I. Introduction
The present contribution is a reply to an article by Professor Michael Mandel, entitled ‘Aggressors’ Rights: The Doctrine of “Equality between Belligerents” and the Legacy of Nuremberg’, published in an earlier number of this journal.Footnote 1 In his article, Professor Mandel makes a case against the separation between, on the one hand, the rules regulating resort to force by states in their international relations (jus ad bellum or jus contra bellum)Footnote 2 and, on the other hand, the rules regulating the relations between belligerent parties in an armed conflict (jus in bello, law of armed conflict or international humanitarian law (IHL)).Footnote 3 He pleads, more specifically, against the principle of equality between belligerents. This principle stands for the equal application of jus in bello to all belligerent parties of an international armed conflict irrespective of who violated jus ad bellum in the first place.Footnote 4 Mandel's point of departure is essentially an international criminal-law one and his main issue is with the impunity for the crime of aggression or ‘crime against peace’.Footnote 5 The author views the equality of belligerents as an element favouring, or at least contributing to, this impunity. From this perspective, he goes on to challenge the existence of the equality of belligerents principle. It should be noted in this respect that the scope of Mandel's thesis is not entirely clear. Despite the fact that he appears to be mostly concerned with aggressor's rights,Footnote 6 the author seems to challenge the equality of belligerents principle in general, as the wording of some of his affirmations in relation to the ‘equality of belligerents’ principle suggests.Footnote 7 In any case, the challenge seems to extend not only to the rights of the aggressor but also to the rights of the victim of aggression, something that Mandel explicitly asserts in his article.Footnote 8 In what appears to be the central part of his thesis, Mandel argues that ‘contrary to the conventional wisdom, the notion of legal equality between belligerents is not supported by the jurisprudence of the Nuremberg era, or developments since, or the arguments usually made for it’.Footnote 9 As indicated in the above-quoted passage, Mandel raises three points for rejecting the equality of belligerents principle. The main one concerns the Nuremberg-era jurisprudence (including the Nuremberg and Far East international military tribunals and the national military tribunals created by the Order No. 10 of the Council). Several Nuremberg-era judgments are referred to and analysed throughout the commented article.Footnote 10 The second point relates to post-Nuremberg developments.Footnote 11 In this regard, Mandel refers to the four Geneva Conventions on the protection of wounded, sick, shipwrecked, prisoners of war and civilians in times of armed conflict, adopted in 1949,Footnote 12 as well as to the first additional protocol to these conventions, adopted in 1977.Footnote 13 In Mandel's view, these international treaties ‘pose no obstacles’Footnote 14 to treating belligerents having violated jus ad bellum differently than those that respect it. In connection to this claim, the International Court of Justice's (ICJ) Nuclear Weapons advisory opinionFootnote 15 is cited as proof against the validity of the equality of belligerents principle.Footnote 16 Finally, the third point deals with doctrinal policy arguments invoked in favour of the practical usefulness of the equality of belligerents principle,Footnote 17 all rejected by Mandel as unconvincing.Footnote 18
This article will demonstrate that, contrary to what is suggested by Mandel, the equality of belligerents is a principle that rests on solid legal ground. It should be noted from the outset that Mandel's analysis focuses too much on the Nuremberg-era jurisprudence and completely ignores, or, at best, downplays, the conventional and state-practice developments since 1945. However, as will be shown, these developments leave no doubt about the existence and legal force of the equality of belligerents principle in international law. Thus Mandel's main argument according to which the jurisprudence related to the Second World War has not consistently applied the equality of belligerents principle is simply not decisive in this respect. It is incapable of trumping the legal nature of the principle in question. In view of the above, this article will demonstrate the legal force of the equality of belligerents principle (section 2). We will then turn to international jurisprudence in order to evaluate to what extent it reflects the principle (section 3). On the basis of these sources, some basic elements of the scope and content of the principle will be examined (section 4). In conclusion, we will discuss some of the policy arguments raised by Mandel (section 5).
2. The ‘equality of belligerents’: a legal principle solidly anchored in conventional and customary international law
Contrary to the arguments advanced by Mandel, it will be shown that there is more than sufficient evidence confirming the legal force of the equality of belligerents principle. This section will examine in turn the conventional (2.1) and customary (2.2) sources of the principle.
2.1. The equality of belligerents principle in conventional international law
This subsection will show that both the 1949 Geneva Conventions (2.1.1) and the 1977 first additional protocol (2.1.2) contain clauses prohibiting a differential application of IHL rules on the basis of jus ad bellum. As such, they both constitute conventional sources of the equal application of IHL to all belligerent parties.
2.1.1. The 1949 Geneva Conventions
Articles 1 and 2 common to the four 1949 Geneva Conventions uphold the equal application of the Conventions’ rules to all belligerent parties, without any adverse distinction flowing from jus ad bellum violations. Indeed, common Article 1 stipulates that states parties ‘undertake to respect and ensure respect for the present Convention in all circumstances’ and common Article 2 states that the Conventions ‘apply to all cases of declared war or of any other armed conflict’ as well as to ‘all cases of partial or total occupation of the territory of a High Contracting Party’.Footnote 19 These formulations are certainly open enough to offer textual grounding to the equality of belligerents principle. This is confirmed by the International Committee of the Red Cross (ICRC) commentaries to the Geneva Conventions (known also as the ‘Pictet commentaries’).Footnote 20
This view finds support in the travaux préparatoires of the Conventions. Denmark had proposed to include the civilians ‘who participate in the defence of their country against illegal aggression or occupation’ to the list of persons entitled to prisoner-of-war status.Footnote 21 The UK delegation reacted, insisting on the principle of equal application of IHL rules even in case of illegal wars.Footnote 22 No delegation opposed these remarks and the Danish proposal was not included in the relevant article. Moreover, the Danish delegation itself espoused the separation between jus ad bellum and jus in bello and the principle of equal application of jus in bello to all belligerents.Footnote 23
Aside from the Geneva Conventions’ travaux, and perhaps most importantly, several states themselves regard common Articles 1 and 2 as conventional sources of the equality of belligerents principle. In their written statements to the ICJ in the context of the Wall advisory proceedings, Indonesia and Jordan invoked these two articles as sources of the application of the GC IV to all occupations, be they a jus ad bellum violation or not.Footnote 24 Belgium has taken a similar view, in the context of the ‘war against terrorism’,Footnote 25 a view the US Department of Defense also seems to share. Indeed, during the invasion of Iraq by the US-led coalition in 2003, at a press briefing, the Department's experts asserted that
the law of war, all of it, has taken the traditional view that it doesn't make any difference who started the war. . . . The four 1949 Geneva Conventions specifically state in there that it doesn't make any difference who started the war, who is the party who was first off or what have you; that in any case, the conventions will apply. That's to sort of keep people from saying, ‘Well, he started it, and therefore, I don't have to follow the law of war.’ Regardless of who started the conflict, each side has an obligation to follow the law of war.Footnote 26
The use of the term ‘specifically state’ clearly indicates that the equal application of IHL is grounded on the text of the Geneva Conventions. Common Articles 1 and 2 are the obvious reference alluded to by the experts.
There is therefore sufficient evidence that, contrary to Mandel's position,Footnote 27 the Geneva Conventions do not allow for a differentiated application of IHL rules between belligerent parties.
2.1.2. The 1977 first additional protocol
The First Additional Protocol to the Geneva Conventions (AP I or Protocol) in the fifth paragraph of its Preamble ‘reaffirms’ that
the provisions of the Geneva Conventions of 12 August 1949 and of this Protocol must be fully applied in all circumstances to all persons who are protected by those instruments, without any adverse distinction based on the nature or origin of the armed conflict or on the causes espoused by or attributed to the Parties to the conflict.Footnote 28
Despite this straightforward reaffirmation of the equality of belligerents principle, Mandel refuses to seriously consider AP I as a conventional basis of the principle. In respect to the Protocol, and in a rather cursory manner, Mandel advances two arguments. First, he notes that the Protocol has not been ratified as widely as the Geneva Conventions have been. Second, he suggests that the paragraph cited above ‘tries to separate’ jus ad bellum from jus in bello only with respect to protected persons, defined by Mandel as follows:
‘Protected persons’ are defined as ‘those who . . . find themselves, in case of a conflict or occupation, in the hands of a Party to the conflict or Occupying Power’ – in other words, the occupied, not the occupiers, or, if it were to be stretched in any direction at all, those targeted for killing, not the targeters.Footnote 29
Both arguments are unconvincing. First of all, as far as the ratification argument is concerned, the travaux préparatoires of AP I confirm that, despite positions to the contrary expressed by the Democratic Republic of Vietnam and Romania,Footnote 30 the principle stated in the fifth preambular paragraph of the Protocol was ultimately accepted by all states participating in the negotiations.Footnote 31 This includes states that have decided not to ratify the Protocol, like Israel, the United States, India, and Indonesia.Footnote 32 This decision may reflect these states’ objection to other provisions of the Protocol,Footnote 33 but cannot, in any case, be interpreted as a rejection of the principle enshrined in the Protocol's preamble. For example, India, who has not ratified the AP I, recognized the legally binding force of the equality of belligerents principle, by explicitly referring to the fifth preambular paragraph of the Protocol:
The legality of war does not release the participants from the application of the rules regulating the conduct of armed conflicts. An aggressor violating the law of the Charter has to comply with limitations on the weapons used. Similar restraint has to be exercised by those fighting in self-defence. The application of rules of law of armed conflicts does not depend on the legality of the defended causes; both aggressor or victim are equally subject to the laws of war – a principle reflected in the fifth preambular paragraph of Protocol I.Footnote 34
Turning to the argument relating to the scope ratione personae of the fifth preambular paragraph of AP I, Mandel reads the terms ‘persons who are protected by those instruments’ mentioned in this paragraph as being basically limited to ‘protected persons’ in the sense of Article 4(1) of the Fourth Geneva Convention (GC IV). His definition of the term ‘protected persons’ is based on this article.Footnote 35 At most, he accepts that the ratione personae scope of the paragraph covers ‘those targeted for killing’ but not the ‘targeters’.Footnote 36
Such limitations to the personal scope of application of the equality of belligerents principle are inconsistent both with the text of the Protocol's preamble and with the states’ interpretation of the principle. First, equating the scope of the fifth preambular paragraph to that of GC IV is in clear contradiction with the letter of the paragraph itself. Indeed, the paragraph refers to persons protected by ‘those instruments’. The wording of the fifth paragraph of the AP I preamble clearly shows that ‘these instruments’ are all four 1949 Geneva Conventions as well as AP I.Footnote 37 This means that the equality of belligerents principle cannot be interpreted as referring only to the ‘occupied’, as Mandel suggests. The principle's scope of application ratione personae is as diverse as the relevant scope of application of the four Geneva Conventions and the Protocol itself. Thus, this scope of application covers, among others, the wounded, sick, and shipwrecked members of the armed forces of belligerent states;Footnote 38 prisoners of war;Footnote 39 and civilians who find themselves in the hands of a party to the conflict who is not an occupying power,Footnote 40 as well as civilians in general – that is civilians not necessarily finding themselves in the hands of a party to the conflict, as far as the application of articles listed in Part IV of AP I are concerned.Footnote 41 Thus, Mandel's distinction between the ‘occupied’ and the ‘occupier’ as far as the application of the ‘equality of belligerents’ principle is concerned is untenable. The fallacy of such a distinction is revealed by the following example. Mandel argues that in case of a state reacting to an aggressive occupation, the targeting of the occupier's civilians by the occupied state victim of aggression would not be covered by the equality of belligerents principle, since these civilians do not constitute protected persons under the preamble of AP I.Footnote 42 This position runs counter to the scope of AP I. Attacks against civilians are prohibited by Article 51 of the Protocol.Footnote 43 For the purposes of applying Article 51, a civilian is defined in Article 50 as ‘any person’ not belonging to the categories listed in Article 4(A)(1), (2), (3), and (6) of GC IV and in Article 43 of AP I.Footnote 44 Therefore, the text of AP I itself indicates that, contrary to Mandel's suggestion, all civilians are protected by Article 51 of AP I, including the nationals of an occupying power.Footnote 45 This is nothing more than the logical consequence of the normal application of IHL rules relating to the conduct of hostilities. Indeed, in situations where the civilians of the occupying power are targeted by the occupied state, all that matters is that the targeted individuals are civilians and, as such, should not be the object of an attack. The fact that these civilians are nationals of an occupying power, responsible for an occupation illegal under jus ad bellum or not, is irrelevant for the application of the principle of distinction laid down in Article 51 of AP I. Thus, the text of AP I leads to the conclusion that all civilians are covered by the equality of belligerents principle. Consequently, again contrary to Mandel's suggestion, the targeting of civilians of an aggressive occupying power by the occupied state is a violation of jus in bello, even if it meets ‘the criteria of self-defence’ and even if it is ‘the only means of ousting a militarily superior occupier immune to conventional warfare’.Footnote 46
Second, the persons ‘protected by those instruments’ to which the fifth preambular paragraph of AP I refers cannot, as Mandel suggests, be limited to ‘those targeted for killing’ and exclude the ‘targeters’.Footnote 47 First of all, the personal scopes of application of both GC IV and AP I explicitly include both the population of the ‘occupier’ and the ‘targeter’ in general.Footnote 48 Indeed, Article 13 of GC IV stipulates that the provisions of Part II of the Convention ‘cover the whole of the populations of the countries in conflict, without any adverse distinction based, in particular, on race, nationality, religion or political opinion’.Footnote 49 The same applies to persons covered by the provisions of Part II of AP I pursuant to Article 9 of the Protocol.Footnote 50 Moreover, some of the most important articles of the Protocol stipulate obligations addressed precisely to the ‘targeters’ (such as the obligation not to direct attacks against civilians, civilian objects, cultural objects, objects indispensable to the survival of the civilian population, or installations containing dangerous forces, as well as the obligation to take precautionary measures in attack).Footnote 51 Distinguishing ‘those targeted for the killing’ from the ‘targeters’ is illusory because the provisions concerning the ‘targeters’ are an indispensable element of the protection accorded to the ‘targeted’; they constitute the corollary of this protection.Footnote 52 This is also confirmed by the travaux préparatoires of the Protocol. Indeed, at no point was it suggested that the separation between jus ad bellum and jus in bello applied only to the victims of the targeting and not to the ‘targeters’.
Therefore, contrary to what is proposed by Mandel, and in conformity with the object and purpose of the separation itself, states have not introduced any limitations as to the personal scope of application of the principle expressed in the fifth preambular paragraph of AP I. This is also evident from state practice supporting the principle's customary character.
2.2. The equality of belligerents principle in customary international law
Apart from its conventional sources, the equality of belligerents principle is firmly established in customary international law. This is supported both by general statements of states and by state practice in relation to particular conflicts.
As far as general statements are concerned, states have repeatedly asserted that IHL applies in the same way both to the aggressor and to the victim of aggression. A number of military manuals state this principle in general terms, leaving no room for limitations or exceptions (of a ratione personae character or otherwise). For example, the UK Manual of the Law of Armed Conflict states,
One of the most important characteristics of the law of armed conflict is its universal application. It applies with equal force to all parties engaged in an armed conflict, whether or not any party is considered to be ‘an aggressor’ or ‘a victim of aggression’.Footnote 53
This position is confirmed by statements adopted by states in other circumstances, such as in the context of advisory proceedings before the ICJ.Footnote 54
Most importantly, the equality of belligerents principle is confirmed through state practice in the context of specific armed conflicts. Indeed, authors who have examined the jus ad bellum/jus in bello separation cite only one precedent where a state involved in an international armed conflict made an explicit link between the two legal regimes. This precedent is the Vietnam War and the position referred to is the one adopted by the Democratic Republic of Vietnam, who refused to recognize captured American soldiers as prisoners of war, qualifying them as criminals due to their participation in the war of aggression launched by the US against the Democratic Republic of Vietnam.Footnote 55 However, the precedent does not undermine the legal status of the equality of belligerents principle for two main reasons. Primo, Vietnam has ratified AP I, thus accepting the principle expressed in its preamble.Footnote 56Secundo, the Vietnamese position has been modified by subsequent practice: Vietnam recognized the prisoner-of-war status of captured enemy soldiers despite accusations of aggression against the soldiers’ state of nationality.Footnote 57
Apart from this isolated incident, states have recognized, explicitly or implicitly, the equal application of IHL rules to all parties to an armed conflict irrespective of which party is in breach of jus ad bellum. As one would expect, incidents of explicit recognition are rare. An example of such recognition is the position expressed by Cameroon in its memorial deposited to the ICJ in relation to a territorial dispute with Nigeria:
Même s'il est reconnu que l'occupation militaire en violation du droit international est en soi illégale et que l'utilisation de la force en soi ne peut générer de droits, de telles situations, quand elles se présentent, ne sont pas totalement ignorées du droit international. Tout au contraire, un ensemble de règles juridiques a été élaboré précisément afin de venir en aide aux victimes de conflits armés. . . . Comme le Tribunal militaire des Etats-Unis l'a souligné dans In re List (Jugement des Otages), ‘international law makes no distinction between a lawful and an unlawful occupant in dealing with the respective duties of occupant an population [sic] in occupied territory’ . . ., puisque l'objectif est la protection des civils.Footnote 58
Cameroon not only recognizes the equal application of IHL to all occupations, irrespective of their legal or illegal nature from a jus ad bellum point of view, but it does so by referring explicitly to the Hostages judgment, thus reaffirming the relevance of the US military tribunal case law in this respect.Footnote 59
Turning to less explicit precedents, a survey of recent international armed conflicts confirms that, despite the arguments states advance in order to justify their military interventions under jus ad bellum, they recognize that they are bound by jus in bello. Indeed, states do not argue that the legality of their actions under jus ad bellum absolves them from their obligation to respect IHL.Footnote 60 An example can be found in the US position in relation to the 1983 military intervention in Grenada.Footnote 61 The US defended the legality of their actions under jus ad bellum and recognized the applicability of the four Geneva Conventions in the hostilities resulting from the intervention.Footnote 62 Significantly, in a memorandum explaining the US position on IHL application in this conflict, the Judge Advocate General affirms that mere de facto hostilities suffice to trigger the application of the Geneva Conventions and that arguments relating to self-defence do not alter that conclusion.Footnote 63 In the same vein, in relation to the 2008 hostilities with Georgia, the Russian Federation affirmed that ‘because an armed conflict existed between the Russian Federation and Georgia . . ., both parties were bound by humanitarian law provisions governing such situations and conflicts’,Footnote 64 making no allegation that the legality of the Russian resort to force would alter the scope of these provisions.
Even in relation to the 2001 intervention in Afghanistan and the 2003 intervention in Iraq, which are usually viewed as being problematic in this respect, states have not explicitly argued that the legality of the operation under jus ad bellum created exceptions in IHL application. Concerning the 2001 intervention in Afghanistan, the ICRC affirmed that it had received assurances from all parties to the conflict that IHL rules applicable in international armed conflicts would be respected.Footnote 65 In the same vein, the US White House Fact Sheet on the status of detainees at Guantánamo excluded Taliban and al Qaeda detainees from prisoner-of-war status based on (questionable) interpretations of the Geneva Conventions themselves and not on the legality under jus ad bellum of the US intervention in Afghanistan.Footnote 66 As far as the 2003 intervention in Iraq is concerned, both the UK and the US voted in favour of Security Council Resolution 1472 (2003) inviting all parties to the conflict to respect IHL.Footnote 67
Therefore, there is sufficient state practice to substantiate the customary status of the equality of belligerents principle.
3. Jurisprudence
The fact that the equality of belligerents principle is solidly anchored in both conventional and customary international law places international and national jurisprudence in a new perspective. Indeed, since the principle's solid legal basis in international law has been confirmed, jurisprudential precedents lose their key role in establishing the principle. In other words, proving that in some cases courts have not applied the jus ad bellum/jus in bello separation is not in itself sufficient to prove that the separation is devoid of legal force in international law. That being said, as a brief survey of the jurisprudential precedents shows, in the majority of cases the separation has been respected by international courts and tribunals. We will start off by examining the Nuremberg-era jurisprudence, which forms the basis of Mandel's argument (subsection 3.1). We will then proceed to recent international case law, namely that of the ICJ and the International Criminal Tribunal for the Former Yugoslavia (ICTY) (subsection 3.2).
3.1. The Nuremberg-era jurisprudence
The fact that the jurisprudence after the Second World War was not unanimous in applying a strict separation between jus ad bellum and jus in bello is not new in legal doctrine. Already back in 1970, in his seminal work on the equality of belligerents principle, Henri Meyrowitz identified judgments that are problematic in this respect.Footnote 68 More recently, Alexander Orakhelashvili has also examined case-law precedents after the Second World War. Insisting for the most part on the same cases as those cited by Mandel, he has reached the conclusion that ‘judicial practice is divided, some decisions are not so straightforward and may even uphold the principle of aggressor discrimination’.Footnote 69 On the other hand, after thorough analysis of all the Nuremberg-era case law, Meyrowitz concluded that it confirms the solid character of the equality of belligerents principle.Footnote 70
Even if there have been some questionable precedents from the point of view of the equality of belligerents principle, the present author agrees with Meyrowitz's conclusion that the jurisprudence in question, for the most part, confirms the principle. Leaving aside unconvincing parts in Mandel's analysis of certain judgments,Footnote 71 even if part of the Nuremberg-era jurisprudence can be read as conflating jus ad bellum and jus in bello, this is only valid for that part of the jurisprudence.Footnote 72 It does not diminish the value of precedents confirming the equality of belligerents principle. This is even more so as some states’ declarations in support of the principle do so by explicitly referring to the Hostages trial judgment.Footnote 73 Moreover, as will be seen next, the principle has also been confirmed in recent case law.
3.2. International jurisprudence confirming the equality of belligerents principle
Very few cases have obliged the ICJ look into to the jus ad bellum/jus in bello separation. The Court has clearly upheld the separation in the judgment handed down in the Armed Activities case opposing the Democratic Republic of the Congo to Uganda.Footnote 74 The case involved violations of both jus ad bellum and jus in bello, the Court ultimately finding that Uganda had violated both legal regimes.Footnote 75 In this judgment, the ICJ analysed each regime separately, with no indication that the violation of jus ad bellum by Uganda had any impact on the interpretation of jus in bello. The declarations and opinions of certain judges confirm that the equality of belligerents principle had not escaped the Court's mind when dealing with the legal issues of the case.Footnote 76
The Nuclear Weapons advisory opinion is the notorious ICJ precedent on the jus ad bellum/jus in bello separation.Footnote 77 This opinion is invoked by Mandel as proof of the doubts concerning the legal status and scope of the equality of belligerents principle.Footnote 78 The opinion has been the object of exhaustive legal analysis that need not be reproduced here.Footnote 79 Suffice it to say that, if the Court missed an opportunity to affirm the separation between jus ad bellum and jus in bello, the opinion does not have ‘far-reaching implications’Footnote 80 for the equality of belligerents principle, nor can it carry all the anti-jus ad bellum/jus in bello separation expectations that have been attributed to it. There are three main reasons for this.
First, the opinion itself is ambiguous and offers ample support to the equality of belligerents principle. Indeed, in the text of the opinion, the ICJ affirms that ‘a weapon that is already unlawful per se, whether by treaty or custom, does not become lawful by reason of its being used for a legitimate purpose under the Charter’.Footnote 81 In the same vein, the Court goes on to admit that ‘a use of force that is proportionate under the law of self-defence, must, in order to be lawful, also meet the requirements of the law applicable in armed conflict which comprise in particular the principles and rules of humanitarian law’.Footnote 82 Thus, alongside its problematic operative part, the opinion includes statements explicitly upholding the separation between jus ad bellum and jus in bello.Footnote 83
Second, a reading of the operative part as challenging the jus ad bellum/jus in bello separation would be going further than the submissions of all the states that participated in the advisory proceedings. Indeed, no state, not even the so-called ‘nuclear states’, argued that the legality of the use of nuclear weapons under jus ad bellum could influence the legality of their use under jus in bello.Footnote 84 In his separate opinion, while claiming that jus ad bellum may exercise some influence over jus in bello,Footnote 85 Judge Guillaume admits that all the states which appeared before the Court ‘argued as if these two types of prescription [i.e. jus ad bellum and jus in bello] were independent, in other words as if the jus ad bellum and the jus in bello constituted two entities having no relation with each other’.Footnote 86 This admission places the judge's claim in favour of a jus ad bellum influence over jus in bello in the realm of lex ferenda.
Third, it is also important to note that the Nuclear Weapons advisory opinion has not triggered any change in state practice with respect to the jus ad bellum/jus in bello separation. Indeed, there is no evidence that, following the pronouncement of the opinion, states have moved to adopt the position espoused by Judge Guillaume in favour of the jus ad bellum influence over jus in bello. At best, some states reproduced the opinion's operative part in the section of their military manuals referring to nuclear weapons, without indicating that it might constitute an exception to the equality of belligerents principle.Footnote 87 More importantly, the conventions regulating the use of arms that were concluded after 1996 do not contain any exception along the lines suggested by Judge Guillaume.Footnote 88 Moreover, none of the states that have ratified these conventions has made a reservation invoking the Nuclear Weapons advisory opinion in order to introduce an exception to the assumed obligations in circumstances of extreme self-defence.Footnote 89 On the contrary, the advisory opinion has been cited by both states and international tribunals as confirming the equality of belligerents principle. In this regard, reference is made to the opinion's paragraphs that confirm the principle and the problematic pronouncement of the Court has been completely discarded.Footnote 90 These are strong indications that the exceptions to the equality of belligerents principle suggested by Judge Guillaume are not confirmed in state practice. In view of the foregoing, the importance of the Nuclear Weapons advisory opinion should not be overestimated and its impact in undermining the solid legal foundations of the equality of belligerents principle should not be exaggerated.
Contrary to the ICJ, the ICTY has explicitly asserted the independence of jus in bello from jus ad bellum. The Statute of the Tribunal does not include the crime of aggression among the crimes falling under the ICTY's ratione materiae competence. Thus the question of the jus ad bellum/jus in bello separation has not arisen before the ICTY in the same manner as it did, for example, before the Nuremberg International Military Tribunal. However, in some cases, the ICTY has referred to the equality of belligerents principle explicitly, in order to reject arguments raised by the defence of the accused.Footnote 91 In this respect, it should be noted that these reaffirmations have occurred in cases concerning either situations of non-international armed conflict or situations of armed conflict that the Tribunal has not qualified as being international or non-international. Despite this, the Tribunal's case law remains relevant for two reasons. Primo, the ICTY's reaffirmation of the equality of belligerents principle is made in general terms, and in some cases by citing sources applicable in international armed conflicts, such as the AP I preamble.Footnote 92Secundo, these precedents indicate that the jus ad bellum/jus in bello separation is invoked in relation to a non-international armed conflict; that is, in relation to a conflict not covered by jus ad bellum rules and therefore, a priori, not falling under the scope of the equality of belligerents principle.Footnote 93 This invocation confirms a fortiori the principle's legal force concerning international armed conflicts, which are traditionally regulated by the jus ad bellum/jus in bello separation.
Similarly, the Special Court for Sierra Leone has also reaffirmed the equality of belligerents principle, by referring explicitly to the AP I preamble.Footnote 94 Along the same lines, the Eritrea–Ethiopia Claims Commission has confirmed the principle by dealing separately with claims resulting from jus ad bellum and jus in bello violations.Footnote 95
4. Scope and content of the equality of belligerents principle
After demonstrating that equality of belligerents is a principle binding upon states, under both conventional and customary international law, it is important to present briefly some aspects of its content. The cornerstone of the analysis is that both jus ad bellum and jus in bello apply simultaneously to international armed conflicts. As a result of the independence between jus ad bellum and jus in bello, once a state engages in hostilities, its actions are subject to and will be evaluated under the prism of both legal regimes.Footnote 96 This simultaneous application of jus ad bellum and jus in bello can have four possible outcomes: first, state actions can be legal under IHL, while violating jus ad bellum; second, state actions can be legal under jus ad bellum, while violating IHL; third, state actions can be legal under both jus ad bellum and jus in bello; and fourth, state actions can constitute violations of both jus ad bellum and jus in bello.Footnote 97 The equality of belligerents principle reflects the independence between jus ad bellum and jus in bello by stipulating that IHL rules will be applied in the same manner irrespectively of whether the state party concerned has violated jus ad bellum or not. In this context, it should be kept in mind that jus in bello does not strictly speaking ‘justify’ actions of a belligerent party which are illegal under jus ad bellum. Even if they are in conformity with jus in bello rules, such actions will remain illegal under jus ad bellum.
Much of the problem with the equal application of IHL to all parties to an international armed conflict lies with the ‘belligerent rights’ recognized by IHL provisions. In this respect, scholars usually advance a distinction between IHL provisions that are of a ‘humanitarian’ character and others that are not, pleading for respect of the equality of belligerents principle only with regard to the former.Footnote 98 It is submitted that this approach should be rejected for two main reasons. First, the premise upon which the approach rests, the distinction between ‘humanitarian’ and ‘non-humanitarian’ IHL provisions, is problematic. Second, there is no support in state practice and case law for the contention that IHL provisions establishing ‘belligerent rights’ are excluded from the scope of the equality of belligerents principle.
As to the first point, distinguishing between ‘humanitarian’ and non-humanitarian’ IHL is less easy than is usually suggested. ‘Humanitarian’ provisions cannot be limited to rules prohibiting torture, pillage, or hostage taking.Footnote 99 For example, the definition of international armed conflict laid down in common Article 2 of the GCsFootnote 100 or the definition of belligerent occupation provided for in Article 42 of the 1907 Hague RegulationsFootnote 101 do not strictly speaking set out any protection in favour of individuals. They do, however, have a ‘humanitarian’ character since they define the scope of application of the relevant IHL rules. Even ‘substantial’ IHL rules do not easily fit in the proposed distinction. Take, for example, Article 51(2) of GC IV. This provision stipulates that
The Occupying Power may not compel protected persons to work unless they are over eighteen years of age, and then only on work which is necessary either for the needs of the army of occupation, or for the public utility services, or for the feeding, sheltering, clothing, transportation or health of the population of the occupied country.Footnote 102
This provision is one of a ‘humanitarian’ character for protected persons who are under 18 years of age since it prohibits their compulsory labour. On the other hand, it gives the ‘right’ to the occupying power to compel protected persons aged over 18 years to work. Thus, for these protected persons, the provision's ‘humanitarian’ character can be put to doubt. Things are further complicated depending on the nature of work protected persons are compelled to do. Indeed, aside from working for the needs of the occupying army, protected persons may also be compelled to work for the feeding, sheltering, etc. of the occupied population. In such a case, at least from the point of view of the occupied population benefiting from the forced labour, the provision can be seen as having a ‘humanitarian’ character. These examples reveal the illusory character of distinguishing ‘humanitarian’ IHL provisions from ‘non-humanitarian’ ones. In fact, all IHL provisions are born from and form part of the same fundamental balance that lies at the origin of jus in bello itself: the balance between humanitarian and military considerations.Footnote 103 In this respect, all IHL rules have a humanitarian character to some extent.
Turning to the second point, contrary to what Mandel seems to suggest, the equal application of IHL also covers provisions establishing ‘belligerent rights’. Exceptions founded on military necessity constitute a useful example in this regard. Article 53 of GC IV prohibits destruction of private property in occupied territory ‘except where such destruction is rendered absolutely necessary by military operations’.Footnote 104 Mandel seems to oppose the idea of allowing an aggressor occupant the possibility to invoke such an exception.Footnote 105 Mandel's approach finds no support in state practice. This is confirmed by the positions adopted by states in the context of the Wall advisory proceedings, where no state advanced a view similar to Mandel's. On the contrary, the positions adopted by several states prove that aggressors are allowed to invoke necessity exceptions laid down in IHL provisions. For example, in its written statement, the League of Arab States qualified Israel as an aggressor and affirmed that the Wall constitutes a violation of jus ad bellum.Footnote 106 Were the approach defended by Mandel an accurate reflection of international law, this qualification would exclude the invocation of military necessity by Israel under jus in bello. Therefore, the League of Arab States should not engage in a discussion of whether Israel's actions are covered by IHL military-necessity exceptions. Nevertheless, this is exactly what the League did in its written statement. After affirming that Israel had violated jus ad bellum, the League went on to examine whether actions by Israel also violated IHL or whether they fell under the relevant military-necessity exceptions and were thus legal from a jus in bello point of view.Footnote 107 The same reasoning was followed by other states intervening in these proceedings.Footnote 108 The same holds true also in relation to the legal effects of the exercise of such rights. Thus, for example, even in case of an occupation which is illegal under jus ad bellum, the occupying power acting in conformity with IHL occupation provisions will validly acquire and transfer title to property.Footnote 109 The aforementioned analysis shows that the equality of belligerents principle comprises two main facets: primo, the belligerent party that violated jus ad bellum does not have fewer rights or more obligations than the one that did not violate jus ad bellum; secundo, conversely, the belligerent party that did not violate jus ad bellum does not have more rights or fewer obligations than the one that did.
It should be recalled here that, as was explained before, the legality of these acts under jus in bello leaves their illegality under jus ad bellum unaffected. The case law of the Eritrea–Ethiopia Claims Commission is highly instructive in this regard. The Commission had concluded that Eritrea's actions had violated jus ad bellum.Footnote 110 In one of the partial awards, it had also concluded that the bombing by Eritrea of the Mekele airport in Ethiopia was not a violation of IHL since the airport constituted a legitimate military target.Footnote 111 Nevertheless, in its final award, the Commission awarded compensation to Ethiopia for casualties and damage resulting from this attack. This compensation was founded upon Eritrea's jus ad bellum violation.Footnote 112 This finding unequivocally confirms both the parallel application of and the separation between jus ad bellum and jus in bello.
5. In conclusion: two policy considerations
Having demonstrated the legal force of the equality of belligerents principle, its confirmation by international case law, and its content, we will now turn to two policy considerations raised by Mandel's article. The first concerns the argument that making the application of IHL dependent on jus ad bellum leads to an erosion of jus in bello rules (section 4.1). This argument is rejected by Mandel. The second is Mandel's suggestion that the equality of belligerents principle ends up legitimizing aggression (section 4.2).
5.1. Making jus in bello dependent on jus ad bellum would erode the application of jus in bello
One of the arguments frequently advanced by legal scholars in favour of the equality of belligerents principle is that making jus in bello application dependent on jus ad bellum would inevitably lead to the erosion of the application of jus in bello,Footnote 113 since, in every international conflict, every side claims to have respected jus ad bellum and accuses the other side of having committed acts of aggression. Mandel finds it hard to see the basis for the argument:
All sides usually claim they respect the jus in bello, too. It is not a question of what each side claims, but what they are proven to have done. . . . There seems no reason to suppose that jus in bello crimes are easier to prove than jus ad bellum ones. . . . Nor is it a question of ‘denying the enemy the benefits of the jus in bello on the ground that it is the aggressor state’, but rather one of how to apply the law of war to distinguish between the aggressor and victim.Footnote 114
Mandel's reservations seem to stem from the fact that he is looking at the issue from an international criminal-law point of view. One can, of course, assume that, in front of an international criminal tribunal, jus in bello crimes are not easier to prove than jus ad bellum ones. However, this argument relates to the issue of international criminal responsibility, which will arise ex post; that is, after the commission of the acts and, usually, after the end of the hostilities. Aside from that issue, there is also the equally crucial one of the respect for jus in bello in the course of hostilities. In this case, if a link is accepted between jus ad bellum and jus in bello, claims regarding the respect for the first will influence respect for the second. The 2008 conflict between Georgia and the Russian Federation can serve as a case study in this regard. During this conflict, both countries exchanged accusations of aggression and claimed that their own military actions were taken in exercise of their right to self-defence and were thus justified under jus ad bellum.Footnote 115 According to Mandel's position, a state that is a victim of aggression ‘has wider jus in bello rights’, meaning that ‘violations of jus in bello may be legitimate if they meet the criteria of self-defence’.Footnote 116 Were this position to be applied during the 2008 hostilities by the parties to the conflict, it would mean that Georgia could directly target Russian civilians, claiming that there is no possibility of a jus in bello violation because its actions are a response to Russian aggression. At the same time, the same line of reasoning would be invoked by the Russian Federation, given its allegations on jus ad bellum. On this basis, the Russian side could equally target Georgian civilians, claiming that it is not bound by related jus in bello obligations. This would lead inevitably to a complete disregard for jus in bello, during the conduct of hostilities, since all sides to the conflict would consider themselves as ‘having wider jus in bello rights’ and, in fine, as not being bound by jus in bello obligations that would limit their allegedly defensive operations. Thus, it is clear that linking jus in bello with respect to the legality of military operations under jus ad bellum erodes the application of jus in bello.
These considerations illustrate a crucial point: allowing for jus ad bellum to trump jus in bello obligations wil lead states to claim that jus in bello obligations have not been violated because they are not applicable to the victim of aggression in the first place. It is true, as Mandel points out,Footnote 117 that states already claim that they have not violated jus in bello. But these claims are based on an analysis of the rules and limitations of jus in bello itself. In other words, they are based on the assumption that jus in bello applies – and applies equally – to all parties to the conflict. Referring, for example, to the targeting of civilians, states will try to justify such attacks by invoking exceptions to the prohibition of targeting civilian population, such as direct participation in hostilities or casualties that are not excessive in view of the concrete military advantage anticipated.Footnote 118 This line of reasoning presupposes that the prohibition of targeting civilians is applicable both to the aggressor and to the victim of aggression. Such arguments are fundamentally different from Mandel's position which offers to the victim of aggression (that is, as the Russia/Georgia example shows, in reality to both states) the possibility to argue that the prohibition to target civilians is not applicable at all, due to the state's status as the victim of aggression. The second line of reasoning empties jus in bello of its substance, inter alia by abolishing any deterrent effect IHL rules may have over the way belligerent parties act when involved in an armed conflict.
5.2. The equality of belligerents principle does not legitimate aggression
We will conclude this reply by responding to one last argument advanced by Mandel, according to which the equality of belligerents principle ends up legitimizing aggression.Footnote 119 The argument is hardly a new one and can be traced back to, at least, 1949, when the UN International Law Commission refused to embark on the codification of IHL rules for fear that
if the Commission, at the very beginning of its work, were to undertake this study, public opinion might interpret its action as showing lack of confidence in the efficiency of the means at the disposal of the United Nations for maintaining peace.Footnote 120
The same reasoning motivated the negative stance taken by the Democratic Republic of Vietnam and Romania on the equality of belligerents during the AP I negotiations.Footnote 121
States were conscious of the possibility of abusively perceiving the equality of belligerents principle as making aggression legally irrelevant and sought to eliminate it by explicitly stating in many IHL-related instruments that their rules cannot be ‘construed as legitimizing or authorizing any act of aggression or any other use of force inconsistent with the Charter of the United Nations’.Footnote 122 Article 89 of AP I excludes the possibility of invoking violations of the Protocol or of the four Geneva Conventions in order to legalize military operations:
In situations of serious violations of the Conventions or of this Protocol, the High Contracting Parties undertake to act jointly or individually, in co-operation with the United Nations and in conformity with the United Nations Charter.Footnote 123
Consequently, from a legal point of view, it is clear that jus in bello violations cannot be invoked as a legal basis for a military intervention not justified under jus ad bellum. Therefore, irrespective of any violations of IHL, respect for jus ad bellum will always be relevant. In view of the above, neither the equality of belligerents principle nor, more generally, the development of jus in bello rules can be seen as undermining the prohibition to resort to force in international relations and legitimizing aggression. Moreover, in the words of Christopher Greenwood:
The argument that the existence of the ius in bello merely encourages conflict by displaying a lack of confidence in the ius ad bellum and by making war more palatable simply does not hold good. It is not the existence of rules for the conduct of war which causes states to resort to force but more fundamental factors in international relations. Nor is there any evidence that if there were no humanitarian restraints on war states would be more likely to avoid it . . . .Footnote 124
This last argument reveals the problem at the heart of Mandel's approach. Indeed, as has already been noted at the introduction of this contribution,Footnote 125 Mandel's core issue lies with impunity for the crime of aggression. His main concern is that, contrary to the development of war crimes and crimes against humanity, the crime of aggression has long been neglected by international criminal law. In his pleading for an evolution towards activating international criminal responsibility for this crime, he takes on the equality of belligerents principle. In that, Mandel has the wrong target. Whatever the reasons for the deficiencies in international criminal responsibility for aggression, respect for jus in bello and the equality of belligerents are not part of them. And, whatever the means of effectively reinvigorating international criminal responsibility for the crime of aggression may be, they cannot, nor need they, involve the undermining of the equality of belligerents principle and the separation between jus ad bellum and jus in bello.
