As international law evolves beyond the ancient percepts of sovereignty, it should incorporate new thinking about pre-emptive strikes, human rights violations as casus belli and the role and standing of international organizations, insurgents and liberation movements.
Yet, inevitably, what constitutes "justice" depends heavily on the cultural and societal contexts, narratives, mores, and values of the disputants. Thus, one cannot answer the deceivingly simple question: "Is this war a just war?" - without first asking: "According to whom? In which context? By which criteria? Based on what values? In which period in history and where?"
Being members of Western Civilization, whether by choice or by default, our understanding of what constitutes a just war is crucially founded on our shifting perceptions of the West.
Imagine a village of 220 inhabitants. It has one heavily armed police constable flanked by two lightly equipped assistants. The hamlet is beset by a bunch of ruffians who molest their own families and, at times, violently lash out at their neighbors. These delinquents mock the authorities and ignore their decisions and decrees.
Yet, the village council - the source of legitimacy - refuses to authorize the constable to apprehend the villains and dispose of them, by force of arms if need be. The elders see no imminent or present danger to their charges and are afraid of potential escalation whose evil outcomes could far outweigh anything the felons can achieve.
Incensed by this laxity, the constable - backed only by some of the inhabitants - breaks into the home of one of the more egregious thugs and expels or kills him. He claims to have acted preemptively and in self-defense, as the criminal, long in defiance of the law, was planning to attack its representatives.
Was the constable right in acting the way he did?
On the one hand, he may have saved lives and prevented a conflagration whose consequences no one could predict. On the other hand, by ignoring the edicts of the village council and the expressed will of many of the denizens, he has placed himself above the law, as its absolute interpreter and enforcer.
What is the greater danger? Turning a blind eye to the exploits of outlaws and outcasts, thus rendering them ever more daring and insolent - or acting unilaterally to counter such pariahs, thus undermining the communal legal foundation and, possibly, leading to a chaotic situation of "might is right"? In other words, when ethics and expedience conflict with legality - which should prevail?
Enter the medieval doctrine of "Just War" (justum bellum, or, more precisely jus ad bellum), propounded by Saint Augustine of Hippo (fifth century AD), Saint Thomas Aquinas (1225-1274) in his "Summa Theologicae", Francisco de Vitoria (1548-1617), Francisco Suarez (1548-1617), Hugo Grotius (1583-1645) in his influential tome "Jure Belli ac Pacis" ("On Rights of War and Peace", 1625), Samuel Pufendorf (1632-1704), Christian Wolff (1679-1754), and Emerich de Vattel (1714-1767).
Modern thinkers include Michael Walzer in "Just and Unjust Wars" (1977), Barrie Paskins and Michael Dockrill in "The Ethics of War" (1979), Richard Norman in "Ethics, Killing, and War" (1995), Thomas Nagel in "War and Massacre", and Elizabeth Anscombe in "War and Murder".
According to the Catholic Church's rendition of this theory, set forth by Bishop Wilton D. Gregory of the United States Conference of Catholic Bishops in his Letter to President Bush on Iraq, dated September 13, 2002, going to war is justified if these conditions are met:
"The damage inflicted by the aggressor on the nation or community of nations [is] lasting, grave, and certain; all other means of putting an end to it must have been shown to be impractical or ineffective; there must be serious prospects of success; the use of arms must not produce evils and disorders graver than the evil to be eliminated."
A just war is, therefore, a last resort, all other peaceful conflict resolution options having been exhausted.
The Internet Encyclopedia of Philosophy sums up the doctrine thus: