If the “Why” of War Shapes the “How” of Law, Who is Accountable?
The ongoing armed conflicts in Ukraine and Gaza illustrate the dangerous consequences of conflating jus ad bellum and jus in bello. This conflation risks undermining the universality of international humanitarian law (IHL) and reducing international criminal law (ICL) to a tool of selective enforcement driven by political and moral biases. This post argues that the preservation of the distinction is essential to safeguarding the effectiveness of international legal frameworks.
The principles of jus in bello are designed to apply universally and impartially, regardless of the legality of a belligerent’s cause under jus ad bellum. This distinction ensures that the protection of noncombatants, the regulation of hostilities, and the accountability of perpetrators remain unaffected by subjective judgments about the “rightness” of war. For instance, the International Criminal Court’s (ICC) Rome Statute criminalizes grave breaches of IHL without regard to the underlying justification for the conflict. This separation allows ICL to function as a neutral mechanism for prosecuting violations, holding all parties to the same standards.
Conflating these two bodies of law risks introducing moral relativism into enforcing international norms. If we go this route, perpetrators could evade accountability by invoking the perceived justness of their cause. Such erosion of ICL’s impartiality risks transforming it from a mechanism of universal accountability into a tool of selective justice (if it remains relevant at all after such conflation).
Alternatively, those fighting on a conflict’s “right” side might be given more freedom to break the rules than their opponents. This would undermine the fairness of the law, as violations by the “right” side might only be punished if they are “even graver,” effectively creating a double standard. It would be practically impossible to hold all parties equally accountable and weaken the legal system’s clarity and consistency.
This post examines these risks through the lens of ICL, highlighting the relevance of the Rome Statute of the ICC to today’s conflicts.
The Core Distinction Between Jus Ad Bellum and Jus In Bello
The long-standing separation of jus ad bellum and jus in bello remains central to preserving the neutrality of IHL. However, this distinction is often misunderstood and challenged. Understanding the origins and purpose of this separation is crucial before addressing how its erosion undermines international legal norms.
Jus ad bellum governs the conditions under which States may resort to armed force, as outlined in the UN Charter, including the prohibition on the use of force and its exceptions, such as self-defense and Security Council authorization. Jus in bello, also known as the law of armed conflict (LOAC) or IHL, regulates the conduct of parties during armed conflicts. It functions by continuously evaluating specific issues in the context of armed conflict. These evaluations cover areas such as determining lawful targets, safeguarding civilians and other vulnerable groups, managing detention and internment, and assessing the status of individuals and objects in warfare.
Proponents of blurring the line between jus ad bellum and jus in bello often suggest that strict adherence to IHL might hinder a nation’s ability to defend itself effectively, especially when facing existential threats. Therefore, assessing the appropriateness of tactics that cause excessive incidental harm to civilians or civilian objects requires weighing the potential outcomes of the conflict. For example, a tactic leading to a speedier victory could ultimately reduce civilian suffering by shortening the war. Otherwise, the nation’s security would be compromised, resulting in even greater civilian harm.
However, this (the “sliding scale”) argument, though appealing to moral responsibility and pragmatism, collapses under real-world scrutiny. For instance, granting Ukraine greater latitude to inflict incidental harm on civilians under the pretext of defending itself against Russia would neither guarantee a speedier victory nor necessarily tip the scales in its favor. On the contrary, such actions could provide Russia—a far stronger adversary—with a pretext to escalate its operations and inflict even greater harm on civilians. Russia could frame its response as a lawful reprisal. Reprisals, while generally prohibited, are exceptionally considered lawful when aimed at compelling an adversary to cease IHL violations. Therefore, Ukraine’s actions could inadvertently legitimize Russia’s broader targeting of civilian infrastructure under the guise of enforcement, exacerbating civilian suffering rather than mitigating it.
Moreover, if Ukraine is afforded such allowances, other States or non-State actors may demand the same flexibility, leading to a system where IHL becomes contingent on subjective assessments of a party’s cause or circumstances. Such an approach would fundamentally compromise the impartial framework of ICL that ensures equal accountability for all belligerents.
Proportionality and Distinction
The risks posed by the sliding scale argument are not merely theoretical; they manifest in the practical application of IHL principles on the ground. To fully grasp the dangers of conflation, we must examine how the principles of distinction, proportionality, and humane treatment of prisoners of war operate within the framework of IHL and how their violation risks transforming ICL into a selective mechanism of justice. The principles of distinction and proportionality are cornerstones of IHL. Codified in the Geneva Conventions and their Additional Protocols and criminalized in the Rome Statute, they exemplify the impartiality and universality that underpins IHL.
The principle of distinction, set out in Article 48 of Additional Protocol I (AP I), requires conflicting parties to always differentiate between civilians and combatants and between civilian objects and military targets. The deliberate targeting of civilians and civilian objects, prohibited under AP I Articles 51 and 52 and Common Article 3 of the 1949 Geneva Conventions, is classified as a war crime under Articles 8(2)(b)(i)-(ii) of the Rome Statute, respectively. Similarly, the principle of proportionality, outlined in AP I, Articles 51(5)(b) and 57 prohibits attacks where the incidental harm to civilians and civilian objects is expected to be excessive concerning the anticipated concrete and direct military advantage. The violation of this principle is codified as a war crime under Article 8(2)(b)(iv) of the Rome Statute.
Ukraine’s defensive operations against Russia’s aggression, though widely recognized as lawful under jus ad bellum, must still adhere to the strict standards of distinction and proportionality. For example, targeting Russian forces embedded within civilian infrastructure requires a meticulous assessment to avoid disproportionate harm, as mandated under Article 8(2)(b)(iv) of the Rome Statute. In Prosecutor v. Blaškić, the International Criminal Tribunal for the Former Yugoslavia (ICTY) rejected the argument that strategic motives could justify civilian harm, emphasizing that IHL principles are absolute and must remain independent of broader military or political goals (paras. 508-10). Similarly, the Prosecutor v. Galić case underscored that indiscriminate attacks, even when intended to achieve legitimate objectives, violate proportionality when civilian harm outweighs the military advantage (paras. 57-62).
In Gaza, the principle of distinction is routinely tested. Hamas’s indiscriminate rocket fire targeting Israeli civilians constitutes a clear breach of distinction under Article 8(2)(b)(i), as it fails to differentiate between civilian and military targets. Conversely, Israeli airstrikes on densely populated areas, while often justified as targeting Hamas infrastructure, must comply with proportionality. These actions, if found to cause expected and excessive civilian harm, would violate Article 8(2)(b)(iv) of the Rome Statute. The Israel Supreme Court’s decision in the Targeted Killing Case reinforces the necessity of a case-by-case assessment, emphasizing that even national security concerns cannot override proportionality requirements (paras. 40, 45-46).
The International Court of Justice case against Israel on genocide allegations and the ICC investigations into Israeli leaders for individual responsibility underscores the critical danger of conflating the two legal frameworks. These proceedings rely on concrete and well-documented breaches of IHL. If Israel’s actions were justified under its self-defense claims—particularly in the wake of Hamas’s heinous attack—these violations could be shielded from legal accountability.
The Sliding Scale Fallacy
What I fear from conflating jus ad bellum and jus in bello is precisely what is happening in Gaza. Israel’s claim to self-defense, particularly after the October 7, 2023, massacre by Hamas, stands on solid legal ground. At the same time, the Palestinian cause for self-determination, recognized under UN General Assembly Resolution 2105 (XX) 1965, further complicates perceptions of legitimacy. While international law permits the use of force in national liberation struggles, this right is reserved for recognized movements, not groups like Hamas. Despite this, many Palestinians and their supporters justify the atrocities committed on October 7, conflating the justness of the cause with the legality of the means employed.
Critics of the traditional separation of jus ad bellum and IHL might argue that they do not seek to dismantle the entire IHL framework but instead propose selective flexibility. For instance, they may suggest that rules prohibiting torture or physical mutilation of prisoners of war (POWs) remain absolute in any case. However, IHL is not a collection of independent rules but a cohesive legal framework. Undermining one component inevitably weakens the entire system. Allowing flexibility in targeting civilians, for example, makes it far more difficult to demand strict adherence to rules governing the humane treatment of POWs. Once the door is opened to selective enforcement, belligerents can justify broader deviations, eroding the protections IHL seeks to guarantee for all.
Between March 2023 and August 2024, the Office of the High Commissioner for Human Rights conducted confidential interviews with 205 Russian POWs held by Ukraine. 104 POWs reported consistent accounts of torture or ill-treatment, from severe beatings and electric shocks to sexual violence and threats of rape. This is not about downplaying the severity of IHL violations by Russian forces, which far exceed those by Ukraine. Instead, it exposes the absurdity of the sliding scale approach. Such an approach risks effectively decriminalizing grave IHL violations, whether it involves the treatment of POWs, disproportionate or indiscriminate attacks, or other serious breaches. If actions by victim parties are no longer considered violations, they cease to be crimes, fundamentally eroding the accountability framework of ICL.
History illustrates the pitfalls of this approach. During the Vietnam War, North Vietnam denied POW status to captured American pilots, claiming that they were “aggressors” responsible for alleged war crimes. Reviving such selective adherence today would risk a similar collapse, with violations in one area quickly spreading to others. Moreover, a system that allows one side to justify excessive harm to civilians while expecting strict compliance with other rules is inherently contradictory. Adversaries will not respect such distinctions, leading to reciprocal violations and an escalation of harm. IHL, and by extension ICL, would lose its universality, enforced only when it aligns with political or strategic interests. Therefore, IHL must be upheld as a whole. Its principles—distinction, proportionality, and humane treatment of POWs—are interdependent and non-negotiable. Only by maintaining its integrity can IHL and ICL serve their purpose: limiting the human cost of war and providing a neutral framework for accountability.
Concluding Thoughts
Those who argue why we fight should shape how we fight present it as lex ferenda, a vision for a better law to improve the current framework. Yet, the shift is already happening. Political leaders and commanders on the battlefield justify IHL violations by invoking the righteousness of their cause. The anticipated “better law” has already taken root in practice, with devastating consequences. This is why we must double down on the equality of belligerents and the universality of IHL to preserve ICL as a functioning accountability framework.
No party admits to being the wrongdoer in a conflict. Every side claims to be the victim, forced into action. This self-attribution of legitimacy, or its endorsement by partisan supporters, underscores the fundamental danger of conflating legal frameworks. While the rationale behind the separation is often dismissed as overly simplistic, it is precisely this division that safeguards IHL’s protections and obligations from being undermined by subjective claims of righteousness.
Many IHL rules, including the obligation to respect civilian immunity and humane treatment, are erga omnes obligations, duties owed to the entire international community. These obligations cannot be denied to the aggressor without being denied to the entire international community, as they exist independently of the conflict’s cause. This is further reinforced by the concept of ICL, where grave breaches are not merely violations against a specific party but offenses against the international community as a whole. Additionally, the 1949 Geneva Conventions’ Common Article 1, which mandates that States ensure respect for IHL “in all circumstances,” becomes meaningless if selective enforcement based on political or moral grounds is permitted. How can the international community’s active responsibility to uphold these rules be fulfilled if the very framework is undermined by conflation?
Furthermore, key components of IHL, such as the prohibitions on torture, targeting civilians, and disproportionate attacks, are peremptory norms from which no derogation is permitted. Allowing violations of these norms based on case-by-case considerations compromises the legal integrity of IHL. These obligations must remain absolute, applying equally to all parties, without exceptions grounded in subjective assessments of the justice of their cause.
Finally, the broader implications for ICL are equally dire. If this corpus of international law enforcement becomes contingent on the perceived legitimacy of a party’s jus ad bellum arguments, it ceases to function as a neutral mechanism for accountability. The Rome Statute is designed to prosecute grave breaches of IHL by the same standards for all parties. Importantly, ICL itself, recognizing the separation, is not oblivious to the significance of jus ad bellum and its breaches. The Rome Statute uniquely addresses acts of aggression under Article 8 bis. This provision criminalizes leaders who plan, prepare, initiate, or execute acts of aggression, defined as the use of force by one State against another in contravention of the United Nations Charter. Therefore, we must leave the “why” of war and the “how” of law separate to preserve the relevance and integrity of IHL and ICL.
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Davit Khachatryan is an international law expert and researcher with a focus on operational law, international criminal law, alternative dispute resolution, and the intersection of various legal disciplines.
Photo credit: IDF Spokesperson’s Unit
