The article provides an account of the unlikely revival of the medieval Just War Theory, due in large part to the efforts of Michael Walzer. Its purpose is to address the question: What is a just-war theorist? By exploring contrasts between scholarly activity and forms of international activism, the paper argues that just war theorists appear to be just war criminals, both on the count of aiding and abetting aggression and on the count of inciting troops to commit war crimes.