• conflict;
  • ethics;
  • just war;
  • military ethics;
  • survey research;
  • United States of America;
  • use of force;
  • war

To what degree were the wars waged by the United States ethically just? The answer is necessarily subjective, but would experts from across the political spectrum score conflicts in a similar fashion? In a survey of more than 100 international studies experts, the 18 major conflicts fought by the United States since 1900 were assessed. World War II was rated as the most just, whereas the Iraq Invasion was considered the most unjust. Respondents also scored each conflict under seven just war criteria: just cause, right intent, net benefit, legitimate authority, last resort, proportionality of means, and right conduct. The average of the criteria, the “Just War Index” (JWI), correlated strongly with the participants’ measure of each conflict's overall justness, indicating the importance of the criteria. Participants who identified themselves on the political right gave higher JWI values for almost all conflicts than those on the left. The left rated seven conflicts unjust while the right found all to be just, though three only slightly so. Nonetheless, the ranking of conflicts was quite similar between the two groups. Though no conflict was deemed completely just or unjust, the US war spectrum ranged from highly “just” to highly “unjust.” The JWI approach offers a quantified and nuanced analysis of important ethical criteria—an approach that could be applied to other conflicts, including future ones.