1. Fruit of the loom: custom revisited
Customary international law nowadays is often referred to as a recently discovered exotic fruit to be explored and exported all over the world. Despite current reference to its novelty, customary law is regarded as the oldest branch of international law and one of its main sources.Footnote 1 What is novel, however, is the renewed interest in the codification and methodology of rules of customary international law. The importance of this burgeoning awareness holds especially true for customary international humanitarian lawFootnote 2 and the way it protects persons and objects in armed conflict.
With increasing suspicion some merely perceive the customary Trojan horse wheeled in under a humanitarian banner, binding them to rules and norms by which they explicitly did not want to be bound. Yet others find it debatable whether one can codify rules that they deem not to exist in the first place.Footnote 3 The challenge was finally met by the publication of the long-awaited study, Customary International Humanitarian Law (Study) that has been prepared by the International Committee of the Red Cross (ICRC) at the request of the International Conference of the Red Cross and the Red Crescent.Footnote 4 This impressive publication of more than 4,400 pages is the result of an extensive process of worldwide consultations and research that, due to the scope of its investigation, took over ten years to complete. The importance attached to the Study by numerous parties is significant not least because it instigates debate and further research on topics of customary international humanitarian law that are still far from clarified. It distinguishes itself by the thoroughness and density of collected practice that, with its publication, is brought within the ambit of, among others, academics, civil servants, non-governmental organizations, and military personnel.
In an era of globalization, internationally available information about conflicts, which is supplied by civil society, states, and international organizations, facilitates the identification of the prospects of and challenges to international humanitarian law. In confronting challenges in this area of law, heavily regulated by treaties, customary international humanitarian law to this day remains an essentially important institution of law for which the ICRC president, Jacob Kellenberger, identifies three reasons: ‘First, while the Geneva Conventions enjoy universal adherence today, this is not yet the case for other major treaties, including the Additional Protocols’ (Vol. I, p. x).Footnote 5 Consequently, depending on which states ratified which treaties, different international humanitarian law treaties apply to different conflicts (p. xxvii). Contrary to treaties that apply only to the parties that ratified them, once a rule of customary international law has been established it generally applies to all states, even when they have not formally consented to it (p. xxxix). As a result, all states are especially affected by the crystallization of customary international humanitarian law and have a specific interest in participating in the process of its formation.
The second driving factor contributing to the initiation of the ICRC Study is the changing nature of conflict, which makes it difficult to apply traditional rules and ideas about armed conflict. Today the vast majority of armed conflict is of a non-international character that occurs in practically every region of the world. The particular difficulty with this type of conflict is the fact that non-international armed conflicts are subject to fewer treaty rules than international armed conflicts. Consequently, non-international armed conflicts are governed by a limited protection regime which itself has insufficient detail in regulation (pp. xxvii, xxix). Thus international law appears deficient in meeting the needs for protection in non-international armed conflicts, since they are not governed by the same legal regime as international armed conflicts, whereas the needs arising from the factual situation of war are essentially the same (p. x). As stated above, customary international humanitarian law, however, applies to all conflicts, irrespective of their international or internal nature. The ICRC Study asserts that the majority of customary international humanitarian law rules applicable to international armed conflicts also apply to non-international armed conflicts, and that state practice in fact ‘has gone beyond existing treaty law and expanded the rules applicable to non-international armed conflicts’ (p. xxix).
Third, customary law, by its nature ever developing, can influence and complement treaty law when that is necessitated by current developments.Footnote 6 Where the black letter treaty rules leave room for uncertainties or ambiguities, customary international law, and any debate concerning customary international law, can facilitate their interpretation and further clarification (p. x).
Reactions to the Study are now emerging, voiced at the launching conferences of the Study, in recent publications,Footnote 7 and in initial reactions issued by government institutions or officials.Footnote 8 At first glance both positive constructive criticism and negative reception of the Study seem fragmented. A closer look reveals that both the Study and the different ways in which it has been received revolve around two fundamental questions related to the general theory of law and the nature of customary rules in international law.Footnote 9 The first such question seeks a clarification as to why law is law. The second question relates to the much-heard criticism that, in order to accept a rule as law, as legitimate, one has to be able to examine the black box. In other words, it has to be clear where the authority to determine the law lies and what the process that governs that assertion is.Footnote 10
In customary international law the material element of state practice is a function of the normative element opinio juris. The application of this formula in doctrine will lead to different outcomes. This is not generally caused by errors in the evaluation of factual data, but rather stems from divergent views on ‘the established passage of fact into law, from the world of sein into the world of sollen’.Footnote 11 The particular exercise of the process of formation of a rule of customary international law is viewed either as a process of law creation or as the exact opposite, a process of law declaration.
Doctrines will essentially adopt two attitudes: these may, in effect, either seek to explain the appearance of the norm – to ‘found’ law – or they may limit themselves to recording the existence of the norm, to establishing the existence of law.Footnote 12
On the face of it, the mandateFootnote 13 under which the ICRC effectuated the study on the current rules of customary international humanitarian law requires the latter, a declaration of the law. Indeed the Study in offering its findings promises in its results not to amalgamate lex lata with lex ferenda by strictly stating the law as it stands. However, drawing a strict separation between law creation and law declaration is by virtue of the normative element required for the establishment of a rule of customary international law an extremely difficult exercise. In particular, the specific characteristics of international humanitarian law and the situations to which international humanitarian law applies provide an additional hurdle in the application of the above-mentioned seemingly straightforward equation to the process of formation of customary international humanitarian law. This evaluation of the ICRC's customary international humanitarian law study describes the mandate and the overall procedure that was used to execute the mandate. In addition it aims to articulate the complications involved and to unveil some of the critiques that have been issued so far.
2. The overall procedure and the plan of action
In armed conflict breaches of the law can have severe consequences and result in unbearable human suffering and death. Sadly, it is generally perceived that infringements of the rules do not result from their inadequacy but rather from
an unwillingness to respect the rules, from insufficient means to enforce them, from uncertainty as to their application in some circumstances and from a lack of awareness of them on the part of political leaders, commanders, combatants and the general public. (p. xxvii)Footnote 14
The problem of protection of victims under the rules of international humanitarian law and the prevention of violations of these rules is understood to be related to the effective implementation of international humanitarian law (p. xxvii).Footnote 15
That conviction led to the establishment of an Intergovernmental Group of Experts for the Protection of War Victims,Footnote 16 convened by the Swiss government. This group adopted a series of recommendations in 1995 recognizing the need to enhance preventive measures and increase knowledge of and respect for the law of war.Footnote 17 In support of these recommendations, the usefulness and necessity of an investigation into the rules and theory of customary international law regulating an armed conflict was identified in 1996 by the 26th International Conference of the Red Cross and the Red Crescent. The Conference formally mandated the ICRC to prepare a report in accordance with recommendation II, proposing that
The ICRC be invited to prepare, with the assistance of experts in IHL [international humanitarian law] representing various geographical regions and different legal systems, and in consultation with experts from governments and international organizations, a report of customary rules of IHL applicable in international and non-international armed conflicts, and to circulate the report to States and competent international bodies.Footnote 18
Under this mandate the ICRC embarked on an enormous research project in undertaking to increase respect for, and knowledge and implementation of, international humanitarian law. In addition, the Study reflects the ongoing discussion and factual situation related to the proclamation that rules of international humanitarian law, and the protection they offer by placing limitations on the ways to conduct a war, should not be applied equally to international and non-international armed conflicts. Not only was the purpose of the Study to provide evidence of the equal application of customary international law rules to both types of conflicts but, in order to overcome impediments to the application of treaty law, it also aimed to demonstrate that state practice has in fact ‘gone beyond existing treaty law and expanded the rules applicable to non-international armed conflicts’ (p. xxix). For all these reasons substantial knowledge of rules of customary international humanitarian law is important to, among others, academics, members of the judiciary, and government functionaries, but also, most importantly, to fighters and others literally involved in the armed conflict and in need of protection.
In determining the most favourable manner in which to organize the study, the study steering committeeFootnote 19 decided on a plan of action which arranged the research into six parts: part I, principle of distinction; part II, specifically protected persons and objects; part III, specific methods of warfare; part IV, weapons; part V, treatment of civilians and persons hors de combat; and part VI, implementation.Footnote 20 Research into the different parts of the study was based on both national and international materials that reflect state practice and on research into the archives of the ICRC, which document nearly forty recent armed conflicts (p. xlvii). The first group were assembled through co-operation with national researchers,Footnote 21 who included in their respective country reports material such as military manuals, national legislation, national case law, instructions to armed and security forces, military communiqués during war, diplomatic protests, opinions of official legal advisers, comments by governments on draft treaties, executive decisions and regulations, pleadings before international tribunals, statements in international organizations and at international conferences, and government positions taken with respect to resolutions of international organizations (pp. xlv, xlvi).
Six research teams,Footnote 22 each assigned to one of the six parts of the study, collected the international materials consisting of practice within international organizations, particularly the United Nations and its organs,Footnote 23 preparatory works of treaties, state submissions to international and regional courts, and international case law. An attempt was made to be as globally representative as possible through the contributions of legal scholars around the world, the composition of the steering committee, the country reports, and the other materials that were used.Footnote 24 In the end all the collected materials were consolidated into the six identified areas of the study and formed the basis of an ‘executive summary’ that was prepared by the international research teams for each of the six areas (p. xlvii). The executive summaries were the subject of three rounds of consultations with the steering committee. The last two of these meetings included consultations and evaluations with a group of academic and government experts (p. xlvii). The reviewed assessment of the steering committee provided the starting point for the eventual writing of the report, whose authors, Jean-Marie Henckaerts and Louise Doswald-Beck,Footnote 25 scrutinized the formulation and the sequence of the rules, and bear responsibility for drafting the commentaries thereto.
The result of this impressive enterprise is a capacious two-volume publication. Volume I contains the rules according to the findings of the ICRC and Volume II contains the relevant collected practice that was used to evidence the findings in Volume I. Each rule in Volume I makes reference to the relevant chapter and section in Volume II that provides the reader with the state practice used to support the rule.Footnote 26
3. Method matters: selected practice and application of method
An adequate assessment of the contribution made by the ICRC Study views it in connection with the time and period during which it developedFootnote 27 and highlights the legal method and theory that form the underlying basis for its assessment.Footnote 28 A closer look at the current academic debate on the methodology (that should be) used to identify customary international humanitarian law resolves that it has mostly to do with one's view on the status of customary international humanitarian law and the way in which it is interpreted.
Behind the apparent first step of analysing the elements involved in the process of rule creation lies a particular approach towards international law and the choice in method that has been made. Method for many if not most scholars generally refers to ‘the application of a conceptual apparatus or framework – a theory of international law – to the concrete problems faced in the international community’.Footnote 29 Each legal theory, be it international legal process, legal positivism, or feminist jurisprudence,Footnote 30 employs its own method.Footnote 31 Although differentiation between methods may at times prove difficult because they can share common denominators or pursue the same goal, the preference for a certain method presupposes certain assumptions one has about international law. The method implies assumptions about the nature of international law and its function, and about who the decision makers are whose acts of law creation, interpretation, and application are relevant to the general process of rule creation in international law.Footnote 32 The authors of the ICRC Study display a modern positivist view on international law in describing the law as it is and in regarding it as a unified body of treaty and customary law rules that is based on formal criteria and subject to the consent of states (p. i).Footnote 33 It assumes that states are the primary actors under international law, negating the role of non-state actors in the process of law creation. However, modern positivism, as opposed to traditional positivism, seems to allow a broader perspective to this framework in that it acknowledges that decisions of international courts and tribunals (in taking into account the particular value of such decisions – p. xxxiv) and, owing to their international legal personality, the practice of international organizations fulfil a role in the process of law creation (p. xxxv). Nonetheless, the predominant exclusion of potential contributions of non-state actors, such as armed opposition groups, from the international lawmaking process by the method decided on by the ICRC is evident. The practice generated from these specific groups is mentioned in the study as ‘other practice’ (p. xxxvi), leaving it unclear in what way, if any, it contributes to the process or how it influences the eventual conclusion (rule) reached by the ICRC.
3.1. Dilemma
Within the choice of legal philosophy underlying the approach to international law there is a methodology that is used to appraise what the rules of customary international law are. Textbooks on international law generally follow the jurisprudence of the International Court of Justice (ICJ) and identify customary international law to be a source of law, the rules of which are created on the basis of two elements: state practice (usus) and opinio juris (opinio juris sive necessitates). References to the two-element doctrine would include passages of the North Sea Continental Shelf cases, in which the ICJ analyses general custom creation:
Not only must the acts concerned amount to a settled practice, they must also be such, or be carried out in such a way, as to be evidence of a belief that this practice is rendered obligatory by the existence of a rule of law requiring it. The need for such a belief, i.e., the existence of a subjective element, is implicit in the very notion of the opinio juris sive necessitates.Footnote 34
In legal reasoning two main approaches can be distinguished with regard to establishing a new rule: deductive methodology and inductive methodology. The inductive methodology entails that one starts with the facts, the instances of practice, from which one can derive the existence of the general rule. The deductive methodology on the other hand assumes a general statement of the rule which is then further supported by instances of practice that can be found. The essential difference is that ‘in a deductive argument, the truth of the premises is supposed to guarantee the truth of the conclusion; in an inductive argument, the truth of the premises merely makes it probable that the conclusion is true’.Footnote 35
The choice to be made between the two seemingly straightforward methodologies is not at all apparent. The dilemma and its complexities become evident when one attempts to apply this twofold methodology to the formation of customary international law rules, specifically customary international humanitarian law rules, based on the two-element doctrine. Experience in the practical application of the theory leads to the conclusion that the elements can easily become intertwined with the methodology and that, depending on the case, they are often difficult to assess separately. The available variety of opinions suggesting types of interpretation of the theoretical models demonstrates that many different appraisals are indeed possible. Roberts, for example, links the distinction between traditional and modern customary law to the distinction between inductive and deductive methodology.Footnote 36 The traditional approach to custom implies that one looks at the practice and then assesses the opinio juris. Roberts seems to describe this operation as one of induction, the two elements of custom being the two pillars of the inductive approach. The new modern approach of custom, mainly focusing on opinio juris, would then be assimilated to deduction, as starting by the psychological element would amount to stating the existence of a rule. Therefore Roberts makes a connection between the intellectual operation and elements to be weighed.
An example of an entirely different exercise given by CortenFootnote 37 demonstrates a link between flexibility or rigidity in the approach or methodology and the way in which one understands the constitutive elements of custom. According to Corten, each approach has a different understanding of what amounts to state practice and, in fact, of which element – practice or opinio juris – has the more dominant role in the assessment of custom. The extensive approach places emphasis on the act of deduction by viewing practice as the dominant element, while the restrictive approach assigns this role to opinio juris.Footnote 38
The Study decisively states that it ‘sought to analyse issues in order to establish what rules of customary international law can be found inductively on the basis of State practice’ (p. xxx, emphasis added). However, the careful depiction of the inductive methodology as claimed to be employed in the Study proves less transparent as one delves deeper into individual assessment of rules and finds that the distinction between what is assessed by means of induction becomes blurred with what is assessed by deduction. As Meron articulates this development, ‘The movement from the inductive to the deductive method of ascertaining custom is a result of the expansion in what counts as practice of States and the enhanced significance of opinio juris.’Footnote 39
3.2. A classical approach and a cautious choice
After the publication of the ICRC Study, state representatives and academic experts seemed determined to identify ‘apparent’ flaws in the Study and particularly to fire their ammunition at part IV, dealing with weapons. Constructive criticism should of course be received as positive input which will further advance both debate and law. However, it would be helpful to appraise the quality of the work with which both authors were charged, in the light of its place in legal literature and, especially, the manner in which they argue the existence or emergence of a rule of customary international humanitarian law.
Volume I of the Study, containing the assessment of customary international humanitarian law rules, is based on the evidence provided in Volume II, offering a dense coverage of state practice. The rules are stated to be derived from the evidence. As mentioned, some of the practice in Volume II concerns materials that do not form part of state practice, such as jurisprudence from international courts and tribunals, practice from international organizations, and so-called ‘other practice’, generated by armed opposition groups. In addition, one finds expert opinions that were considered useful to give expression to different interpretations of theory, rules, and formulation. The Study emphasizes that what is written down reflects not what ought or should be the rules of customary international humanitarian law, lex ferenda, but rather what could be found to be the current rules of customary international humanitarian law based on the actual practice of states, lex lata, at that point in time. Before the ICRC could draw conclusions on the contents and formulation of the rules two difficult questions had first and foremost to be answered: how does one decide what constitutes state practice, and when does that practice contribute to the creation of a rule of customary international humanitarian law?
These questions go back to the assessed arena for this exercise that features on the one hand a wide and flexible notion of methodologyFootnote 40 favouring flexibility in the place and content of customary law, but on the other hand a narrow and rigid approach to methodology that favours strict interpretation and inflexibility towards changes or new exceptions to a rule.Footnote 41 These opposite poles have complicated and finely divergent variants in between. However, in order to facilitate what is a difficult dialogue these two approaches are distinguished.
In the broad interpretation method of the wide or flexible approach custom is both a formal and a material source.Footnote 42 Because this method of legal interpretation takes political and moral considerations into deliberation it is in effect policy-oriented. The narrow methodology takes international treaties, especially the UN Charter, as a point of reference. In this framework of reasoning, Article 38 of the ICJ Statute is of critical importance, since it is considered to form the constructive basis of a ‘textually-oriented, hierarchical series of sources set out in Articles 31 and 32 of the Vienna Conventions’.Footnote 43
In effect there are different ways to approach the issue of formation of customary law.Footnote 44 One example is doctrine which emphasizes the need to recognize that ‘new’ or contemporary custom is not custom as we traditionally understand it but a new process of formationFootnote 45 which includes non-state actors.Footnote 46 The ICRC chooses a classical approach based on Article 38(1)(b) of the ICJ Statute,Footnote 47 under which customary international humanitarian law as ‘a general practice accepted as law’ traditionally holds two constitutive elements: practice (usus) and opinio juris (opinio juris sive necessitates) of states.
3.2.1. Selection of state practice
In the assessment of rules of customary international law in areas involving controversial issues such as state responsibility, protective rules in non-international armed conflict, or humanitarian intervention, the lack of state practice proves a constant source of concern for the international positivist lawyer. Modern positivist views, however, promote a ‘broader view of the ways and fora in which states can express their will’, including through the practice of international institutions, such as international tribunals, ‘and of states in accepting the jurisprudence of those tribunals’.Footnote 48 The selection of state practice that was found to be relevant ‘official practice’ consists of both physical and verbal acts contributing to the creation of a rule. Although many critics do not consider verbal acts to constitute state practice, the ICRC finds that their inclusion as such is consistent with the approach taken by states and international bodies such as the International Court of Justice, the International Law Commission (ILC), the International Criminal Tribunal for the former Yugoslavia (ICTY), and the International Law Association (pp. xxxii, xxxiii).
The term ‘official practice’ is not defined in the Study; however, with reference to Article 4 of the ILC Draft Articles on ‘Responsibility of States for Internationally Wrongful Acts’ in combination with the examples of practice listed in the Study (pp. xxxiv–xxxvi), it could be concluded that ‘official practice’ means the conduct of any state organ (executive, legislative, or judicial branch), including a person or entity which has that status in accordance with the internal law of the state. It is not entirely clear from the chapter ‘Assessment of Customary International Law’ whether the ICRC follows Articles 5 and 8 of the ILC's Draft Articles on the attribution of conduct to a state by including conduct of persons or entities exercising elements of government authority (Art. 5) or conduct of person(s) that is directed or controlled by a state (Art. 8). The latter type of conduct is a material form of attribution and would, for the purpose of the Study, arguably be close to impossible to assess. In fact, the ICRC lists further requirements to official practice that would exclude this conduct for the most part. For official practice to be relevant it ‘has to be public or communicated to some extent’ (p. xxxiv) to at least one other state or international organization. Undisclosed acts are not considered to contribute to the creation of a rule, neither are internally inconsistent acts.
The choice to accept both physical and verbal acts as state practice seems all-encompassing and potentially problematic. Although the two are not always easily distinguished, verbal acts seem to belong to the realm of opinio juris; however, they are presented as state practice. The complexity of assessing battlefield practice in the midst of armed conflict understandably leads current debate on what counts as practice to allow official statements of states to be included in that category. The ‘fog of war’ also led the ICTY to conclude that in the process of identifying customary international humanitarian law it is justifiable to look at what states ‘say’ rather than what they ‘do’.Footnote 49 In the same breath the ICTY indicates military manuals as being an element that is relevant to the equation. In line with this reasoning Volume II of the Study contains as practice military manuals, which arguably, in particular according to military lawyers,Footnote 50 do not constitute state practice.Footnote 51 However, military manuals form the basis of the ‘skills and drills’ and ‘techniques, tactics and procedures’ (TTP) on which military personnel act in the field. Consequently, the contents of the rules of military manuals have a direct effect in the field and on the actions of the involved military personnel. The authors of the Study maintain that individual actions and exercises of individual military personnel are indeed difficult to assess in the course of armed conflict; however, the actions are in fact based on the prescribed military instructions manuals. The same reasoning also holds true for national case law condemning military personnel for violations of international humanitarian law during armed conflict.Footnote 52
Evidently, international organizations and international courts and tribunals are not state organs. Nonetheless, practice derived from these institutions has a particular value which the Study takes into account in the assessment of customary international humanitarian law: ‘Although decisions of international courts do not constitute state practice their decisions have nevertheless been included because a finding by an international court that a rule of customary international law exists constitutes persuasive evidence to that effect’ (p. xxxiv).Footnote 53 Moreover, their decisions have a potential influence on state practice and on the practice of international organizations. The latter are equipped with international legal personality. The Study proposes that international organizations, by virtue of possessing international legal personality,
can participate in international relations in their own capacity, independently of their member states. In this respect their practice can contribute to the formation of customary international law.23 . . . In addition, official ICRC statements . . . have been included as relevant practice because the ICRC has international legal personality25 . . . [and] works under its official mandate from states. (p. xxxv)
23 See, e.g. Case concerning Reservations to the Convention on the Prevention and Punishment of the Crime of Genocide, Advisory Opinion, 28 May 1951, [1951] ICJ Rep. 15, p. 25.
25 See, e.g., ICTY, Prosecutor v. Simić et al., Case No. IT-95–9-PT, Decision on the Prosecutor's Motion . . ., 27 July 1999, . . . para. 46 and footnote 9.
International organizations have, irrefutably, an effect on the international legal order. However, that assumption derived from a more detailed assessment of the status of the organization in question, and the extent to which its practice contributes to rules of customary international law seems to cut a few corners,Footnote 54 in particular considering the impossibility of providing an unambiguous answer to whether or not ‘the term practice as used in Art. 38 of the ICJ Statute includes the practice of international organizations’.Footnote 55
With regard to practice derived from international organizations, the Study makes an important distinction between the process preceding the adoption of a resolution and the resolution itself. The preceding process involves the negotiation and adoption of resolutions which constitute acts of the states (p. xxxv, n. 25), while the resolution itself constitutes an act of the organization. The weight and the effect of a resolution on the process of formation of a rule of customary international law depends in large part on which organization adopted the resolution, and particular circumstances such as ‘its content, its degree of acceptance and the consistency of state practice outside it’ (pp. xxxv–xxxvi).
3.2.2. One swallow does not make a summer
To draw unambiguous conclusions based on the particular forms of practice as described above requires a form of authoritative abstraction and thus a normative evaluation of available practice. This, frequently overlooked, requirement ‘results from the fact that norms and the linguistic objectifications cannot be induced from such data alone. The individual instances of practice from which customary law is derived are never identical, as is often presupposed implicitly.’Footnote 56
To address the second question, of how to assess the selected state practice, the ICRC follows the criteria of the ICJ in the North Sea Continental Shelf cases to assess whether a rule is of sufficient ‘density’. The practice needs to be virtually uniform, extensive, and representative (p. xxxvi).Footnote 57 The passage of a long period of time is not a necessity since density of practice can develop over a reasonably short period of time. The fact that practice should be virtually uniform means that it ought not to be substantially different.Footnote 58 However, at the same time the ICJ considered it enough for practice to be sufficiently similar: ‘too much importance need not be attached to a few uncertainties or contradictions, real or apparent’.Footnote 59
Furthermore, contrary state practice does not necessarily prevent the creation of a rule of customary international humanitarian law ‘as long as this contrary practice is condemned by other States or denied by the government itself and therefore does not represent its official practice’ (p. xxxvii, emphasis in original). In these particular cases the rule is in fact reaffirmed by the reactions of states or the government in question: ‘Instances of State conduct inconsistent with a given rule should generally have been treated as breaches of that rule, not as indications of the recognition of a new rule’.Footnote 60
The further consideration in the ICJ's finding that state conduct incompatible with the rule, that is attempted to be justified or to be regarded as an exception to the rule, has particular significance for international humanitarian law, in the sense that this attitude strengthens rather than weakens the rule.Footnote 61 In the Study and the collected materials representing state practice much emphasis is placed on battlefield behaviour and violations of rules of international humanitarian law. The mere fact that violations of certain rules are mostly condemned actually affirms the existence of the rule rather than weakens its position as a rule of customary international humanitarian law. The expression of the Court in the Nicaragua case is applied analogously to case law concerning conduct of individuals in an armed conflict, and to resolutions of international organizations condemning a certain act. The condemnations show that these practices are considered to be violations of existing rules and not practices accepted as, or aimed at, establishing new rules.Footnote 62
Extensive and representative practice, as is required when assessing the density of a rule, implies the qualitative criterion of state practice, articulated by the ICJ in the North Sea Continental Shelf cases, that the practice involved must ‘include that of states whose interests are specially affected’.Footnote 63 Specially affected states on the one hand can establish a rule of customary international law through their practice without the active participation of a majority of states, and on the other hand can prevent the establishment of a rule by not accepting the practice. The International Law Association (ILA) dealt with the issue of specially affected states.Footnote 64 Exactly who is ‘specially affected’ seems to be a case-by-case decision. However, when it comes to ‘specially affected’ states in international humanitarian law the ICRC assessed that all states have ‘a legal interest in requiring respect for international humanitarian law by other States, even if they are not a party to the conflict (see the commentary to Rule 144)’ (p. xxxix).Footnote 65 Therefore the Study deems all state practice in this regard to be relevant.Footnote 66
3.2.3. Opinio juris
The legal obligation establishing a rule cannot just be derived from a general practice. In order for a practice to generate a legal obligation it is required that the practice is seen as an action based on the conviction that one is acting under a legal obligation. Again, on this issue different views are distinguished. Some argue that states must express the conviction that they are legally bound through their practice, while others maintain that there must be a belief that what they (states) have done is legally correct. Both theories have their strengths and weaknesses. The theory of consent is difficult in cases where states have not made any statement at all on an issue because they may not have been specifically interested or affected at that time. A solution to this dilemma is to say that the states in question have acquiesced to a rule; they have given a silent consent to it. Should you approach the issue from the perspective of what a state believes to be legally binding you are faced with the difficulty of how to measure that. It is close to impossible to assess what states believe. The only possible way to have an indication of such beliefs is to look at what a state says it believes through statements, military manuals, and national case law. Through this practice the belief of what is considered to be legally binding is transmitted. What in this respect is done on a regular, extensive, and repeated basis becomes the rule and the guiding conduct for all states.
The discussion by the ICRC explicitly leaves aside the issue of whether and how states can persistently object to the emergence of a customary rule binding on a particular state. It is generally argued that, even though customary law by nature applies to all states, the controversial persistent-objector principle can free them of their obligations under customary international law. The persistent-objector principle holds that if states utter express and consistent objections to the first developments contributing to the formation of a rule of customary international law at the right point in time, they can avoid being bound by that rule by virtue of being a persistent objector. However, it is unlikely that this position can be maintained when the rule, after its inception, has been established as a rule of customary international law. Some commentators hold it to be impossible for a state to claim persistent-objector status in the case of a norm of jus cogens, while others deny that the concept exists in international law in the first place. The notion of persistent objection was considered a controversial topic, and its existence as a doctrine under international law is not uncontested. Therefore the ICRC study took no view on the legal possibility of the concept of persistent objector (p. xxxix).Footnote 67 If, however, the Study's point of departure is consent, an assessment of the persistent-objector concept is unavoidable.
Although in principle state practice and opinio juris are two separate elements contributing to the formation of a rule of customary international humanitarian law, it turns out that they are very difficult to separate in practice. In fact the ICRC found that often ‘one and the same act reflects practice and legal conviction’ (p. xl). In identifying a rule of customary international humanitarian law an abundance of available state practice makes it less necessary to demonstrate the existence of separate opinio juris, since the latter is often contained within the practice. On the other hand, however, when there is little, or only ambiguous, practice to provide evidence to a rule, it is essential to identify opinio juris in order to decide whether the practice in fact establishes a rule of customary international humanitarian law. Omissions and abstentions from certain conduct constitute a particular problem in this respect.
4. The product: contents, comments, and criticism
4.1. What you can(not) find in the Study
The foreword of the Study, emphasizing the need for it, its timeliness, and the challenges that lie ahead, is followed by the introduction that outlines the mandate, drafting history, and purpose of the Study. Additionally, the introduction details the scope and organization of the Study and the way in which the elements of customary international law were assessed for the purposes of the Study. The reader then dives straight into the substance of the rules, starting with Rule 1 on the distinction between civilians and combatants as contained in chapter 1 of part I. Parts I to VI of the Study deal respectively with the principle of distinction, specifically protected persons and objects, specific methods of warfare, weapons, treatment of civilians and persons hors de combat, and implementation. The parts are divided into 44 chapters that together cover the 161 rules of customary international humanitarian law identified by the Study.
The Study is not exhaustive in nature, nor was it intended to be. Some issues were, for a number of reasons, not included. For example, chapters on general principles, identification, or occupation are missing. The Study specifically emphasizes treaties not universally ratified, such as the Additional Protocols, the Hague Convention for the Protection of Cultural Property, and specific conventions on the use of weapons, because that was considered more pressing than universally ratified treaties such as Geneva Conventions. Topics that might be included in future updates of the Study are, for example, the Martens Clause, identification of specifically protected persons and objects, and civil defence.
In addition, a number of topics that have been included in the Study are revealed as requiring further clarification.Footnote 68 The definition of ‘civilians’ in non-international armed conflict has not been clarified in practice or treaty law (Rule 5, p. 19). Although the protection of civilians is often mentioned in treaties, there is no definition of who is included in this category. It is particularly unclear in the case of members of armed opposition groups and in the case of civilians who become engaged in the armed conflict. Consequently, it is equally unclear whether individuals in captivity who are categorized as such should or should not be granted prisoner-of-war status.
The concept of direct participation in hostilities is also far from transparent. Although some human rights bodies have distinguished between ‘direct’ and ‘indirect’ participation (Rule 6, pp. 22–3),Footnote 69 ‘a clear and uniform definition of direct participation in hostilities has not been developed in State practice’ (Rule 6, p. 23). Civilians lose their immunity from attack when they engage, or directly participate, in an armed conflict; however, it is not clear exactly when that is. The temporal scope or the acts that constitute direct participation have not been identified.Footnote 70 In dealing with crimes against persons taking no active part in hostilities, the ICTY trial chamber in the Tadić case stated that
it is unnecessary to define exactly the line dividing those taking an active part in hostilities and those who are not so involved. It is sufficient to examine the relevant facts of each victim and to ascertain whether, in each individual's circumstances, that person was actively involved in hostilities at the relevant time.Footnote 71
This approach was also taken by the United States, which includes the following paragraph in its naval handbook:
Direct participation in hostilities must be judged on a case-by-case basis. Combatants in the field must make an honest determination as to whether a particular civilian is or is not subject to deliberate attack based on the person's behaviour, location and attire, and other information available at the time.
In 2003 the ICRC started a series of expert consultations to explore further and identify the scope and legal consequences of the concept of direct participation (p. 23, n. 137).Footnote 72
The issue of qualification of a person as a civilian in case of doubt is related to the concept of direct participation and requires further investigation into its complexities. Additional Protocol II to the Geneva Conventions (APII) offers a solution by stating that in case of doubt a person should be qualified as a civilian; however, since this provision of APII was the object of a number of state reservations and declarations, the Study could not draw any conclusion as to the customary nature of this rule.
4.2. Vexing issues
The following section aims to provide an overview of some critical issues in relation to the Study that consist either of general comments or of detailed concerns. As previously discussed, much criticism has been ventilated as regards subjects that are missing from the Study's content or issues that were not properly addressed or clarified to a satisfactory level. In addition, the basis on which the assertion of rules has been made is subject to query. In particular, certain sources, such as military manuals, are often deemed unsuitable to serve as a source of evidence for the Study, since they are considered to be an expression of policy and not necessarily of what is believed to be the law. This criticism has received firm rebuttal from the authorsFootnote 73 and holds less authority than arguments related to, for example, the density of practice from which some rules have been derived or the failure to include deviant practice. A striking example in this respect is that, despite the Study's intention of including worldwide state practice, the analysis of statutory limitation of international crimes, commencing with Rule 160,
does not represent all legal systems and case law on this aspect. For instance, its survey on domestic provisions on the non-applicability of statutory limitations to international crimes failed to include such provisions contained in Latin American legal systems, except for Cuba. In addition, the ICRC study fails to include deviant state practice on this matter.Footnote 74
Some doubts regarding the customary nature of specific rules in the Study stem from the belief that the legal reasoning based on the evidence used to support a rule is not persuasive enough at all times to affirm a rule of customary international humanitarian law. For example, Rule 108 of the Study, granting states the right to deny mercenaries combatant or prisoner-of-war status, could have alarming consequences, to which Guantánamo Bay bears witness.
If Rule 108 is truly a rule of customary law, then it applies to all states, including parties to the Geneva Conventions who are not parties to Additional Protocol I. Rule 108 thus implies that specific provisions of the 1949 Geneva Conventions can be altered not only through the amendment process of the conventions themselves, but also through subsequent customary practice.Footnote 75
Another point of contention that has been identified is the use of certain terminology and the way in which the rules of the Study are phrased: the language of the Study differs in many instances from treaty language. On the one hand this practical approach seems reasonable and in fact it keeps simple what is simple by e.g. calling captives what they are: ‘persons deprived of their liberty’ (chapter 37, p. 428). On the other hand terms used such as ‘humane treatment’ are not clarified, leaving ambiguity regarding the actual implementing treatment.Footnote 76 Not to mention the difficulties that arise while applying and interpreting the law when a codification of customary international law rules applies such different wording from the simultaneously applicable treaty body of law.
In explaining this approach in formulating and articulating, the authors of the Study indicated that they concluded their formulations on basis of the actual state practice that was found, and in fact the language of that practice differed substantially from treaty language.Footnote 77 For instance rule 42 addresses potential attacks on works and installations containing dangerous forces (Rule 7, p. 25) and is related to the protection of civilians. Dams, dykes, and nuclear power plants may not be the object of any attack if they are civilian objects; however, this immunity from attack is revoked when they become military objects. Additional Protocol I deals with this in a very elaborate and complicated ruleFootnote 78 which has not been ratified by a number of states. The Study identifies the grave concerns states have in relation to such attacks and embedded these considerations in the formulation of Rule 42, which is considered to be a norm of customary international humanitarian law applicable in both international and non-international armed conflicts. Rule 42 cannot be found in treaty law and in fact appears less restrictive than the formulation of Article 56 of Additional Protocol I.
Another example relates to the use in two different contexts of the term ‘combatant’ in a number of rules in the Study. First, Rule 1 (p. 3) talks about combatants in referring to the fact that one participates in an armed conflict and therefore is a combatant. In this sense the term has a broad meaning that relates to the action, the activity. In the second context, Rule 106 (p. 384) refers to the combatant as indicating a certain status. The problem with this specific use of the term ‘combatant’ is that a word is employed that has legal connotation and significance. The original term used to indicate the first context was ‘fighter’; by mixing two different concepts the meaning has become unclear.
A third example to illustrate that some rules might be phrased with more clarity is Rule 137, which prohibits the participation of children in hostilities. The commentary that follows the rule elaborates on the age limit that is put on the participation in hostilities and states that ‘there is agreement that it should not be below 15 years of age’ (p. 488). There is no mention of age in the rule itself, although this is an important piece of information that could have been made clear in the rule.
It is important to assess the forum through which states can react to the findings of the Study. So far, most reactions have come from scholars and relate to the methodology and conclusions drawn. However, emerging reactions from a military perspective often focus on the accuracy of the formulation of rules relating to weapons. In addition, there appears to be quite some disagreement with the theory that many rules of Additional Protocol I, although differing in wording and scope in some instances, now also apply as customary rules to non-international armed conflict, particularly in consideration of the fact that states specifically did not sign the protocol. These reactions are to be noted seriously as they, directly or indirectly, voice the challenge by states to certain rules. It is in the reactions of states to the Study that we can find affirmation or denial of the existence of a rule of customary international humanitarian law. Also, the question is raised of whether customary law is not in fact an implementation of treaty obligations. The next section deals with the interplay between these two sources of law – treaty rules and rules of customary law – and pays special attention to criticisms related to the assessment of rules on weapons.
4.3. The relationship between treaty rules and rules of customary international humanitarian law and some specific issues relating to weapons
Customary international law and treaties have a particular effect on each other. The relevance of treaties to the interpretation and assessment of customary international law is that treaties give expression to the view of states on certain rules.Footnote 79 Treaties can reflect customary international law when they codify already established customary international law. On the other hand, the treaty can be the normative framework, the first step, stimulating the creation of a new rule of customary international law. The jurisprudence of the ICJ, as summarized by the ILA, provides four ways in which customary international law and treaty law influence each other:
[I]t [a multilateral treaty] can provide evidence of existing custom; it can provide the inspiration or model for the adoption of new custom through State practice; it can assist in the so-called ‘crystallization’ of emerging custom; and it can even give rise to new custom of ‘its own impact’ if the rule concerned is of a fundamentally norm-creating character and is widely adopted by States with a view to creating a new general legal obligation. (pp. xliii–xliv)
By using the widespread ratification of treaties as indicative evidence that they should be appraised in conjunction with other state practiceFootnote 80 giving evidence to the existence of a rule, the ICRC is vigilant in its approach (p. xliv).
After the publication of the study, much of the debate reflected in publications and held among military practitioners and legal advisers attending international conferences focused on practical issues such as weapons, since the Study draws conclusions on issues related to weapons whose customary nature is subject to debate. The discussion of some issues related to weapons might further clarify how the ICRC dealt with the relation between treaty rules and rules of customary international humanitarian law and how they have been formulated.
Practice involving exploding bullets (weighing less than 4 g), which have been banned by the St Petersburg Declaration of 1868, shows that this type of bullet has in fact been used and there have been no objections.Footnote 81 Therefore, according to the assessment of the ICRC, the ruleFootnote 82 that has developed in custom is slightly different from the treaty rule. In effect, according to formulation in the customary law study, the anti-personnel use of exploding bullets is prohibited; however, the anti-material use is nowadays accepted.
The second example concerns the use of land mines. The 1997 Ottawa Convention banning the use of anti-personnel minesFootnote 83 is not universally ratified. Even though the majority of states are party to the Ottawa Convention and as such are bound by the prohibitions under this convention, there is sufficient official contrary practiceFootnote 84 that the use of land mines cannot clearly be considered as prohibited under customary international humanitarian law. Therefore the rule was not at this stage found to be customary. With regard to specific restrictions to the anti-personnel and anti-vehicle use of land mines there are a number of provisions such as Protocol II to the Convention on Certain Conventional Weapons (CCW) and the amended Protocol II to the CCW. The ICRC did not assign all these detailed rules as customary, but at the same time it is noted that there is much concern among states at the way in which land mines are used. The ICRC therefore included a general rule in the study indicating that all steps must be taken to limit their indiscriminate effects.Footnote 85 The same can be said for the rules in the Study that deal with the issue of the placing and removal of land mines.Footnote 86 These rules are not the same rules as can be found in treaty law since they are less detailed; however, they more or less summarized the many instances of practice that can be found dealing with this issue.
The third and last example concerns Rule 86,Footnote 87 dealing with blinding laser weapons. The use of these weapons was outlawed by Protocol IV to the CCW, adopted in 1995. This prohibition was found to be a rule of customary international law even though the protocol was only adopted ten years ago. This particular example illustrates that the formation of custom does not require age-old practice but can develop rather quickly.Footnote 88 This can also be seen with regard to developments regarding, for example, peacekeeping forces or the prohibition of crimes of sexual violence.
4.4. Practicalities: the user-friendliness of the Study for the practitioner
From the perspective of a researcher or practitioner some criticism of the user-friendliness of the Study would be justified, as it is not necessarily easy to retrieve information from it. The first point relates to the overall relation between appendix and preceding text, that could use further clarification. All sources that were used throughout the study can be retrieved from the appendices to Volume II. However, since there is no reference to where they are used in the Study, it is impossible to assess the extent to which state practice from a specific country contributes to which rules. This could be the indirect result of having national reports that were then merged into the international reports from which the ICRC later again extracted national practice. Another slight hindrance when using the Study is that the appendices contain long lists of resolutions and cases, for which there is no index. It is near impossible to find a particular resolution, for example a resolution on child soldiers as adopted by the European Parliament. In addition, it is also not possible to assess the effect and contribution of specific situations to the formulation of a rule. For example, one could not find information by searching under the term ‘Kosovo’. A final practical point is that the authors have, either in writing or in statements,Footnote 89 drawn main conclusions from the Study that have not been clearly articulated as such in the Study itself. They can be found implicitly or in a few sentences scattered throughout the introduction; it would have been useful to have them clearly and separately identified.
5. Conclusions
5.1. The contributions of the Study to international humanitarian law
If one were to assess the chief contributions of the Study to international humanitarian law, the following three crucial points, as a bare minimum, should be identified. The first evident achievement of the ICRC in this respect is that, finally, a written document identifying rules of customary international humanitarian law and their scope of application to international or non-international armed conflicts has been produced. Although not all the rules identified by the ICRC are universally accepted, there seems to be a widespread practice and acceptance of basic rules and principles, such as rules relating to the conduct of hostilities or the treatment of persons in the power of a party to the armed conflict.
Second, a comparison of the rules that the Study deems applicable to international armed conflicts and non-international armed conflicts shows that the normative framework for non-international armed conflicts is much more detailed in customary law than it is under treaty law. State practice seems to have substantially developed rules and obligations that have gone beyond existing treaty law and increased the rules applicable to non-international armed conflicts.
The third distinct advantage offered by the Study relates to the difficulties in qualification of conflicts. Qualification of the type of conflict – international or non-international – triggers the appropriate regime of protection under international humanitarian law. The protective regime applicable to international armed conflicts is much broader than the protective rules available for non-international armed conflict. In practice, the decision of how to qualify a conflict can be very difficult to make, while the past decade has shown that the majority of conflicts nowadays are internal in nature. The Study seems to indicate that a common standard of behaviour has developed that applies to all armed conflicts regardless of whether the conflict in question is international or non-international – of the 161 rules that the study contains 155 are declared to apply to both international and non-international armed conflicts. There seems to have developed an understanding of forms of behaviour that are required from a party to an armed conflict and others that are absolutely prohibited. The particular importance of this assessment is that the level of protection that is provided to parties involved in an armed conflict no longer depends on this complex appraisal of the nature of armed conflict.
5.2. Closing remarks
The Study can be considered to be an epic work whose conclusions are not always accepted. Faced with its magnitude, some choose to narrow their focus and highlight a specific part or number of rules as the object of their criticism. Many reactions so far to the Study centre on the question of whether it is justifiable either to criticize or to applaud the method of assessment employed by the ICRC. While some might consider the debate on methodology a capricious fashion among scholars, the discussion is still very much alive, since it touches on the grey area between law, policy, and policy-oriented interpretation of the law.
For a comparative perspective, the milestone decision on jurisdiction of the Appeals Chamber of the International Criminal Tribunal for the former Yugoslavia in the Tadić caseFootnote 90 gave rise to similar dialogue reflecting this train of thought.Footnote 91 In the Tadić case the grounds for the defendant's challenge to the jurisdiction of the ICTY offered ample opportunity for the Tribunal to make statements on some important questions of law and to develop the law further, in particular extending the international humanitarian law applicable to non-international armed conflict. However, the decision received criticism, mostly related to the methodology it employed to arrive at its just conclusions.Footnote 92 The Tribunal's at first apparently cautious approach develops a very broad assessment of international humanitarian lawFootnote 93 to elucidate the basis of its legal findings, while in the end substance is tackled in accordance with the Tribunal's mentioned objective by the use of a ‘reverse methodology’.Footnote 94 This tendency seems to have been followed in the Study, at the risk of amalgamating lex lata and lex ferenda, in pursuit of a lofty purpose.
There was also criticism for the incremental vagueness of the Tribunal's statement on ‘general principles’; however, the comparison with the Study ends here. The Study should be commended for its effort to articulate the rules with clarity, while ‘the whole exercise of identifying general customary law has become immensely complex, and correspondingly uncertain; and in so many areas it is not just a question of enquiry but also of a policy-choice’.Footnote 95 That the fine line between law and policy is not always evident does not appear so odd when one comes to realize that law is a social phenomenon which originates from within society and which is in constant need of an active moral conscience that compels it to develop further in accordance with the interests of the people it governs.
Impossible as it is to write a thorough review of the study as a whole in a single article it remains essential to observe simultaneously results and methodology. While making use of the traditional two-element approach of state practice and opinio juris, the study also contains practice other than state practice. However, it is left unclear what influence is accorded to contributing other practice on the formation of a rule of customary international humanitarian law. It is regrettable that, whereas the study contains detailed information on how weight is attributed to, for instance, resolutions from international organizations, this is not specified at all for non-state actors or persistent objectors. It seems a less important question in situations where state practice overwhelmingly points in the same direction; the issue becomes more pressing, however, when there is little state practice available and the weight accorded to other practice has consequence for the formation of a rule of customary international humanitarian law. The present author maintains that a view of the content of the ‘black box’ would have made a stronger case for general acceptance of the innovative and most welcome rules put forward by the ICRC.
I would venture to conclude that anyone with a genuine interest in the process of law creation would immediately identify the ICRC Study as an impressive example of the influence exercised by a unique institution that, by virtue of its special status in international law, with certain authority affects the process of discourse on the law. If anything a primary objective of the ICRC Study has been to instigate further debate and dialogue, and to identify areas in the law that require clarification and further development. The Study is beyond doubt impressive and the first, most wide-ranging word on this particular topic; however, it should certainly not be the last. Although the Study offers an invaluable reference guide on actual practice it should not be mistaken for a legal document but understood as a statement of the law. It is an important tool in a worldwide process of discourse on the law that should lead to more insights into the current state and the process of the formation of customary international humanitarian law. The Study will, hopefully, find its way to the bookshelves of many practitioners, policymakers, and military specialists, where it may provide guidance and its statements may stimulate the expansion of the protection that is provided to those unfortunates exposed to the brutalities of warfare.
