In Honor of Françoise Hampson – Calibrating the Balance Between Military Necessity and Humanity in LOAC Practice

Editors’ note: This post is part of a series to honor Françoise Hampson, who passed away on April 18, 2025. These posts recognize Professor Hampson’s work and the significant contribution her scholarship made to our understanding of international law.

Reflecting on 30 years of teaching the law of armed conflict (LOAC) to law students, military personnel, and humanitarian staff, Françoise Hampson suggested in 2008 that it would be “counter-productive” to interpret LOAC constraints on military action with the aim of making conflict unfightable.

If the rules were such as to make lawful fighting impossible, the result would not be no fighting. It would be fighting conducted unlawfully. In order for there to be any chance of the rules being respected, it must be possible to fight according to the rules.

With the devastating human toll of current conflicts in Ukraine, Sudan, and Gaza again bringing the balance between military necessity and humanity into the spotlight, her insight serves as a starting point. The relationship between humanity and military necessity in LOAC is often conceived and argued as a zero-sum game, where military advantage is in danger of being thwarted by humanitarian considerations or humanity overridden by remorseless military logic. But Françoise reminds us that both are required if LOAC is to work in practice.

It is difficult to say anything new on such a foundational subject for LOAC as the balance between humanity and military necessity but, in the spirit of Françoise’s practical concerns—she always characterized herself modestly as a “plumber” in the law—this post comments on how the balance is interpreted in practice and, in particular, by whom.

Relationship with LOAC Rules

Given the significance of military necessity and humanity for LOAC, there is surprisingly little agreement in the literature on how they should be described. For Dinstein, they are “driving forces.” For Sassòli, they are included among the principles that “inspire as well as support existing rules.” It is, however, settled that they do not in themselves have the character of rules; that is to say, they do not have the force to challenge or displace extant rules of LOAC, whether derived from treaty or custom.

If the position were different, and either humanity or military necessity could be played as a trump card, many LOAC rules would in effect collapse. The prohibition on chemical weapons, for example, would not survive a carve-out for military necessity. Conversely, the obligation to give effective advance warning of any attack which may affect the civilian population would extinguish the possibility of surprise if there were no exemption for where “circumstances do not permit” (Additional Protocol (AP) I, art. 57(2)(c)).

The understanding that the appropriate balance between military necessity and humanity is already captured in the existing rules of LOAC has, however, two main exceptions. The first is where there is no specific rule available. A few years ago Françoise contributed a chapter to a collection I was editing, writing on one such effective gap in the law: powers of internment or administrative detention in non-international armed conflict (NIAC). In the cases of Serdar Mohammed and Abd Ali Hameed Al-Waheed, the English courts had not been able to conclude that LOAC provided authority to detain in relation to extraterritorial NIACs in Afghanistan and Iraq. While this finding was celebrated by human rights campaigners, for Françoise it was important “to consider what is likely to happen if internment is not an option, legally, politically or militarily.” If individuals could not be legally held, they might be killed (lawfully or unlawfully), arbitrarily detained, or disappeared. “In other words, the alternative to internment is not as simple as liberty.” Where LOAC is silent, both humanity and military necessity need to be considered in developing practice (in this case encouraging States to recognize a customary right to introduce an internment regime in extraterritorial NIACs).

The other exception is the rare occasion where a LOAC rule itself invokes military necessity. A particular example is the rule against wanton destruction. Article 53 of Geneva Convention IV prohibits any destruction by an occupying power of real or personal property “except where such destruction is rendered absolutely necessary by military operations.” Article 8(2)(iv) of the Rome Statute of the International Criminal Court also classes extensive and wanton destruction as a war crime.

This particular rule has a long history. Originally codified in Article 23(g) of the Hague Regulations, it proved critical in two trials at Nuremberg, leading to different verdicts in relation to essentially the same conduct. Before the International Military Tribunal, Alfred Jodl was convicted for (among other crimes) ordering in October 1944 a scorched earth policy in northern Norway. But two years later, in the Hostage case, the U.S. Military Tribunal acquitted Lothar Rendulic for his role in carrying out the same destruction, on the grounds that he had believed it to be militarily necessary to prevent Soviet pursuit as the Wehrmacht retreated. While the latter case is now best known as the origin of the LOAC rule that commanders’ actions must be judged in light of the information reasonably available to them at the time, the Tribunal’s judgment included a firm rebuttal of the old German legal theory of Kriegsräson:

It is apparent from the evidence of these defendants that they considered military necessity a matter to be determined by them, a complete justification of their acts. We do not concur in the view that the rules of warfare are anything less than they purport to be. Military necessity or expediency does not justify a violation of positive rules.

For the Tribunal, military necessity was at once a permission for, and a limitation on, military action: “There must be some reasonable connection between the destruction … and the overcoming of the enemy forces” (p. 1253-54).

In acquitting Rendulic on the scorched earth charge (he was convicted of separate charges related to the killing of civilians in the Balkans), the Tribunal nonetheless adopted a permissive interpretation of military necessity which has in key respects been outdated by the prohibition of scorched earth tactics in AP I (art. 54(2)).

Who Controls Interpretation?

If neither military necessity nor humanity can be invoked to overwrite existing rules of LOAC, the controversy about which should prevail can quickly re-emerge when it comes to deciding who interprets the rules. This was vividly illustrated when the International Committee of the Red Cross (ICRC) published its Interpretative Guidance on Direct Participation in Hostilities (see, e.g. here and here).

In practice, the question often crystallizes in the concept of reasonableness. Here, for example, is the U.S. Air Force guidance for commanders on the proportionality rule: “If the commander can clearly articulate in a reasonable manner what the military importance of the target is and why the anticipated civilian collateral injury or damage is outweighed by the military advantage to be gained, this will generally satisfy a ‘reasonable military commander’ standard” (p. 16).

At a symposium at the U.S. Naval War College on NATO’s Kosovo campaign, Professor Michael Bothe criticized the decision to define the applicable standard by reference to a “reasonable military commander.” He argued, “In a democratic system, the value judgment which matters most is that of the majority of the society at large. The military cannot and may not constitute a value system of its own …” (p. 184). Bothe acknowledged that his view was influenced by the recent history of his own country, Germany. In response, Leslie Green countered,

A reasonable man is the man on a downtown bus; that is not the reasonable soldier. One of the reasons that I don’t like civilian judges trying military offenses is that they don’t know the circumstances that were prevailing at the time that led to the soldier’s actions. The question of what is reasonable in times of conflict depends on what is reasonable in the eyes of the man who is involved in that conflict (p. 212).

Green’s contrast with the man on the bus reminds us that the reasonable military commander is a sub-species of law’s reasonable person; that is, the personification of an objective standard of reasonableness. That standard may be qualified by specialist expertise. In a case concerning, say, medical negligence, a court assessing what was reasonable in relation to the prescription of drugs or the performance of surgery would not consider the view of a passenger on public transport but rather look to the figure of the reasonable doctor. A decision to launch an attack will always be taken by military commanders. An assessment of what constitutes reasonable conduct therefore needs to reflect their specialist knowledge and skills.

This argument, however, cuts both ways. Military advantage may well be better understood by commanders, but civilian harm, including in particular the reverberating effects of attacks, might be better appreciated by humanitarian actors. More generally, beyond the conduct of hostilities, LOAC obligations towards persons within the power of a party to conflict, including civilian populations under occupation, may be better understood by humanitarians. If a civilian official is unlikely to have much appreciation of the alternative means and methods of warfare available to a commander at any particular instant (AP I, art. 57(2)(ii)), for example, so too a military commander may have little idea of likely patterns of population displacement or of the types and amounts of food and medical supplies adequate to sustain a given civilian population (GC IV, art. 55). Here a determination of what is reasonable needs to recognize the specialist knowledge of the humanitarian. As the current example of the operations of the Gaza Humanitarian Foundation tragically illustrates, to disregard that expertise and allow an approach ostensibly overridden by military considerations may have deadly consequences for civilians.

The question of whose specialist expertise is admissible in the practical application of LOAC goes beyond strict interpretation of legal rules to invite questions of a more philosophical character. What does it mean, in Green’s phrase, to be “involved in” a conflict? In an age where the preponderance of casualties in most (although not all) wars are civilian, who fundamentally has the more informed understanding of the nature of contemporary conflict: the professional soldier who conducts war or the civilian who registers its most harmful effects?

Re-calibrating the Balance

According to the latest ICRC Challenges Report, the framework balancing humanity and military necessity is under strain. Citing attacks on hospitals and schools, the impeding of humanitarian access and attacks based on expansive conceptions of direct participation in hostilities, it explains,

[International Humanitarian Law] owes its credibility to its pragmatism: many of its prohibitions have narrow exceptions that are intended to ensure that the law takes military necessity into account and does not confer humanitarian protections that an adversary can exploit for military advantage. But some interpretations of those exceptions are widening with dangerous consequences … narrow exceptions become wide legal loopholes for circumventing vital protections (p. 7).

In September 2024 the ICRC, together with a number of States, duly launched a Global Initiative to galvanize political commitment to LOAC, planned to culminate with a High-Level Meeting to Uphold Humanity in 2026.

Re-calibrating the balance is indeed first and foremost the task of States coming together to clarify the rules, including, if necessary, by concluding treaties to amend them. But if the problem is less about the rules themselves than about their interpretation, what effective constraints exist to ensure this is done in good faith? The traditional answer is the reciprocal effect of LOAC, for which public opinion or “naming and shaming” is a poor substitute. (On this view, the ultimate test of an argument for military necessity is not scrutiny in the New York Times but whether it would ever be accepted if pleaded by the enemy.) However, the asymmetric nature of much contemporary conflict considerably weakens the power of reciprocity.

I would suggest that military lawyers, who educate and advise armed forces on the LOAC and support its implementation, have a natural interest in enabling legal issues (as distinct from policy questions) to be authoritatively determined. Unfortunately, the mechanisms for doing so are currently insufficient. The Geneva Conventions are universally ratified but the lack of a compromissory clause means that a State is generally unable to refer a dispute over LOAC to the International Court of Justice (introducing such a provision might be one concrete outcome from the Global Initiative). War crimes trials provide a potential forum but they are comparatively rare, deal only with egregious cases, and necessarily focus on the culpability of individuals rather than the responsibility of States and other parties to conflict.

For Françoise Hampson, who served for many years on UN human rights bodies, human rights law provided a partial answer. Internationally, human rights monitoring bodies and regional courts have to an extent filled the gap in LOAC monitoring, but their authority is limited, particularly in cases of active hostilities in international armed conflicts.

In the absence of a dedicated mechanism to adjudicate the interpretive balance between military necessity and humanity, there has been a turn towards using domestic litigation to give effect to LOAC norms. Take the right under LOAC of families to know the fate of their relatives (AP I, art. 32). Armed forces routinely refuse on security grounds to release information on civilian harm held by combatant commands (while simultaneously arguing that determining a LOAC violation is impossible without access to information held by the commander of an attack).

But in the United Kingdom the relatives of civilians killed in special forces operations in Afghanistan have used administrative law to force a statutory public inquiry into so-called “direct detention operations.” In the Netherlands, the law on civil wrongs has been used to discover and challenge information on target identification and secure compensation for the families of civilian victims. Even in the United States, where a combat activities exception in the Foreign Claims Act (10 U.S.C. §2734-2736) presents a formidable obstacle to litigating LOAC violations, freedom of information legislation has been used to obtain extensive data on civilian harm in Iraq, Syria and Afghanistan.

Concluding Thoughts

Recent years may have registered a tipping of the balance towards military necessity, but they have also seen unprecedented public interest in the substance and operation of LOAC rules. For those of us working to support the implementation of LOAC, from both military and humanitarian backgrounds, this presents an opportunity to consider how both military necessity and humanity can be fairly argued—and the balance adjudicated—in practice.

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Mark Lattimer is executive director of Ceasefire Centre for Civilian Rights.

The views expressed are those of the author, and do not necessarily reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense. 

Articles of War is a forum for professionals to share opinions and cultivate ideas. Articles of War does not screen articles to fit a particular editorial agenda, nor endorse or advocate material that is published. Authorship does not indicate affiliation with Articles of War, the Lieber Institute, or the United States Military Academy West Point.

Photo credit: IDF Spokesperson’s Unit