The Just War Tradition 291Belgium, and France have had difficulty in “taking effective enforcement mea sures”
against terrorists, although each has shut down many terrorist financial networks and
enhanced security in airports and ports. After all, the terrorists who attacked New
York’s World Trade Center and the Pentagon on September 11, 2001, learned to fly
commercial airplanes in Florida. And some of the terrorists responsible for the Paris
bombings in 2015 were French citizens or were living in Belgium.
the Just War tradition
When, if ever, is it just for states to go to war? Is war always an illegal and immoral
act, or is it acceptable under certain conditions? What constitutes an appropriate
justification— jus ad bellum—to enter into war? And what constitutes moral and ethi-
cal conduct— jus in bello— once a state decides to go to war? Normative po liti cal theo-
rists draw our attention to the classical just war tradition. Although a Western and
Christian doctrine dating from medieval times, just war theory draws on ancient Greek
philosophy and precepts found in the Koran. As developed by Saint Augustine, Saint
Thomas Aquinas, Hugo Grotius, and, more recently, the po liti cal phi los o pher Michael
Walzer, just war theory asserts that several criteria can make the decision to enter a
war a just one.^23 There must be a just cause (self- defense or the defense of others, or a
massive violation of human rights) and a declaration of intent by a competent author-
ity (which, since the formation of the United Nations, has been interpreted to mean
the UN Security Council). The leaders need to have the correct intentions, desiring to
end abuses and establish a just peace. They also need to have exhausted all other pos-
sibilities for ending the abuse, employing war as a last resort. Actors must rapidly remove
forces after securing the humanitarian objectives. Because states choose war for a vari-
ety of reasons, however, it is rarely easy to assess the justness of a par tic u lar cause or
par tic u lar intentions.
The just war tradition also addresses legitimate conduct in war. Combatants and
noncombatants must be differentiated, with the latter protected from harm as much
as pos si ble. Vio lence must be proportionate to the ends to be achieved. Combatants
should avoid causing undue human suffering and using particularly heinous weapons.
Because mustard gas caused especially cruel deaths during World War I, it was subse-
quently outlawed, thus providing the basis for future chemical and biological warfare
conventions. Many of the extended norms of the just war tradition were codified in
the four 1949 Geneva Conventions and the two additional protocols concluded in
- These are designed to protect civilians, prisoners of war, and wounded soldiers,
as well as to ban par tic u lar methods of war and certain weapons that cause unneces-
sary suffering.