In an age of terrorism, guerilla and total warfare medieval doctrine of Just War needs to be re-defined. Moreover, issues of legitimacy, efficacy and morality should not be confused. Legitimacy is conferred by institutions. Not all morally justified wars are, therefore, automatically legitimate. Frequently efficient execution of a battle plan involves immoral or even illegal acts.
As international law evolves beyond ancient percepts of sovereignty, it should incorporate new thinking about pre-emptive strikes, human rights violations as casus belli and role and standing of international organizations, insurgents and liberation movements.
Yet, inevitably, what constitutes "justice" depends heavily on cultural and societal contexts, narratives, mores, and values of disputants. Thus, one cannot answer 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 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 authorities and ignore their decisions and decrees.
Yet, village council - source of legitimacy - refuses to authorize constable to apprehend 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 felons can achieve.
Incensed by this laxity, constable - backed only by some of inhabitants - breaks into home of one of more egregious thugs and expels or kills him. He claims to have acted preemptively and in self-defense, as criminal, long in defiance of law, was planning to attack its representatives.
Was constable right in acting way he did?
On one hand, he may have saved lives and prevented a conflagration whose consequences no one could predict. On other hand, by ignoring edicts of village council and expressed will of many of denizens, he has placed himself above law, as its absolute interpreter and enforcer.
What is greater danger? Turning a blind eye to exploits of outlaws and outcasts, thus rendering them ever more daring and insolent - or acting unilaterally to counter such pariahs, thus undermining 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 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 Catholic Church's rendition of this theory, set forth by Bishop Wilton D. Gregory of 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 aggressor on 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; use of arms must not produce evils and disorders graver than 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 doctrine thus:
"The principles of justice of war are commonly held to be: