Jus in Bello

Michelle Maiese

June 2003

Fighting Well and Limited War

The rules of jus in bello aim to confine the destructiveness of war, rule out certain kinds of weapons, protect civilians, and limit the area and range of fighting.

Many note that the methods of contemporary war, nuclear warfare in particular, are inescapably in violation of the principles of proportionality and non-combatant immunity.

Must such warfare be rejected as a moral possibility on just war grounds?

The rules of jus in bello (or justice in war) serve as guidelines for fighting well once war has begun. Some maintain that morality does not exist in warfare, and therefore object to just war theory. War is hell, the argument goes, and one is entitled to do whatever is necessary to ensure victory for one's own side. Just war theory, on the other hand, sets forth a moral framework for warfare and rejects the notion that "anything goes" during times of war. Belligerent armies are entitled to try to win, but they cannot do anything that is, or seems, necessary to achieve victory.[1] There are restraints on the extent of harm, if any, that can be done to noncombatants, and restraints on the weapons of war.[2] These restraints aim to limit war once it has begun.

The principles of humanitarian law are thought to apply in conflict, and to regulate the conduct of military forces.[3] The rules of warfare aim to safeguard human life and some other fundamental human rights, and to ensure that war is limited in its scope and level of violence. Total war, where neither discrimination nor proportionality serve as mitigating considerations, is to be avoided.[4]

Jus in bello also requires that the agents of war be held responsible for their actions. When soldiers attack non-combatants, pursue their enemy beyond what is reasonable, or violate other rules of fair conduct, they commit not acts of war, but acts of murder.[5] International law suggests that every individual, regardless of rank or governmental status, is personally responsible for any war crime that he might commit.[6] If a soldier obeys orders that he knows to be immoral, he must be held accountable. War crimes tribunals are meant to address such crimes.

Note that the guidelines governing justice in war are distinct from those of jus ad bellum, or justice of war. Even if a nation lacks just cause for war, it may fight justly once war has begun. Conversely, a nation with just cause may fight unjustly. The two central principles of jus in bello, discrimination and proportionality, establish rules of just and fair conduct during warfare. The principle of discrimination concerns who are legitimate targets in war, while the principle of proportionality concerns how much force is morally appropriate.

Discrimination and Non-Combatant Immunity

The principle of discrimination recognizes that individuals have a moral standing "independent of and resistant to the exigencies of war."[7] Since killing is morally problematic, just war theory must provide an account of why soldiers can become legitimate targets of attack.[8] It must also answer whether a combatant's status changes depending on whether his cause is just or unjust, and establish "how those victims of war who can be attacked and killed are to be distinguished from those who cannot."[9]

No individual can justly be attacked unless he has, through his own action, surrendered or lost his basic human rights.[10] However, because individuals with combatant status forfeit some of these basic rights when they become soldiers, their death can be morally justified. Civilians, on the other hand, have not forfeited these rights, and are never permissible targets of war. Houses, places of worship, and schools should be immune from attack as well. Thus, the principle of non-combatant immunity suggests that war is a fight between combatants, and that only military objectives are legitimate targets of attack. Many believe that noncombatants may never be subject to direct, intentional attack, even if one is fighting on the just side of the war.[11]

However, civilian deaths are sometimes unavoidable, and the practicalities of war may require that the absolutist conception of non-combatant immunity be abandoned. The term "collateral damage" refers to destruction unavoidably incurred in the act of destroying a target deemed to be of military significance.[12] Many believe that targeting a military establishment in the middle of a city is permissible, even if there is collateral damage, because the target is legitimate.

The doctrine of double effect suggests that civilian casualties are justifiable so long as their deaths are not intended and merely accidental.[13] Targeting a munitions factory, for example, aims to destroy military capabilities and not to kill munitions workers. This is a way of "reconciling the absolute prohibition against attacking noncombatants with the legitimate conduct of military activity."[14] Any harm to noncombatants must be a secondary result, indirect and unintentional.[15]

Some just war theorists have added the further stipulation that the foreseeable threat posed to civilian lives be reduced as far as possible and every effort taken to avoid killing them.[16] Most agree that the deaths of civilians are justified only if they are unavoidable victims of a deliberate attack on a military target. Thus, munitions workers, or others employed in industries associated with the war effort, are legitimate targets while at work in the factory. But they are not liable to attack when in their homes.

However, others believe that noncombatants do not require such extreme protection if the war is just. "Where the war is just, collateral killing of noncombatants in connection with a legitimate military operation is to be allowed," and this evil can be limited in terms of the jus ad bellum criterion of proportionality.[17]

In some cases, forces must override the accepted immunity of noncombatants in order to protect the very values that ultimately guarantee the safety of such persons.[18] Noncombatants are then regrettably, mournfully, made the subjects of attack. The question of how to balance military objectives and civilian casualties is no doubt a difficult one.

Yet another difficult question is how to define who is a combatant and who is not. While combatants usually carry arms openly, guerillas disguise themselves as civilians. International law suggests that the inhabitants of non-occupied territory, who take up arms on the approach of the enemy and resist the invading troops, even if they have not had time to organize themselves, count as armed forces.[19] However, without uniforms, it is difficult to distinguish these armed forces from unarmed civilians. Some have maintained that in these cases, the burden is on the government to identify combatants, while others argue that "the nature of modern warfare dissolves the possibility of discrimination."[20]


The principle of proportionality deals with what kind of force is morally permissible in warfare. It suggests that the injury caused should be proportional to the objective desired, and that the extent and violence of warfare must be tempered to minimize destruction and casualties.[21] Restriction of means aims to protect all involved from unnecessary suffering, to safeguard human rights and to "restrict the amount of damage likely to be long-term extending beyond the period of hostilities."[22]

Central to proportionality is the notion that parties should oppose force with similar force, and "thwart the assailant's purpose using the minimum force necessary to do so."[23] One may not kill the opponent if it is possible to achieve the desired end by only injuring him. In addition, "the evil produced by the war must not be greater than the good done or the evil averted by it."[24] Costs must not outweigh benefits.

Just as the jus ad bellum principle of right intention suggests that wars must be fought for limited objectives, the notion of limited war suggests that there must be restraint with regard to the quantity and quality of weaponry used during warfare.[25] First, weapons that do not discriminate between combatants and non-combatants cannot be used. The use of asphyxiating or poisonous gases, the starvation of civilians as a method of warfare, and the destruction of objects that are indispensable to the civilian population are prohibited.[26] In addition, weapons that cause long-term environmental damage are prohibited.[27] This includes destruction or contamination of foodstuffs, crops, livestock, and drinking water.

Finally, the law of armed conflict forbids acts that go beyond the purpose of defeating the enemy party and cause unnecessary injury. If a choice is possible among military objectives, the one selected should be that likely to cause the least destruction and casualties.[28]

Rights of Soldiers

Although soldiers do forfeit some of their rights when they assume combatant status, they do not forfeit them permanently or completely. Once a soldier has laid down his arms and surrendered, he assumes the status of a non-combatant and cannot be killed or attacked. His property must not be destroyed or seized, unless this is imperatively demanded by the necessities of war. In addition, it is forbidden to steal from prisoners of war or the sick and wounded, or to mutilate or steal from corpses.[29] The wounded enemy are to be collected and cared for.

Combatants that are captured in battle must be humanely treated. Prisoners of war are entitled to basic human respect and are to be protected against any acts of violence or intimidation. They cannot be tortured or forced to work in support of the enemy's war effort, and must be provided with proper food, shelter, and medical treatment.[30]

[1] Michael Walzer, Just and Unjust Wars: A Moral Argument with Historical Illustrations, 2nd Edition. (New York: Basic Books, 1997), 44. 4th Edition (2006) available here.

[2] James Turner Johnson, Just War Tradition and the Restraint of War: A Moral and Historical Inquiry. (New Jersey: Princeton University Press, 1981), xxiii. <http://books.google.com/books?id=6aCSQgAACAAJ>.

[3] L.C. Green, The Contemporary Law of Armed Conflict. (Manchester, Canada: Manchester University Press, 1993), 17. Updated edition (2008) available here.

[4] Johnson, 223.

[5] Alex Moseley," Just War Theory," in The Internet Encyclopedia of Philosophy (2009, accessed February 3, 2003). <http://www.utm.edu/research/iep/j/justwar.htm>.

[6] Green, op. cit 292.

[7] Walzer, op. cit 135.

[8] Moseley, op cit.

[9] Walzer, op. cit 41.

[10] Walzer, op. cit 135.

[11] Johnson, op. cit 197.

[12] Johnson, op. cit 221.

[13] Moseley, op. cit

[14] Walzer, op. cit 153.

[15] Johnson, op. cit 198.

[16] Walzer, op. cit 156.

[17] Johnson, op. cit 201.

[18] Johnson, op. cit 223.

[19] Green, op. cit 104.

[20] Moseley, op. cit.

[21] Moseley, op cit.

[22] Green, op. cit 123.

[23] Johnson, op. cit 198.

[24] Johnson, op. cit 204.

[25] Johnson, op. cit 194.

[26] Green, op. cit 136.

[27] Don Hubert and Thomas G. Weiss et al. The Responsibility to Protect: Supplementary Volume to the Report of the International Commission on Intervention and State Sovereignty. (Canada: International Development Research Centre, 2001), 144. <http://books.google.com/books?id=31qFeSkSb5IC>.

[28] Green, op. cit 148.

[29] Green, op. cit 144.

[30] Green, op. cit 193.

Use the following to cite this article:
Maiese, Michelle. "Jus in Bello." Beyond Intractability. Eds. Guy Burgess and Heidi Burgess. Conflict Information Consortium, University of Colorado, Boulder. Posted: June 2003 <http://www.beyondintractability.org/essay/jus-in-bello>.

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