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.

This article focuses on the analysis by the International Court of Justice of the principle of non-intervention in domestic affairs in its judgment of 27 June 1986 in the case concerning Military and Paramilitary Activities in and against Nicaragua and contrasts it with the evolution of international law and practice in this field. It is proposed that the Court's 1986 analysis not only remains of actuality today, but also constitutes a precursor to legal developments that have since taken place. This is particularly the case with regard to the relationship between the protection of human rights on the one hand and the safeguard of state sovereignty and the collective security regime on the other. The 1986 judgment helped to clarify the content of humanitarian assistance. It constituted the starting point for the development of this concept in a series of GA resolutions that were subsequently adopted. The controversial doctrine of ‘humanitarian intervention’, as well as state practice in violation of this principle, in no way led to modifying existing international law. Similarly, the new concept of ‘responsibility to protect’, which places emphasis on collective security and discounts unilateral action, has not led to the disappearance of the principle of non-intervention either.

Transnational environmental law is the subject of growing scholarly interest. Yet, much work remains to be done to fill in both the conceptual and empirical contours of this field. One methodological challenge that transnational law poses is the need to look beyond traditional sources of international and national law. This article contributes to efforts to understand transnational law's multilayered architecture by drawing attention to the use of transnational contracts as a mechanism to protect habitats and species. The diverse and proliferating examples of conservation contracts discussed in this article – which include forest carbon agreements, conservation concessions, debt-for-nature swaps, conservation performance payments, and private protected area agreements – reveal an ongoing and intensifying transnational attempt to use private contracts to address some of the most pressing issues of common concern. This article draws on fairness theory in both contract and international environmental law to argue for law's relevance in interpreting conservation's call for contracts.

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 notion of ‘armed attack’ is at the heart of the law on the use of force in self-defence. The ICJ first addressed the issue in its judgment in Nicaragua; however, its formulation of the legal parameters of ‘armed attack’ has not been without controversy. In particular, the high threshold of force required for an ‘armed attack’ and the consequent distinction between ‘armed attack’ proper and acts of lower intensity (termed ‘frontier incidents’) is said to have reduced the barrier to armed aggression. More recently, the formulation has also been criticized for not being fully applicable to large-scale terrorist attacks such as the events of 11 September 2001. This article examines the Court's first pronouncement on the concept of armed attack, with a specific focus on the rationae materiae aspect of ‘armed attack’, which situates it in the context from which it arose and analyses its development through subsequent case law, particularly the Court's judgments in Oil Platforms and Armed Activities (Congo v. Uganda) and the decision of the Eritrea–Ethiopia Claims Commission.

International criminal tribunals try defendants for horrific acts: genocide, war crimes, and crimes against humanity. At sentencing, however, evidence often arises of what I will call defendants’ ‘good deeds’ – humanitarian behaviour by the defendants towards those on the other side of the conflict that is conscientious relative to the culture in which the defendants are operating. This article examines the treatment of good deeds in the sentencing practices of the International Criminal Tribunal for the former Yugoslavia and International Criminal Tribunal for Rwanda. I show that the tribunals’ approaches are both undertheorized and internally inconsistent. I argue that the tribunals should draw upon the goals that underlie international criminal law in developing a coherent approach to considering good deeds for sentencing purposes.

This ‘interview’, prepared posthumously with original material from Judge Antonio Cassese, traces the origins of his academic and professional career. It further attempts to shed some light on Antonio Cassese's multifaceted contributions to the fields of human rights, self-determination, and international criminal law. In particular, it attempts to show in his own words the passion and rigour with which Judge Cassese approached the establishment of the International Criminal Tribunal for the former Yugoslavia (ICTY) as well as its seminal first steps, which marked a resurgence of international criminal justice and paved the way for a host of contemporary international criminal institutions.

This article provides a reappraisal of the International Court of Justice's approach to jurisdiction and applicable law in Nicaragua, 25 years later. In the first phase of the proceedings arising from the US support of the activities of the Contras against the Sandinista government, the Court robustly asserted its jurisdiction despite the US reliance on its multilateral treaty reservation and the subsequent attempted modification of its Optional Clause declaration. At the same time, the Court approached the related question of applicable law with a wide, if not effusive, reliance on multilateral customary international law operating conjunctively with treaty law. The Court's dismissal of negotiations as a procedural precondition for invoking its jurisdiction in Nicaragua is contrasted with its recent findings in Georgia v. Russia.

This presentation is twofold. The first part shows that the Nicaragua case played a significant role in reconciling the Third World with the International Court of Justice and, more generally, in revitalizing the Court. In the second part, the author, who was counsel for Nicaragua in that case, casts an eye as external analyst on the judgments of 1984, about which he has some reluctance, and 1986, which he largely approves of, even though Nicaragua did not win 100 per cent and some points may be debatable.

Having identified the differences between the concept of legality and the much more complex concept of legitimacy, the author scrutinizes the legality and the legitimacy of the existing international criminal tribunals. Their legality has been put in doubt only concerning the International Criminal Tribunal for the former Yugoslavia (ICTY) and the Special Tribunal for Lebanon (STL), but the criticisms have been or could be overcome. Assessing the legitimacy of these tribunals is instead a more difficult task. In fact, misgivings have been voiced essentially concerning the legitimacy of the ICTY and the STL, but not the International Criminal Court (ICC) and the other international criminal courts. The legitimacy of the STL in particular deserves to be discussed: even assuming that the STL initially lacked some forms of legitimacy, it could achieve it – or confirm it – through its ‘performance legitimacy’. The author then suggests what the realistic prospects for international criminal justice are. Convinced as he is that it is destined to flourish even more, he tries to identify the paths it is likely to take in future years.