International criminal tribunals have developed a number of legal theories designed to hold individuals responsible for their role in collective criminal conduct. These doctrines of criminal participation, known as modes of liability, are the subject of significant scholarly commentary. Yet missing from much of this debate, particularly as regards the International Criminal Court, has been an analysis of how current doctrine on modes of liability responds to the need to hold collective perpetrators criminally responsible for crimes of sexual and gender-based violence (SGBV). Indeed, many writings in this area of the law address perceived shortcomings in the theoretical underpinnings of modes of liability doctrine in the abstract but ignore the application of this doctrine in concreto. As a result, facially neutral writings on modes of liability may in fact be gendered in application, either because they fail to account for the specific characteristics of sexual and gender-based violence or because they are applied in a manner that requires higher thresholds for finding culpability for the commission of SGBV crimes. This article fills the gap between theory and practice, examining past and present doctrine, and suggesting ways in which the treatment of modes of liability by international criminal courts and tribunals can both properly respond to the need for personal culpability and the dangers of collective criminal activity, particularly as regards SGBV crimes.

In 2012, James Stewart published an article in this journal. The piece – ‘The End of “Modes of Liability” for International Crimes’ – argued for the abolition of accomplice liability in international criminal law and the adoption of a unitary model of participation in crime. This article argues that Stewart's proposal is flawed. As a matter of moral responsibility, the distinction between principals and accomplices follows from the recognition of individuals as moral agents. Turning to ordinary criminal responsibility, neither practical benefits nor expressive benefits nor the mitigating effects of the distinctive institution of criminal sentencing justifies the abolition of the distinction between principals and accomplices. Moreover, despite the collective nature of many international crimes, international criminal law ought to strive to accurately differentiate, in the attribution of responsibility, among participants. Only a differentiated model of participation can accurately and defensibly capture the different ways that individuals contribute to wrongdoing.

This article draws on well-established understandings of international treaty interpretation and the role of the judicial function to propose seven canons of treaty construction that may serve as the basis of a principled interpretation of the substantive law of the Rome Statute. This interpretative framework is then applied to the seemingly intractable debate within the Court and among scholars over the correct interpretation of Article 25, on modes of liability. The seven canons provide guidelines that may enable the ‘Rorschach blot’ of Article 25, capable of many divergent interpretations, to become uniformly and consistently understood and interpreted.

Both the International Criminal Tribunal for the former Yugoslavia (ICTY) and the International Criminal Court (ICC) have struggled to combine vertical and horizontal modes of liability. At the ICTY, the question has primarily arisen within the context of ‘leadership-level’ joint criminal enterprises (JCEs) and how to express their relationship with the relevant physical perpetrators (RPPs) of the crimes. The ICC addressed the issue by combining indirect perpetration with co-perpetration to form a new mode of liability known as indirect co-perpetration. The following article argues that these novel combinations – vertical and horizontal modes of liability – cannot be simply asserted; they must be defended at the level of criminal-law theory. Unfortunately, courts that have applied indirect co-perpetration have generally failed to offer this defence and have simply assumed that modes of liability can be combined at will. In an attempt to offer the needed justification, this article starts with the premise that modes of liability are ‘linking principles’ that link defendants with particular actions, and that combining these underlying linking principles requires a second-order linking principle. The most plausible candidate is the personality principle – a basic principle that recognizes the inherently collective nature of leadership-level groups dedicated to committing international crimes. Like Roxin's theories describing the collective organizations that can be used as a form of indirect perpetration, the personality principle treats the horizontal leadership group as an organization or group agent whose collective nature potentially justifies the attribution of vertical modes of liability to all members of the horizontal group. Although this article does not defend the doctrine of indirect co-perpetration, it does conclude that combined vertical and horizontal modes of liability, whether at the ICTY or ICC, implicitly or covertly rely on something like the personality principle in order to justify collective attribution to the horizontal collective.

Modes of liability, such as ordering, instigation, superior responsibility, and joint criminal liability, are arguably the most-discussed topics in modern international criminal justice. In recent years, a wide range of scholars have rebuked some of these modes of liability for compromising basic concepts in liberal notions of blame attribution, thereby reducing international defendants to mere instruments for the promotion of wider sociopolitical objectives. Critics attribute this willingness to depart from orthodox concepts of criminal responsibility to international forces, be they interpretative styles typical of human rights or aspirations associated with transitional justice. Strangely, however, complicity has avoided these criticisms entirely, even though it, too, fails the tests international criminal lawyers use as benchmarks in the deconstruction of other modes. Moreover, the source of complicity's departures from basic principles is not international as previously suggested – it stems from international criminal law's emulation of objectionable domestic criminal doctrine. If, instead of inheriting the dark sides of domestic criminal law, we apply international scholars’ criticisms across all modes of liability, complicity disintegrates (as do all other modes of liability) into a broader notion of perpetration. A unitary theory could also attach to all prosecutions for international crimes, both international and domestic, transcending the long-endured fixation on modes of liability within the discipline.

The International Criminal Court (ICC) has issued its third confirmation decision against Jean-Pierre Bemba Gombo,1 the former president of the rebel Mouvement de Libération du Congo (MLC) and commander in chief of its military wing, the Armée de Libération du Congo (ALC).2 The decision is, in principle, to be welcomed, since it constitutes a further consolidation of the ICC case law and breaks new ground in some important areas, for example the law of crimes against humanity (Art. 7 of the ICC Statute3)4 and command responsibility (Art. 28).5 From an outsider's perspective it also seems that the Chamber, on the basis of the available (disclosed) evidence, took the right decision when it changed the Prosecutor's liability from (co-)perpetration (Art. 25(3)(a)) to command responsibility. Yet there are some fine legal-technical points where the Chamber did not dig deep enough, incurred conceptual errors, or drew some illogical conclusions. These issues shall be discussed briefly here, not in a destructive spirit but to contribute constructively to the improvement of the future case law.