ and ‘modern international law’ suggested that (forcible) humanitarian intervention is regulated by customary international law and, in any event, not covered by Article 25.

The claim of the Commission that humanitarian intervention is regulated by primary norms rather than secondary norms may be disputed.47 As a specific armed response to violations of human rights obligations, it falls into the same category as countermeasures and that topic has been included and regulated in the Draft Articles on State Responsibility.48

(p. 1170) In essence, the Commission’s position, correctly in the mind of the present author, appears to be that (customary) international law requires the existence of a specific exception to the peremptory prohibition of the use of armed force.49 The codification of the secondary rules of state responsibility needs to be based on an analysis of state practice and opinio juris and on that basis the conclusion can indeed be drawn that customary international law accepts necessity as a circumstance precluding wrongfulness with its attendant conditions.50 However, the practice relied upon to support necessity as a circumstance precluding wrongfulness only shows a few examples in which the use of armed force was at stake and only one when the Commission adopted the provision in 1980.51

B.  Specific Exceptions and Derogation

Regarding specific exceptions to the prohibition on the use of armed force, the ILC indicated in its 1966 commentary on jus cogens that states may generally contract out of the majority of general rules of international law and that jus cogens rules are precisely those that bar derogation of such a rule ‘by agreement between particular States’.52 As the concept of jus cogens envisages a limitation to the otherwise existing freedom to contract out of rules of international law, it is intended to disallow states, acting inter partes, to derogate from peremptory norms.53 The basic argument here is that rules that allow all states equally to invoke an exception to the prohibition of the use of armed force simply would not constitute ‘derogation’. This could be taken to mean that the right of self-defence, the Security Council’s powers under Article 42 of the Charter, and other (potential) justifications recognized under universal rules of customary international law do not transgress the peremptory norm prohibiting the use of armed force.

An advantage of this kind of reasoning is that there is no need to explain a pretend conflict between the peremptory prohibition and the existence of the exception of (p. 1171) self-defence and Security Council powers under the Charter. If such a conflict were thought to exist, the consequence would be that the Charter ought to be considered void (Art 53 VCLT, first sentence; Art 64 VCLT). It may be noted that the Security Council powers as such do not constitute an exception to the Charter prohibition on the use of armed force, since Article 2(4) addresses the member states and not the UN itself.54 However, authors do claim that the Security Council is bound by jus cogens,55 and as such the question of conflict with and derogation from the prohibition of the use of armed force cannot be avoided even in relation to its powers under the Charter.56

However, this reasoning also makes the limitation as to modification unintelligible. Article 53 VCLT stipulates that a peremptory norm ‘can be modified only by a subsequent norm of general international law having the same character.’ To argue for a restrictive interpretation of the word derogation also implies that new exceptions may be established through ordinary international lawmaking, that is, through the conclusion of a treaty or development of a (new) rule of customary international law.57 Leaving aside that a treaty only binds the parties and therefore would constitute an inter se arrangement conflicting with the peremptory norm under discussion, admitting this possibility deprives the requirement that a peremptory norm can only be modified by another peremptory norm of its content. Carving out exceptions from the peremptory prohibition would allow for further limitations of that prohibition even when those did not possess peremptory character themselves.

Nevertheless, the Commission had considered that modification of a peremptory norm would likely occur by a general multilateral treaty that would fall outside the scope of the provision, but pointed out that a peremptory norm ‘can be modified only by a subsequent norm of general international law having the same character.’58 This, however, would appear to require that the multilateral treaty would not merely lay down a novel exception, but that it should qualify such an exception as jus cogens.

(p. 1172) C.  Specific Exceptions as Jus Cogens

All the same, authors writing on this matter do not generally take the route of interpreting the word derogation restrictively.59 Rather, some tend to go for a second line of reasoning, namely to argue that not just the prohibition of the use of force is a peremptory norm, but that other rules of the law regulating the use of armed force are also jus cogens. Some hold that the entire regime of the jus ad bellum as a whole is peremptory,60 some claim that the right of self-defence is (or exceptions are) necessarily included in the provision of Article 2(4) of the Charter,61 and some that the right to self-defence is or the exceptions are (a) peremptory norm(s).62 With respect to these last two perspectives, one may therefore either argue that exceptions are (necessarily) part and parcel of the peremptory prohibition and as such limit its scope, or that such exceptions have independent status as peremptory norms and as such would prevail in the case of conflict.

The first claim, that the entire jus ad bellum is part of jus cogens, founders because of the objection that many rules contained within that field cannot be shown to have been accepted and recognized by states as norms from which no derogation is permitted.63

The second claim, that exceptions form part of the peremptory prohibition and limit its scope, is subject to the same kind of objections as voiced earlier as to the restrictive interpretation of the word derogation. Over and above this, Green has asserted that to incorporate self-defence and Security Council powers to use armed force and all their related conditions and requirements into one peremptory norm, means to produce a lengthy and overcomplicated norm and that such lack of clarity is undesirable for a fundamental peremptory norm.64

The third claim, that the right to self-defence, or exceptions more generally, could have a status as independent peremptory norm(s), might of course crumble under the weight of the same objections as those voiced with respect to the first claim. (p. 1173) Moreover, do states accept and recognize the right to self-defence as a peremptory norm, or to be more exact as a norm from which no derogation is permitted?

And to follow up on this last specification, what would it mean to say that states cannot derogate from the right of self-defence? Derogation in relation to jus cogens is taken to mean that a rule of international law cannot be displaced or abrogated by (some) states in their mutual relations. Derogation in relation to the right of self-defence would then suggest that it cannot be renounced or perhaps also that it cannot be alienated. But if such is the case, the limitation imposed in Article 51 of the Charter that nothing in the Charter shall impair the right of self-defence ‘until the Security Council has taken measures necessary to maintain international peace and security’ does appear problematic since it provides a restriction to the legitimate exercise of the right of self-defence and, more importantly, subordinates it to the judgement of the Security Council. In the same vein, treaties by which a state outsources the conduct of its international relations and defence could be argued to alienate the right of self-defence and would be in conflict with the peremptory status of the right of self-defence.65

D.  Specific Exceptions and a Limited Scope of the Peremptory Prohibition

The third and final line of reasoning is linked to the idea that the prohibition on the use of armed force is not in its entirety a peremptory norm, but that the peremptory norm is more restrictive in scope and either limited to the prohibition of aggression or to armed force used against the territorial integrity or political independence of a state. The argument that the peremptory norm is more restrictive in scope and limited to the prohibition of aggression may be supported by pronouncements of the ILC in formulating the circumstances precluding wrongfulness in its work on the responsibility of states.

In 1980, the ILC noted in the commentary on necessity that the wrongfulness of conduct could not be precluded if the use of armed force constituted aggression.66 The Commission appeared to envisage the possibility that, hence, necessity might be invoked to allow for preclusion of wrongfulness of conduct otherwise in violation of the prohibition of the use of armed force.67 In 2001, the Commission listed clearly accepted and recognized peremptory norms and included the prohibition of aggression.68

(p. 1174) The choice for the prohibition of aggression as a peremptory norm rather than the prohibition of the use of force seems to be motivated by the perception that aggression is a more limited concept. Whether this is actually the case may be doubted in view of Article 1 of the Definition of Aggression adopted by the General Assembly,69 which stipulates: ‘Aggression is the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations, as set out in this Definition.’ Article 2 then provides that:

The first use of armed force by a State in contravention of the Charter shall constitute prima facie evidence of an act of aggression although the Security Council may, in conformity with the Charter, conclude that a determination that an act of aggression has been committed would not be justified in the light of other relevant circumstances, including the fact that the acts concerned or their consequences are not of sufficient gravity.

Article 3 then sets out a number of acts that qualify as aggression, such as invasion of or attacks on, or bombardment of or use of weapons against, the territory of another state.

In reading this one is struck by the fact that any use of armed force appears to constitute an act of aggression. This follows from the fact that Article 1 simply recounts the text of Article 2(4) of the Charter (though adding sovereignty), that Article 2 stipulates that a first use of armed force shall be prima facie evidence of an act of aggression, and that the examples of Article 3 are formulated in a manner as to encompass the use of armed force generally. This view may be qualified in some measure by the fact that the Security Council may come to a conclusion, based on all relevant circumstances including the gravity and consequences of the acts concerned, that a determination of aggression is not justified.70 Similarly, one could also mention that the Preamble observes that ‘aggression is the most serious and dangerous form of the illegal use of force’, and as such not all (illegal) uses of armed force would fall under the term.71

However, all in all, it seems that any use of armed force could be branded as an act of aggression, and as such the prohibition of aggression does not appear to have a less restrictive scope than the prohibition of the use of armed force.72 A preference (p. 1175) for granting peremptory status to the prohibition of aggression rather than the prohibition on the use of armed force cannot be derived from this, and branding the prohibition of aggression as a peremptory norm would then not necessarily accommodate the exceptions to the peremptory prohibition.73

Some authors have put forward that the status of the jus cogens norm on the use of force is the prohibition of aggressive use of armed force or aggression.74 Yet what would constitute the distinguishing mark of aggressive force or aggression remains somewhat sketchy.75 Hannikainen discusses the use of armed force to rescue nationals abroad and armed intervention for humanitarian purposes and comes to the conclusion that these do not constitute aggressive use of armed force when limited in duration and the means employed. In his view, such uses of armed force are not of (direct) interest to jus cogens.76 One might be inclined then to see the distinguishing mark between aggression and a ‘merely’ illegal use of armed force to lie with a ‘benevolent’ or altruistic motivation.77 Another option could be to limit the scope of the peremptory prohibition to the use of armed force for certain purposes only, for instance to the use of armed force directed against a state’s territorial integrity or political independence.78

In conclusion, if the peremptory prohibition were restricted to a suitably and adequately limited notion of aggression, both existing and possible future exceptions to such a prohibition would not normally fall under its scope. However, the absence in law of an animus aggressionis or purpose requirement undermines this line of reasoning.

(p. 1176) IV.  Jus Cogens Demands for Forcible Action

The introduction of the concept of jus cogens into international law and the recognition of specific peremptory norms have led to increased attention to questions of effectiveness and enforcement. The question arises, therefore, whether the jus cogens status of a norm may be invoked to justify the use of armed force against a state for the enforcement of a peremptory norm.

Certainly, it seems unlikely that this claim could be made with respect to just any violation of a peremptory norm. In this respect it may be noted that the ILC, discarding the notion of international crimes of state, introduced into Article 40 of its Draft Articles on State Responsibility the conception of serious breaches of obligation under peremptory norms.79 According to paragraph 2 of this provision, a serious breach involves a ‘gross or systematic failure’ to fulfil the obligation. The commentary specifies that a ‘gross’ breach refers to the intensity or effects of a violation, whereas a ‘systematic’ breach entails that the violation is carried out in an organized and deliberate manner.80 The Commission then lists certain factors that may be relevant to determine the seriousness of the breach:81 ‘intent to violate the norm; the scope and number of individual violations; and the gravity of their consequences for the victims.’ The Commission further claims that breaches of the prohibitions of aggression and genocide by their very nature require an intentional and large-scale violation.82

The consequences of serious breaches of obligations under peremptory norms are then laid down in Article 41, which in paragraphs 1 and 2 imposes three obligations:83 (1) to cooperate to bring to an end, through lawful means, the serious breach; (2) not to recognize a situation created by a serious breach; and (3) not to render aid and assistance in maintaining such a situation.84 For the purposes of this chapter, only the first obligation mentioned is relevant, since the question will be whether the use of armed force may be covered as fulfilment of this obligation.

(p. 1177) In this respect the commentary, invoking the diversity of situations covered, does not provide detail as to the forms that such cooperation might entail, but it continues by specifying that this may entail cooperation with(in) a competent international organization, such as the UN, but also in a non-institutionalized sense.85 Moreover, the Commission fails to indicate what kinds of measures would be covered by this positive duty, but it observes that they ought to be taken by both individually affected states and other states as part of a joint and coordinated effort.86 Noticeable in this respect is the reference in the text of the provision to ‘lawful means’, a phrase that might lead us to the savings clause in Article 54, which states that the chapter on countermeasures is without prejudice to the right of states other than an injured state to take ‘lawful measures’.87

Two thorny issues will be addressed in this section: first, whether legal consequences may be deduced from the claim that jus cogens norms are hierarchically higher than ‘ordinary’ norms; secondly, what is to be understood by a conflict of norms and whether a duty to prevent breaches of peremptory norms conflicts with the (peremptory) prohibition of the use of armed force or aggression.

A.  Legal Consequences Attached to Jus Cogens Norms

Legal consequences attached to jus cogens norms were laid down initially in Articles 53 and 64 VCLT.88 The former stipulates that a treaty is void if it conflicts with a peremptory norm. The latter provides that a treaty becomes void and terminates when it conflicts with a new peremptory norm. Over and above the consequences specified in the law of treaties, legal consequences have been included in the Draft Articles on State Responsibility. These are the inability of invoking circumstances precluding wrongfulness with respect to acts that are not in conformity with a peremptory norm (Art 26; see Section III.A); the right of an injured or other state to invoke the responsibility of another state for breaches of obligation owed to the international community as a whole (Arts 42 and 48);89 and various obligations imposed on states to repress serious breaches of obligations under peremptory norms (Arts 40 and 41). Otherwise, the question whether other states are entitled to adopt countermeasures or lawful measures is reserved (Art 54).

A starting point for discussion of additional legal consequences could be the Furundžija case, decided in 1998 by a Trial Chamber of the International Criminal (p. 1178) Tribunal for the former Yugoslavia, in which the principle proscribing torture was held to be a peremptory norm.90 On that basis it continued to argue that this meant:91

a norm that enjoys a higher rank in the international hierarchy than treaty law and even ‘ordinary’ customary rules. The most conspicuous consequence of this higher rank is that the principle at issue cannot be derogated from by States through international treaties or local or special customs or even general customary rules not endowed with the same normative force.

The Trial Chamber followed up by claiming that it delegitimizes any legislative, judicial, or administrative act authorizing torture, and that individuals remain bound to comply with the prohibition and may be held criminally accountable at the national level.92 Apparently not satisfied with these already far-reaching consequences, it proceeded to assert that the jus cogens nature of the prohibition of torture entitled states to exercise universal jurisdiction, that statutes of limitations may not cover torture, and that political offence exceptions to extradition do not apply.93

In 1999, the ILC considered, upon the proposal of Special Rapporteur Crawford,94 the adoption of a provision in the Draft Articles on State Responsibility that would have introduced compliance with a peremptory norm as a circumstance precluding wrongfulness.95 The Drafting Committee of the Commission actually adopted a provision to that effect in 2000,96 though this mysteriously disappeared in the final draft adopted by the Commission in 2001.

Also in 2001, controversy erupted over the question whether a state ought to deny another state’s claim of immunity when this obstructs enforcement in relation to breaches under peremptory norms.97 The debate was sparked, among others, by the Al-Adsani case decided by the European Court of Human Rights (ECtHR), in which it held by the narrowest majority possible that by upholding Kuwait’s immunity the UK had not violated its obligation to provide access to court under Article 6 of (p. 1179) the (European) Convention for the Protection of Human Rights and Fundamental Freedoms to a resident Kuwaiti citizen subjected to torture in Kuwait.98 Though the ECtHR accepted that the prohibition of torture constituted a peremptory norm, it denied that this entailed loss of immunity for civil claims concerning acts taking place abroad.99 The judges in dissent argued that a state (allegedly) violating the jus cogens prohibition of torture ‘cannot invoke hierarchically lower rules (in this case, those on state immunity) to avoid the consequences of the illegality of its actions.’100

Other legal consequences have been asserted by states drawing logical inferences from the hierarchically higher status of peremptory norms. In 2006, in the Armed Activities case, the ICJ rejected an argument by Congo to set aside a Rwandan reservation to the Court’s jurisdiction under the Genocide Convention on the basis that such a reservation was incompatible with the peremptory prohibition of genocide.101 The Court held that even if a dispute relates to compliance with a peremptory norm this does not establish a basis of jurisdiction for the Court to settle such a dispute, and it later noted that no peremptory norm requires a state to consent to the Court’s jurisdiction to settle a dispute in relation to the Genocide Convention or the Convention against Racial Discrimination.102 In addition, the Court found that Article 66(a) VCLT, allowing an application to the Court in respect of the interpretation and application of Articles 53 and 64, could not be invoked to establish its jurisdiction regarding the Conventions mentioned in view of Article 4 establishing the non-retroactivity of the VCLT.103 The mere fact that peremptory norms are at stake cannot as such constitute an exception to consent as the basis for its jurisdiction.104 In the Genocide case, the Court denied its jurisdiction to settle disputes otherwise unrelated to the Genocide Convention even if the violations alleged concerned obligations arising under peremptory norms.105

Focarelli has drawn attention to the tendency of some to use a deductive rather than an inductive approach. The former entails an appeal to the very notion of jus cogens justifying ‘special’ and ‘derogatory’ effects to effectively safeguard basic human rights or the interstate system without the need to found this in state practice or opinio juris.106 In his view, a fully inductive approach to establish the ‘special’ (p. 1180) effects of jus cogens norms is the only viable methodology, basically requiring such effects to be established on the basis of existing customary international law.107 Restating the issue, it is therefore not sufficient to establish that jus cogens is embodied in positive law, but one must further substantiate that the legal effects flowing from the characterization of a rule as a peremptory norm can be found in applicable treaties or rules of customary international law.108

Applying this to the question of demands for forcible action, this entails that the use of armed force to enforce a peremptory norm will require the existence of a justification under the Charter or customary international law. For the latter, it will be necessary to establish state practice and the acceptance of that practice as law (opinio juris). Clearly, with respect to armed force in the exercise of the right to self-defence or resorted to pursuant to a Security Council authorization, the Charter provides for an adequate legal basis, and the former is also accepted under customary international law (though the contours and conditions for its exercise are less clearly established).109 Armed responses to violations of the peremptory prohibition of the use of armed force or aggression are therefore covered, at least when the scale and effects of those violations cross a certain threshold.

The use of armed force to repress (serious) violations of the peremptory prohibitions of genocide, slavery, racial discrimination, torture, and possibly war crimes and crimes against humanity remains problematic from this perspective. Though examples of state practice and opinio juris may be found that support a right of humanitarian intervention, on balance genuine humanitarian interventions have been rare, the legal justification(s) offered by intervening state(s) varied and these did not always invoke humanitarian intervention; moreover, overall responses by other states to such interventions have been to condemn such interventions, and hence international law does not provide for a justification of humanitarian intervention.110

(p. 1181) The concept and doctrine of Responsibility to Protect, proposed initially by the International Commission on Intervention and State Sovereignty set up by the Canadian government,111 has not led to any change in this respect. This may be shown especially by reference to the World Summit Outcome document adopted by the General Assembly in 2005.112 Though accepting a responsibility for states to protect their populations from genocide, crimes against humanity, war crimes, and ethnic cleansing, on the crucial issue of enforcement the General Assembly claimed:

In this context, we are prepared to take collective action, in a timely and decisive manner, through the Security Council, in accordance with the Charter, including Chapter VII, on a case-by-case basis and in cooperation with relevant regional organizations as appropriate, should peaceful means be inadequate and national authorities manifestly fail to protect their populations from genocide, war crimes, ethnic cleansing and crimes against humanity.

On the use of force under the Charter, the General Assembly stressed:113 ‘We reaffirm that the relevant provisions of the Charter are sufficient to address the full range of threats to international peace and security. We further reaffirm the authority of the Security Council to mandate coercive action to maintain and restore international peace and security.’ Since then, the Security Council has indeed invoked the concept, most prominently in resolutions concerning the conflict in Libya with respect to which it specifically authorized member states to use force to protect civilians or civilian-populated areas under threat of attack.114

However, the interpretation of this last phrase, ‘civilians and civilian-populated areas under threat of attack’, and the manner of implementation of this authorization, essentially supporting the Libyan armed resistance in overthrowing the Libyan government, now at least partially accounts for the obstruction by Russia and China of more decisive action by the Council in relation to Syria.115 Moreover, the use of armed force resorted to in the Libyan crisis sits uncomfortably with the peremptory prohibition of aggression, since overthrowing a government appears to endanger the ‘political independence’ of a state. It may be noted that General Assembly Resolution 2625, the Declaration on Principles of International Law, stipulates that states shall not assist in ‘the violent overthrow of the régime of another State’.116 Surely to overthrow a (p. 1182) government must endanger the political independence of a state, even when the use of armed force was authorized by the Council and benevolent motives underlie the choice to support the armed resistance in overthrowing a government.

B.  Conflict of (Peremptory) Norms

Without going into detail about the qualification of various rules that have been declared peremptory norms, the proliferation of peremptory norms might suggest a larger potential for conflict. At the same time it may be noted that most of the peremptory norms suggested are grafted upon human rights norms and limited to prohibitions, and as such conflict between such norms is not all that likely. This may appear different when considering the peremptory prohibitions of the use of armed force or aggression on the one hand, and the human rights-oriented peremptory norms on the other hand.

One of the essential attributes of jus cogens norms is that they cannot be derogated from and this has led many to argue that they are at the pinnacle of all international law norms, that is, that they are hierarchically higher than ‘ordinary’ norms.117 The non-derogability of peremptory norms as the single distinguishing feature of jus cogens is widely interpreted as setting substantive limits on the freedom of states to conclude any treaty with whatever content.118 However, the legal consequence of a treaty being ‘void’ follows only, according to Articles 53 and 64 VCLT, when a treaty is ‘in conflict with’ a peremptory norm. This is one of the fault lines of the conflict between proponents and opponents of an enhanced role of jus cogens.119

The question of conflict has recently been addressed by the ICJ in the case between Germany and Italy on Jurisdictional Immunities of the State. Italy claimed that the rules on state immunity conflicted with jus cogens rules of international humanitarian law prohibiting murder of civilians in occupied territory and deportation of civilians and prisoners of war for the purposes of slave labour. The Court assumed, for the sake of argument, the jus cogens status of the rules concerned, but then bluntly stated that no conflict existed between the rules concerned and maintained:120

The rules of State immunity are procedural in character and are confined to determining whether or not the courts of one State may exercise jurisdiction in respect of another State. They (p. 1183) do not bear upon the question whether or not the conduct in respect of which the proceedings are brought was lawful or unlawful.

Following up on this, the Court noted that the same applied with respect to the duty to make reparation for breaches of (jus cogens) obligations, and denied, in light of a century of practice of peace treaties and settlements, that the duty to compensate war victims could be said to have been accepted as a rule from which no derogation was permitted.121

The Court’s judgment has been both criticized and supported, but raises the question how to determine whether a conflict exists between norms. In the fragmentation report, a study group of the ILC considered a conflict to be present if:122 ‘two norms that are both valid and applicable point to incompatible decisions so that a choice must be made between them.’ The common perspective of norm conflict is perhaps shown by Boudreault, who claims that modern legal theory shows two definitions:123

– two norms are ‘in a relationship of conflict if one constitutes, has led to, or may lead to, a breach of the other’.

– ‘There is a conflict between two norms, one of which may be permissive, if in obeying or applying one norm, the other one is necessarily or possibly violated’.

Be that as it may, the Court is correct in claiming that no conflict exists between the rules of state immunity and jus cogens norms. The reason for this is that peremptory norms are, invariably though perhaps not necessarily, based on prohibitive rules.124 Even the right of peoples to self-determination, already mentioned by the ILC in 1966 (though as a principle)125 and affirmed by the Court in 1995 as a right erga omnes,126 can be restated to prohibit colonial domination, alien occupation, or (p. 1184) racist rule in denial of self-determination,127 and one might argue that only in case of conflict with those prohibitions would one be able to assert conflict with the peremptory norm of self-determination. The customary rules of state immunity therefore do not violate peremptory prohibitions, since a state giving effect to such rules is not itself committing torture, or violations of international humanitarian law or human rights, etc.

It has been contended by Espósito that, nevertheless, a conflict does exist between the rules concerned. In making this claim, he points to the fact that the distinction between procedural and substantive rules is overly formalistic and that the two categories of rules do not constitute radically differentiated systems of rules.128 Upon further scrutiny, however, one may note that he makes this criticism because of the obstacle that procedural barriers pose to ‘the effective protection of human rights’ and that ‘peremptory norms impose procedural obligations on international law subjects to prevent their primacy and effectiveness from being undermined by barriers to action aimed at ending violations.’129

However, the Court has a different view about rules that pose obstacles to the enforcement of peremptory norms and claimed:130

To the extent that it is argued that no rule which is not of the status of jus cogens may be applied if to do so would hinder the enforcement of a jus cogens rule, even in the absence of a direct conflict, the Court sees no basis for such a proposition. A jus cogens rule is one from which no derogation is permitted but the rules which determine the scope and extent of jurisdiction and when that jurisdiction may be exercised do not derogate from those substantive rules which possess jus cogens status, nor is there anything inherent in the concept of jus cogens which would require their modification or would displace their application.

Hence, the existence of conflict must be established between a rule or its application and the peremptory norm concerned, but such a conflict does not exist when the conduct in question does not violate the peremptory prohibition. Thus, a conflict of norms will exist only if and when a rule would impose an obligation on a state to violate a peremptory prohibition or the right to do so.131

Applying this to the question of jus cogens demands for forcible action, it can be said that no such conflict exists. If a state were to consider, or resort to, armed force to enforce a peremptory norm, for instance the prohibition of genocide, the obstacle presented by the prohibition of the use of force does not create a conflict (p. 1185) because such a state may refrain from the use of armed force and comply with both prohibitions simultaneously. In other words, complying with the prohibition on the use of armed force does not constitute a violation of the (peremptory) prohibition of genocide.

Not resorting to armed force to stop (an ongoing) genocide might be considered as conflicting with a state’s obligation to prevent the commission of genocide,132 but two qualifications are in order. First, only the prohibition of genocide is considered to constitute a peremptory norm and not also the obligation to prevent genocide.133 Secondly, although the Court held that a state’s obligation to prevent genocide is not limited as such to territories under its jurisdiction or control,134 and that a state must use all means reasonably available to it,135 it also noted in respect of a state’s capacity to influence another state that136 ‘it is clear that every state may only act within the limits permitted by international law’.

Therefore a state wishing to intervene militarily to stop genocide would have to show, in the absence of a justification for the use of armed force laid down in the Genocide Convention and lacking authorization by the Security Council, that customary international law permits such action. Thus, even if one were to consider that the prohibition of the use of armed force is not a peremptory norm, but rather the prohibition of aggression, this will still not dispense a state from having to invoke a justification for its use of armed force under customary international law. And again the circle is squared: state practice and opinio juris are required, but provide insufficient evidence to arrive at such a conclusion.

Theoretically another conflict might exist: one between peremptory norms. Thus, Kolb appears to envisage that a contradiction may exist between the peremptory prohibition on the use of armed force and peremptory norms protecting the most elementary fundamental human rights.137 However, as with the norm conflict suggested between a peremptory norm and an ordinary norm, it is difficult to see what conflict may be considered to exist. A state resorting to armed force may perhaps be violating the peremptory prohibition of the use of force or of aggression, or neither, but in either (or all) case(s) the choice for that particular state is not which peremptory norm to choose to comply with. In essence, this is a false conflict since the obligations that flow from the peremptory norms address different subjects of law: on the one hand, the state resorting to armed force, and on the other hand, the state that is violating fundamental human rights.

(p. 1186) V.  Concluding Observations

This chapter has shown various difficulties related to the proposition that the prohibition of the use of force constitutes a peremptory norm, and other difficulties with the claim that the prohibition of aggression is such a norm. The main problem that arises comes from the necessity to accommodate (existing) exceptions to the prohibition, and none of the lines of argument bar the development of new rules of customary international law that may justify the use of armed force. Nevertheless, it seems likely that any new rule justifying the use of armed force, requiring state practice and opinio juris, will be hard to establish. The generally available circumstance precluding wrongfulness of necessity might have filled the gap, but the ILC has plugged this by stating that Article 25 of the Draft Articles on State Responsibility is not intended to cover the use of armed force.

Moreover, even if it is claimed that the prohibition of aggression constitutes jus cogens, controversy will persist where the use of armed force intentionally or perchance leads to loss of territory (Serbia and Kosovo) or regime change (Libya). After all, Article 2(4) of the Charter specifically protects a state’s territorial integrity and political independence. Therefore, though the peremptory prohibition of the use of force or of aggression does not per se bar the development of international law and hence provides less of a restriction than might be imagined, the onus will lie with states wishing to intervene to state their case and to respect those essential and paramount limitations.

When it comes to demands for forcible action, less again can be gleaned from the status of certain rules as jus cogens than one might find desirable. Thus, the hierarchically higher rank of peremptory norms cannot lead one to deductively construe legal effects or consequences to the violation of peremptory norms that are not otherwise established under international law. As such, it will be necessary to find a justification either under the Charter or customary international law for any use of armed force. Such a justification may be extant when acting in the exercise of a right of self-defence against an armed attack or pursuant to Security Council authorization. However, other potential justifications, such as humanitarian intervention, appear to stumble on the insufficiency of state practice and opinio juris.

Finally, invoking a conflict of norms to suggest priority for a peremptory norm will in most circumstances not provide any sustenance either. Recent case law of the ICJ has denied the existence of conflict of norms on various grounds. Moreover, any pretended conflict between peremptory norms, for example the prohibitions on the use of armed force and genocide, is false because the prohibitions impose obligations on different states and a state wishing to intervene militarily will not therefore have to choose between complying with either one or the other prohibition.

Footnotes:

Many thanks to Marcel Brus, Antenor Hallo de Wolf, Jörg Kammerhofer, Abel Knottnerus, and Andrej Zwitter for their detailed comments on an earlier draft, and Patricia Agoncillo for her research assistance. Responsibility is mine alone.

The 1969 Vienna Convention on the Law of Treaties, 1155 UNTS 331–53.

But see Carin Kahgan, ‘Jus Cogens and the Inherent Right to Self-Defense’ (1997) 3 ILSA Journal of International and Comparative Law 767; Ole Spiermann, ‘Humanitarian Intervention as a Necessity and the Threat or Use of Jus Cogens’ (2002) 71 Nordic Journal of International Law 523; Charles Leben, ‘Obligations relating to the Use of Force and Arising from Peremptory Norms of International Law’ in James Crawford, Alain Pellet, and Simon Olleson (eds), The Law of International Responsibility (Oxford: Oxford University Press, 2010), 1197; James Green, ‘Questioning the Peremptory Status of the Prohibition of the Use of Force’ (2011) 32 Michigan Journal of International Law 215; and Alexander Orakhelashvili, ‘Changing Jus Cogens through State Practice? The Case of the Prohibition of the Use of Force and its Exceptions’, Chapter 7 in this volume. Cf also Lauri Hannikainen, Peremptory Norms (Jus Cogens) in International Law, Historical Development, Criteria, Present Status (Helsinki: Finnish Lawyers’ Publishing Co, 1988), 323–56; and Olivier Corten, The Law against War: The Prohibition on the Use of Force in Contemporary International Law (Portland, OR: Hart, 2010), 198–213.

The 1945 Charter of the United Nations, United Nations Conference on International Organization, vol XV, 335–54.

eg Corten, The Law against War, 201–13; Alexander Orakhelashvili, Peremptory Norms in International Law (Oxford: Oxford University Press, 2006), 50–1.

With even the ICJ now recognizing its existence: Armed Activities on the Territory of the Congo (New Application: 2002) (DRC v. Rwanda), Jurisdiction and Admissibility, Judgment, ICJ Rep 2006, 6, 31–3, paras 64–70; Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v. Serbia and Montenegro), Judgment, ICJ Rep 2007, 43, 104–5 and 110–11, paras 146–8 and 161–2; Jurisdictional Immunities of the State (Germany v. Italy: Greece Intervening), Judgment, ICJ Rep 2012, 99, 140–2, paras 92–7. See also North Sea Continental Shelf, Judgment, ICJ Rep 1969, 3, 42; Barcelona Traction, Light and Power Company, Limited, Judgment, ICJ Rep 1970, 3, 32, paras 33–4; Case concerning Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. US), Merits, ICJ Rep 1986, 14, 100–1, para 190.

eg Kyoji Kawasaki, ‘A Brief Note on the Legal Effects of Jus Cogens in International Law’ (2006) 34 Hitotsubashi Journal of Law and Politics 27, 29. Contrary Malcom Shaw, International Law (6th edn, Cambridge: Cambridge University Press, 2008), 127; and Yoram Dinstein, War, Aggression and Self-Defence (5th edn, Cambridge: Cambridge University Press, 2012), 105, referring to (quasi-)universal treaties.

cf Władysław Czapliński, ‘Jus Cogens and the Law of Treaties’ in Christian Tomuschat and Jean-Marc Thouvenin (eds), The Fundamental Rules of the International Legal Order, Jus Cogens and Obligations Erga Omnes (Leiden: Martinus Nijhoff, 2006), 83, 89–90; Kawasaki, ‘A Brief Note’, 29–30; earlier André de Hoogh, Obligations Erga Omnes and International Crimes, A Theoretical Inquiry into the Implementation and the Enforcement of the International Responsibility of States (The Hague: Kluwer Law International, 1996), 45–6.

See Natalino Ronzitti, ‘Use of Force, Jus Cogens and State Consent’ in Antonio Cassese (ed), The Current Legal Regulation of the Use of Force (Dordrecht: Martinus Nijhoff, 1986), 147, 149; Andreas Paulus, ‘Jus Cogens in a Time of Hegemony and Fragmentation’ (2005) 74 Nordic Journal of International Law 297, 302; Kawasaki, ‘A Brief Note’, 30; Shaw, International Law, 126–7. For a different view, see Orakhelashvili, Peremptory Norms in International Law, 117–20; and Alexander Orakhelashvili, ‘Changing Jus Cogens through State Practice? The Case of the Prohibition of the Use of Force and its Exceptions’, Chapter 7 in this volume, Section III.

See Commentary Art 50 (renumbered 53), Yearbook of the International Law Commission, 1966, vol II, 247, 247–248, para 2, noting that a prohibition to derogate from a provision included in a treaty does not endow such a provision with jus cogens status.

10  Nicaragua, Merits, 98–102, paras 187–92 (also 92–7, paras 172–82).

11  Armed Activities on the Territory of the Congo (DRC v. Uganda), Judgment, ICJ Rep 2006, 168, 223–7, paras 148–65.

12  Commentary Art 50 (renumbered 53) (1966), 247, para 1.

13  eg Corten, The Law against War, 201–13; Orakhelashvili, Peremptory Norms in International Law, 50–1.

14  Green, ‘Questioning the Peremptory Status’, respectively at 225–9 (use vs threat of force), 229–36 (existing exceptions), and 236–41 (new exceptions or interpretations).

15  Green, ‘Questioning the Peremptory Status’, 245–52.

16  United Nations Conference on the Law of Treaties, 1st Sess (New York: United Nations, 1969), 471, para 4. Acceptance and recognition by the ‘international community as a whole’ has been explained to mean that a very large majority of all states ought to support the peremptory status of a norm (472, para 12). The ILC decided against including any examples, leaving this to state practice and international jurisprudence. Commentary Art 50 (renumbered 53) (1966), 248, para 3.

17  Corten, The Law against War, 201–13.

18  See Leben, ‘Obligations relating to the Use of Force’, 1202, making a distinction between simple peremptory norms, eg the prohibition on the use of force, and reinforced peremptory norms, eg the prohibition of torture: the first type allows for the same kind of act to be adopted as a sanction, whereas the second type prohibits the act in all circumstances.

19  Draft articles on responsibility of States for internationally wrongful acts, Yearbook of the International Law Commission, 2001, vol II (2), 26–30.

20  Commentary Art 49 (2001) in conjunction with Commentaries Arts 29–31 and 34–7, Yearbook of the International Law Commission, 2001, vol II (2), respectively 129–31, 88–94, 95–107.

21  Commentary Art 54, Yearbook of the International Law Commission, 2001, vol II (2), 137–9; also Commentary Art 22, Yearbook of the International Law Commission, 2001, vol II (2), 75–6, 76, para 6. Cf Jan Wouters and Sten Verhoeven, ‘The Prohibition of Genocide as a Norm of Ius Cogens and Its Implications for the Enforcement of the Law of Genocide’ (2005) 5 International Criminal Law Review 401, 413–15.

22  Commentary Art 22 (2001), 75–6, paras 1, 2, and 5; Commentary Art 54 (2001), 137–9, paras 3–4.

23  Commentary Art 50, Yearbook of the International Law Commission, 2001, vol II (2), 131–4.

24  Commentary Art 50 (2001), 132, paras 3–4.

25  Commentary Art 50 (2001), 132–3, para 9. Though the commentary seems to speak against this (ibid), the phrase ‘other obligations under peremptory norms’ in Art 50(1)(d) has been interpreted to mean that the obligations related to the threat or use of force, the protection of fundamental human rights, and provisions of a humanitarian character prohibiting reprisals also constitute peremptory norms. See Leben, ‘Obligations relating to the Use of Force’, 1198–9.

26  In other commentaries the Commission refers to the prohibition of aggression as a peremptory norm: see later in this section and Section III.D.

27  Commentary Art 20, Yearbook of the International Law Commission, 2001, vol II (2), 72–4.

28  Commentary Art 20 (2001), 73, para 7; Commentary Art 26, Yearbook of the International Law Commission, 2001, vol II (2), 84–5, 85, para 6; Ronzitti, ‘Use of Force’, 148.

29  Commentary Art 20 (2001), 72 and 73–4, paras 1 and 9; Armed Activities, Judgment, 198–9, para 52, 210–12, paras 98–105, 224, para 149 (more generally, 196–212, paras 42–105).

30  Commentary Art 20 (2001), 73–4, para 9; Commentary Art 26 (2001), 85, para 6; Paulus, ‘Jus Cogens in a Time’, 306–7; Kawasaki, ‘A Brief Note’, 37 fn 40.

31  James Crawford, ‘Second report on State responsibility’, Yearbook of the International Law Commission, 1999, vol II (1), 3, 63, para 240(b); Affef Ben Mansour, ‘Circumstances Precluding Wrongfulness in the ILC Articles on State Responsibility: Consent’ in Crawford, Pellet, and Olleson, The Law of International Responsibility, 439, 447, noting that the practice related to consent suggests that the prohibition of the use of armed force is not of peremptory character; and Spiermann, ‘Humanitarian Intervention as a Necessity’, 535. In Armed Activities, Judgment, 196–7, paras 45–7, the Court determined that consent by Congo had been given to certain activities of Uganda, but did not specifically examine the validity of that consent.

32  Nicaragua, Merits, 126, para 246.

33  Ronzitti, ‘Use of Force’, 153–63; Hannikainen, Peremptory Norms (Jus Cogens), 349–55. Ex post facto consent raises similar issues and relates to acquiescence or a valid waiver of claims and may entail the loss of the right to invoke responsibility. See Commentary Art 46, Yearbook of the International Law Commission, 2001, vol II (2), 123–4, para 4, where the ILC indicates that the validity of a waiver arises especially when the situation involves a serious breach of obligation under a peremptory norm.

34  Ademola Abass, ‘Consent Precluding International Responsibility: A Critical Analysis’ (2004) 53 International and Comparative Law Quarterly 211, 223–4. He does note that a consensual use of force could not be ‘directed towards aggressive purposes’ (at 224) and that not every obligation under Art 2(4) of the Charter is peremptory (at 225). Art 10 of the 1999 Protocol relating to the Mechanism for Conflict Prevention, Management, Resolution, Peace-Keeping and Security, available at <http://www.comm.ecowas.int/sec/index.php?id=ap101299&lang=en>; and Art 4(h) of the 2000 Constitutive Act of the Africa Union, 2158 UNTS 33.

35  In this sense, Corten, The Law against War, 254–5.

36  Commentary Art 33, Yearbook of the International Law Commission, 1980, vol II (2), 34–52.

37  Commentary Art 25, Yearbook of the International Law Commission, 2001, vol II (2), 80–4, 83, para 15.

38  Spiermann, ‘Humanitarian Intervention as a Necessity’, 527; Gelijn Molier, ‘Humanitarian Intervention and the Responsibility to Protect after 9/11’ (2006) 53 Netherlands International Law Review 37, 53–6.

39  Commentary Art 33 (1980), 43, para 22 (more broadly 42–5, paras 22–6).

40  Commentary Art 33 (1980), 43, para 22.

41  Commentary Art 33 (1980), 43, para 23. See the discussion in Spiermann, ‘Humanitarian Intervention as a Necessity’, 538–42.

42  Commentary Art 33 (1980), 44, para 23.

43  Commentary Art 33 (1980), 44, para 24.

44  Commentary Art 33 (1980), 45, para 24.

45  Commentary Art 26 (2001), 85, para 5; Commentary Art 40, Yearbook of the International Law Commission, 2001, vol II (2), 112–13, 112, para 4.

46  Commentary Art 25 (2001), 84, para 21 (relevant footnotes omitted).

47  cf Eric David, ‘Primary and Secondary Rules’ in Crawford, Pellet, and Olleson, The Law of International Responsibility, 27; and Herbert L. A. Hart, The Concept of Law (2nd edn, Oxford: Clarendon Press, 1994), 80–1 and 94, for a different perspective on the distinction between primary and secondary rules.

48  The same issue arises with respect to self-defence. For opposing positions: Spiermann, ‘Humanitarian Intervention as a Necessity’, 534; David, ‘Primary and Secondary Rules’, 29–33.

49  Contrary Spiermann, ‘Humanitarian Intervention as a Necessity’, 543; and Molier, ‘Humanitarian Intervention and the Responsibility to Protect’, 57.

50  See Gabčikovo Nagymaros Project (Hungary/Slovakia), Judgment, ICJ Rep 1997, 7, 40–1, paras 51–2.

51  See Molier, ‘Humanitarian Intervention and the Responsibility to Protect’, 55; and Sarah Heathcote, ‘Circumstances Precluding Wrongfulness in the ILC Articles on State Responsibility: Necessity’ in Crawford, Pellet, and Olleson, The Law of International Responsibility, 491, 498–9, both mentioning the examples of the Congo (1960) and Kosovo (1999). Corten, The Law against War, 225–47, has shown that states have generally not invoked circumstances precluding wrongfulness to justify the use of armed force in situations that might have called for this.

52  Commentary Art 50 (renumbered 53) (1966), 248, paras 2 and 4 (emphasis added).

53  Arguing along these lines, Robert Kolb, ‘Observation sur l’évolution du concept de jus cogens’ (2009) 113 Revue Générale de Droit International Public 837, 845 and 846–8; Shaw, International Law, 125, noting that jus cogens will bar the development of local or special custom; and Corten, The Law against War, 200–1.

54  Though Art 24(2) of the Charter does enjoin the Security Council to act in accordance with the purposes and principles of the Charter.

55  eg Erika de Wet, The Chapter VII Powers of the United Nations Security Council (Oxford/Portland, OR: Hart, 2004), 187–91; Orakhelashvili, Peremptory Norms in International Law, 413–29. See also Application of the Convention on the Prevention and Punishment of the Crime of Genocide, Provisional Measures, Order of 13 Sept 1993, ICJ Rep 1993, 325, Separate Opinion of Judge Lauterpacht, 440–1, paras 100–4, 442, para 106, and 447, para 123.

56  Note that authorizations of the Security Council to (member) states function as a justification, or circumstance precluding wrongfulness, to use armed force otherwise in violation of the prohibition of the use of force enshrined in Art 2(4) of the Charter and customary international law.

57  In this sense, Crawford, ‘Second Report’, 72, para 289, discussing necessity opined: ‘it seems enough to say that either modern State practice and opinio juris license humanitarian action in certain limited circumstances, or they do not. If they do, then such action would appear to be lawful in those circumstances, and cannot be considered as violating the peremptory norm reflected in article 2(4) of the Charter.’

58  Commentary Art 50 (renumbered 53) (1966), 248, para 4.

59  eg Green, ‘Questioning the Peremptory Status’, 229, referring to the right of self-defence and authorizations pursuant to the Security Council powers under Art 42 of the Charter, notes that: ‘the prohibition of the use of force is a rule from which derogation is explicitly and uncontrovertibly permitted.’

60  Orakhelashvili, Peremptory Norms in International Law, 51.

61  Kahgan, ‘Jus Cogens and the Inherent Right’, 783–9. Crawford, ‘Second Report’, 72, para 288, ranked not only Art 2(4) of the Charter as a peremptory norm but also Art 51. This position is possibly predicated upon the view that the exercise of self-defence cannot be seen as a breach of Art 2(4) (at 74, para 298). See the critique of Jörg Kammerhofer, Uncertainty in International Law: A Kelsenian Perspective (London/New York: Routledge, 2011), 49–51.

62  Commentary Art 34, Yearbook of the International Law Commission, 1980, vol II (2), 52–61, 58, para 18. De Wet, The Chapter VII Powers, 191; and, critically, Green, ‘Questioning the Peremptory Status’, 231–2.

63  Green, ‘Questioning the Peremptory Status’, 230–1, pointing to the example of the reporting requirement in Art 51 of the Charter and the Court’s treatment thereof. Cf Nicaragua, Merits, 105, para 200.

64  Green, ‘Questioning the Peremptory Status’, 232–4.

65  Overall of historical interest as regards protectorates, see Mirja Trilsch, ‘Protectorates and Protected States’ in Rüdiger Wolfrum (ed), Max Planck Encyclopedia of Public International Law (Oxford: Oxford University Press, 2008), available at <http://www.mpepil>.

66  Commentary Art 33 (1980), 43, para 22 (more broadly 42–5, paras 22–6).

67  See further Section III.A.

68  Commentary Art 26 (2001), 85, para 5; Commentary Art 40 (2001), 112, para 4.

69  GA Res 3314 (XXIX), Annex, adopted 14 Dec 1974, available at <http://www.un.org/Depts/dhl/resguide/r29.htm>.

70  In a similar vein, Art 8bis (crime of aggression) of the Rome Statute, adopted by the Review Conference in 2010, refers to the character, gravity, and scale of an act of aggression. ICC, Review Conference, Res RC/Res.6, Annex I, available at <http://www.icc-cpi.int/iccdocs/asp_docs/Resolutions/RC-Res.6-ENG.pdf>. See also Annex III, paras 6–7. See also Sean D. Murphy, ‘The Crime of Aggression at the International Criminal Court’, Chapter 24 in this volume.

71  Bernard V. A. Röling, ‘The 1974 U.N. Definition of Aggression’ in Cassese, The Current Legal Regulation, 413, 416 and 419.

72  cf Paulus, ‘Jus Cogens in a Time’, 306–7, noting that attempts to distinguish aggression from illegal uses of force have not been successful (fn 29).

73  Supported by Art 5(1) of the Definition of Aggression, stipulating that political, economic, military, or any other kind of considerations may not serve as a justification for aggression. But note that Art 6 preserves the provisions of the Charter envisaging a lawful use of force.

74  Hannikainen, Peremptory Norms (Jus Cogens), 323–56; Dinstein, War, Aggression and Self-Defence, 105–7, discussing the example of a ‘pact of aggression’; Molier, ‘Humanitarian Intervention and the Responsibility to Protect’, 54–5; and, implicitly, Ronzitti, ‘Use of Force’, 150 and 153–4, 158–60.

75  Note the discussion between Paulus and Kreß on whether the crime of aggression has been properly defined and the difficulties as to the assessment of the character, gravity, and scale of an act of aggression: Andreas Paulus, ‘Second Thoughts on the Crime of Aggression’ (2010) 20 Leiden Journal of International Law 1117, 1119–24, and Claus Kreß, ‘Time for Decision: Some Thoughts on the Immediate Future of the Crime of Aggression, A Reply to Andreas Paulus’ (2010) 20 Leiden Journal of International Law 1129, 1137–42.

76  Hannikainen, Peremptory Norms (Jus Cogens), 336–7 (broader 323–56).

77  In a somewhat different sense, one could say that the state should lack the animus aggressionis. See Dinstein, War, Aggression and Self-Defence, 146, on individual responsibility for the crime of aggression.

78  Kreß, ‘Time for Decision’, 1139–40, discussing proposals to limit the crime of aggression to force used for the purpose of annexation or subjugation of a victim state, coercing a state to change government or its political regime, or to attack its military, political, and economic system. See also de Hoogh, Obligations Erga Omnes, 181–2, 193–4, 336; Ronzitti, ‘Use of Force’, 149–52; and Kahgan, ‘Jus Cogens and the Inherent Right’, 777–81.

79  Commentary Art 40 (2001), 112.

80  Commentary Art 40 (2001), 113, para 8.

81  Commentary Art 40 (2001), 113, para 8.

82  Commentary Art 40 (2001), 113, para 8.

83  Commentary Art 41, Yearbook of the International Law Commission, 2001, vol II (2), 113–16. It may be noted that these concern obligations for other states rather than the author state of the serious breach and this to a large extent, as the Commission acknowledges, appears to be a matter of progressive development (at 114, para 3). See also Paulus, ‘Jus Cogens in a Time’, 315–16.

84  The ICJ recently held, referring to Art 41 of the Draft Articles on State Responsibility, that giving effect to the immunity of a state under customary international law does not imply recognition of, or aid and assistance in maintaining, a situation brought about by a serious breach of obligation under a peremptory norm. Jurisdictional Immunities, Judgment, 140, para 93.

85  Commentary Art 41 (2001), 114, para 2.

86  Commentary Art 41 (2001), 114, para 3.

87  As noted in Section III.A, lawful measures in Art 54 appear to relate exclusively to economic or other measures and not to the use of armed force.

88  See also Art 71 VCLT for the consequences of the invalidity due to conflict with a peremptory norm.

89  Commentary Art 42, Yearbook of the International Law Commission, 2001, vol II (2), 117–19; Commentary Art 48 (2001), 126–8.

90  International Criminal Tribunal for the former Yugoslavia, Trial Chamber, Prosecutor v. Anton Furundžija, Judgment of 10 Dec 1998, para 153 (see also para 144), available at <http://www.icty.org/x/cases/furundzija/tjug/en/fur-tj981210e.pdf>.

91  Furundžija, Judgment, para 153.

92  Furundžija, Judgment, paras 154–5.

93  Furundžija, Judgment, paras 156–7.

94  cf Crawford, ‘Second Report’, 76–8, paras 308–15, and 87, para 358 (Art 29bis).

95  Yearbook of the International Law Commission, 1999, vol II (2), 75–7, paras 306–18.

96  Yearbook of the International Law Commission, 2000, vol II (2), 67 (Art 21 on compliance with a peremptory norm). See Maja Ménard, ‘Circumstances Precluding Wrongfulness in the ILC Articles on State Responsibility: Compliance with Peremptory Norms’ in Crawford, Pellet, and Olleson, The Law of International Responsibility, 449–53.

97  cf generally Orakhelashvili, Peremptory Norms in International Law, 320, and Carlos Espósito, ‘Jus Cogens and Jurisdictional Immunities of States at the International Court of Justice: “A Conflict Does Exist”’ (2012) XXI Italian Yearbook of International Law 2011 161, favouring the setting aside of state immunity for conflict with jus cogens. Otherwise Andrea Gattini, ‘The Dispute on Jurisdictional Immunities of the State before the ICJ: Is the Time Ripe for a Change of the Law?’ (2011) 24 Leiden Journal of International Law 173, and Stefan Talmon, ‘Jus Cogens after Germany v. Italy: Substantive and Procedural Rules Distinguished’ (2012) 25 Leiden Journal of International Law 979–1002, rejecting such a position.

98  ECtHR, Al-Adsani v. UK (App no 35763/97), Judgment of 21 Nov 2001, paras 60–7.

99  Al-Adsani, para 66.

100  Al-Adsani, Joined Dissenting Opinion of Judges Rozakis and Caflisch joined by Judges Wildhaber, Costa, Cabral Barreto, and Vajić, para 3 (broader paras 1–4), and also Dissenting Opinions of Judges Ferrari Bravo and Loucaides.

101  Armed Activities (New Application: 2002), Jurisdiction and Admissibility, 29–33, paras 56–70.

102  Armed Activities (New Application: 2002), Jurisdiction and Admissibility, respectively 32, para 64, 33 and 35, paras 69 and 78.

103  Armed Activities (New Application: 2002), Jurisdiction and Admissibility, 51–2, para 125.

104  Armed Activities (New Application: 2002), Jurisdiction and Admissibility, 52, para 125.

105  Genocide, Judgment, 104–5, paras 146–8 (see also 110–11, paras 161–2).

106  Carlo Focarelli, ‘Promotional Jus Cogens: A Critical Appraisal of Jus Cogens’ Legal Effects’ (2008) 77 Nordic Journal of International Law 429, 444–8.

107  Focarelli, ‘Promotional Jus Cogens’, 449, emphasizing that this will obviate the need to rely on the jus cogens nature of norms as the same effect will then follow based on existing international law (also 450–5). In support of this argument, see Kolb, ‘Observation sur l’évolution’, 840–1.

108  Contrary to Focarelli, ‘Promotional Jus Cogens’, 449–59, this aspect does not necessarily entail the uselessness of jus cogens or limit it to a promotional role, since some of the legal effects identified may be limited to peremptory norms; however, if international law embodies a certain rule independently from jus cogens, this may restrict the utility of the concept.

109  See Nicaragua, Merits, 102–6, paras 193–201.

110  Anthony C. Arend and Robert J. Beck, International Law & the Use of Force: Beyond the UN Charter Paradigm (London/New York: Routledge, 1993), 128–37 (discussion of practice, 114–28); Gelijn Molier, De (on)rechtmatigheid van humanitaire interventie, Respect voor staatssoevereiniteit versus bescherming van mensenrechten (Groningen: Boom Juridische Uitgevers, 2003), 217–324, esp 272–3 and 323–4 for conclusions concerning state practice and opinio juris; Corten, The Law against War, 526–49. Contrary Fernando Téson, Humanitarian Intervention: An Inquiry into Law and Morality (3rd edn, Ardsley, NY: Transnational, 2005), 219–78 and 373–413. See also Sir Nigel Rodley, ‘Humanitarian Intervention’, Chapter 35 in this volume.

111  International Commission on State Sovereignty and Intervention, Responsibility to Protect, Dec 2001, esp 31–7, available at <http://responsibilitytoprotect.org/ICISS%20Report.pdf>.

112  GA Res 60/1, 2005 World Summit Outcome, adopted 24 Oct 2005, paras 138–9, available at <http://www.un.org/depts/dhl/resguide/r60.htm>.

113  GA Res 60/1, para 79.

114  SC Res 1970, S/RES/1970, adopted 26 Feb 2011, Preamble, para 9; 1973, S/RES/1973, adopted 17 Mar 2011, para 4, both available at <http://www.un.org/en/sc/documents/resolutions/2011.shtml>.

115  Constantine Antonopoulos, ‘The “Legitimacy” to “Legitimise”: The Security Council Action under Resolution 1973 (2011)’ (2012) 14 International Community Law Review 359, 371, 375–7.

116  GA Res 2625 (XXV), adopted 24 Oct 1970, Annex, Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations, principle of non-intervention, available at <http://www.un.org/Depts/dhl/resguide/r25.htm>.

117  eg Orakhelashvili, Peremptory Norms in International Law, 7–11.

118  Michael Glennon, ‘De l’absurdité du droit impératif (Jus cogens)’ (2006) 110 Revue Générale de Droit International Public 529, 531.

119  Antonio Cassese, ‘For an Enhanced Role of Jus Cogens’ in Antonio Cassese (ed), Realizing Utopia: The Future of International Law (Oxford: Oxford University Press, 2012), 158–71, though he does not address the question of ‘conflict’. He does claim, among others, various legal effects of jus cogens rules (160–2), the need to submit disputes over, and the determination of, jus cogens rules to courts or the ICJ (163–4 and 168–70), and arguing for implementation and integration of jus cogens into domestic legal orders at the constitutional level (167–8).

120  Jurisdictional Immunities, Judgment, 140, para 93 (see also 140–1, para 94).

121  Jurisdictional Immunities, Judgment, 140–1, para 94.

122  ILC, Conclusions of the Study Group on the Fragmentation of International Law: Difficulties arising from the Diversification and Expansion of International Law, in Report of the International Law Commission 2006, A/61/10, 407, 409, point 2, available at <http://untreaty.un.org/ilc/reports/2006/2006report.htm>. See also Report of the Study Group, finalized by Martti Koskenniemi, ‘Fragmentation of International Law: Difficulties arising from the Diversification and Expansion of International Law’, ILC, A/CN.4/L.682 (13 Apr 2006), 17–20, paras 21–6, available at <http://untreaty.un.org/ilc/sessions/58/58docs.htm>.

123  François Boudreault, ‘Identifying Conflicts of Norms: The ICJ Approach in the Case of the Jurisdictional Immunities of the State (Germany v. Italy: Greece Intervening)’ (2012) 25 Leiden Journal of International Law 1003, 1010 (footnotes omitted). See generally Joost Pauwelyn, Conflict of Norms in Public International Law: How WTO Law Relates to Other Rules of International Law (Cambridge: Cambridge University Press, 2003), 164–88; Kammerhofer, Uncertainty in International Law, 141–6; and Robert Kolb, ‘Conflits entre normes de jus cogens’ in Droit du pouvoir, pouvoir du droit: mélanges offerts à Jean Salmon (Brussels: Bruylant, 2007), 481, 483.

124  Earlier de Hoogh, Obligations Erga Omnes, 45, 49, 68.

125  Commentary Art 50 (renumbered 53) (1966), 248, para 3.

126  East Timor (Portugal v. Australia), Judgment, ICJ Rep 1995, 90, 102, para 29. Critical André de Hoogh, ‘Australia and East Timor, Rights Erga Omnes, Complicity and Non-Recognition’ (1999) Australian International Law Journal 63, 70–5.

127  See Art 1(4) of the Protocol Additional to the Geneva Conventions of 12 Aug 1977, and relating to the victims of international armed conflicts (Protocol I), 1125 UNTS 4.

128  Espósito, ‘Jus Cogens and Jurisdictional Immunities’, 170–1.

129  Espósito, ‘Jus Cogens and Jurisdictional Immunities’, 170, 171 (and also 172–4). He adds, under reference to Art 41 of the Draft on State Responsibility, that such procedural limitations may be understood as assisting in the impunity of violations of peremptory law (at 171–2).

130  Jurisdictional Immunities, Judgment, 141, para 95 (also para 141–2, 96).

131  Earlier de Hoogh, Obligations Erga Omnes, 45–6.

132  Art 1 of the 1948 Convention on the Prevention and Punishment of the Crime of Genocide, 78 UNTS 277.

133  Genocide, Judgment, 104–5 and 110–11, paras 146–8 and 161–2, and Wouters and Verhoeven, ‘The Prohibition of Genocide’, 403–6, neither addressing the status of the obligation to prevent genocide as such.

134  Genocide, Judgment, 130, paras 183–4 (see also 107, para 154).

135  Genocide, Judgment, 221, para 430.

136  Genocide, Judgment, 221, para 430.

137  Kolb, ‘Conflits entre normes de jus cogens’, 495–8.