This chapter begins by discussing how the crime of aggression differs from all other core international crimes in being inextricably linked to an act of aggression by a state against another state. It then turns to a discussion of the history of the crime of aggression, including its inclusion in the Statute of the International Criminal Court (ICC). It covers the definition of the crime of aggression as set out in Article 8bis of the ICC Statute, as well as its relationship with other crimes. It also examines the material elements: (1) by a perpetrator in a leadership position in a state (2) who has participated (3) in an act of aggression by the state (4) which ‘by its character, gravity and scale, constitutes a manifest violation of the Charter of the United Nations’. It also explains the mental elements as set out in Elements 4 and 6 of the ICC’s Elements of Crime; the jurisdiction of the ICC over aggression, including the role of the Security Council; and the implications of an ICC prosecution of the crime of aggression.

In response to two conflicts in the 1990s - the Yugoslav wars of dissolution and the Rwandan genocide of 1994 - the United Nations (UN) UN Security Council created the International Criminal Tribunals for the Former Yugoslavia and Rwanda (ICTY and ICTR). This chapter begins with the creation of the ICTY through UN Security Council Resolution 827, the court’s three organ structure (Registry, Office of the Prosecutor, and Chambers), jurisdiction, and relationship with national courts. The chapter examines the milestones of the ICTY, from its first case through to the conflict in Kosovo, prosecution of former Heads of States, and implementation of its Completion Strategy, and assesses the critiques of the tribunal. The chapter then turns to the history of the creation of the ICTR, its structure (which was similar to that of the ICTY), and its jurisdiction. It then examines the practice of the ICTR, from its initial troubles through the prosecution of the leaders of the genocide, and the implementation of its Completion Strategy. Both Tribunals have now closed and transitioned into a residual phase.

This chapter begins the application of Pragmatic Constructivism by interpreting and assessing how, as a community of practice at the macro level, international society has responded to mass atrocity and its challenge to the practices of state sovereignty. It demonstrates how political mobilization on behalf of excluded publics (vulnerable populations) contributed to a reimagining of sovereignty as a responsibility to protect, as well as a normative reassignment of that responsibility to international society when states ‘manifestly fail’. It applies the two tests – inclusionary reflexivity and deliberative practical judgement – to the micro level by assessing the working practices (e.g. penholding, veto reform) of the UN Security Council. While greater inclusivity signposts ways in which the Council can better respond to the public interest, the impact of micro-adaptation is ultimately contingent on a deeper level of change in the identity of member states. Practices of atrocity prevention in the R2P context can act as a pedagogic tool, helping to mobilize the transnational activism that is a necessary part of that progressive change. This discussion extends to nuclear atrocity prevention and the way vulnerable publics deconstructed the Cold War, a lesson that should inform a renewed commitment to deep arms control practices.

Some 66 billion years ago, a cataclysmic collision between the Earth and an asteroid ten to 15 kilometres in diameter caused the extinction of the non-avian dinosaurs. In 1908, an asteroid 50 to 70 metres in diameter levelled over 2,000 square kilometres of forest in Siberia, while in 2013 an asteroid 19 metres in diameter produced a shockwave over Chelyabinsk, Russia, sending over a thousand people to the hospital. The field of ‘planetary defence’ involves the detection, characterisation, risk assessment and, if necessary, deflection of asteroids and comets that have the potential to strike Earth. Yet there has been a lack of high-level diplomacy on this issue. In particular, the low probability of a major Earth impact happening in our lifetime makes planetary defence a low priority for political leaders, despite the existential consequences of impacts and their eventual certainty of occurring. There is also a shortage of widely agreed international law, including on the potential use of nuclear explosive devices for deflecting asteroids. Most importantly, there is a lack of agreement on who is responsible for vetting the science, assessing the risks and making decisions if Earth were faced with an actual impact threat. Is it the United Nations Security Council that decides? What if a Security Council decision is blocked by one of its veto-holding permanent members? Would a state that acted unilaterally be excused any illegality because of the necessity of its actions, according to the international law on ‘state responsibility’?

This chapter provides an in-depth analysis of the role reciprocity plays in treaties. First looking at treaty law and how reciprocity functions in the rules on reservations to treaties, the chapter goes on to examine reciprocity’s role in bilateral treaties, drawing on the examples of air transport agreements and energy agreements in particular, before looking at reciprocity’s role in multilateral treaties of the bilateralizable, interdependent, and integral types. It then analyzes treaties creating international organizations, particularly the EU and ILO, and differentiated obligations in environmental and trade law, illustrating how reciprocity operates in these types of instrument. Finally, the chapter addresses "objective regimes" and the effects of treaties on third parties. While some limitations exist on reciprocity, these do not depend on the substance of obligations but rather on the legal equality of the subjects involved.

This chapter deals with Germany’s perspective on and activities in the United Nations and other international organisations. The first part deals with Germany’s involvement in a UN Security Council reform, Germany failing to integrate climate security into the work of the Security Council and Germany’s position that the UN headquarters must be accessible to all member States. Germany’s take on Security Council Resolution 2510 (2020) will be criticised. It will be assessed why Germany opposes the US interpretation of Security Council Resolution 2331 (2015). Germany’s position on civil society briefers to the Security Council, Germany accusing Russia and China of obstructing the implementation of resolutions, Germany’s difficulties as chair of the Libya Sanctions Committee, Germany’s membership of the Economic and Social Council and criticism against Germany for its handling of the Afghanistan file in the UN General Assembly is also addressed. Russia’s and China’s criticism of the German Security Council membership and reviews of the German membership will also be examined. The second part encompasses Germany’s position on youth participation in international organisations.

This chapter is concerned with Germany’s perspective on the foundations and functions of international law. It is structured in two parts: international law in general and sources of international law. The second part examines Germany’s view of the Joint Comprehensive Plan of Action (JCPoA) that sought to limit Iran’s nuclear programme. It is argued that the political aims of Germany do not justify the twisting of international law. The Federal Government portrayed the document as a binding international treaty. It did so by speaking of an ‘agreement’, from which the US had decided to ‘withdraw’ and by depicting the participants as ‘parties’. Further, Germany argued that Iran is bound by ‘obligations’ under the JCPoA. Germany also spoke of ‘Articles’ in the JCPoA and asserted that the document was ‘signed’. Moreover, Germany argued that the JCPoA became international law through the endorsement of the UN Security Council. However, the UN Security Council never marked its endorsement as a binding decision. Four and half years after the adoption of the JCPoA, Germany admitted that the JCPoA constitutes only a record of mutual political commitments and is therefore ‘soft law’.

The United Nations Security Council has the authority to adopt binding decisions and to authorise military means to ensure international peace and security. Whereas the Security Council is not typically associated with animal protection, wildlife issues have become an international security concern. Wildlife poaching and trafficking of wildlife products finance criminal networks and armed groups. The Security Council has adopted several resolutions addressing wildlife poaching and trafficking as commodities with implications on international security. Poaching and trafficking of wildlife have also been met with militarised anti-poaching enforcement – on a few occasions in cooperation with United Nations Peacekeeping forces. The militarised responses may contribute to protect wildlife, but they also risk escalating the violence affecting local communities. The chapter argues that the Security Council needs to address wildlife poaching and trafficking broadly, resorting to binding decisions. It should authorise military means only as a last and temporary resort.

This chapter offers a plausibility probe of IST in the case of China and the contemporary liberal international order. The LIO – a multifaceted set of institutions covering a range of security and non-security issues – has contributed immensely to China’s economic growth, diplomatic influence, and national security. China, nonetheless, opposes some and embraces other parts of the international order. The chapter shows that existing theories of revisionism struggle to explain this pattern of cooperation and discord in China’s approach. It then traces China’s status aspirations in the post-Cold War period and applies IST’s predictions to China’s stances in various prominent international institutions. The chapter concludes that IST can broadly apply in this case across institutions and issue areas, though further research is required to decisively demonstrate this claim.

Chapter 2 lays out the book’s theory, presenting the two hypotheses that guide the rest of the analysis: a distributional theory, where combatants where combatants are motivated by many different goals to seek out UN involvement in peacemaking and peacekeeping; and a credible commitment theory, where combatants are primarily motivated by security concerns. I begin by articulating the structural nature of peace operations, demonstrate how we can observe the social connection between peace operations by examining the high politics of the UN Security Council, and note multiple intellectual traditions anticipate this social connection. I then argue parties to conflict seek the UN’s involvement in negotiation and settlement because they are interested in the distributive and symbolic benefits of intervention— not just international actors’ abilities to manage mistrust between warring parties and resolve credible commitment problems, but what intervention can give them, and what international actors can bring to the post-conflict state.We may be better poised to understand why parties to a conflict seek out UN peacekeeping if we reframe it as a potential solution to a range of security, tactical, material, and symbolic problems. The chapter concludes with observable implications for both hypotheses.

Chapter 5 embarks upon an analysis of the UNSC’s approach to ‘conflict resources’ by considering its use of sanctions, panels/groups of experts, and peacekeeping missions. It will show that UNSC commodity-focused interventions have sought to address the economic motivations for starting and prolonging armed conflict, while failing to bring about the systemic changes necessary to achieve ‘positive peace’. By securitising resource extraction in conflict zones and supporting ‘good governance’ reforms in post-conflict countries, questions of sustainability and more equitable access/distribution of natural resources have been sidelined. Thereafter, through engaging with ongoing debates on the peace and security implications of climate change, the chapter illuminates the limits of existing conceptual/legal frameworks underpinning the practice of the UNSC and the need to rethink what peace and security mean in times of ecological disruption.

This chapter asks how do international institutions adjust to changes in the number, diversity, and relative power of system members? It combines the Weberian concept of social closure and the idea of club goods to argue that, as IOs come under pressure to open up to new and more heterogenous members, the logic of closure creates incentives for incumbent members to create institutional designs that preserve their privileges. In the face of membership diversity, rules that promote procedural equality—i.e., consensus and majority voting rules—challenge status quo interests. In response, incumbents pursue designs that preserve clubs of like-minded actors through assimilative, hierarchical or exclusive multilateralism. The chapter discusses how self-determination, the principled basis for membership expansion, serves as a rule of closure. Then it considers the cases of the United Nations at its founding, the United Nations during its main period of expansion under demands for a New International Economic Order, and the G20, which many have pointed to as a new model of inclusive governance. Each case shows how expanding institutional membership may improve formal equality while triggering a decrease in procedural equality, creating institutional arrangements in which all are equal, but some are more equal than others.