One of the perennial realities of human existence is war. From the earliest recorded events of human history all the way through to modern times, human communities have engaged in armed conflict as a method of dispute resolution. While war has been a constant part of the human experience, there has also been a tendency within virtually all human civilisations to limit the extent of war and the methods by which warfare may be conducted.(1) In Western civilisation, this limitation on warfare has taken shape as an effort to limit both the determination of when war is appropriate and the means used in battle.(2)
Within the Western moral, legal, and political arena, the connected questions of when war is appropriate and what means are acceptable in warfare has been the subject of a great deal of examination. The basic theory which has arisen within Western culture to evaluate the legitimacy of military action is called just war theory.(3) The just war theory has received widespread acceptance both within Western culture and in the international community as a means by which a war may be determined to be justified or not.(4) Just war theory, which has both religious and secular proponents, is perhaps the most universally recognised moral theory by which the use of force may be evaluated.
II. A GENERAL OVERVIEW OF JUST WAR THEORY
Just war theory has a varied and diverse background.(5) The just war tradition includes the contributions of philosophers and theologians dating back to Roman times. As James Tuner Johnson has pointed out,
Just war is an historical tradition formed by experience
and reflection, including much that is neither specifically
theological (or even religious), nor philosophical. It has
been strongly influenced by international law, the traditions
of chivalry, and soldierly practices derived from the
Just war theory as a method of evaluating military actions has been recognised historically by thinkers as varied as Cicero, St. Augustine, St. Thomas Aquinas, Grotius, and Daniel Webster. It is a theory which has been used by Christians and non-Christians alike to determine whether or not the decision to go to war and the means used to prosecute that war are just. It is crucial to keep this varied and complex pedigree of the just war tradition in mind when dealing with just war theory, otherwise it becomes possible to restrict the “breadth and diversity of the tradition,”(7) which could in turn lead to a serious misapplication of the theory in a particular circumstance.
Understanding, then, that the theory of just war is one in which many sources mingle over the course of centuries, it is helpful to make a brief overview of those sources before delving into the main task of explaining just war theory.
1. The Religious Sources of Just War Theory
Many of the key thinkers who have expounded on just war theory through the centuries have identified themselves with the Christian faith, both in its Catholic and Protestant varieties. Just war theory has also gained a general acceptance among Christian theologians, philosophers, and jurists as a method of passing judgement on the morality or immorality of a particular conflict.(8) The general Christian conception of just war theory forms the core of secular just war theory and as such has had a tremendous influence on the secular conception of the just war.(9)
Early Christian approaches to war were largely pacifistic in nature, due to a focus in the early Church to the notion that Christians were distinct from the rest of society.(10) However, with the growing Christianization of the Roman Empire, and the increasing political and social influence of the Christian Church, Christian theologians during the fourth and fifth centuries began to develop justifications for the use of force which would eventually take shape over time as just war theory.(11)
The first major Christian theologian to address himself to the task of determining the circumstances under which war is legitimate was St. Augustine of Hippo.(12) Augustine held that “the natural order, which is suited to the peace of moral things, requires that the authority and deliberation for undertaking war be under the control of a leader.”(13) For Augustine, war is a permissible part of the life of a nation, and the power of prosecuting a war was part of the natural powers of a monarch, ordained to uphold peace.(14) War, far from being something which Christians should shun, is part of the life of a nation, ordained by natural law, a law which according to the New Testament is ordained by God.
Augustine’s conception of the just war did not create a carte blanche for bloodshed.(15) In formulating his ideas on war, St. Augustine was careful to state the purposes for which war may be fought, and the procedural means which must be satisfied in order for a war to be just. “For it makes a great difference,” he wrote, “by which causes and under which authorities men undertake the wars that must be waged.”(16) For Augustine, for a war to be just, it must be fought for the right reasons, and it must
be waged under rightful authority.(17)
Augustine held that the only reason which justified war was the desire for peace. “Peace is not sought in order to provide war, but war is waged in order to attain peace.”(18) Augustine criticises other motives for war, such as “the desire for harming, the cruelty of revenge, the restless and implacable mind, the savageness of revolting, the lust for dominating, and similar things,”(19) and refers to them as things which are “justly blamed in wars.”(20) In fighting a war, the goal must be to do that which is necessary to obtain peace; “let necessity slay the warring foe, not your will.”(21) Augustine also includes under the subject of necessity the just treatment of prisoners and conquered peoples, making it clear that mercy should be shown to the vanquished, particularly if they are no longer a threat to peace.(22)
Besides right intention, St. Augustine also held that it was necessary for a war to be waged under lawful authority.(23) The purpose of the war-making powers of the state is to ensure peace, which in turn helps to foster the common-good of those in society.(24) Augustine recognised that it was necessary for the authority and decision to undertake war to be made by a recognised leader.(25) In addition, the soldiers who serve under the leader must serve the peace and common-good of society.(26) Warfare which is declared by unlawful authority therefore fails to meet this criteria, as does warfare which is not directed toward peace and the common good.
The second major Christian thinker to deal with the issue of war is St. Thomas Aquinas (1225-1274).(27) Aquinas based himself upon St. Augustine’s view of war, elaborating on the teachings of the bishop of Hippo.(28) In explicating his theory regarding the justness of a war, Aquinas focused on defining the right to make war and the importance of the intent which stands behind the decision to go to war.(29) In his attempt to formulate a simple rule which would give guidance on these issues, Aquinas argued that a war is justified when three basic, necessary conditions were met: 1. the war was prosecuted by a lawful authority with the power to wage war;(30) 2. The war was undertaken with just cause;(31) and 3. the war was undertaken with the right intention, that is, “to achieve some good or to avoid some evil.”(32) Together with St. Augustine, Aquinas’ views on the justification of war form the basic core of just war theory, and it is from their concepts that the theory of just war is adapted and expanded by later thinkers.
2. Secular Sources of Just War Theory
The secular sources for just war theory span a considerable length of time. They include such philosophers as the ancient Roman Cicero and the Dutch Protestant Hugo Grotius. In addition, modern decrees on justifiable warfare, such as the commission to the
Nuremberg War Crimes Tribunal and the United Nations Charter also act to flush out the modern conception of just war theory.
Cicero, the great Roman orator, jurist, and philosopher was one of the first to deal with the questions of justifiable war. Cicero held that the use of force was justifiable only when the war was declared by an appropriate governmental authority acting within specific limits.(33) For Cicero, the ability to wage war rested with the state, and the state alone, and could be lawfully waged only “after an official demand for satisfaction has been submitted or warning has been given and a formal declaration made.”(34) In addition, Cicero also proposed the existence of a universal norm for human behaviour which transcended the laws of individual nations and governed their relations with each other. (35) Cicero’s belief in this universal norm was grounded in his view that there was a humani generis societas, a “society of mankind sic rather than of states.”(36) This view of a universal standard of behaviour for nation-states which exists outside of promulgated law would have a profound impact on later just war theorists, particularly on Hugo Grotius.
Grotius was a 16th century Dutch Protestant who is sometimes referred to as the father of international law.(37) Grotius, who lived in the aftermath of the brutal Thirty-Years War in Europe, wrote extensively on the right of nations to use force in self-defence in his book Jure Belli ac Pacis (“On the Rights of War and Peace”), which was published in 1625.(38) It was largely Grotius who secularised just war theory,(39) making the theory more acceptable for the age of the Enlightenment. For Grotius, a war is just if three basic criteria were met: 1) the danger faced by the nation is immediate; 2) the force used is necessary to adequately defend the nation’s interests; and 3) the use of force is proportionate to the threatened danger.(40)
Grotius grounded his agreement with Cicero’s notion of the need for a declaration of war in the natural law, and also argued that the purpose of just war theory is to provide “succour and protection for the sick and wounded in war, combatants and civilians alike.”(41) A result of this view is the notion that just war theory exists externally of any recognised legal system, that it is a part of the “law of nations” which is followed by all civilised nations.(42) For Grotius, it is not necessary to prove just war theory by consulting with any of the established laws of the nations of Europe, or their customs.(43) Rather, those laws are known through the universal medium of the natural law, a law which transcends nations and their own particular legal codes, a law which is binding on all human societies in their interactions with each other.(44)
After Grotius, just war theory underwent relatively few modifications until the nineteenth century. During the first century of it’s existence, the United States’ government came to acknowledge the legitimacy of just war theory. In 1842, the U.S. Secretary of State, Daniel Webster, acknowledged the legitimacy of the customary norms employed by Grotius to define the just war.(45) This recognition occurred as a result of attempts to resolve the so-called “Caroline Incident.”(46)
The Caroline Incident occurred when the British attempted to prevent supplies from reaching Canadian rebels.(47) In their attempts to restrict the flow of material to the rebels, the British burned the U.S. ship Caroline and killed several U.S. citizens.(48) When the United States protested, the British government responded that its actions were justified as a matter of self-defence.(49) Webster responded by stating that the only way for the British claim to self-defence to stand was if it met the traditional elements of just self-defence.(50) Webster outlined those elements as consisting of necessity of self-defence, and the reasonable and not excessive use of force.(51) In essence, this definition of just self-defence mirrors that proposed by Grotius.
During the remainder of the 19th and early 20th centuries, just war theory underwent modest development. There were treaties, such as the Hague Conventions, which codified just war theory, but there was little major development in just war theory. That changed with the end of the Second World War. As a result of World War II, two basic documents were issued which resulted in increased recognition of just war theory in the international arena. The first document is the charter for the Nuremberg war crimes trials, and the second is the United Nations Charter. The Nuremberg Charter encapsulated the reigning notion of just war theory as represented by both St. Thomas Aquinas and Grotius.(52) The Nuremberg Tribunal established that just war theory, as Grotius understood it, is universally binding customary law.(53)
The United Nations Charter also has contributed to just war theory by recognising the inherent right of each sovereign nation to self-defence.(54) Article 51 of the U.N.
Charter affirms the right of each nation to self-defence, until the Security Council can take action in order to restore and stabilise international peace and security.(55) Article 51 states two key points in regard to international relations and the rightful use of force in international disputes: 1) the regulation of the use of force; and 2) collective security.(56) The U.N. Charter effectively outlaws the use of military force as a method of resolving international conflicts between nation-states.(57) At the same time, the charter recognises the inherent right of each nation to defend itself from an attack from an exterior foe which is by its very nature unlawful.(58) This right of a nation to engage in defensive military actions has also been upheld by the International Court of Justice in its ruling in the case of Nicaragua v. United States of America. In that case, Nicaragua brought action against the United States for its support of insurgency forces attempting to overthrow the Sandinista government in Nicaragua. The International Court of Justice in its ruling held that the right of a nation to engage in self-defence, as customarily understood, was incorporated into Article 51 of the U.N. Charter.(59) As the Court stated, “in the language of Article 51 of the United Nations Charter, the inherent right
(or droit naturel) which a State possesses in the event of an armed attack, covers both collective and individual self-defence.”
B. GENERALLY RECOGNIZED PRINCIPLES OF
As the proceeding section has demonstrated, just war theory, despite its diverse sources and historical development, has several commonly recognised elements. These elements are traditionally divided into two basic categories which deal with the two basic fundamental issues regarding the legitimacy of war.(60) The first issue, sometimes referred to in Latin as the jus ad bellum (literally, “that which is right or just to engage in resort to war”(61)), concerns when it is appropriate to resort to war as a method of conflict resolution.(62) The second issue, jus in bello (literally, “that which is right or just within war”(63)) deals with what methods of warfare are permissible within the context of a war which meets the criteria of the jus ad bellum.(64)
The core elements of the jus ad bellum consist of those principles which were originally recognised by the medieval commentators on just war theory as being most central to the whole doctrine of just war.(65) As elucidated by St. Thomas Aquinas, the core principles consist of the following three elements: 1) just cause; 2) competent authority; and 3) right intention.(66)
Just cause is classically understood to refer to self-defence.(67) The use of military force is justified when it is used to repel an unjust aggressor and to retake that which the unjust aggressor has taken.(68) It is generally acknowledged that a nation may use force to protect a neighbouring state from attack from an outside hostile power.(69) Thus, defence of self, or defence of another, are legitimate reasons for a nation-state to resort to military force.
The second element of jus ad bellum is that the war must be declared by competent authority.(70) As recognised by theorists like Cicero and Aquinas, for a war to be just, the decision to go to war must be lawfully made.(71) If an illegal or non-legal authority within an nation made the decision to go to war, such a decision would be unjust, for it would violate the basic principles of how a given society is governed.
Finally, the war must be fought with right intention, meaning that the motives for the war must not be to inflict undue suffering on the enemy state; the defending nation must use only that amount of force which is necessary for it to achieve its just cause. The motives of those engaged in making the decision to go to war must not be tinged with vengeance or a desire for retribution. Rather, the decision to go to war must be essentially protective; the goal of war is to obtain a just and durable peace. Such a peace is unlikely if the war is waged out of hateful or vengeful motives, with a desire not solely for self-protection but the total destruction of the enemy. If in it’s actions, the defending state’s use of force exceeds what is necessary for the success of its just cause, the defending state’s right intention is problematic. Seen this way, right intention serves to reinforce the requirement that the state which seeks to justly use force be acting in a truly defensive capacity, rather than engaging in military adventurism on the pretext of self-defence.
Just war theory is an attempt to think morally about war. The theorists who have recognised and shaped just war theory throughout Western civilisation have included both secular and religious writers, including some of the greatest names of Western philosophy and legal theory. Just war theory has been recognised and used widely in the 20th century in an attempt to limit the horrors of war, and has been incorporated into international law through the United Nations Charter, and the Nuremberg Charter. Generally construed, just war theory consists of two basic categories: jus ad bellum and jus in bello.
1. James Turner Johnson, “Just War Tradition and
Low-Intensity Conflict” in Legal and Moral Constraints on
Low-Intensity Conflict, 147, 148 (Alberto R. Coll, et al.
2. Examples of the efforts of the international community
to limit warfare are quite extensive, and stretch back well
into the Middle Ages. As Judith Gail Gardam points out in
her article Proportionality and Force in International Law,
87 Am. J. Int’l L. 391, 395 (1993), the Catholic Church
was active in the Middle Ages in limiting warfare, as seen
by the Second Lateran Council’s prohibition in 1139 of
the use of crossbows, bows and arrows, and siege
weapons in conflicts between Christian nations.
3. Johnson at 148.
4. The widespread use of just war theory by both
Western countries and the international community can be
seen in the use of just war theory by the International
Military Tribunal at Nuremberg. The Nuremberg tribunal
used the basic just war categories to determine if the
actions taken by the Axis powers were in accord with
international law. See Article 6(a) and (b) of the
Nuremberg Charter, reprinted in Telford Taylor, The
Anatomy of the Nuremberg Trials 648 (1992)..
5. Johnson at 147-149.
6. Id. at 148.
7. Id. at 149.
8. Paul Ramsey, War and the Christian
Conscience (1961) and The Just War: Force and Political
9. Gardam at 817.
10. Id. at 223.
11. Id., citing R. Bainton, Christian Attitudes Toward War
and Peace 14 (1960).
12. Id. at 223.
13. St. Augustine of Hippo, Against Faustus the
Manichaean XXII.73-79, in Augustine: Political Writings,
222 (Michael W. Tkacz and Douglas Kries, trans, Ernest
L. Fortin and Douglas Kries, eds. 1994).
14. Id. at 220.
15. Augustine at 221-222.
16. Id. at 222.
17. Id. at 220, 222.
18. Id. at 220.
19. Id. at 221.
20. Id. at 222.
21. Augustine at 220.
23. Id. at 222.
24. Id. at 220-222.
25. Id. at 222.
26. Augustine at 222.
27. St. Thomas deals with the question of the legitimacy of
war in his Summa Theologicae, Part II, II, Q. 40, Art. 1.
28. Id., especially Reply Obj. 1-3 where St. Thomas
bases his arguments heavily on the writings of St.
29. Aquinas, Summa Theologicae, II, II, Q. 40, Art. 1.
33. David J. Bederman, Reception of the Classical
Tradition in International Law: Grotius’ De Jure Belli Ac
Pacis, 10 Emory Int’l L. Rev. 1, 31-32 (1996).
35. Id. at 6.
37. Bederman at 1.
39. Johnson at 151.
40. Hugo Grotius, The Law of War and Peace, Bk. II,
Ch. 1 (1949) cited in Ziyad Motala and David T.
ButleRitchie, Self-Defense in International Law, the
United Nations, and the Bosnian Conflict, 57 U. Pitt. L.
Rev. 1, 10 n.75 (1995).
40. Bederman at 32.
41. Roberts at 225.
42. Bederman at 32.
44. Motala at 10.
48. Id. at 11.
49. Motala at 11.
51. See the Nuremberg Charter, art. 6(a)-(c). The charter
lists the waging of aggressive war, “violations of the laws
or customs of war,” and the extermination and
enslavement of civilians among its examples of wartime
52. Rostow at 169-70.
53. United Nations Charter, articles 2(4) and 51. See also
Gardam at 403-11; Motala at 3.
54. U.N. Charter art. 51.
55. Motala at 4.
58. Motala at 11.
59. Johnson at 149; Bederman at 29. The tradition of
dividing just war theory into two distinct analytical
categories has its roots in the work of Grotius, Aquinas,
Augustine, and Cicero.
60. Johnson at 149
61. Johnson at 149
65. Aquinas, Summa Theologicae, II, II, Q. 40, Art. 1.
66. Johnson at 158
67. Johnson at 158.
68. U.N. Charter art. 51.
69. Johnson at 158. Johnson compares the concept of
“right authority” with the modern concept of sovereignty
and argues that the just war notion of authority basically
mirrors the modern notion of sovereignty. Id.
70. Bederman at 31-32; Aquinas, Summa Theologicae,
II, II, Q. 40, Art.1..
71. Aquinas, Summa Theologicae, II, II, Q. 40, Art. 1.