What do we owe to others when interacting with them and what should we know when asking this question? Those seemingly straightforward queries get quickly more complicated when we realize that many of our actions take place not only in institutional contexts – such as promising or contracting – but also in organizations when we are vested with ‘authority’. In both cases special responsibilities are created, but in the latter case they can no longer be ascribed to us as ‘persons’ when we act as ‘managers’ of an organization, or as magistrates, holding public office.

The success of any arms control treaty generally depends on its ability to achieve its primary objectives and intended outcomes. At the heart of measuring such success are effective compliance criteria and verification mechanisms. This includes the ability to apply metrics to assess tangible outcomes and measurable outputs and benchmarks of achievement, including on-site visits. In relation to nuclear issues, this also means that verification of both the non-diversion of nuclear material from declared peaceful activities (i.e., correctness of conduct), and the absence of undeclared or clandestine nuclear activities in a particular state (i.e., completeness in following treaty terms).

The TPNW was welcomed at the UN General Assembly, under the participation of a wide range of humanitarian groups and civil society organizations, supported by a groundswell of nations around the world. The Treaty firmly implants new law into the international legal landscape for states who wish to ratify it, sowing the seeds of potentially new normative behavior within the global community more generally. Indeed, the TPNW purports to strive for universality, raising significant questions regarding its ambitions in achieving legal unity within the wider international legal order. The dedication to the spirit of the Treaty cannot be ignored, nor can the optimism to ban nuclear weapons.

The adoption of the Treaty on the Prohibition of Nuclear Weapons (TPNW) at the United Nations General Assembly and its movement toward ratification raises both hopes amongst some and fears amongst others regarding the development of customary practice under international law. Although the TPNW purports to strive for universality, significant questions remain regarding the Treaty’s aims and achieving legal unity within the international legal order. The purpose of this chapter is to explore these and other issues regarding the TPNW’s prospects of achieving universality under customary international law and opinio juris.

In the public sphere, it is unequivocal that the language of virtues impregnates much of our discourse and analyses about domestic and international leaders. Dominique Strauss-Kahn, Christine Lagarde, Donald Trump, Luis Moreno Ocampo or Silvio Berlusconi often trigger(ed) heated reactions about their official and private behaviours deemed to be inappropriate and found wanting from a moral standpoint. On the other side of the fence, Barack Obama, António Guterres, Nelson Mandela or Dag Hammarskjöld and Greta Thunberg are or have been praised as being virtuous and inspirational leaders capable of moving the world towards a brighter future.

International organizations (IOs) were once expected to guarantee the ‘salvation of mankind’ but have increasingly come to be questioned. On the one hand, waves of populism, nationalism and isolationism threaten the stability of the international legal order and the capacity of IOs to address policy dilemmas. On the other hand, these policy dilemmas keep piling up – for example, the influx of refugees, climate change, global health issues, cyber wars, growing inequality and widespread poverty. It appears that what is needed are more global cooperation and leadership, at a time when the mission and capacities of IOs may be at risk. Compounding the problem, the latter are also often accused of corruption, embezzlement, negative externalities, political capture, poor and immoral performance and so on.

One of the fundamental problems with the TPNW is that the five officially recognized nuclear-weapons states – Russia, the United States, China, France and the United Kingdom, collectively the NWS – and four other states who possess nuclear weapons – India, Pakistan, Israel and North Korea – have boycotted the Treaty negotiations and refused to sign or ratify it. Despite moves toward neo-universalism, this leaves an important gap in the TPNW legal framework, because it does not directly bind the NWS and it seems unlikely that these NWS will join the Treaty or be bound under opinio juris. One way to remedy this problem and fill the legal gap is to appeal to an existing set of legal obligations found in international jurisprudence to which NWS are already bound. Specifically, the International Court of Justice (ICJ) has highlighted that states owe obligations erga omnes – toward all – that derive from other international laws, legal principles and conventions.

This chapter develops an exemplarist virtue approach to ethical leadership in international organizations. An exemplarist virtue theory of ethical leadership endorses a virtue perspective on ethical leadership that assigns a prominent role to exempla. This approach involves two central commitments about the structure of a theory of ethical leadership: first, a commitment to the view that virtues, rather than rules or consequences, are the primary concepts in a theory of ethical leadership, and second, a commitment to the claim that exempla of ethical leadership occupy a central stage within the theory. The development of an exemplarist virtue approach to ethical leadership thus draws on two main, connected, traditions of moral theory: virtue ethics and exemplarism.

During the second year of the Peloponnesian War (430BC) the city-state of Athens was ravaged by a plague. The great historian Thucydides, who survived himself the disease, documented the social effect of the pandemic upon the city, where almost 100.000 people died. According to his account on the moral decadence the epidemic caused, he wrote that ‘the catastrophe was so overwhelming that men, not knowing what would happen to them next, became indifferent to every rule of religion or law.’ The ancient plague had triggered an ethical crisis, but the Athenian democracy had to survive, due to its main characteristics as highlighted by Pericles in his famous Funeral’s Oration. In this speech dedicated to the dead fighters, of the first year of the war, Pericles emphasized, that one of the emancipatory elements of the Athenian democracy was the sensibility of measure and a combination of philosophy with action.