Luban: The Crime of Aggression: Its Nature, the Leadership Clause, and the Paradox of Immunity

David Luban (Georgetown Univ. - Law) has posted The Crime of Aggression: Its Nature, the Leadership Clause, and the Paradox of Immunity (in Research Handbook on International Legal Theory, Eliav Lieblich & Tom Dannenbaum eds., forthcoming). Here's the abstract:

The paper, written for a research handbook, critically surveys some fundamental philosophical, historical, and doctrinal issues in the crime of aggression. The two introductory sections set the theoretical issues in the context of Russia’s invasion of Ukraine, and explain the origins of criminalizing aggression under the heading of “crimes against peace.” Section 3 explores an ambiguity between aggression as first use of force and aggression as unprovoked use of force, while section 4 discusses the doctrinal distinction between acts of aggression and wars of aggression.

Sections 5 and 6 turn to the theory of aggression. Section 5 examines modern versus early modern just war theorists’ views of just cause. Section 6 explores various theories of what exactly makes aggressive war so evil that it belongs in the pantheon of core crimes, side by side with genocide, crimes against humanity, and other war crimes. The basic question is whether aggression is fundamentally a crime against states, a crime against human rights, or a crime against peace itself. I reject the first, statist, version, and endorse the human rights version. I examine three versions of the view that aggressive war is fundamentally about its human costs: that aggressive wars lead to atrocities (Trainin); that aggressive wars lead more generally to unjustified killings (Dannenbaum); and that aggressive wars lead to both unjustified killings by the aggressor, and to unnecessary killings that include the justified killings of aggressors’ troops by defenders (Mégret). As for crimes against peace, I argue that this theory of aggression’s evils comes in two “flavors,” one of which has justly been criticized by postcolonial writers, and one of which I think is legitimate. The former originates in Judge Pal’s famous dissenting opinion in the IMTFE, and argues that criminalizing aggression is a move by colonial powers to freeze the oppressive status quo. The more legitimate version is that in an age of catastrophically destructive weapons, the risks of escalation in armed conflict –the threat that conflicts will spiral into world wars–are simply too great in human terms. Thus, the legitimate version of “crimes against peace” is part and parcel of the human rights analysis.

The final sections break new ground. Section 7 considers whether aggression is solely a leadership crime. Everyone agrees that it would be wrong to punish ordinary soldiers for the crime of aggression launched by their leaders. The questions is why, and it is not easy to answer. Examining it brings us to a contemporary dispute over which leaders can be prosecuted: only those who control or direct the aggressive policies (as per the ICC’s Rome Statute), or others as well, who “shape or influence” the policy without necessarily directing it (as the customary rule used to be formulated). I argue against any narrowing of the leadership clause.

Section 8 explores the “paradox of immunity”: Under the legal principle of sovereign immunity, apex leaders are immune from prosecution in the courts of another state. But under the narrow leadership clause, only apex leaders can be prosecuted. Here I argue for a surprising conclusion: that in fact there never was a customary rule of immunity for the crime of aggression. If so, the paradox of immunity disappears. This resolution also helps cut the Gordian knot of a current debate about whether a relatively small subset of states (the EU, perhaps) can form an aggression tribunal and call it “international.”