Introducing the special issue, we point out how the notion of an ‘enemy of all humanity’ challenges the very foundations of international (criminal) law. We also give an overview of the other contributions.

Trationally, the term “enemy of all humanity” (hostis generis humani) referred to pirates. In contemporary international criminal law, it refers to perpetrators of crimes against humanity and other core. This essay traces the evolution of the concept, and then offers an analysis that ties it more closely to ancient tyrants than to pirates. Some object that the label is dehumanizing, and justifies arbitrary killing of the “enemy of humanity.” The essay admits the danger, but defends the concept if it is restricted to fair trials. Rather than dehumanizing its target, calling the hostis generis humani to account in a court of law is a way of recognizing that radical evil can be committed by humans no different from any of us.

In ‘The Enemy of All Humanity’, David Luban provides an insightful and plausible account of the idea of the hostis generis humani (one that shows that the hostis need not be understood to be an outlaw), and of the distinctive character of the crimes against humanity that the hostis commits. However, I argue in this paper, his suggestion that the hostis is answerable to a moral community of humanity (in whose name the ICC must thus claim to speak) is not tenable. Once we recognize the intimate connection between criminal law and political community, we can see that the hostis should answer to the local, domestic political community in and against which he commits his crimes; and that the proper role of the International Criminal Court, acting in the name of the community of nations, is to provide a second-best substitute for such answering when the local polity cannot or will not hold him to account.

This article discusses empirical examples from international trial transcripts to see if and why there is a need to use the ‘enemy of all humanity’ label in contemporary international criminal justice discourse. It shows an absence of explicit uses of the concept and an ambiguous set of implicit references; the hosti generis humani concept is simultaneously too precise and too broad for ICJ discourse. Based on these findings, the article challenges David Luban’s suggestion that the term can be undone from its dehumanizing potential and used adequately in the ICJ context.

In his contribution to this special issue, David Luban proposes to revive the age-old concept of ‘the enemy of all humanity.’ On his view, this concept supports the aims of international criminal justice by emphasizing that atrocity and persecution crimes are ‘radically evil’ and therefore ‘everyone’s business.’ Criticizing Luban’s proposal, this paper shows that in the past, the ‘enemy of all humanity’ concept has often served to establish parallel systems of justice, depriving these ‘enemies’ of their rights as suspects under criminal law and as lawful combatants under the laws of war. Thus, even if the ‘enemy of all humanity’ concept is used with the intention to bring today’s perpetrators of ‘radical evil’ to justice, it risks undermining, rather than protecting, the rule of law.

Piracy holds a special place within the field of international law because of the universal jurisdiction that applies. This article reconsiders the role of piracy in the development of universal jurisdiction. While usually a connection is established between Cicero’s ‘enemy of all’ and modern conceptions of pirates, it is argued that ‘enemy of the human species’ or ‘enemy of humanity’ is a medieval creation, used by Bartolus, which must be understood in the wake of the Renaissance of the twelfth century and the increased interest for the study of Roman Law. The criminalization of the pirate in the late Middle Ages must be understood not only as a consequence of royal power claiming a monopoly of violence at sea. Both the Italian city-states and the Hanse may have preceded royal power in criminalizing pirates. All the while, political motives in doing so were never absent.

Antony Duff, Marc de Wilde, Louis Sicking, and Sofia Stok offer several criticisms of my “The Enemy of All Humanity,” but central to all of them is concern that labeling people hostis generis humani dehumanizes them, and invites murder or extrajudicial execution. In response I distinguish political, legal, and theoretical uses of the ancient label. I agree with the critics that the political use is toxic and the legal use is dispensable. However, the theoretical concept is crucial in international criminal law, which rests on the assumptions that the moral heinousness of core crimes makes them the business of all humanity. Furthermore, far from dehumanizing their perpetrators, calling them to account before the law recognizes that they are no different from the rest of humanity. This response also offers rejoinders to more specific objections raised by the critics.