By: Roc Thomas Kiyirembera | Date: September 25, 2025
It is well established that, for the purposes of the law governing the conduct of hostilities, there exists no legal vacuum: a person is either a combatant or a civilian. This binary classification stems from the principle of distinction, cornerstone of international humanitarian law (IHL), so firmly embedded in customary international law that it is often regarded as possessing jus cogens status. As one author aptly notes, “in combat situations, the entire body of IHL can be reduced to the obligations to observe the principle of distinction.”
Yet, the ongoing armed conflict between the armed forces of the Democratic Republic of the Congo (DRC) and the M23 rebel group reveals a disturbing pattern. All parties to the conflict have consistently “disregarded IHL obligations of distinction, proportionality and precautions, affecting civilians, displacement camps, civilian dwellings and medical facilities.” At first glance, this may appear unsurprising in a region where violence has become a lifestyle. However, the justifications advanced by all parties and the “war of narratives” that shapes their public and diplomatic rhetoric highlight a deeper problem. The principle of distinction comes under particular strain in wars waged under highly moralistic pretexts. This phenomenon echoes some interpretations of just war theory, which support an unequal application of the law of armed conflict, privileging the “just cause”.
This brief reflection will demonstrate why it is crucial to maintain a strict separation between jus ad bellum (the law governing the resort to force) and jus in bello (the law governing the conduct of hostilities) to limit the horrors of protracted, seemingly endless wars such as those afflicting the DRC. Upholding this distinction remains essential for preserving the protective function of IHL and preventing the instrumentalization of humanitarian law in the service of political or military objectives under the guise of “just” causes.
Trying to interpret IHL through the jus ad bellum
According to certain interpretations of just war theory, the rights and obligations of combatants should vary depending on which party is deemed to possess a more justified or righteous cause. In essence, combatants fighting under a legitimate jus ad bellum claim are considered entitled to broader jus in bello privileges than combatants on the unjustified side and may inflict harm on non-combatants to a degree that correlates with the perceived virtue of their cause.
This interpretation is notably reflected in the current conflict in the DRC. Congolese armed forces, and their affiliated local militias—the so-called Wazalendo—have reportedly targeted individuals they perceived to be affiliated with M23 or Rwanda. These perceptions are often based solely on physical appearance or linguistic markers. The Congolese forces attempt to justify such indiscriminate violence by asserting that the DRC faces aggression. Their argument aligns with just war theorists, who argue that a political community may be justified in breaching fundamental in bello norms if doing so is necessary to prevent its destruction at the hands of a military aggressor.
Likewise, United Nations experts have documented a pattern of targeted killings and summary executions conducted through house-to-house searches by M23 and Rwandan forces. These operations are directed against civilians suspected of having links to the FDLR, the remnants of the perpetrators of the 1994 genocide. Both Rwandan and M23 officials defend these abuses by claiming that the FDLR poses an existential threat to all Tutsis, whether they live in Rwanda or in Congo. By designating the FDLR a terrorist group, M23 and Rwandan forces emulate the rhetorical posture of the United States during the “war on terror.” They thereby eschew the conventional framework of IHL, arguing instead that strict adherence to IHL could hinder their military efforts. The principle of distinction is, in this view, criticized for affording terrorists an unfair advantage.
However, as history consistently demonstrates, there is profound and persistent uncertainty about what constitutes a “just cause” for war. Most combatants are convinced of the justice of their own side. In such a context, allowing jus ad bellum considerations to determine jus in bello obligations threatens to undermine the very neutrality and protective function of IHL. More importantly, as the International Military Tribunal at Nuremberg famously held:
“The contention that the rules and customs of warfare can be violated if either party is hard pressed in any way must be rejected. War is by definition a risky and hazardous business…To claim that they can be disregarded when one belligerent considers his own situation to be critical means nothing more or less than to abrogate the laws and customs of war entirely.”
This principle underscores the critical importance of upholding the separation between jus ad bellum and jus in bello. Allowing subjective interpretations to dictate the application—or suspension—of the rules governing the conduct of hostilities would undermine the integrity of IHL, erode the protective purpose of the law, and further entrench cycles of violence and impunity in protracted conflicts such as those devastating the DRC.
Why is it so important to maintain the distinction?
No matter how accustomed we have become to the brutality that characterizes armed conflicts in the DRC, the contemporary tendency to resurrect just war theory to justify widespread violations of IHL makes it imperative to recall why maintaining the distinction between jus ad bellum and jus in bello is crucial.
The willingness of States and non-state actors to abide by IHL is, in part, predicated on the principle of reciprocity. IHL presupposes a mutual interest in compliance among belligerents: parties agree to limit their conduct during hostilities because they anticipate their adversaries adhering to the same constraints. However, when one party systematically disregards these rules, the practical incentive for compliance by the other side diminishes, exacerbating the collapse of legal norms in conflict zones. Although Protocol I Additional to the Geneva Conventions and customary international law place the primary responsibility for compliance with IHL on the attacking party, in practice, violations by one side often provoke reciprocal violations by the opposing party, setting in motion a vicious cycle of lawlessness.
Another compelling reason lies in the grim reality that abandoning the distinction between jus ad bellum and jus in bello risks returning humanity to a medieval era where the objective of war was the total annihilation of the enemy. During such times, the status of prisoners of war was determined by subjective judgments rather than the clear prescriptions found in IHL.
The conflicts in the DRC provide a stark illustration of this danger: adversaries are often labelled “criminals” rather than recognized as combatants, based on the perceived legitimacy—or illegitimacy—of the cause for which they fight instead of their conduct in hostilities. This selective denial of IHL protections is as problematic as the blanket application of IHL to acts of terrorism, though for different reasons.
Combatants should not be simply equated with criminals. First, they have significantly less freedom than criminals in choosing the cause for which they fight, as they are often mobilized by state structures or armed groups within contexts of systemic violence and coercion. Second, an important incentive for respecting IHL is eroded if combatants are denied their status under IHL and treated as criminals solely because of the cause they serve. Whereas violent acts outside of combat are typically criminal regardless of the target or circumstances, combatants are entitled to combatant immunity for lawful acts of war that comply with IHL. For combatants, the promise of immunity for acts conducted in accordance with IHL provides tangible motivation to comply with the law of armed conflict. Stripping this incentive undermines the normative structure of IHL and risks intensifying the brutality of conflicts, particularly in contexts, such as the conflicts in the DRC, where the erosion of legal norms has already produced devastating humanitarian consequences.
Conclusion
It is imperative—particularly in light of ongoing efforts to justify violations of IHL under the pretext of pursuing a “just” cause—that we preserve a strict and unwavering separation between jus ad bellum and jus in bello. Upholding this distinction remains essential if there is to be any hope of mitigating the brutality of armed conflict and safeguarding a minimal standard of humanity in warfare, even amid the enduring violence that continues to plague the DRC. As Georges Fletcher aptly writes,
“the reason for adopting a rigorous distinction between jus ad bellum and jus in bello is to heed for a bright line cleavage that is workable in the field of battle. Soldiers do not have to think about who started the conflict. They know that whoever started the conflict, certain means of warfare are clearly prohibited.”
His words serve as a stark reminder that moral and legal clarity on the battlefield depends on the neutrality and universality of in bello obligations, irrespective of the perceived justice of the cause.
Roc Thomas Kiyirembera is a researcher affiliated with the Faculty of Law at Université Catholique du Graben in Kivu, Democratic Republic of Congo. His research focuses on the challenges posed by proxy militia groups, state failure, and the role of competing narratives in armed conflicts. He is the author of L’interventionnisme du Rwanda en République Démocratique du Congo: Hégémonie ou puissance prédatrice (L’Harmattan, Paris, 2024).