Chapter 8 looks at the general rules which apply to the means and methods of warfare, and what kinds of weapons have been prohibited or restricted under IHL. The general principles governing how warfare is conducted are explained – the prohibitions on causing unnecessary suffering and superfluous injury, and on indiscriminate means and methods. The chapter examines a number of particular weapons, such as dum-dum bullets, mines and booby-traps, weapons that leave non-detectable fragments in the human body, incendiary weapons, blinding laser weapons, cluster munitions and chemical and biological weapons. Chapter 8 also looks at the problem of explosive remnants of war being left in the conflict zone, as well as a number of means and methods which have been the focus of much attention but whose legality is highly contested, including nuclear weapons, white phosphorus, depleted uranium munitions, cyberwarfare, drone warfare and targeted killings. The chapter also explains prohibited methods of warfare such as ordering ‘no quarter’, perfidy, siege and pillage, along with the particular rules relating to belligerent reprisals, mercenaries, espionage and autonomous weapons.

Chapter 2 outlines the contemporary legal framework of IHL, examining the treaty and customary laws that govern conduct in armed conflict, and exploring the fundamental principles of the law. The distinction between the jus in bello and the jus ad bellum is explained, as well as some of the different terms used in IHL (Hague Law, Geneva Law, war vs armed conflict, etc). The main sources of IHL are explained – treaties and customary international humanitarian law. The chapter then explains the main principles governing IHL – distinction, discrimination, military necessity, proportionality, prohibition on unnecessary suffering, neutrality and humanity.

This chapter suggests three legal strategies to leverage international humanitarian law for the protection of weaponised animals in armed conflict in the absence of a direct prohibition of animal weapons. Firstly, one could rely on international, regional organisation and domestic law during non-international armed conflict. Secondly, states can be confronted with their obligation to conduct weapons reviews (relating to international armed conflict). Thirdly, states proposing a ban or regulation on lethal autonomous weapons could be encouraged to promote or support comparable action towards weaponised animals. Even all three strategies in combination would not result in a universal prohibition against weaponising animals. The admittedly patchwork outcome(s) would only offer some measure of protection of animals where little currently exists. Additionally, each line of argument has the potential of gaining additional traction, whether as a matter of law, custom or policy, thus increasing the protection of animals.

The chapter casts light on the emerging body of law applicable to military experiments on animals. It first shows that these experiments are a large-scale phenomenon, not only because of the number of animals affected by them but also due to harm and suffering inflicted on these animals. It proceeds by providing an overview of two main sets of legal rules that are of relevance in this field: national legal acts and international treaties or other rules of international law. Whereas these rules are primarily designed for civil research, they apply – or could apply – to military experiments as well. Based on the analysis of these two sets of rules, the chapter identifies the main parameters of the gradually emerging legal rules on military experiments on animals, focusing on their scope of application, their content and on the legal consequences of violations.

Chapter Four charts the emergence of human dignity in the context of international humanitarian law, providing the setting for its first constitutive stage. It begins in the second half of the nineteenth century, with human dignity’s symbolic entrance into the fabric of international law with the adoption and entry into force of the Hague Law (Martens Clause, 1899 and 1907 Conventions). The process to impose legal restraints on the conduct of hostilities preceded the Martens Clause and the actual consolidation of this stage was only completed in the aftermath of the Second World War with the watershed represented by the adoption of the Four Geneva Conventions in 1949 and, subsequently, the two Additional Protocols of 1977. Thus, this historical process extends over more than a century, with a range of different legal manifestations which can singled out as the key milestones.

Chapter 7 discusses LOAC’s core principles. This text holds that there are four core principles, per the International Court of Justice. Distinction requires that Parties to a conflict always distinguish between civilians and civilian objects and combatants, and fire only on military objectives. Military necessity, the second principle, is very elastic, holding that all lawful measures to defeat the enemy quickly and efficiently are allowed in LOAC. The third principle, unnecessary suffering, directs that one may not employ weapons or projectiles that cause superfluous injuries or unnecessary suffering in enemy fighters. This principle is directed only to combatants, not civilians who should not be targeted at all. Finally, the principle of proportionality directs that civilian injury or loss of life, and damage or destruction of civilian objects, may not be excessive in relation to the direct and concrete military advantage to be gained. The problem with the four principles is definitional: what will “quickly” defeat the enemy? What injuries are “superfluous”? What incidental civilian death is “excessive” to a military advantage? Such answers as there are, are in this chapter.

This chapter discusses the law governing the nature and design of weapons as it relates to autonomous weapon systems. It is presented in three parts. The first part covers prohibitions and restrictions on specific types of weapons. At present there is no law directed specifically at autonomous weapon systems, but it is conceivable that autonomous capabilities may be added to types of weapons that are subject to special regulation; the permissibility and effects of such development are considered. The second part discusses requirements imposed on weapons by general rules of IHL based on their nature and intended use. The fundamental principles of distinction and the avoidance of superfluous injury and unnecessary suffering are most at issue here. The main finding of this part is that an expanded understanding of ‘accuracy’ is required in order to effectively apply the principle of distinction to autonomous weapons. The third part discusses the Martens Clause, finding that, whether a broad or narrow interpretation of the Clause is adopted, it does not, at present, inhibit development or use of autonomous weapons.

This chapter presents the scope of combatants as lawful targets in light of considerations of military necessity. Hereunder the scope of the rule prohibiting unnecessary suffering on combatants.