On its seventy-fifth anniversary last year, the Nuremberg war crime trials moved again into the spotlight of public attention. To the present day, Nuremberg is mainly portrayed as the birth of international criminal law being the first tribunal that held individuals accountable for war crimes committed during the Second World War. As we argue in this article, there is an often-overseen dark legacy of Nuremberg as it represents an unused opportunity to establish accountability for inhumane military practices, especially in air warfare, being of tragic influence for the postwar development of International Humanitarian Law (IHL) as a whole. Going beyond the existing criticism already voiced on Nuremberg’s shortcomings, we hold that the Tribunal’s reluctance to prosecute bombing practices sowed the seeds for the decay of IHL by creating institutionalized silences, especially for massive violations of the principle of distinction. The tribunal thereby sidelined pre-war IHL and infected the development of post-war IHL by retroactively legitimating the bombing practices of the Axis powers and at least indirectly of the Allies. We argue that the failure to prosecute ‘total war’-practices and reestablish former restrictive legal structures regarding aerial bombardment has fundamentally eroded the pre-war meaning of the principle of distinction leading to its downfall in the First Additional Protocol to the Geneva Convention of 1977. We describe these developments as a form of judicial desuetudo, meaning the abrogation of a rule through its subsequent non-enforcement by an international court during and after massive law violations because of perceived or real political constraints.

Military artificial intelligence (AI)-enabled technology might still be in the relatively fledgling stages but the debate on how to regulate its use is already in full swing. Much of the discussion revolves around autonomous weapons systems (AWS) and the ‘responsibility gap’ they would ostensibly produce. This contribution argues that while some military AI technologies may indeed cause a range of conceptual hurdles in the realm of individual responsibility, they do not raise any unique issues under the law of state responsibility. The following analysis considers the latter regime and maps out crucial junctions in applying it to potential violations of the cornerstone of international humanitarian law (IHL) – the principle of distinction – resulting from the use of AI-enabled military technologies. It reveals that any challenges in ascribing responsibility in cases involving AWS would not be caused by the incorporation of AI, but stem from pre-existing systemic shortcomings of IHL and the unclear reverberations of mistakes thereunder. The article reiterates that state responsibility for the effects of AWS deployment is always retained through the commander's ultimate responsibility to authorise weapon deployment in accordance with IHL. It is proposed, however, that should the so-called fully autonomous weapon systems – that is, machine learning-based lethal systems that are capable of changing their own rules of operation beyond a predetermined framework – ever be fielded, it might be fairer to attribute their conduct to the fielding state, by conceptualising them as state agents, and treat them akin to state organs.

Despite the existence of a definition of civilian status in international humanitarian law (IHL), differences in the application of this definition – both in theory and in practice – continue to be observed. One of the contexts where these differences remain palpable (and do so for various fighting parties) is Afghanistan, a country where civilian harm has remained high for several years. This article explores the legal concepts of civilian and civilian population, including how they have been formed and interpreted and, ultimately, what protection they afford to persons who belong in these categories. The second part of the article brings these questions into the Afghan context, one that is complex and where cultural and religious implications should not be overlooked. Public statements, reports and codes of fighting parties in the country which touch upon civilian status are presented, followed by the civilian experience in Afghanistan, particularly focusing on the reported harm. Ultimately, it is proposed that despite the factual and contextual confusion, the existing legal rules and interpretations, when applied in good faith, suffice to ensure both that those who are civilians under IHL are protected and that the threats which some civilians’ behaviour might pose can be effectively addressed without a status change.

Up to now, the Chinese government has only made very general comments on the application of international humanitarian law to cyberspace. There are indeed Chinese academic papers concerning this issue, but the discussion of the principle of distinction is limited both in length and in academic depth. Compared with the West, research by Chinese scholars on this topic is still in a relatively preliminary stage. At present, there is no specific deconstruction or clarification of the application of the principle of distinction in cyberspace in Chinese academia. As the first paper written by Chinese scholars specifically devoted to this question, this piece provides a different perspective by injecting the positions of Chinese officials and the views of Chinese scholars. The authors aim to clarify whether the existing rules are still completely applicable in the cyber context, and if needed, to find out what kind of improvements and clarifications can be made. Weighing in on these debates, we argue that despite the potential technical challenges and uncertainties, the principle of distinction should be applied to cyberspace. It should also be carefully re-examined and clarified from the standpoint of preventing over-militarization and maximizing the protection of the interests of civilians. For human targets, the elements of combatant status identified in customary international law and relevant treaties are not well suited to the digital battlefield. Nevertheless, cyber combatants are still obligated to distinguish themselves from civilians. In applying the principle of distinction, we argue that it makes more sense to focus on substantive elements over formal elements such as carrying arms openly or having a fixed distinctive sign recognizable at a distance. In interpreting “direct participation in hostilities”, the threshold of harm requires an objective likelihood instead of mere subjective intention; the belligerent nexus should be confirmed, and the causal link should be proximate. Applying the “cyber kill chain” model by analogy helps us to grasp the whole process of direct participation in hostilities during cyber warfare. For non-human targets, all military objectives must cumulatively fulfil both the “effective contribution” and “definite military advantage” criteria, which are equally indispensable. The same requirements apply to dual-use objects. Furthermore, certain data should fall within the ambit of civilian objects.

The civilian-combatant frame persists as the main legal lens through which lawyers organize the relationships of conflict zone actors. As a result, little attention has been paid in international legal scholarship to different gradations of ‘civilianness’ and the ways in which some civilians might compete to distinguish themselves from each other. Drawing attention to international humanitarian actors – particularly those working for NGOs – this article explores the micro-strategies these actors engage in to negotiate their relative status in war. Original qualitative empirical findings from South Sudan illuminate the way in which humanitarians struggle over distinction with individuals working for the UN peacekeeping mission, UNMISS. As is shown, humanitarian actors are doing away with a static civilian-combatant binary in their daily practice. A more fluid logic informs both their self-conceptualization and their interactions with others who share the operational space. Humanitarian actors envision civilianness as a contingent concept, and they operate according to a continuum along which everything is a matter of degree and subtle gradation. As civilianness is detached from the civilian, any given actor might acquire or shed civilian-like, or combatant-like, characteristics at any moment. The distinction practices that humanitarian actors enact can be understood as a bid for legibility, so that they might be rendered intelligible in international law and in the eyes of other actors as a special kind of civilian – the ‘civilian plus’.

While the rules of the jus in bello are generally operative in cyberspace, it appears to be problematic to apply the fundamental principle of distinction because of the systemic interconnection of military and civilian infrastructure in the cyber realm. In this regard, the application of the accepted legal definition of military objectives will make various components of the civilian cyber infrastructure a legitimate military objective. In order to avoid serious repercussions for the civilian population that might follow from this inherent interconnectedness, different concepts are analysed that could provide potential solutions for a clearer separation of legitimate military targets and protected civilian installations and networks. The approaches discussed range from the exemption of central cyber infrastructure components that serve important civilian functions, to the creation of ‘digital safe havens’ and possible precautionary obligations regarding the segregation of military and civilian networks. As a solution, the authors propose a dynamic interpretation of the wording ‘damage to civilian objects’ within the principle of proportionality of Article 51(5)(b) of Additional Protocol I, an interpretation that would comprise the degradation of the functionality of systems that serve important civilian functions.

The ICRC, following extended discussions with a large group of experts, has adopted and issued a non-legally binding document entitled ‘Interpretive Guidance on the Notion of Direct Participation in Hostilities under International Humanitarian Law’ consisting of ten recommendations and about fifty pages of related commentary. The discussion process which preceded production of the Interpretive Guidance was contentious and no consensus was reached on the issue of Direct Participation in Hostilities. As the result, the ICRC, as it was entitled to do, issued its own interpretation of the applicable law. The author of this article, who was involved in all of the expert meetings, reviews and comments on the Interpretive Guidance and attempts to make an assessment of its general viability and of its acceptability to the wider IHL community.

A central concept found in the 1907 Hague Regulations Respecting the Laws and Customs of War on Land is the notion of ‘belligerents’. The formal status of ‘belligerents’ or, in more modern terms, ‘combatants’, is limited to international armed conflicts. One of the crucial functions that the status fulfils relates to distinguishing those who are legitimate objects of attack from those who enjoy protection. Combatants are legitimate targets, while civilians are not, unless and for such time as they directly participate in hostilities. Civilians are defined as all those who are not combatants. Because the formal status of ‘combatant’ is limited to international armed conflicts, the principle of distinction cannot be conceptualized in the same way in non-international armed conflicts. Who, then, may be targeted in non-international armed conflicts and under what conditions and who is conversely immune from being made the object of attack and enjoys protection against the dangers arising from military operations by virtue of the status of ‘civilian’? This article argues that, in principle, members of armed forces of both state and non-state parties to a non-international armed conflict are legitimate targets and all those who are not such members are to be considered civilians. However, the practical operationalisation of the principle of distinction in this way faces a number of difficulties. Due to the variety and changing nature of organised armed groups, a more differentiated approach is required in striking a reasonable balance between military considerations and humanitarian concerns.