1. Introduction
The International Law Commission (ILC) Special Rapporteur on the Identification of Customary International Law, Sir Michael Wood, initially recognized that there might be different approaches to the identification of the rules of customary international law (CIL) in specific fields of public international law, such as international human rights law (IHRL), international humanitarian law (IHL) and international criminal law (ICL).Footnote 1 Indeed, many have observed the struggle of these substantive fields of public international law to remain faithful to the classic doctrine of identifying CIL.Footnote 2 Evidence of the varying approaches to CIL in ICL is easily found in the jurisprudence of the ICTY, in both the Tadić Interlocutory Appeal on Jurisdiction and the Kupreškić Trial Judgement.Footnote 3 In fact, it is these two cases that the Special Rapporteur on the identification of CIL is referring to in his reports when he speaks of different approaches to the identification of CIL.Footnote 4
A significant part of the literature seems to reflect the opinions of the Special Rapporteur on CIL. Steven Ratner, for one, cited the Tadić and Kupreškić judgments as examples of the ‘judicial flouting’ of the classical sources doctrine.Footnote 5 Their impact is visible even in other ICL jurisdictions than the ICTY. For instance, the Extraordinary Chambers in the Courts of Cambodia, in the Duch case, merged the language of Tadić and Kupreškić to uphold that in ICL ‘State practice may actually be less stringent than in other areas of international law, and the requirement of opinio juris may take pre-eminence over the usus element of custom.’Footnote 6 Although some scholars have argued that the strict codification contained in the Rome Statute for an International Criminal Court (Rome Statute) marks the decline of CIL as a source of ICL,Footnote 7 there are still some issues, even within the terrain of the International Criminal Court (ICC) where ascertaining CIL plays a vital role.Footnote 8 The highly contested Decision on Malawi's Failure to Arrest and Surrender Al-Bashir (where a customary exception to head of state immunity was foundFootnote 9), is an example of a case where the ICC's findings could only be defended by adopting, as Kress puts it, a ‘modern positivist approach to customary international law’.Footnote 10 Indeed, CIL is still present in ICL, and it appears to be as malleable as in the times of Tadić and Kupreškić.
The ICTY Appeals Chamber, in the Tadić Interlocutory Appeal, accepted the two element approach to CIL but ‘on account of the inherent nature of this subject-matter’ discarded operational state practices contrary to opinio juris.Footnote 11 Thus, it reversed the traditional methodological order in identifying rules of customary IHL applicable in non-international armed conflicts (NIACs).Footnote 12 In Kupreškić, the ICTY Trial Chamber admitted the insufficiency of state practice to confirm that the prohibition of reprisals is a rule of CIL, but held that ‘[t]his is however an area where opinio juris is decisive to establish a customary rule’.Footnote 13 Tadić and Kupreškić present obstacles to the emergence of a unified approach to CIL.Footnote 14 Indeed, both rely on the peculiarity of the area at stake to postulate altered rules on the identification of CIL. This, as Michael Wood puts it, runs ‘counter to the systemic nature of international law’.Footnote 15
Arguably, the phenomenon that this article identifies in both Tadić and Kupreškić can be traced back to the Advisory Opinion on the Reservations to the Genocide Convention Footnote 16 and it is even more evident in the Nicaragua Judgment,Footnote 17 where the International Court of Justice (ICJ) was accused by commentators of swapping the means for identifying CIL.Footnote 18 The Nicaragua Judgment, indeed, spurred a debate amongst international lawyers on the proper methodology to ascertain customary norms under international law. Reacting to the Nicaragua Judgment, Kirgis contended that there is a ‘sliding scale’ relationship between the amount of practice and opinio juris necessary to postulate the existence of a customary norm. Concordant state practice and opinio juris are described as interchangeable.Footnote 19 In ‘vital’ areas, such as the law on the use of force and IHRL, the requirements of world order may, in Kirgis’ view, necessitate ‘primary reliance on normative words rather than on a combination of words and consistent deeds’.Footnote 20 Tasioulas adopted Kirgis’ ‘sliding scale’ and integrated within it Dworkin's interpretive theory of adjudication.Footnote 21 Tasioulas, therefore, replaced the sliding scale between opinio juris and custom with the ‘fit’ and ‘substance’ of Dworkin.Footnote 22 According to Tasioulas, the element of ‘fit’ is satisfied if the putative customary norm fulfils the traditional two elements approach to identifying CIL. ‘Substance’ is determined, on the other hand, by the ‘moral soundness’ of the customary norm.Footnote 23 Finally, Tasioulias posits that ‘fit’ and ‘substance’ must be balanced against each other. But, according to Tasioulias, the more compelling the ‘substance’ is, the less it has to ‘fit’ within the traditional approach to CIL.Footnote 24
The self-contained approach on CIL identification stipulated in Tadić and Kupreškić may be seen as fitting within Kirgis’ and Tasioulas’ ‘sliding scale’ theories. However, as this article will demonstrate, the ICTY Chambers did not simply find new norms of CIL, merely mixed opinio juris and state practice, or inattentively perused the two elements. Rather, the ICTY Chambers have firmly pioneered alternative approaches to the identification of CIL as being the new rules.
The aim of this article is to demonstrate that explicitly applying and setting out newfangled approaches to identify CIL in the Tadić and Kupreškić cases was, in fact, a conflict avoidance technique.
In a nutshell, conflict avoidance consists in interpreting away the incompatibility between the apparently conflicting norms.Footnote 25 The argument set out in this article is that if one adopts a wide definition of norm conflict – one that includes situations where two norms simply suggest different ways of dealing with a problem – it becomes apparent that the Chambers perceived that they were faced with a conceptual clash between IHL and IHRL. That is, they were torn between the underdeveloped state of customary IHL (and ICL) in dealing with non-international armed conflicts (NIACs) and the demands of IHRL. If the Chambers had applied the traditional method to ascertain CIL, IHL would have prevailed over IHRL. To reconcile both fields, the Chambers adopted a ‘modern’ approach to ascertain CIL. In doing so, the criminal aspect of IHL was ‘updated’ and thus converged with the human rights of the victims of war crimes committed in NIACs. This article argues that the ICTY Chambers’ ‘modern’ approach to CIL was inappropriately used as a conflict avoidance tool between two fields that did not in fact, stricto sensu, conflict.
This article is composed of four parts. Section 1 outlines how CIL is traditionally identified. Here the author illustrates that the prevailing method on the identification of CIL is the inductive doctrine. However, another methodology exists which is known as ‘modern custom’.
The article then turns to delineate the varying doctrines on custom identification applied in Tadić and Kupreškić. We will see that the ICTY Chambers failed to prove that CIL ascertained in the traditional, and perhaps even in the modern sense, supported their findings. Section 2 examines the role played by the Martens Clause in the Chambers’ appraisal of the state of CIL. In this section, we will see that the Martens Clause's normative element was used to apply new approaches to custom, as well as providing evidence of opinio juris. In Section 3, the concept of norm conflict will be unpacked as it underpins the main argument set out in this article. Section 3 demonstrates that lato sensu conflicts allow for an ideological project to be integrated within the applicable law through the prism of interpretation.
The article then turns to review the relationship between IHL and IHRL and demonstrates how both fields of law are applicable law in situations of armed conflict. The author then shows how ICL, through the ad hoc tribunals, deals with the relationship between IHL and IHRL. Having set out the applicable law at the ICTY and the inherent tensions between IHL and IHRL in ICL, this article then exposes the norm conflicts that preoccupied the Tadić Appeal Chamber and the Kupreškić Trial Chamber. In Section 4, it is argued that the doctrine of modern custom was used as a conflict avoidance technique. This article concludes by highlighting the pros and cons of the use of this conflict avoidance technique which has been identified in the article and identifies some of the dangers in employing the conflict avoidance strategy.
2. Pushing out the wheel of customs
In both the Tadić and Kupreškić cases, the ICTY Chamber explicitly stated that they will apply an alternative approach to identifying and ascertaining CIL. Article 38(1)(b) of the Statute of the ICJ, which has been widely understood as reflecting the ‘traditional’ approach, requires that CIL be found where there is (i) general state practice; and (ii) acceptance of such practice as law (opinio juris).Footnote 26 Traditionally the identification of CIL is an inductive process which requires, firstly, ascertaining extensive and virtually uniform state practice and, secondly, evidence, generally in the form of texts and statements, that such practice occurred as recognition of a legal obligation. Conversely, the doctrine of modern custom gives priority to words (opinio juris) over deeds (state practice).Footnote 27 Though not very new to public international law,Footnote 28 it is the process of identifying custom that is said to be modern in that it is deductive.Footnote 29 A deductive process focuses primarily on general statements of rules rather than on actual practices of states. First, it relies on texts and statements, such as General Assembly resolutions and treaties, and transforms these into CIL that binds all states. The methodologies for both approaches are thus opposite. Our two case studies demonstrate that opting to apply one instead of the other could be contingent on the specificities of the field of international law at stake.
3. Ironing out uniformity and consistency: The ‘Tadic’ method
The ICTY Appeals Chamber in the Tadić Interlocutory Appeal on Jurisdiction found that serious violations of IHL in NIACs gave rise to individual criminal responsibility under CIL. The Tadić Interlocutory Appeal on Jurisdiction is undoubtedly one of the most important examples of successful judicial creativity.Footnote 30 No other tribunal had found, prior to this groundbreaking decision, that violations of IHL norms applicable in NIACs gave rise to individual criminal responsibility.
Responding to the jurisdictional challenge that the ICTY Statute did not cover NIACs,Footnote 31 the Appeals Chamber designed a test with four requirements that must be met for an offence to be subject to prosecution as violation of the laws and customs of war in an NIAC.Footnote 32 The two important requirements for the purpose of this article – and the ones that have actually been addressed in detail by the Chamber – are: (i) the existence under the CIL of IHL rules governing NIACs; and (ii) that the violation of such rules gave rise to individual criminal responsibility.
The Appeals Chamber first affirmed that the dichotomy between internal and international armed conflicts (IACs) was preposterous in the human rights age.Footnote 33 Hence, the desired outcome of the Tadić Chamber became quite evident.Footnote 34 Thus, the Chamber employed a tactical move:
[I]n appraising the formation of customary rules or general principles one should therefore be aware that, on account of the inherent nature of this subject matter [i.e., IHL in NIACs], reliance must primarily be placed on such elements as official pronouncements of States, military manuals and judicial decisions.Footnote 35
Usually, statements by states, military manuals, and judicial decisions are taken as evidence of opinio juris.Footnote 36 The Chamber further asserted that inconsistent state practice in the battlefield was irrelevant for the ascertainment of custom,Footnote 37 thus removing the requirement that state practice be uniform and consistent.Footnote 38 In fact, by erasing all state practice contrary to opinio juris, the Appeals Chamber puts enormous emphasis on the latter. Furthermore, in addition to focusing on specific types of state practice that can only be representative of the establishment of the purported norm, the Chamber decided to count them as evidence of opinio juris. Footnote 39
Wouters and Ryngaert praised what they coined the ‘Tadić method’ as it makes customary norms of IHL easier to find.Footnote 40 Indeed, the Appeals Chamber did succeed in establishing many more rules than one might have believed existed at the time.Footnote 41 The ICJ had already held that Common Article 3 of the 1949 Geneva Conventions, which applies to NIACs, reflects ‘elementary considerations of humanity’.Footnote 42 However, the ICTY went one step further and concluded that ‘elementary considerations of humanity’ make it obvious that ‘[w]hat is inhumane, and consequently proscribed, in international wars, cannot but be inhumane and inadmissible in civil strife’.Footnote 43 Hence, the rules on methods and means of warfare (the sphere of IHL also known as ‘Hague Law’) that apply in IACs was found to also apply to NIACs. However, as noted by many authors, the actual evidence of the customary character of these rules in NIACs is supported by little more evidence than deduction from principles.Footnote 44
As examples of state practice revealing that minimum rules applied in IACs as well as NIACs, the ICTY Appeals Chamber relied mostly on statements made with respect to the Spanish Civil War (1936–39) and on the Nicaragua Judgment.Footnote 45 It should be noted, that the ICJ's judgment may only be taken as an indirect example of state practice.Footnote 46 In contrast, the ICTY Chamber did not refer to any national court decisions – which would have had more weight as direct evidence of state practice.Footnote 47 The ICTY Appeals Chamber also referred to resolutions of the UN General Assembly and the Council of Europe which had declared that Common Article 3 applied to IACs and NIACs. As affirmed by the ICJ, such resolutions may be taken as a form of opinio juris, which still needs to be supported by state practice. Footnote 48
Having established the rules applicable in NIACs, the ICTY Chamber turned to the question of whether a violation of these rules entailed individual criminal responsibility. Only two years before the Appeals Chamber's decision, the ICRC and the Commission of Experts on the former Yugoslavia had unequivocally declared that according to CIL the notion of war crimes was limited to situations of international armed conflict.Footnote 49 Despite these authoritative opinions, the Chamber affirmed that it had ‘no doubt’ that CIL imposed individual criminal responsibility for serious violations of IHL in NIACs.Footnote 50 Once again, the Chamber referred to the ‘elementary considerations of humanity’ plus a limited amount of state practice and opinio juris to find that serious violations of IHL in NIACs constituted war crimes. The Appeals Chamber then stated that certain ‘factors’ were retained in the Nuremberg judgment to find that a certain prohibition gives rise to individual criminal responsibility: the unequivocal nature of the rules, the intention of states to criminalize the practices, and the punishment of violations by national courts.Footnote 51 In essence, this was a reiteration of a theory of custom that looks primarily for opinio juris rather than at state practice.Footnote 52 As Schlütter observes, the ascertainment of CIL conducted by the Appeals Chamber in Tadić only served to support the general considerations stated in the preliminary stage.Footnote 53 That is exactly what modern custom is – a method which ‘enabled the ICTY to overcome a fundamental obstacle to its operation, namely the fact that individual criminal responsibility had barely been established in international law, and certainly not with regard to crimes committed in an NIAC’.Footnote 54
4. Would it be easier if we had some state practice?: The Kupreškić account
During the Kupreškić proceedings, some witnesses raised the issue that both camps involved in the situation under examination had committed crimes.Footnote 55 Hence bringing the infamous tu quoque argument,Footnote 56 as well as the possibility of claiming that unlawful acts committed by the defendants were undertaken in reprisal to unlawful acts committed by the enemy, i.e., in an effort to persuade this force to desist from committing further unlawful acts.Footnote 57 Having discarded the plea of tu quoque,Footnote 58 the Chamber addressed the defence of belligerent reprisals against the civilian population.Footnote 59
Belligerent reprisals against the civilian population and objects are prohibited under Articles 51(6) and 52(1), respectively, of the 1977 First Additional Protocol (AP I) to the Geneva Conventions, which applies to IACs.Footnote 60 However, as the Chamber acknowledged, important states such as the US, France, India, Indonesia, Israel, Japan, Pakistan and Turkey were not party to AP I.Footnote 61 The Second Additional Protocol (AP II), which regulates NIACs more extensively, does not mention reprisals.Footnote 62 This ominous silence in AP II on reprisals has been considered as either an affirmation that reprisals have no place in an NIAC, or, on the contrary, as an acceptance of its use in such type of conflicts.Footnote 63 It appears that the Kupreškić Trial Chamber considered that reprisals constituted part of the legal regime applicable in an NIAC as it affirmed that the purpose of its inquiry was to assess whether the prohibition contained in AP I had ‘subsequently been transformed into general rules of international law’.Footnote 64
The Trial Chamber in Kupreškić admitted that there was not enough state practice to assert that the prohibition of belligerent reprisals was a customary rule under the traditional doctrine.Footnote 65 However, the Chamber then stated that ‘under the pressure of the demands of humanity or the dictates of public conscience’ we can resort to modern custom.Footnote 66
Only two examples of state practice were cited by the Trial Chamber: Dutch and US military manuals.Footnote 67 As evidence of opinio juris, the Chamber referred to General Assembly Resolution 2675 coupled with the absence of arguments to the contrary among states, the adoption of the First Additional Protocol of 1977 and a comment by the ILC to sub-paragraph (d) of former Article 14 of the Draft Articles on State Responsibility of 1995.Footnote 68 To be fair, even the existence of opinio juris on this issue does not appear to be proven.Footnote 69 Hence, one may be tempted to conclude that the prohibition of reprisals against civilians was not warranted by a customary norm but by ‘consideration of humanity’.Footnote 70
5. Was it Martens’ fault?
Since the customary nature of the findings in Tadić and Kupreškić are far from established, this section critically explores the role that the Martens Clause may have played in these two decisions. The Martens Clause, as adapted in AP I, states that ‘civilians and combatants remain under the protection and authority of the principles of international law derived from established custom, from the principles of humanity and from the dictates of public conscience’.Footnote 71 Needless to say, the Martens Clause has been interpreted in various ways. In essence, it has been taken to affirm that even if the applicable law does not prohibit certain conduct, it does not mean that the same conduct is necessarily permitted: This is because persons remain under the protection of the principles of humanity and the dictates of public conscience.Footnote 72 It has also been claimed that the Martens Clause gives room, in case of doubt, for interpreting the law in accordance with the ‘principles of humanity’ and the ‘dictates of public conscience’.Footnote 73 In this sense, the Martens Clause serves as an interpretative guideline. Cassese and Meron attribute the push towards basing the existence of customary IHL primarily on opinio juris to the Martens Clause.Footnote 74 Finally, the most radical argument is that the Clause introduced new and free-standing sources of law in IHL, namely ‘the laws of humanity’ and ‘the dictates of public conscience’.Footnote 75 The Tadić and Kupreškić cases both infused the Martens Clause with almost all of these interpretations.
5.1. Tadić and the Martens Clause
There was no explicit reference to the Martens Clause in the Tadić Interlocutory Appeal Decision but rather to the ‘elementary considerations of humanity’ as held at the ICJ. Indeed, Tomuschat affirmed that ‘[o]ne needs no prophetic gifts to conclude that the reasoning of the Court [i.e. ICTY Appeals Chamber] . . . was inspired by the famous Martens clause’.Footnote 76 The Martens Clause played a role in three forms in the Tadić case: Firstly, as evidence that Common Article 3 was part of CIL; secondly, to argue that the dichotomy between IACs and NIACs was senselessness when considered in light of the elementary consideration of humanity; and thirdly, as an evidence that as a rule of custom a violation entailed individual criminal responsibility.Footnote 77
Certainly, the considerations of the Martens Clause as expressed in the ‘elementary considerations of humanity’ constituted the main evidence to prove the customary character of the Appeals Chamber's findings.Footnote 78 However, as set out below, the ‘elementary considerations of humanity’ did not trigger the Chamber's recourse to ‘modern custom’. The ‘elementary considerations of humanity’ proved instead to be a form of opinio juris to which the Chamber gave decisive weight.
5.2. Kupreškić and the Martens Clause
In Kupreškić, the resort to ‘modern custom’ was explicitly said to be a result of considerations of the Martens Clause. Indeed, according to the Trial Chamber the application of the Martens Clause by other tribunals:
Clearly shows that principles of international humanitarian law may emerge through a customary process under the pressure of the demands of humanity or the dictates of public conscience, even where State practice is scant or inconsistent. The other element, in the form of opinio necessitatis, crystallising as a result of the imperatives of humanity or public conscience, may turn out to be the decisive element heralding the emergence of a general rule or principle of humanitarian law.Footnote 79
Despite the Chamber's assertion that custom for the issue at stake may be identified through opinio juris solely, it failed to really provide evidence of this element, except for stressing the ‘pressure exerted by the requirements of humanity and the dictates of public conscience’.Footnote 80 In fact, the Kupreškić Trial Chamber's use of the Martens Clause is circular: The Martens Clause opens the door to a theory of custom that places the emphasis on opinio juris,Footnote 81 and by the same token opinio juris against reprisals is demonstrated by the Martens Clause.Footnote 82 Hence, one might conclude that it is the Martens Clause that prohibited the use of reprisals against the civilian population.Footnote 83 The Trial Chamber, however, fell short of providing a standalone status to the Martens Clause. Indeed, it stressed that the ‘principle of humanity’ and ‘dictates of public conscience’ have not attained the status of a source of law.Footnote 84 If it was neither the Martens clause per se, nor a genuine ascertainment of custom, even of modern custom,Footnote 85 then it must be something else that justified the Chamber to find that belligerent reprisals were prohibited under CIL.
We will see below that the answer lies in the argument the Chamber offered in addition to the Martens Clause's effect: The conceptual inconsistency between reprisals and the rights to life of the victims of such reprisals. Furthermore, the Trial Chamber integrated the right to life of the victims of belligerent reprisals into its discussion of the principles of the Martens Clause. Many argue, Cassese included, that the Martens Clause has now to be read in line with IHRL.Footnote 86 In this sense, IHRL would fill in the details of the vague notions that are the ‘principles of humanity’ or ‘the dictates of public conscience’. In other words, the normative conflict between indiscriminate attacks against civilians resulting from reprisals and the right to life of the victims of such reprisals informed the ‘dictates of public conscience’. It is the latter IHRL norm – i.e., right to life – that preoccupies the Trial Chamber and that, under the umbrella of the dictates of public conscience, will form the opinio necessitatis. Footnote 87
6. Defining norm conflict
In the foregoing, this article has attempted to show that the Tadić and Kupreškić cases propounded alternative approaches to custom identification. It has been argued that in both cases the Chamber barely proved that their findings were established rules of CIL and that the Martens Clause does not provide sufficient legal explanations to justify these findings. However, it is also important to decipher why the Chambers decided to flout the traditional approach to custom identification. This article argues that the resort to modern custom by the Chambers was expounded as a means to avoid a norm conflict between two bodies of international law, namely IHL and IHRL. Before turning to illustrate how the Chambers dealt with the dilemmas they consider to be exposed to, it is important to first understand what is meant by a ‘norm conflict’.
There is a large and longstanding debate in international law regarding what constitutes norm conflict.Footnote 88 The consequences of the answer are far-reaching because as soon as a genuine norm conflict is recognized, established principles of norm conflict resolution are supposed to be applied by the adjudicators. This is clearly important when one considers that conflict resolution principles are devices for diminishing the discretional power of the judge or judges who are faced with incompatible norms and have the task of deciding which norm should apply.
While it has generally been asserted that there are two definitions of norm conflict in international law – a broad and a narrow one – Mario Prost points out that in reality three different forms of conflicts have been offered in the literature: stricto sensu; medio sensu; and lato sensu. Footnote 89 The narrow definition (stricto sensu) considers that there is a conflict only ‘where giving effect to one international obligation unavoidably leads to the breach of another obligation or right’.Footnote 90 A broader definition (which is, in Prost's lexicon, medio sensu) is exemplified by Kelsen's definition: ‘[a] conflict between two norms occurs if in obeying or applying one norm, the other one is necessarily or possibly violated’.Footnote 91 This definition of norm conflict includes not only scenarios of incompatibility between two norms, but also contradictions between permissions and obligations. While the latter definition is broader than the strict definition, Prost identified a third definition of conflict which is even wider (i.e., lato sensu). The lato sensu notion of conflicts can be taken as the one defined by Martii Koskenniami: ‘[A] situation where two rules or principles suggest different ways of dealing with a problem’.Footnote 92
The latter definition of norm conflict – which I will now refer to as the wide definition – includes not only scenarios of incompatibility or contradiction between two norms, but also situations where application of one norm simply frustrates the object and purpose of another.Footnote 93 In this sense, the term conflict encompasses tensions between opposing concepts and policies underlying the norms or regimes in which the norms are enshrined.Footnote 94 Wolfrum and Matz have also advocated for a definition of conflict that includes ‘conceptual conflicts between different approaches’.Footnote 95 The author accepts this overly broad definition as also forming part of what a conflict is, as they show the type of factors that, according to the judge, may ‘seem to point to different directions’.Footnote 96 Indeed, even in the absence of a direct conflict of norms, judges may attempt to mediate the tensions and minimize the conceptual conflicts they are facing.
The adjudicator, when seeking to rule on a particular issue, must first determine the ‘applicable law’. Thus, a prima facie assessment will be formed on what are the relevant norms applicable to the specific (legal) issues at stake. A choice is, therefore, taken by the adjudicator to consider and potentially apply such a norm instead of the other norm.Footnote 97 By adopting a wide notion of norm conflict we may decipher more exactly the adjudicator's weighing of opposite teleologies.Footnote 98
Pauwelyn rightly stresses that the narrower the definition of conflict one adopts, the less room there is on how to avoid the alleged conflict.Footnote 99 When a norm conflict is recognized legal reasoning calls to either seek to harmonize the norms in conflict through interpretation or, if that seems impossible, by applying norm conflict resolutions methods.Footnote 100 There are, indeed, different norm conflicts – the apparent ones and the genuine ones. An apparent norm conflict can be avoided, most often by interpretative means. What was then appearing as two contradictory norms is now construed as two rules that are part of the same legal system. The conflicting norm is therefore interpreted as engendering and intended to engender effects in harmony with existing law and not in violation of it.Footnote 101
To properly examine the specific type of conflicts between IHL and IHRL that took place in Tadić and Kupreškić it is also critical to address the relationship between these two bodies of law and how ICL perceives and deals with the interaction of IHRL and IHL. This is the focus of the following sections of this article.
6.1. The relationship between IHL and IHRL
Despite some initial resistance it has been recognized that IHRL applies at all times, including in times of armed conflict.Footnote 102 The ICJ in the Nuclear Weapons case acknowledged that IHRL in situations of armed conflict is conditioned by the lex specialis of IHL.Footnote 103 For instance, the lex generalis of IHRL regarding what is an ‘arbitrary’ deprivation of life is to be assessed under the lex specialis rules of IHL.Footnote 104 This does not mean, however, that IHL always trumps IHRL. In The Legal Consequences of the Construction of a Wall, the ICJ addressed the relationship between IHL and IHRL in the following terms:
As regards the relationship between international humanitarian law and human rights law, there are thus three possible situations: some rights may be exclusively matters of international humanitarian law; others may be exclusively matters of human rights law; yet others may be matters of both these branches of international law. In order to answer the question put to it, the Court will have to take into consideration both these branches of international law, namely human rights law and, as lex specialis, international humanitarian law.Footnote 105
It is only where the two regimes diverge on a specific legal issue that the Court will consider whether the lex specialis of IHL should be applied. In DRC v. Uganda, the ICJ re-cast the relation between IHRL and IHL as one governed by the presumption of co-application, whereby both bodies of law inform the overall legal framework.Footnote 106 In the same vein, the UN Human Rights Committee defines the relationship between IHL and IHRL as ‘complementary, not mutually exclusive’.Footnote 107 The Inter-American Court of Human Rights in Mapiripan Massacre v. Colombia, espoused a ‘convergence’ approach, whereby IHL and IHRL either ‘complement each other or become integrated to specify their scope or their content’.Footnote 108 As a replacement for the lex specialis principle the European Court of Human Rights, in Hassan v. United Kingdom, took IHL into account within its operative regime through the prism of Article 31(3)(c) of the Vienna Convention on the Law of Treaties which calls for interpretation in harmony with other rules of international law.Footnote 109 This illustrates how the two spheres of law can be operationally complementary.
With the stark development of both sets of rules, the scope of application of IHL and IHRL increasingly overlaps. Thus, it is not surprising that a legal issue be addressed by both regimes in diverging directions. Furthermore, there is an increasing tendency in legal scholarship to define a norm conflict between these two regimes on the basis of their different telos.Footnote 110 Having examined how IHL and IHRL may interact, this article now turns to examine how ICL embraces these two fields.
6.2. What does ICL have to do with IHL and IHRL and their relationship?
International criminal law enshrines the idea of individual criminal responsibility for serious violations of IHL and IHRL. Cassese defines ICL as a ‘hybrid branch of law’ which sits within public international law, derives principles from criminal law, and brings together IHL and IHRL.Footnote 111 As Ambos notes, ‘the concept of prosecuting an individual for a specific (macro-criminal) act is derived from criminal law’.Footnote 112 This entails that general principles of criminal law such as the principles of legality (nullum crimen sine lege), culpability, and fairness are applicable in an ICL trial.Footnote 113
When it established the ICTY, the UN Security Council (UN SC) specified that the Tribunal's mandate was ‘bringing to justice persons responsible for serious violations of international humanitarian law in the former Yugoslavia’.Footnote 114 The list of crimes within the ICTY Statute was not, however, limited to serious violations of IHL. The Tribunal was given jurisdiction over the ‘core crimes’, that is, war crimes, crimes against humanity, and genocide.Footnote 115 The latter two are closer to IHRL than to IHL. While the UN SC appeared to have subsumed IHRL under IHL, many describe their relationship in the opposite sense or simply conflate the two bodies of law when identifying the foundations of ICL.Footnote 116 For instance, Bassiouni viewed the internationalization of the criminalization process, including for war crimes, as a form of IHRL enforcement.Footnote 117 In his critique of the ‘identify crisis’ of ICL Robinson, indeed, observed that in ICL prosecution and conviction are often treated as the fulfillment of the victim's right to an effective remedy.Footnote 118
It is held that ICL lies in public international law as the ‘core crimes’, as well as the principle of direct individual criminal responsibility for committing such crimes, are embedded in sources of international law.Footnote 119 While the Rome Statute contains its own set of sources for the Court to apply,Footnote 120 the Statutes of the ad hoc tribunals did not set a clear hierarchical relationship between the Statutes and other sources of international law. Hence, the ad hoc tribunals’ sources of law are those of international lawFootnote 121 – normally considered to be those enumerated in Article 38 of the ICJ Statute, with a particular emphasis on CIL.Footnote 122
As Ambos’ quote reveals, ICL is preoccupied with macro-criminal acts, that is, crimes conducted in the context of wide-scale atrocities.Footnote 123 It is often, perhaps even typically, believed that only the state has the necessary apparatus to commit war crimes, genocide, and crimes against humanity.Footnote 124 This, obviously, creates a tension with the objective element of custom – i.e., state practice – since states are seldom willing and/or able to criminalize and prosecute the conduct of their own officials.Footnote 125 This difficulty partly explains the shift to opinio juris evidenced in our two case studies.Footnote 126 The other explanation, or leitmotiv, for the resort to modern custom is reflected by Robinson's observation that ICL is often conceptualized as a form of justice that functions as a means for fulfilling a victim's IHRL-based right to a remedy.Footnote 127
6.3. A sovereignty-oriented versus human-being-oriented approach: Tadić
If we are to assume from the foregoing that ICL merges both IHL and IHRL (two fields often clashing in the narrow sense) this section builds upon this and illustrates how the ICTY Appeals Chamber in Tadić encountered a clash between these two branches in a wide sense. Before ascertaining the extent of customary IHL norms governing NIACs,Footnote 128 the Appeals Chamber proffered some general considerations:Footnote 129 Firstly, the Chamber highlighted that there has traditionally been a dichotomy between NIACs and IACs. IHL – a much older branch of law than IHRL – was originally strictly concerned with inter-state relations, leaving internal strife outside its purview. This situation significantly changed with the Geneva Conventions and in particular, Common Article 3 which contained a ‘convention in miniature’, regulating to a minimum extent the conduct of the parties to an NIAC.Footnote 130 By the same token, this slight intrusion in the internal matters of states consolidated the dichotomy between IACs and NIACs.Footnote 131 ‘This dichotomy’, says the Appeals Chamber, ‘was clearly sovereignty-oriented’.Footnote 132
Secondly, the Appeals Chamber offered the following reasons for blurring the two: (i) civil wars are frequent; (ii) civil wars are cruel and protracted; (iii) civil wars affect every state; and (iv) the outgrowing of IHRL in today's normative environment.Footnote 133 The first three reasons are more contextual than anything else. Conversely, the fourth point will prove to be conceptually, if not legally, determinant. With respect to the fourth point, the Chamber observed that ‘[a] State-sovereignty-oriented approach has been gradually supplanted by a human-being-oriented approach’.Footnote 134 Indeed, this prompted the Chamber to assert that: ‘If international law . . . must gradually turn to the protection of human beings, it is only natural that the aforementioned dichotomy should gradually lose its weight.’Footnote 135 Here, the Chamber is asserting that the ‘humanization’ of IHL has already taken place, while the Chamber's finding actually constitutes the big bang of this process. Footnote 136
In reality, the Chamber is admitting that there is a conceptual clash between the distinction in IHL of NIACs and IACs and the human right of any individuals to be safeguarded and protected from the scourge of wars, including in NIACs.Footnote 137 Indeed, the raison d’être of IHRL is to limit the power of the state (or the authority exercising jurisdiction) towards its subjects, therefore drastically intruding on intra-state matters. Thus, a regime such as IHL, that affords less protection to victims of intra-state than to those of inter-state conflicts, makes no sense from a human rights perspective.Footnote 138
Furthermore, the obligation to criminalize particularly serious human rights abuses is now firmly rooted in IHRL.Footnote 139 Conversely, in IHL, only the grave breaches, which are solely pertaining to IACs, gave rise to such an explicit obligation under the Geneva Conventions.Footnote 140 Thus, showing once again the discrimination IHL exacts towards victims in NIACs. To avoid unequal treatment of those who are caught in IACs and NIACs, the Chamber had to harmonize customary rules applicable in NIACs with those applicable in IACs.
In sum, the Appeals Chamber, in propelling the modern custom approach, had one objective, namely to ensure that victims in NIACs had the right to have their perpetrator punished just as they would in IACs. The rudimentary state of IHL in NIACs clashed with the advanced stage of IHRL, albeit the two were not in a stricto sensu conflict. ICL's competing anxieties, coupled with the inherent flexibility of the customary process,Footnote 141 made the Appeals Chambers’ judges feel entitled to avoid this conceptual clash by watering down the traditional two elements approach to the identification of CIL. The choice to use an alternative method to identify custom was employed to avoid situations where one field, namely IHL, conceptually prevails over the other, IHRL. Instead, through modern customary adjustment, both IHL and IHRL were fused in order to address crimes committed in NIACs and provide justice to the victims.
6.4. Absolutely inconsistent legal concepts: Kupreškić
The Kupreškić judgment also evinces a deep discomfort in leaving victims of belligerent reprisals without access to international criminal justice. In its reasoning to demonstrate ‘the absolute character of the prohibition of reprisals against civilian populations’ in all armed conflicts,Footnote 142 the Trial Chamber noted the unjust nature of reprisals against the civilian population.Footnote 143 In the words of the Chamber: ‘[I]t cannot be denied that reprisals against civilians are inherently . . . barbarous’.Footnote 144 Their indiscriminate nature was framed as follows: ‘The reprisal killing of innocent persons, more or less chosen at random, without any requirement of guilt or any form of trial, can safely be characterized as a blatant infringement of the most fundamental principles of human rights.’Footnote 145 The most obvious human right at stake in cases of reprisals is the right not to be arbitrarily deprived of life. Having underlined the unjust character of reprisals, the Chamber affirmed:
It is difficult to deny that a slow but profound transformation of humanitarian law under the pervasive influence of human rights law has occurred. As a result belligerent reprisals against civilians and fundamental rights of human beings are absolutely inconsistent legal concepts.Footnote 146
By asserting that reprisals against civilians and IHRL are ‘absolutely inconsistent legal concepts’ the Chamber postulates that it is facing a norm conflict. Indeed, if belligerent reprisal against civilians and the right to life are genuinely conflicting, one norm needs then to prevail over the other.
As Darcy convincingly demonstrated, IHRL precludes reprisals against civilians by governmental forces in an NIAC.Footnote 147 IHRL would also have such effect over governmental forces in an IAC, if the state exercises effective control over the enemy civilians.Footnote 148 However, IHRL, Darcy acknowledges, would fail to impose a prohibition of reprisals on non-state armed groups.Footnote 149 The Kupreškić case concerned soldiers of the Bosnian-Croat forces (HVO), a non-state armed group, who waged a military attack against the Bosnian-Muslims in a village in central Bosnia and Herzegovina. Thus, it concerned a category of perpetrators to which only the customary IHL prohibition of reprisals could be applicable.
The finding that reprisals against civilians is a customary prohibition of IHL had three effects: Firstly, it applied to all actors in any type of conflict; secondly, it avoided recognizing human rights obligations to non-state actors as a whole. Recognition of human rights obligations in general for non-state armed groups would have led to much more political controversies and legal difficulties than demonstrating that there is a customary prohibition of reprisals under IHL.Footnote 150 Indeed, even the progressive views, at least at the time, limited human rights obligations of non-state armed group to such groups that exercise territorial control.Footnote 151 Thirdly, if not prohibited by IHL, the lex specialis rule could have applied in a similar fashion as in the Nuclear Weapons case.Footnote 152 In essence, the right of not being arbitrarily deprived of life would be adjusted to the specific authorization – the lex specialis – to use reprisals in order to force the other party to cease violating IHL.Footnote 153 In other words, a genuine conflict between IHRL and IHL took place. Thus, to interpret away the foreseen clash, the Chamber tried at all costs to find that belligerent reprisals against civilians were prohibited under customary IHL.Footnote 154
In sum, by proclaiming a new approach to identifying CIL and consequently finding that belligerent reprisals against the civilian population in NIACs were prohibited, both laws, that is IHL on belligerent reprisals and IHRL on the right to life, converged. The result was that there was no more inconsistency between the legal concepts at stake. If, on the other hand, the Chamber had failed to find this harmonious solution, the lex specialis doctrine would have prevailed, in that the right to belligerent reprisals would have superseded the right to life of the victims.
7. Using custom identification as a conflict avoidance technique
Conflict avoidance is a process by which interpreting one norm in light of another norm may disband an apparent conflict. In theory, interpretation should be understood in the sense of Articles 31–32 of the Vienna Convention on the Law of Treaties.Footnote 155 In lato sensu conflicts, the object to be interpreted is understood in a wide sense. That is, interpretation of the conflicting norms’ terms as well as their regimes’ teloi can be taken into account. However, in Tadić and Kupreškić, it is not a particular term of IHL that was interpreted but its telos, as well as the rules on the identification of CIL. In his report on the establishment of the ICTY, the UN Secretary General (UN SG) made clear that to respect nullum crimen sine lege the Tribunal had to apply rules of IHL which were beyond any doubt part of CIL.Footnote 156 However, the UN SG did not specify how custom should be identified, arguably because he considered it unnecessary as the traditional method was firmly established and the words ‘beyond any doubt’ sufficiently expressed the idea that the appraisal of custom needed to be strictly undertaken.
The Tadić, Kupreškić cases and inter alia the ILC's work on the formation of CIL demonstrate that there are no ‘hard-and-fast rules for the identification of rules of customary international law’.Footnote 157 This lack of codified ‘rules’ for the formation of customs left a gap which the Chambers could plug with their own alternative approaches.Footnote 158 In order to integrate IHRL's spirit into IHL's diverging spirit, the extent of CIL regulating (the criminalization of) conducts in NIAC was enhanced. Given that the traditional method to identify CIL would have failed to achieve this result, the tool to upgrade IHL was, indeed, to deductively appraise CIL.
Milanović describes three means of conflict avoidance: consistent, creative and forced.Footnote 159 The Kupreškić and Tadić cases lie in between creative and forced avoidance. The two cases are far from ‘consistent’ as they do not ‘fit’ within the two elements approach to CIL. The Tadić case may be seen as creative – as it is making things up – but in a manner that is not completely inobservant of past accounts of how to determine CIL.Footnote 160 Indeed, the ICTY defended its use of modern custom by claiming that contemporary practice in the battlefield required it to do so. This is also a technique used in IHRL.Footnote 161 For example, despite being widely condemned in official statements, the practice of torture remains endemic. This does not, however, challenge the customary character of the prohibition of torture. The Tadić Interlocutory Appeal on Jurisdiction draws on this normative approach. Some years later, the ICRC Study on CIL also used a similar approach,Footnote 162 albeit not without severe criticism.Footnote 163
Kupreškić, on the other hand, appears as forced rewriting of how CIL should be identified. Indeed, the conceptual conflict between the scant regulation of IHL and the protection of the human rights of those caught in armed conflict lies at the centre of why a relaxed approach to custom identification ought to be adopted. However, it is the Martens Clause that officially opened the way to adopt a relaxed approach to the identification of CIL and by the same token provided the main evidence that the desired CIL existed. This was certainly a distorted interpretation of the CIL process.
The main argument of this article is that these alternative methods to custom identification were brought into play in the Tadić and Kupreškić cases as methods of conflict avoidance. In contrast to a reasonable interpretation of conflicting terms, alternative methods of custom identification are per se forced, or at best creative conflict avoidance techniques. What does this conflict avoidance technique mean for international law in general and for ICL in particular? This is the final question that this article now turns to examine.
8. The pros and cons of using custom identification as a conflict avoidance technique
The type of conflict avoidance technique used in Tadić and Kupreškić does not only concern ICL – it may recur any time the issues in a given legal case are taken from a wider perspective and the applicable law provides loopholes whereby CIL can be instrumentalized to avoid an ‘unjust’ result.Footnote 164 Avoiding conflicts of norms by opting for an alternative method to identify CIL has consequences for the unity of public international law in at least two ways – one positive and one negative: Firstly, it may be argued that the Chambers were moved by an effort to consider the issues at stake as part of a systemic and consistent order. As ICL intermeshes IHL and IHRL, it is not surprising that ICL courts issue decisions that fuse its flesh.Footnote 165 Other branches of public international law, such as international trade law or international investment law, have fewer entry points for human rights norms – although human rights concerns are also present.Footnote 166 In contrast with ICL or IHRL bodies, WTO Panels and other arbitration tribunals have, so far, interpreted their jurisdiction and ‘applicable law’ narrowly.Footnote 167 Hence, they have often acknowledged only stricto sensu conflicts. The Tadić and Kupreškić cases, on the other hand, epitomize examples of decisions that conceptualized their ‘applicable law’ broadly; thus, they were concerned with lato sensu conflicts. The aim of bringing IHL and IHRL together appeared to the ICTY Chambers as sufficiently urgent to switch to an unconventional method of identifying CIL. In considering their normative environment widely, as the principle of systemic integration enjoins,Footnote 168 their models to identify CIL are in fact techniques for harmonizing IHL with IHRL. Some may applaud this endeavour whilst some may not.
Secondly, watering down the two-element requirement of custom poses an enormous risk of fragmentation of international law. The Chambers did not simply apply and interpret IHL against the background of IHRL.Footnote 169 Instead, the Chambers overstepped the mark in using their ‘discretion’ by defining the rather flexible prescription of how to determine the scope and content of customary IHL. The danger that this conflict avoidance method poses to the international legal order are evident: it shakes the whole structure of the international legal system as it creates primary norms by fecundating new rules of recognition. To be sure, a regime may set a distinct set of secondary norms designed to ensure the proper application and to resolve conflicts of primary norms.Footnote 170 The ad hoc tribunals did not, however, operate in a fully self-contained regime.Footnote 171 Their applicable law had to be confirmed by CIL – one of the classic sources of international law. It needs to be underlined that providing new rules of recognition should not come as a ‘technique’ to avoid normative conflicts but as concerted rules between law-makers.
Furthermore, if every time a judge is faced with a conceptual conflict she decides to bring forward an alternative theory of custom, it is not only the indeterminacy on what the law is on a certain issue that is at stake, but also how to identify such law. Faced with the same issue, another court or body might rule in a completely opposite manner and thus bring further uncertainties. Certainly, a judge may seek to interpret the terms of the norms to avoid a conflict. But to re-interpret the classical doctrine on the identification of CIL to avoid what appeared to be an unresolvable conflict is a subversion of the conflict of norms theory.
Finally, the conflict avoidance technique used in Tadić and Kupreškić is particularly troublesome in a criminal trial, where the nullum crimen sine lege principle should govern the process of finding the applicable law. Not only should the judge/s determine whether the offence in question existed at the time of the alleged conduct but they should also strictly construe the terms of the offence. Playing with CIL according to one's will renders it impossible for individuals to know whether or not a certain conduct is criminal under international law and which technique will be applied to find this law.
9. Conclusion
This article has argued that in both the Tadić and Kupreškić cases the ICTY resorted to a modern approach for determining CIL in order to avoid a norm conflict between IHRL and IHL. The words of the Chambers clearly illustrated that such conflicts troubled them. It may be claimed, however, that the conflicts avowed by the ICTY Chambers were just arguments made in addition to other legal norms to convince the community to whom it is addressed. In other words, the human rights revolution is not causing the change but just adding a defence to the whole legal claim made. Indeed, judges may come with normative preferences which they would preserve with a human rights normative.Footnote 172 This human rights normative force may be imbued with other humanitarian norms all coming under the umbrella of a ‘rhetoric of justice’.Footnote 173
Many factors were outlined by the Appeals Chamber in the Tadić Interlocutory Decision to justify its findings. In particular, the claim that the purposive approach adopted by the Tribunal is attributable to its mandate – that is, to prosecute persons responsible for the most serious crimes of concern to the international community as a whole.Footnote 174 The UN SC's intent when it established the Tribunal, coupled with a logical and systematic interpretation of its Statute, warranted that the Chamber conclude: ‘Article 3 aims to make [the ICTY] jurisdiction watertight and inescapable’.Footnote 175 However, this part of the ‘analysis’ concerned the jurisdiction of the Tribunal and not the customary nature of the rules governing NIACs. As set out above, the most significant step undertaken by the Appeals Chamber in this respect was the application of an alternative approach to identifying CIL. Unlike the UN SC's intent, the Martens Clause and the Nuremberg factors, the human rights revolution in international law was stated in the Appeals Chamber's general considerations. It shortly preceded the paragraph where the Chamber signaled that it will apply a relaxed model of CIL identification. Not only did the Chamber's general considerations constitute the principles from which it deduced the existence of customary norms but they also set the conceptual conflict it was facing.
In the Kupreškić Trial Judgement, the Chamber pointed out that reprisals are no longer necessary since other ‘means of inducing compliance’ have become available: That is, ‘the prosecution and punishment of war crimes and crimes against humanity by national or international courts’.Footnote 176 The Chamber's efforts to replace the justification of reprisals by the possibility of prosecuting all war crimes perpetrators merely served as a fig leaf to demonstrate that other mechanisms than reprisals existed. It does not, however, intend to be the crux of why custom prohibits reprisals or why only opinio juris should be contemplated.
The main argument presented in this article is that a resort to modern custom has been used as a technique to avoid a conflict between the divergent IHL and IHRL regimes involved in the two cases examined (Tadić and Kupreškić). The Nicaragua judgment also falls in this category. However, on the other hand, it could be argued that if these were the only ways to establish that belligerent reprisals are prohibited in NIACs and that the individuals who committed serious violations of IHL in NIACs are subject to individual criminal responsibility then let us, indeed, compose new customs or use new ways of identifying CIL. One might argue that the end justifies the means. However, in both cases examined, there were actually other means to establish these ends: Firstly, the same findings could have been derived from general principles of law.Footnote 177 General principles of law are also a source of international law under Article 38(1) of the ICJ Statute. Moreover, it is widely recognized that individual criminal responsibility for international crimes can be derived from general principles of law without infringing the fundamental principle of nullum crimen sine lege. Footnote 178 Secondly, many of the reasons for which the ICTY Chambers in Tadić and Kupreškić resorted to a modern approach to the identification of CIL were said in obiter.Footnote 179 They were not necessary for the cases at hand!Footnote 180 The role of the international judge(s) in contributing to the development of international law (as advocated by Judge Lauterpacht) Footnote 181 is a known, but divisive issue.Footnote 182 Judge Fitzmaurice in his separate opinion in the Barcelona Traction case agreed with Lauterpacht when he stated that:
since specific legislative action with direct binding effect is not at present possible in the international legal field, judicial pronouncements of one kind or another constitute the principal method by which the law can find some concrete measure of clarification and development.Footnote 183
Cassese, for his part, asserted that:
Since at present, and on a number of political grounds, states are loath to create new rules by treaties, the scope and impact of customary law on international relations is expanding at a rapid pace. However, the difficulty with custom is that, apart from traditional rules, which are undisputed, emerging rules or rules that are indicative of new trends in the world community need, in order to be recognized, the formal imprimatur or a court of law.Footnote 184
The role of international courts and judges to determine which rules have passed into the corpus of CIL cannot be undermined. Yet, this does not imply that the methodology of how to identify CIL should be rewritten for each case where legislative actions have been absent: Such a judicial attitude to engage in ‘an unbridled resort to customary international law as a catch-all concept’ may end up being countered by an excess in formalism while drafting treaties and their applicable law.Footnote 185 Furthermore, if international courts alter the two elements approach to custom in order to strongly engage in creating new customary rules – thus somehow portraying themselves as a primary source of law – it may affect ‘their authoritative’ role as ‘subsidiary means for the determination of rules of law’. Ultimately, if international courts and tribunals lose their authoritativeness in shedding light on international legal rules, the job of identifying CIL would become almost impossible.Footnote 186
With the aforementioned in mind, there are sufficient reasons to argue that it was not actually necessary in the cases examined in this article for the ICTY to take an alternative approach to identifying CIL. Nevertheless, if one still has any doubts, he or she should keep in mind the faith of some decisions where custom ascertainment was done unorthodoxly. The ICC Decision on Malawi's Failure to Arrest and Surrender Al-Bashir, mentioned in the introduction to this article, led to a serious objection from the African Union, which still affects the Court's operation in the African continent.Footnote 187 Beyond this case, the ICRC Study on CIL, which explicitly (and unnecessarily) referred to Kirgis's ‘sliding scale’,Footnote 188 was severely attacked by the US. And, finally, it must be underlined that the Kupreškić case itself is almost a subject of derision.Footnote 189
The lofty endeavour of the Kupreškić Trial Chamber and its reasoning, unfortunately, failed to be accepted by the international community. The UK Manual of Military Law, for instance, explicitly discards the Kupreškić judgment, holding that ‘the court's reasoning is unconvincing and the assertion that there is a prohibition in customary law flies in the face of most of the state practice that exists’. Footnote 190 Even the ICRC resisted adopting the finding of the Trial Chamber without reservations.Footnote 191 True, the Tadić findings on individual criminal responsibility passed the threshold for being retained:Footnote 192 Indeed, the Rome Statute expressly incorporates a long list of war crimes that can be committed in NIACs.Footnote 193 Nevertheless, this did not forestall the drafters from strictly regulating the sources to be applied by the ICC.Footnote 194 CIL is almost left aside from the Rome Statute.Footnote 195 With respect to IHRL, Article 21(3) of the Rome Statute places it at the top of the law to be applied by the Court.Footnote 196 Hence, the drafters intended to ensure that if a conceptual conflict is to take place between the ICC's applicable law and IHRL, the said conflict will have to be interpreted away without the discretion to subvert the traditional doctrine on custom identification.
