Because the legitimacy of preventive war was embraced and promoted by leading figures in the administration of President George W. Bush, it was easy at the time to identify the preventive war option with the reckless attitudes and actions of President Bush and others who embraced the aggressive neoconservative, foreign policy agenda. Even now, it might be tempting to think of preventive war as an aberration from former policies that has only limited support. This would be a serious mistake for two reasons. First, the Bush administration’s embrace of preventive war did not radically depart from past United States policy. Second, arguments in favor of preventive war are rooted in widely shared moral and political beliefs. If preventive war is to be rejected, its opponents must show why it is wrong and must work to make the reasons for rejecting preventive war part of public understanding so that the general public will resist the arguments of preventive war’s advocates.

My main aim in this paper is to show that traditional just-war theory provides useful criteria for reining in the tendency to engage in preventive war. Had these criteria been better understood and taken more seriously, the Bush administration’s case for the 2003 war attack on Iraq might have been rejected. After discussing the just-war criteria and their application to the 2003 Iraq war, I will show why the traditional, multi-criterion version of just-war theory provides a better basis for rejecting preventive war than the abbreviated version supported by Michael Walzer in Just and Unjust Wars. I will then argue that both the traditional just-war criteria and the prohibition of preventive war can be strongly supported by rule-utilitarian arguments.