The blindfold of justice in the fog of war: genocide, military necessity and the limits of armed force under international law

Cristian González Ruiz
IHR Advisors, London

Ben Keith
IHR Advisors, London

Introduction

When South Africa filed proceedings against Israel at the International Court of Justice (ICJ) in December 2023, alleging violations of the Genocide Convention in Gaza, the application struck at one of the most contested fault lines in international law: the boundary between lawful military operations and acts of genocide. It is a question with no comfortable answers. States and armed groups have invoked military necessity to justify operations that, on closer examination, bear the hallmarks of something far darker. International humanitarian law (IHL) does not operate in isolation: it intersects with international human rights law (IHRL) and international criminal law (ICL), and it is at those intersections that the most difficult questions arise.^[1]

The jurisprudence of the international criminal courts and tribunals has repeatedly tested these boundaries.^[2] This article contends that international law draws a clear and principled distinction between armed operations directed at the military capacities of a belligerent party and operations carried out with the special intent, or dolus specialis, to destroy a protected group as a whole or in part. This conclusion sits within a broader architectural claim. Conduct in armed conflict is governed by three distinct but overlapping bodies of rules – IHL, IHRL and ICL – each pursuing different aims, and lawfulness under one does not foreclose liability under another. Genocide is the starkest illustration of that divergence, but not its only instance: war crimes and crimes against humanity may equally arise from conduct that is facially compliant with IHL’s targeting rules. In this article, we argue that the three frameworks are normatively distinct, taking the scope and limits of military necessity, and showing why acts committed with dolus specialis cannot be subsumed within that doctrine.

These doctrines are currently being examined in the ongoing case of South Africa v Israel at the ICJ. Nonetheless, three fundamental premises remain valid. First, IHL, IHRL and ICL function as separate but overlapping legal frameworks, meaning that actions lawful under one can still result in liability under another. Second, military necessity is a genuine but limited doctrine, which cannot justify acts carried out with genocidal intent. Third, the distinction between lawful warfare and genocide heavily relies on dolus specialis, a specific form of intent that cannot be deduced solely from the outcomes of military actions but must be proven as the intended purpose at the moment the acts occur. The South Africa v Israel proceedings serve as a real-world testing ground for each of these propositions, and the article revisits the case at every stage of the discussion.

IHL, IHRL and ICL: distinct normative frameworks

The ICJ in the Croatia v Serbia case argued: ‘The [Genocide] Convention and international humanitarian law are two distinct bodies of rules, pursuing different aims’.^[3]

IHL is the field of international law that regulates the conduct of hostilities in armed conflict, whether national or international.^[4] IHL differs from IHRL, inter alia, because its provisions are designed to be applied only in the context of armed conflict. By contrast, IHRL is applicable in times of both peace and war, coexisting with IHL during wartime.^[5]

Moreover, IHL differs from ICL, notably because ICL aims to deter the commission of international crimes; its regulatory framework is more reactive, focusing on the procedural and substantive regulation of punishment for such crimes.^[6] IHL is designed primarily to guide the conduct of military commanders and operators on the battlefield.^[7] Although the latter includes specific punitive provisions, these remain relatively vague. Nevertheless, the ad hoc tribunals and the International Criminal Court (ICC) have enforced IHL norms through war crimes prosecutions.^[8]

The tension between these frameworks is partly explained by the fact that IHL was never designed for the courtroom.^[9] It is applied not by lawyers but by soldiers, who must balance military advantage against the protection of civilians and those hors de combat.^[10]

For example, a soldier who attacks an enemy position in compliance with IHL – without excessive civilian harm or prohibited methods – acts lawfully. Yet that same soldier may face criminal liability if the enemy’s retreat is later characterised as a forcible transfer.^[11] This is precisely what arose in Popović, where the International Criminal Tribunal for the former Yugoslavia (ICTY) convicted the accused of forcible transfer as an inhumane act.^[12]

The ICTY’s approach is problematic. It risks creating parallel regimes in which conduct that is lawful under IHL attracts criminal liability under ICL, thereby distorting operational decision-making, where commanders must act in real time.^[13]

These distinctions are now being tested in South Africa v Israel, as the application for proceedings as well as other intervening states have asked the ICJ to apply the Genocide Convention – a treaty rooted in the protective logic of ICL – to conduct taking place within an ongoing armed conflict principally governed by IHL. The proceedings do not collapse these frameworks into one another, but they sharpen the question at the heart of this article: how far can rules designed for post hoc judicial assessment speak to decisions that soldiers and commanders must take in real time on the battlefield?

Military necessity: scope, limits and the codification in Additional Protocol I

Military necessity reflects IHL’s recognition that destroying an adversary’s military capabilities may be unavoidable. It defies static definition: what constitutes a necessary operation depends on the tactical and strategic context.^[14]

The principles governing military necessity were ultimately codified in Articles 49(1) and 52(2) of Additional Protocol I to the Geneva Conventions. Article 49(1) defines ‘attacks’ as ‘acts of violence against the adversary, whether in offence or in defence’. Article 52(2) mandates that attacks be strictly limited to military objectives.^[15]

Military necessity has also been incorporated into ICL. The Rome Statute expressly acknowledges exceptions for military necessity when defining war crimes in Article 8, and several provisions treat the absence of military necessity as a constituent element of the offence.

Whether military necessity is available as a defence before international criminal tribunals remains contested.^[16] A broad military necessity defence for all international crimes would risk subordinating ICL’s protective function to the exigencies of war.

In practice, South Africa v Israel proceedings illustrate both the scope and the contested limits of the doctrine. Israel’s public justifications have consistently invoked military necessity, relying on Hamas’s embedding of military assets within dense civilian areas. South Africa contends, by contrast, that the cumulative scale, pattern and stated objectives of the operations, together with the scope of destruction of civilian infrastructure and protected objects, exceed what any plausible military necessity can sustain.

Genocide and military operations: dolus specialis and the limits of military necessity

Genocide has been characterised by international tribunals as the ‘crime of crimes’.^[17] The prohibition became enshrined in the 1948 Genocide Convention, now ratified by 153 states.

What sets genocide apart from other core crimes is the requirement of dolus specialis: the perpetrator must have intended to destroy a protected group in whole or in substantial part.^[18] It has been established, as in the case of Ntakirutimana by the International Criminal Tribunal for Rwanda (ICTR), that this special intent need not be the primary purpose of the perpetrator when committing the criminal offence. Thus, unrelated motives that explain the defendant’s actions do not preclude proof of the absence of genocidal intent.^[19]

A critical distinction in applying dolus specialis is between motive and intent. Motive explains why the defendant acted; intent identifies the goal at the time of the crime.^[20] What matters for genocide is establishing the intent to destroy a protected group. Motive may be probative, but it is intent that is determinative.^[21]

Regarding the dolus specialis, two further points bear emphasis. Premeditation is not required to establish special intent, though it may serve as evidence.^[22] Nor is a common plan a legal element, though it often evidences intent, which on its own has been enough to conclude that, at least theoretically, genocide can be committed by a single individual.

Neither the Genocide Convention nor the statutes of the ad hoc, nor the Rome Statute, then clarify what the relation is between military necessity and the Genocide Convention. The Genocide Convention suggests that acts constituting actus reus and mens rea of genocide may overlap with actions that could be legitimate under IHL, such as killing or causing serious harm to members of a protected group.

Where a protected group is targeted within military operations, acts otherwise lawful under IHL could constitute the actus reus and mens rea of genocide. A systematic reading of IHL and ICL nonetheless permits a distinction: actions undertaken with the intent to destroy a protected group are not justified under military necessity and constitute a crime under international law.

Although the ad hoc tribunals did not draw this distinction explicitly, they provided the tools to do so. The Krstić trial chamber established that:

‘[W]here there is physical or biological destruction, there are often simultaneous attacks on the cultural and religious property and symbols of the targeted group as well, attacks which may legitimately be considered as evidence of an intent to physically destroy the group. In this case, the Trial Chamber will thus take into account as evidence of intent to destroy the group the deliberate destruction of mosques and houses belonging to members of the group…’^[23]

The Blakić trial chamber found that property destruction during operations in several Bosnian localities lacked military necessity: the offensives had no military justification, and destruction without justification cannot shelter behind military necessity.^[24]

This analytical framework retains acute contemporary relevance. In the context of the ongoing conflict in Gaza, the ICJ has been called upon to examine these distinctions precisely.

The central question is whether military operations directed against Hamas’s military infrastructure, and their consequences for the civilian population of Gaza, are consistent with lawful military necessity or whether they evidence the dolus specialis required to establish genocide. In its Order of 26 January 2024, the ICJ found at least some of South Africa’s claims under the Genocide Convention plausible and indicated provisional measures, without adjudicating the existence of dolus specialis. Subsequent orders of 28 March and 24 May 2024 expanded those measures as conditions deteriorated.

Although the plausibility threshold is deliberately lower than the standard of proof on the merits, none of the orders purports to resolve the intent question. They do, however, demonstrate that the limits between lawful military operations and acts committed with genocidal intent are not merely theoretical, and that the Court is prepared to intervene at the outer limits of military necessity where a protected group’s existence is materially at risk.^[25]

The ICJ supported the criteria outlined by the ICTY, concurring with its conclusion that:

‘Where there is physical or biological destruction, there are often simultaneous attacks on the cultural and religious property and symbols of the targeted group as well, attacks which may legitimately be considered as evidence of an intent to physically destroy the group’.^[26]

When attacks move beyond concrete military objectives and target a group’s existence through the deliberate destruction of cultural sites, discriminatory targeting, or operations devoid of military purpose they cease to be legitimate under IHL and become evidence of genocidal intent. Where the aim is not to defeat the enemy but to destroy an ethnic group, IHL no longer serves its purpose.

This analysis should not obscure the practical difficulty of proving genocidal intent. Evidentiary records are frequently incomplete,^[27] and witness testimony, upon which much depends, is inherently vulnerable to the passage of time and the psychological burden of the events.

Conclusion

Three conclusions follow. First, that IHL renders an act lawful does not preclude criminal responsibility under ICL, but tribunals must exercise caution before criminalising legitimate military operations. Second, military necessity provides no safe harbour for acts committed with the dolus specialis of genocide. Where the object of military operations is not the defeat of an adversary’s armed forces but the destruction of a protected group, military necessity has no application. Third, the line between lawful warfare and genocide turns principally on intent. The targeting of cultural sites, discriminatory selection of victims, and dehumanising rhetoric are, as the ICTY and ICJ confirm, probative evidence of that intent.

Significant evidentiary challenges remain. Evidence in conflict is routinely destroyed or withheld, and witness testimony carries inherent limitations. Some question whether the threshold for dolus specialis renders genocide convictions practically unattainable. That concern has immediate relevance to the ICJ proceedings on Gaza and the ICC investigations into the conflict in Ukraine. The doctrinal framework examined here provides the tools to navigate these questions; applying it with rigour, free from political pressure, is the task that now falls to the international community.

Notes

^[1] Malcolm N Shaw, International Law (6th edn, CUP 2008) www.cambridge.org/core/books/international-law/8CC08AA262B38B75D5D7874D9304E1E3 accessed 15 June 2026.

^[2] Elina Almila, ‘Protecting Children from Sexual Violence in Armed Conflict under International Humanitarian Law: Discrepancies between Conventions and Practice of International Criminal Courts and Tribunals’ (2019) 10(2) Journal of International Humanitarian Legal Studies 217 https://brill.com/view/journals/ihls/10/2/article-p217_217.xml?language=en accessed 15 June 2026.

^[3] Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Croatia v Serbia) (Preliminary Objections) [2008] ICJ Rep 412 www.icj-cij.org/case/118 accessed 15 June 2026.

^[4] Emily Crawford and Alison Pert, International Humanitarian Law (CUP 2015) www.cambridge.org/highereducation/books/international-humanitarian-law/9C337A4C6DF76DB61CC815E52115AD5A#overview accessed 15 June 2026.

^[5] Nasir Qadri, ‘The Relationship of International Humanitarian Law with International Human Rights Law: Difference and Its Implementation’ SSRN Electronic Journal, https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4099882 accessed 15 June 2026.

^[6] Carsten Stahn, A Critical Introduction to International Criminal Law (CUP 2018) www.cambridge.org/highereducation/books/a-critical-introduction-to-international-criminal-law/EFEDBED0B84359DFA281A9079047846F#overview accessed 15 June 2026.

^[7] Rogier Bartels, ‘Discrepancies between International Humanitarian Law on the Battlefield and in the Courtroom: The Challenges of Applying International Humanitarian Law During International Criminal Trials’ in Mariëlle Matthee, Brigit Toebes and Marcel Brus (eds), Armed Conflict and International Law: In Search of the Human Face (TMC Asser Press 2013) 339 https://link.springer.com/chapter/10.1007/978-90-6704-918-4_14 accessed 15 June 2026.

^[8] See n 7 above (Bartels).

^[9] Ibid.

^[10] Carsten Stahn, Jens Iverson and Jennifer S Easterday, ‘“After the War Is Before the War”: The Environment, Preventive Measures Under International Humanitarian Law, and Their Post-Conflict Impact’ in Carsten Stahn, Jens Iverson and Jennifer S Easterday (eds), Environmental Protection and Transitions from Conflict to Peace (OUP 2017) https://global.oup.com/academic/product/environmental-protection-and-transitions-from-conflict-to-peace-9780198784630?cc=gb&lang=en& accessed 15 June 2026.

^[11] See n 7 above (Bartels).

^[12] Prosecutor v Popović (Decision on Interlocutory Appeal) IT-05-88-AR73.1 (ICTY Appeals Chamber, 14 December 2007) www.icty.org/en/case/popovic accessed 15 June 2026.

^[13] Matthew T Zommer, ‘Operationalizing International Humanitarian Law: A Decision-Making Process Model for Assessing State Practice’ (2014) 3(1) International Law Research https://ccsenet.org/journal/index.php/ilr/article/view/39629 accessed 15 June 2026.

^[14] Igor Primoratz and David W Lovell, ‘Are Attacks on Civilians Always Wrong?’ in Igor Primoratz and David W Lovell (eds), Protecting Civilians During Violent Conflict (Routledge 2012) 33 www.routledge.com/Protecting-Civilians-During-Violent-Conflict-Theoretical-and-Practical-Issues-for-the-21st-Century/Primoratz-Lovell/p/book/9781138254565 accessed 15 June 2026.

^[15] Ibid.

^[16] Geert-Jan Alexander Knoops, ‘International Criminal Law Liability for Interrogation Methods by Military Personnel under Customary International Law and the ICC Statute’ (2004) 4(2) International Criminal Law Review 211 www.researchgate.net/publication/46661855_International_Criminal_Law_Liability_for_Interrogation_Methods_by_Military_Personnel_under_Customary_International_Law_and_the_ICC_Statute accessed 15 June 2026.

^[17] This phrase is attributed to Jean-Paul Sartre. See William A Schabas, ‘Introduction’ in Genocide in International Law: The Crime of Crimes (2nd edn, CUP 2009) 1 www.cambridge.org/core/books/abs/genocide-in-international-law/introduction/61B89D52229810607D9AECC62CCE3FF4 accessed 15 June 2026.

^[18] Guénaël Mettraux, ‘Special Genocidal Intent/Dolus Specialis’ in International Crimes: Law and Practice Volume1 I: Genocide (OUP 2019) https://global.oup.com/academic/product/international-crimes-law-and-practice-9780198843115?cc=gb&lang=en& accessed 15 June 2026.

^[19] Prosecutor v Ntakirutimana ICTR-96-10-A and ICTR-96-17-A (Appeal Judgment, ICTR, 13 December 2004) https://unictr.irmct.org/en/cases/ictr-96-17 accessed 15 June 2026.

^[20] See n 18 above (Mettraux).

^[21] Carola Lingaas, ‘Dehumanising Ideology, Metaphors, and Psychological Othering as Evidence of Genocidal Intent’ (2021) 22(5–6) International Criminal Law Review 1044 https://brill.com/view/journals/icla/22/5-6/article-p1044_011.xml accessed 15 June 2026.

^[22] Ibid.

^[23] Prosecutor v Krstić IT-98-33-A (Appeal Judgment, ICTY, 19 April 2004) www.icty.org/en/case/krstic accessed 15 June 2026.

^[24] Prosecutor v Blaškić IT-95-14-A (Decision on Evidence, ICTY Appeals Chamber, 31 October 2003) www.icty.org/x/cases/blaskic/acdec/en/031031.htm accessed 15 June 2026.

^[25] Application of the Convention on the Prevention and Punishment of the Crime of Genocide in the Gaza Strip (South Africa v Israel) (Provisional Measures, Order of 26 January 2024) [2024] ICJ; see further orders of 28 March 2024 and 24 May 2024. See further www.icj-cij.org/case/192 accessed 15 June 2026.

^[26] Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Yugoslavia) (Preliminary Objections) [1996] ICJ Rep 595. See further www.icj-cij.org/case/91 accessed 15 June 2026.

^[27] Terence Anderson and William Twining, ‘Evidential Reasoning in the International Criminal Tribunal for Rwanda: A Case Study of Tharcisse Muvunyi’ (2015) 26(3–4) Criminal Law Forum 373 https://link.springer.com/article/10.1007/s10609-015-9267-y accessed 15 June 2026.