Extending the IHL applicable in IACs to NIACs: Re-examining the Tadić and its aftermath

by Shriya Maini*

(This post is part of a series of posts on contemporary issues of international criminal law and human rights.)

In the decades following the adoption of rights by the Geneva Conventions, there is evidence of an inclination towards the application of the rules and principles regarding International Armed Conflicts (hereinafter “IACs”) to Non International Armed Conflicts (hereinafter “NIACs”). This may be seen in the nascent tendency to either ‘apply, or call for the application of’ IHL in situations of armed conflict, without drawing the distinction as to which ‘type’ of conflict (IAC or NIAC) exists and accordingly, which ‘type’ of law is applicable. Prior to highlighting if, how and why International Tribunals have made the laws of IACs applicable to NIACs, I set out three basic facts to be kept in mind while reading this essay.

Credits: Los Tiempos

Firstly, inspite of the valuable détente between Rules of IHL governing IACs and NIACs (as highlighted in subsequent sections of this essay), it would be grossly incorrect to assume that ‘all’ the rules of IHL applicable in IACs now apply to NIACs (Notion of automatic applicability). This is easily defended by the argument that grave breaches provisions of the Geneva Conventions solely apply to IACs. Judge Meron calls them the ‘lingering distinctions’ between IHL applicable in NIACs and IACs. However, in due course of my essay, I shall not only explain how a ‘rebuttable presumption’ is raised in favour of extending application of rules of IACs to NIACs but also that the jurisprudence evolved by the ICTR and ICTY has indeed been commendable in successfully sealing some of the wide crevices present in IHL.

Secondly, of the 161 customary rules of IHL as identified by the ICRC Study, 142 are uniformly applicable in all armed conflicts, whether IAC or NIAC. In effect, 88 % of customary rules are as on date applicable in all armed conflicts. Though one cannot shy away from the facts and figures (and admit that the distinction between IHL applicable in IACs and NIACs) has substantially blurred), it must be borne in mind that this Study is purely an academic work and not a declaration of law as such. Hence, States may further refute its findings at any stage. For instance, one fundamental principle of IHL pertains to use of weapons and methods of warfare which is now regarded as applicable to both IACs and NIACs as per State practice and the ICRC study. However, the same must be approached with significant prudence and I say this because some weapons of warfare are still regulated solely by IACs.

Lastly, combatants enjoy the Prisoner of War (POW) status only when captured by the enemy country in an IAC and the same can and must not understandably, be extrapolated to a NIAC due to the pre-existing regime of National Human Rights laws.

  1. A Procedural Extension – The Customary Law Exercise

Analyzing the jurisprudence of the ICTR and ICTY, Gauthier de Beco highlights two modes by which the Tribunals while prosecuting war crimes have applied rules of IACs to NIACs – firstly, the evolution of customary law and secondly, internationalization of NIACs. I prefer to term the first as a voluntary “Procedural extension” and deal with it in the Section subsequent to that of Internationalization.

 Internationalization of a NIAC transforming it into an IAC

Gauthier De Beco argues that a conflict was internationalised once a third state intervenes directly with its armed force in an internal armed conflict to support “one of the parties to conflict. The latter may either be the government forces or a rebel group.”[1]

It is stated, with due respect, that de Beco’s interpretation is erroneous.

Even where a third state employs its military force in the territory of the other state, it does not warrant a hasty generalisation that the conflict is thereby “internationalised”. The drawing line is whether the consent of the territorial state is given. If the third state is invited with the consent of the territorial state to fight against the rebel group, the conflict will remain as NIAC.[2] It cannot be internationalised, as there is no interstate use of force.[3] In the situation with direct employment of military force, the conflict can only be internationalised where i) the army of third state joins the rebel group against the territorial state, or ii) the third state employs its military troops on the territorial state without its consent.

To do so, the intervening state must acquire overall control’ (as formulated by the ICTY in Tadić[4] in contrast to ‘effective control test’ proposed by the ICJ earlier) upon a military organised group involved in the NIAC. According to the Appeals Chamber of the ICTY in Tadić, such control exists when

the state wields overall control over the group, not only by equipping and financing the group, but also by coordinating or helping in the general planning of its military activity”.[5]

It is not necessary for that state to give specific orders to be in control of the group and the same is affirmed by State Practice. By doing so it internationalizes the conflict, and the law of IAC becomes applicable. Without doubt, the armed conflict in 1992, between Bosnian Serbs and Herzegovina and Bosnian authorities was International in character since the overall political and military authority was held by the Federal Republic of Yugoslavia.

Even the conflict in Kordić and Čerkez[6] between Bosnian Muslim Army and Croatian Defence Council (HVO) was confirmed to be an IAC, internationalized by Croatia’s exercise of ‘overall control’ over the HVO, including providing logistic support and planning. However, to what extent can International Tribunals with limited jurisdiction minimize such lacunae is arguably evident but may not be exactly determinative of the matter.

Surfacing of Customary IHL (Tadić): Tribunals “..stepped in to fill gaps..”

The first mode assumes greater significance because far fewer treaty laws regulate conduct in NIACs than in IACs. Presumably, States did not want to provide legitimacy and legal status to non-state armed groups. Hence, the Tribunals have crystallized a large number of rules applicable to IACs as customary IHL, hence making them applicable to all instances of armed conflicts, including NIACs. In other words, Customary IHL has been used as a wadding tool to ‘step in’ and fill in many of the lacunae plaguing the current treaty law of NIAC.

Of all the three claims raised by Tadić, the third one related to subject-matter jurisdiction is most pertinent to our discussion. I deal with the arguments at length in the subsequent section explaining how Tadic’s claims were thwarted one by one. As a result, the Appeals Chamber chose to consolidate the IHL applicable in IACs and NIACs and hence, penned down for the first time in the jurisprudential history of IHL, the customary law interpreting Article 3 of the ICTY Statute. It called the Article in question a ‘residual clause’[7]watertight aimed at preventing Tadić from avoiding individual criminal responsibility at any cost. This was necessary since neither did AP II nor Common Article 3 explicitly criminalize its breaches. Besides, the ICTY assumed vast jurisdiction (Competence–Competence) providing for violations of laws and customs of war to cover both IACs and NIACs.

Judge Meron rightfully sums up that Article 3 of the ICTY Statute is broad enough today, to encompass violations of Hague and Geneva Law in IACs and NIACs (except for grave breaches) – including most notably Common Article 3 of the Geneva Conventions (minimum yardstick violations affirmed in Nicaragua v. USA [8] as being customary). This echoes in the ICTR decision Akayesu which agreed with Tadic and held that

i) “the norms of common article 3 have acquired the status of customary law”, and

ii) its violations entails individual criminal responsibility. It went on to state that “there exists a corpus of general principles and norms on internal armed conflict embracing Common Article 3 but having a much greater scope”.[9]

Such a mammoth extension is fortified by the subsequent implied acceptance of states, inferred from lack of opposition from States to the Tadić jurisdiction. Besides, the seminal decision is even more important because the Appeals Chamber clarified that Customary International Law may not require any connection or nexus between such crimes and the conflict itself and Article 5 of the ICTY Statute (pertaining to crimes against humanity) itself formed part of customary IHL.

Countering the Counter-Argument: Implied Exclusion (expressio unius est exclusio alterius)

Many argue that Article 5(g)’s mention of ‘whether International or internal in character’ makes it obvious that the Legislature could have included the same words in Articles 2 and 3 of the ICTY Statute but it chose to abstain and do otherwise. Hence, maybe only Article 5(g) is applicable in both NIACs and IACs and hence, characterization of an armed conflict as an IAC or a NIAC assumes greater importance. This was in fact, the essence of the main argument raised by Tadić – ‘since Articles 2 and 3 of the ICTY applied only to crimes committed in IACs, and that the alleged crimes, even if proven, had been committed in a NIAC and thus, fell outside the scope of the tribunal’s subject matter jurisdiction.’ This argument was however, rejected by the Appeals Chamber.

Judge Meron counters this counter-argument by offering an interesting explanation.[10] He elucidates that if the Appeals Chamber would have decided to accept the Prosecution’s argument and consider the conflict to purely be an IAC, it would have easily been considered a serious violation of the grave breaches provision under the Geneva Convention, hence calling for outright application of IHL. However, the Appeals Chamber adjudicated the conflict to be of a mixed character, i.e. comprising elements of both IACs and NIACs, affirming that serious violations of both are customary in nature, and left it to the Trial Chamber to dissect individually as to which particular conflicts were an IAC or a NIAC.

Question of Distinction between IAC and NIAC largely ‘Irrelevant’?

As elucidated above, the Appeals Chamber decision in Tadić has blurred the distinction between IACs and NIACs to a large extent. Judge Meron concurs reasoning that this has been possible by doing away with the question of determination of whether a conflict is an international one or not, especially because (apart from grave breaches provisions), the same substantive laws of IHL (in essence atleast) as on date, universally apply to both IACs and NIACs. He supports his analysis by quoting the ICTY in Milošević [11], where the Appeals Chamber, in the absence of characterization of the conflict by the Trial Chamber, in its indictment, charged the accused under Article 51(2) of AP I ‘and in the alternative’, Article 13(2) of AP II, emphasizing that both the relevant provisions formed part of Customary IHL and hence, applied to both IACs and NIACs. The blurring of distinction is then further justified by Meron by clubbing his arguments with the teleological interpretation of the concept (based on purposive necessity of IHL), as elucidated subsequent Section.

ICT Prosecutors had tried Dusan Tadic for persecuting muslims in Bosnia. Image Credits: BBC

However, some argue that the Tadić’s consideration that it is ‘rather unnecessary to determine character of armed conflict’[12] by not giving due importance to characterization of conflict has rather complicated and worsened the situation, especially because contemporary international crimes (such as usage of chemical weapons) demand that the conflict be duly characterized as IAC or NIAC, howsoever complicated and tough it maybe. Besides, the intensity threshold question pertaining to the restrictive definition of a NIAC under AP II is irrelevant in an IAC and hence, at times the characterization could assume importance. Besides, the Rome Statue provides for separate lists and Articles prosecuting war crimes committed in IACs and NIACs.

The 2003 Interlocutory appeal of Hadžihasanović [13] affirmed that ‘it is difficult to see why the concept would not equally apply to breaches of the same prohibitions when committed in a NIAC (if they were prohibited in an IAC). This raises a rebuttable presumption, as per Judge Meron not of automatic applicability, but creates an ‘affirmative leaning’ in the direction of applying rules of IAC to NIAC, thereby placing a higher burden of proof upon the Accused to justify as to why customary IHL would not apply in the instance case, merely because of the nature of the conflict being non-international.

Teleological Interpretation of IHL outweighs claims of insufficient State Practice:

Acts do not contribute to the formation of customary international law if they are never disclosed.[14] However, it is often difficult, from a purely practical standpoint, to accurately determine State practice ‘in the field’ during time of armed conflict for States may be unwilling or unable to report on their conduct in the field, thus hindering any attempt to accurately assess the same. Infact, Tadić echoes the same reasoning.[15] Besides, states’ communication with the ICRC in the context of its international mandate to assist in the implementation of IHL and the fact that ICRC may “take cognizance of any complaints based on alleged breaches of [IHL]” makes the communications to the ICRC, while often confidential, not purely private acts and does count as State practice. This yet again justifies the cogent presence of State Practice, sufficient enough to endeavour carving (of customary IHL for NIACs) by the ICTY. The ICTY further stated that in appraising the formation of customary IHL, “reliance must primarily be placed on such elements as official pronouncements of States, military manuals and judicial decisions”. This was again resorted to because of lack of evidence of State Practice.

Judge Meron offers a teleological validation to counter the scarcity of State practice. He observes that,

“given the scarcity of actual practice, it may well be that tribunals have been guided, and may continue to be guided, by the degree to which certain acts are offensive to human dignity (Purposive interpretation). The more heinous the act, the more willing the tribunal will be to assume that it violates not only a moral principle of humanity but also a positive norm of customary law.”[16]

Evidently, the unique demands and purpose of humanitarian law, for instance that of protecting the wounded and the vulnerable in situations of armed conflict (Section II of the essay), exerts an additional force on the forces that create and shape universal customary IHL (applicable in both IAC and NIAC), leading to the creation of rules, even in instances where State practice is negligible.

This approach was demonstrated by the ICTY in Kupreškić [17], even though State practice with regards to reprisals in NIAcs was limited. Kirgis calls this a ‘need for stability when issues of armed force are involved coercing primary reliance on normative words rather than on a combination of words and consistent deeds.[18] The same can also be discerned in relation to the adoption of the Rome Statute of the ICC. As Judge Meron states with regard to the Preparatory Committee on the Establishment of the ICC, ‘many participating governments appear ready to accept an expansive conception of customary international law without much supporting practice’ going on to note ‘the elevation of many principles of international humanitarian law from the rhetorical to the normative, and from the merely normative to the effectively criminalised’.[19]

Thus, the unique nature of the customary international law of armed conflicts, and internal armed conflicts especially, arguably promotes favouring opinio juris over State practice.

ICTR’s subsequent attempts at blurring distinction between IACs and NIACs

The ICTR in Akayesu categorically extended the application of Common Article 3 to NIACs[20] and held that persons belonging to all ranks and categories of public agents could be held criminally responsible for violating common Article 3 (minimum breaches of which may be prosecuted under Article 4 of the ICTR Statute). This was in consonance with the benevolent approach of the ICTY, yet again based on a teleological interpretation broadening the purpose and application of IHL, being ‘quintessential rules of humanitarian aspects and as being above and outside the ambits of the war’. Evidently, the application of laws was no longer dependent on the nature or characterization of the conflict as an IAC or a NIAC. The core of Common Article 3 was recognized as a fundamental element of IHL and the same wad enough to warrant and justify its application.

As for the Nexus Requirement, though Akayesu held that ‘a close nexus between the armed conflict and violations of IHL’ was required. However, the Rutuganda appeal judgment and Kunarac appeal judgment turned the tables around embracing the standard ‘that if the perpetrator acted in furtherance of and under the guise of the armed conflict’. As Judge Meron explains, since the ICTR purely applies to NIACs, it is essential to distinguish between IHL violations and the ‘ordinary’ state crimes.

  1. Revolutionizing the Substantive Elements: Universal application (in IAC or NIAC) of Fundamental Principles of IHL

As elucidated, a scrutiny of State practice and opinio juris reveals that certain elemental principles of IHL have attained the status of ‘customary’ IHL equally applicable in IACs as well as NIACs. This is particularly significant for the latter, as treaty law has remained limited in NIACs. The explanation for the same rests upon the procedural extension argument (that though the Geneva Conventions were designed to cover IACs but their principles embody a much wider scope applicable as customary IHL, thereby extending to NIACS as well). Fundamental IHL principles include, inter-alia others (a) principle of distinction (b) requirement of proportionality and (c) prohibition on employing means of armed conflict which cause unnecessary suffering, on which I intend focus in this Section.

2. Principle of Distinction

Court practice has carved a customary status for the principle of distinction[21] in NIACs. The ICJ in the Nuclear Weapons Advisory Opinion first held that the principle of distinction is considered to be one of the ‘cardinal principles contained in the texts constituting the fabric of IHL… [and is one of the] intransgressible principles of international customary law.’[22] The ICTY subsequently affirmed the same in Tadić (Interlocutory Appeal);[23] in Kordić and Čerkez;[24] in Blaškić;[25] and in Strugar[26], where the Appeals Chamber noted that principles prohibiting attacks on civilians (Article 13 of Additional Protocol II) are customary international law and established that a violation of these would entail individual criminal responsibility.[27]


The same was then affirmed by the Inter-American Commission on Human Rights in the Tablada Case in 1997.[28] Besides, the principle is profoundly reflected in subsequent State practice which has successfully established it as a norm of customary IHL in both IAC and NIAC.[29] UN Security Council Resolution 912, UN Doc/S/RES/912 (1994) condemned the failure to ensure that civilians are not made subject to attack, either deliberately or accidentally in Rwanda, which was purely a NIAC.[30] Hence, such a procedural extension (that though the Geneva Conventions were designed to cover IACs but their principles embody a much wider scope applicable as customary IHL) appears undoubtedly correct.[31]

3. Principle of Proportionality

The ICTY, irrespective of the nature of conflict, in both Martić[32] and Kupreškić [33]reaffirmed the fundamental importance of observing proportionality in attack. Interestingly, the issue has also been addressed in case law in Argentina, in the Military Junta Case, where it was determined that the principle of proportionality was considered to be a customary norm.

4. Prohibition on means and methods of combat (Hague Law)

The principle regarding prohibition on means and methods of warfare that cause superfluous injury or unnecessary suffering (Articles 35 (1) and (2) of Additional Protocol I applicable only in IAC) was acknowledged as a fundamental principle of IHL, applicable in all types of armed conflicts by the ICTY for the first time in Tadić. The ICTY relied upon the Nuclear Weapons decision of the ICJ wherein the latter had noted that the prohibition on causing unnecessary suffering was an ‘intransgressible [principle] of international customary law.’[34] This again seems to blur the distinction between laws applicable to IACs and NIACs.

The ICTY opined that the elementary considerations of humanity make it preposterous that the use by States of weapons prohibited in armed conflicts between themselves be allowed when States try to put down rebellion by their own nationals on their own territory. Simply put, what is inhumane, and consequently proscribed, in international wars (IAC) cannot but be inhumane and inadmissible in civil strife (NIAC). The purposive extension appears accurate, especially in light of the ICRC CHIL Study which accords customary status to the above.[35]

III. The Aftermath:

 Though echoing the Tadić, the Rome Statute interestingly keeps the distinction between IACs and NIACs alive by providing jurisdiction for the ICC to prosecute war crimes in both types of armed conflicts but creates two separate prosecution regimes within the Statute. Hence, to prosecute war crimes under the Rome Statute, the existence of an IAC or a NIAC must first be established. This may appear contradictory to the Tadić approach of doing away with the relevance of the distinction question altogether. Article 8 (2) (a) of the Rome Statute criminalizes grave breaches of the Geneva Conventions and Article 8 (2) (b) other serious violations of the laws and customs of war in IACs. Articles 8 (2) (c) (akin the Tadić)[36] criminalizes serious violations of common Article 3 to the Geneva Conventions and Article 8(2)(e), other serious violations of the laws and customs of war in NIACs. Besides, for IACs, the intensity and duration are irrelevant, which is not the case with NIACs. Below a certain threshold Article 8(2)(e, the latter are considered to be a matter for the sovereign states. The ICC in Thomas Lubanga (referring to Tadic) opined that, when assessing the intensity of a conflict, it can take into account, inter alia, “the seriousness of the attacks and the potential increase in armed clashes, their spread over territory and over a period of time, the increase in the number of government forces”. [37]

In accordance with the customary law approach and with a view to reach a plausible consensus, the Rome Statute has created by consolidation distinct list of war crimes, for NIACs and IACs. However, in my view this entirely defeats the purpose of blurring the distinction between the two kinds of conflicts for leaping gaps still exist (for instance, absence of (1) prohibition on means and methods of warfare (2) combatant immunity and (3) POW status for NIACs) and the same are in no long sight seeming to even faintly blur.

(*Shriya is a practicing advocate at the Supreme Court of India, the Delhi High Court and district courts at New Delhi. She is a graduate of Gujarat National Law University, India and University of Oxford. At Oxford, she completed her Bachelor of Civil Law programme on a full scholarship and obtained a Master’s in Law majoring in International Crime.  A recipient of the Oxford Global Justice Award 2015 for Public International Law, she is currently assisting the President of the International Residual Mechanism for the Criminal Tribunals (MICT).)


[1] Gauthier de Beco, “War Crimes in International versus Non-international Armed Conflicts: New Wine in Old Wineskins?” (2008) 8 ICLR 319 at page 321.

[2] Dapo Akande, “Classification of Armed Conflicts: Relevant Legal Concepts” in Wilmshurt (ed.), International Law and the Classification of Conflicts, [2012, OUP] Chapter 3 at page 56.

[3] Prosecutor v Tadić (Appeal Chambers Judgment) IT-94-1 (15 July 1999) 57.

[4] Prosecutor v. Dusko Tadic , Appeal Judgment, Case No IT-94-1-A, 15 July 1999 (hereinafter Tadić) , § 131 .

[5] Tadic §§ 131 and 137.

[6] The Prosecutor v. Dario Kordić and Čerkez, Appeal Judgment, Case No IT-95-14/2-A, 17 December 2004 (hereinafter Kordić and Čerkez).

[7] Tadic , Interlocutory Appeal, 1995 § § 89 and 91 .

[8] Military and Paramilitary Activities in and against Nicaragua (Merits: Judgement) [1986] ICJ Rep 14.

[9] Prosecutor v Jean-Paul Akayesu (Judgment) ICTR-96-4-T (2 September 1998), § 608.

[10] Ibid.

[11] Prosecutor v Dragomir Milošević (Judgement) IT-98-29/1-A (12 November 2009).

[12] §§  23 (internal citation omitted).

[13] Prosecutor v Enver Hadžihasanović et al. (Decision on Interlocutory Appeal Challenging Jurisdiction in Relation to Command Responsibility) IT-01-47-AR72 (16 July 2003).

[14] ILA, Final Report of the Committee on the Formation of Customary (General) International Law, Statement of Principles Applicable to the Formation of General Customary International Law, Report of the Sixty-Ninth Conference, London, 2000, Principle 5, note 18, p. 726.

[15] Tadić (Interlocutory Appeal) at [99].

[16] Meron, ‘Human Rights and Humanitarian Norms as Customary Law’, (1989) at 42.

[17] “[due] to the pressure exerted by the requirements of humanity and the dictates of public conscience, a customary rule of international law has emerged [on reprisals against civilians in NIAC”.

[18] Kirgis, ‘Custom on a Sliding Scale’ at 147.

[19] Meron, ‘War Crimes Law Comes of Age’ (1998) 92 AJIL 462 at 467, 468. Meron also noted the tendency of international judicial bodies ‘to ignore, for the most part, the availability of evidence of state practice (scant as it may have been) and to assume that noble humanitarian principles that deserve recognition as the positive law of the international community have in fact been recognised as such by states. The ‘ought’ merges with the ‘is’, the lex ferenda with the lex lata.’ See Meron, ‘The Geneva Conventions as Customary Law’ (1987) 81 AJIL 348 at 361.

[20] Prosecutor v Jean-Paul Akayesu (Judgement) ICTR-96-4-T (2 October 1998), § 225 and 631

[21] Distinction, a bi-pronged element of IHL provides for two core criteria. Firstly, the Combatants must distinguish themselves from the civilians, and secondly the latter must not be made the object of attack.

[22] At §§ 78–79.

[23] At [98], [117] and [132].

[24] Decision on the Joint Defence Motion to Dismiss the Amended Indictment for Lack of Jurisdiction based on the Limited Jurisdictional Reach of Article 2 and 3, 2 March 1999, Case No IT–95–14/2 at [25–34]; recognising that Article 13(2) of Additional Protocol II constituted customary IHL.

[25] Prosecutor v Blaškić, Judgment, Case No IT–95–14, 3 March 2000 at § 180.

[26] Prosecutor v Pavle Strugar, Decision on Interlocutory Appeal, Case No IT–01–41–AR72, 22 November 2002

[27] Ibid. At [10]

[28] Abella v Argentina, Case 11.137, Report No 55/97, 18 November 1997, Annual Report of the International American Commission on Human Rights 1997 (17 February 1998) at § 177.

[29] ICRC Study, 2005b, vol. 1

[30] Also, observed in Burundi in 1996 and Sierra Leone in 1998.

[31] A similar statement can be found in UN Security Council Resolution 1296 (2000) on the protection of civilians in armed conflict, reaffirming the principle of distinction as being applicable in all armed conflicts, whether NIAC or IAC.

[32] § 18.

[33] § 513.

[34] Nuclear Weapons Advisory Opinion at §§ 78–79.

[35] ICRC CHIL Study, Rules 70-79 and 86.

[36] Tadić (Interlocutory Appeal) at [110].

[37] Prosecutor v Thomas Dyilo Lubanga (Trial Judgment) ICC-01/04-01/06 (14 March 2012) § 538.


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