International criminal law is the branch of public international law under which individuals may be held criminally responsible for the offenses of genocide, crimes against humanity, war crimes, and the crime of aggression. International criminal law seeks to prevent impunity by holding accountable those individuals who are responsible for serious violations of international criminal law. This chapter begins with the history of international criminal law, starting with the aftermath of the First and Second World Wars, and ending with the creation of a spate of international criminal courts and tribunals in recent decades. The chapter then covers substantive aspects of international criminal law, namely the crime of genocide, crimes against humanity, war crimes, and the crime of aggression. Finally, the chapter covers key procedural aspects of international criminal law, including the jurisdiction of international courts and tribunals, the admissibility of cases, modes of liability, and immunities. The International Criminal Court (ICC) will form a focal point in this chapter.

This chapter explores the foundations of due diligence under international law. Due diligence emerged in the international practice of the nineteenth century concerning diplomatic protection and the security of states, and developed as a notion linked to the responsibility of states in connection with acts of private individuals. For a long time, due diligence was conceived as a concept pertaining to the realm of international responsibility and it was primarily associated with the measure of a state organ’s fault. The chapter illustrates how, during the twentieth century, due diligence migrated from the realm of secondary rules to primary rules. The chapter clarifies the relationship between due diligence and overlapping concepts, like international liability and the notion of general principles of international law. It is argued that due diligence should be construed as an identifier for a typology of international obligations, something that provides meaning and rationale to them. The chapter concludes by clarifying the difference between due diligence as a ‘qualifier’ for primary rules of states, and due diligence as a ‘process’ linked to the activities of non-state actors.

The debate on the compatibility of neutrality with collective security appears to have occupied scholars in the interwar period but not after the end of World War II. However, it remains relevant. Neutrality defers to collective security only if the Charter mechanism works effectively. Even then, however, neutrality is admissible if it does not subvert collective action authorized by the Security Council or the General Assembly under the Uniting-for-Peace resolution.

The law of neutrality is not obsolete. Its validity subsists despite the prohibition of the use of force,the advent of collective security and the violations of the rights of neutrals during the two world wars. The sources of the law are customary laws and treaties. Customary law of neutrality is based on State practice mainly in the form of national military manuals. It is applicable in the event of an international armed conflict irrespective of the existence of a formal state of war and irrespective of the scale and extent of th conflict. Neutrality has withstood the challenge of collective security and the prohibition of the use of force both in the interwar years and after World War II. The gross violations of the rights of neutrals during World Wars I and II have been justified as reprisals or countermeasures; this is a further confirmation that beligerent practice at the time constituted a deviation from the law rather than a change or demise of the law of neutrality.

This chapter sketches the development of international human rights law. The legal position of individuals was perceived by states as a domestic affair of the sovereign state, which could effectively treat its citizens as it pleased. It was not until after the Second World War that this fundamentally changed and international law began to grant individuals rights to protect them from the state. The chapter further presents the main categories or generations of human rights and discusses their key characteristics. Human rights are generally organized in three categories or generations: (a) civil and political rights; (b) economic, social, and cultural rights; and (c) collective rights. This chapter will subsequently turn to several matters concerning the scope of human rights norms, including their addressees, their territorial scope of application, and the circumstances under which human rights may be restricted by the state. Finally, this chapter will explain how human rights are monitored and enforced under international law.

IHL has historically been divided into two main branches, consisting of rules that regulate the “means and methods of warfare”and the rules that deal with the “protection of persons and projects.” The rules governing the means and methods of warfare are known as “Hague Law” due to the fact that the main treaties governing this field of law were, for a long time, the 1899 and 1907 Hague Conventions and the annexed Hague Regulations. The provisions dealing with the protection of persons and objects hors de combat (“out of combat”) are known as “Geneva Law,” as these rules can be found in the Four Geneva Conventions of 1949. The two Additional Protocols of 1997 cover both norms concerning the means and methods of warfare, and those protecting individuals. This chapter begins with the foundations and the history of IHL, before discussing the scope of application of IHL and the law governing the conduct of hostilities, namely the means and methods of warfare. The final sections discuss the law governing the protection of persons during armed conflict, and the implementation and enforcement of IHL.

This chapter traces Chinggisid influences throughout the globalising world order of the sixteenth century. It shows that the European timeline – so foundational to IR – cannot be thought of as free from influences from Asia. As this chapter clearly demonstrates, Charles V and the Habsburgs were very much shaped by their competition with the Ottomans. The chapter then moves to the north and discusses the influences of Chinggisid sovereignty model on Muscovy, specifically on Ivan IV. It also catches up with sixteenth-century developments in Inner Asia and Ming China. The sixteenth-century order, with its centre of gravity in the post-Timurid empires of west Asia, fragmented in the seventeenth century, during the long period of 'general crisis' (often associated with climate change) which frayed both the material and ideational connections across Eurasia. Though some Asian polities were relatively unaffected by this period of crisis and others bounced back economically, no world ordering projects were successfully launched out of the East after this period. This was a major contributor to the perception of Eastern decline.

This chapter explores the relationship between intellectual cooperation and the formation of International Relations (IR) scholarship. It begins by briefly chronicling the idea of intellectual cooperation. The second section traces the origins of the International Committee on Intellectual Cooperation (ICIC) in Geneva, while the third one deals with the International Institute of Intellectual Cooperation (IIIC) and its activities in Paris. The next section demonstrates how their projects became politicised, particularly those in the field of IR. Finally, the last section discusses the universalist motives of inter-war intellectual cooperation and contrasts these ambitions with the political realities of the 1930s. The chapter concludes that IR benefitted enormously from the League of Nations but, at the same time, suffered from its political context and ultimately fell prey to the kind of aggressive foreign policy it set out to prevent.

The rules of state responsibility are set out in the International Law Commission’s (ILC) Articles on the Responsibility of States for Internationally Wrongful Acts. This chapter introduces the basic features of the ILC’s Articles on State Responsibility, beginning with an explanation of what constitutes an internationally wrongful act. The following section discusses the circumstances precluding wrongfulness that may be invoked by states seeking to avoid responsibility for an internationally wrongful act. The chapter then covers the aftermath of an internationally wrongful act, which can involve legal consequences, such as reparations, as well as countermeasures. This chapter focuses specifically on the responsibility of states, rather than the responsibility of international organizations or individuals.

This chapter examines ‘collective security’ during the first half of the 1930s as it informed government decision-making and shaped public debate. Rather than retrofitting it into a particular International Relations (IR) theory, it draws attention to the contingency and fluidity of ‘collective security’. First, it recounts the evolution of ‘collective security’ as a political idea and as a policy instrument from the First World War to the 1930s. The next section explains how an institutional apparatus emerged under the League of Nations and how sanctions were supposed to be employed. The third section shows how the crises in Asia, Africa, and Europe tested the concept of ‘collective security’ and questioned the logic of IR scholarship. The final section examines how the architects of IR dealt with these challenges, and it discusses whether the failure of ‘collective security’ caused a ‘great debate’ between so-called ‘idealist’ and ‘realist’ IR authors.

After a sketch of the history of the law of the sea and the traditional freedoms of the sea, this chapter discusses the various efforts to codify the law of the sea during the twentieth century, which culminated in the adoption of UNCLOS in 1982. Subsequently, the chapter examines the legal regimes governing the various maritime zones, as well as two international areas: the high seas and the Area. The chapter then takes up thematic issues in the law of the sea, namely the delimitation of maritime boundaries, the protection of the marine environment, the special interests of developing countries, and the system for the settlement of law of the sea disputes. The chapter concludes by noting that, despite the relatively comprehensive scope of UNCLOS, a number of new challenges have arisen with respect to the law of the sea, especially as a result of human-driven climate change.

The conclusion of the book briefly reappraises the main findings of the previous chapters. It argues that a study of the foundations of due diligence from the dogmatic perspective of obligations serves both a cognitive and a normative function. First, the conclusion argues that the theoretical reconstruction of due diligence undertaken by the book has helped to overcome their elusiveness and to better understand the nature of due diligence obligations and how they are operationalised in practice. Second, the conclusion argues that construing due diligence as an identifier for a certain class of primary rules supplies a normative function, as it allows normative considerations to be made about how state responsibility for the violation of these rules accrues.

The aplication of the law of neutrality in a civil war setting was contingent upon the recognition of belligerency of the rebels. However, the experience of the Spanish Civil war with the ill-fated policy of non-intervention in favour of either side in the conflict has established the inadmissibility of neutrality in non-international armed conflicts. Thus, neutrality is not applied as a matter of principle and by virtue of the rule that in the event of a civil war, assistance is permissible to the government but not to the rebels.