The same is true of the sorts of act required by

The same is true of the sorts of act required by participation in an unjust war – namely,
killing people who have done no wrong, collaborating in the destruction of their political
institutions and way of life, and so on. These acts are beyond the limits of what can be
made permissible by a person _ s institutional obligations. This is in part because of the
gravity of the harms inflicted; but it is also, and equally essentially, because of the moral
status of the victims. Just combatants, in taking up arms in a just cause – most commonly,
defense against unjust aggression – do nothing to lose their right not to be attacked or killed
or to make themselves morally liable to attack; they are innocent in the relevant sense.
Merely posing a threat to the unjust combatants who have attacked them is, as we have
seen, not enough to make them liable. So in fighting against just combatants, unjust
combatants would be attacking and killing the innocent. It is generally believed to be
wrong, except in the direst circumstances, to kill the innocent even as a means of averting a
greater evil. How, then, could it be permissible to kill the innocent as a means of achieving
aims that are unjust ?
It is often suggested that if some soldiers or draftees refuse on moral grounds to fight in
an unjust war, this could compromise the efficient functioning and perhaps even threaten
the survival of valuable institutions to which these people would rightly be committed. But
even if this is true, those who create, serve, and are served by valuable institutions must
themselves bear the burdens when those institutions malfunction, thereby causing or
threatening unjust harm to others. It would be unjust to impose the costs of their own
mistakes or wrongdoing on others.
Yet the consequences for just institutions of people refusing to fight in unjust wars are
unlikely to be calamitous. If the refusal to cooperate were sufficiently extensive or
widespread, it could seriously degrade the ability of the aggressor (as I will call a country
that fights an unjust war) to prosecute the unjust war and could even contribute to its defeat.
This might be bad for the aggressor overall, but there are reasons for doubting whether it
would be bad for the aggressor _ s just institutions – and it is just institutions rather than
overall national self-interest that is the focus of the argument we are considering. Victory in
an unjust war may serve the national interest but is likely on balance to have a corrupting
effect on just institutions. Would just institutions in Germany, for example, have benefited
from victory in World War II?
Why Jus in Bello Cannot be Independent of Jus Ad Bellum
Recall that the jus ad bellum requirement of just cause is a constraint on the type of good
that may permissibly be pursued by means of war. Just cause is an extrapolation into the
domain of war of the insistence that one may not seriously harm or kill another person
except for certain highly specific reasons, such as to defend oneself or another against an
unjust threat of extreme gravity. Just as one may not kill a person as a means of promoting