Under international criminal law (‘ICL’), individuals can be prosecuted and punished for conduct that is criminalised under customary international law and/or treaty. This differs from most branches of international law, which concern the rights and obligations of states. The rationale for holding individuals to account for such crimes was articulated in 1946 by the International Military Tribunal at Nuremberg, which stated: ‘Crimes against international law are committed by [people], not by abstract entities, and only by punishing individuals who commit such crimes can the provisions of international law be enforced.’ This chapter introduces this branch of international law, citing examples involving Australia as well as many other states. The chapter gives an overview of some of ILC’s key principles and aims, andoutlines the historical development of ICL. It explains how ICL is currently being enforced, considers the core crimes in ICL and discusses individual criminal responsibility and defences.

The previous chapter described the extent of a state’s physical territory; this chapter looks at how far a state’s legal power extends. As will be seen, international law places certain limits on the right of a state to make, apply and enforce its laws – its jurisdiction – and these limits are considered in Section 6.2. International law also recognises two principal bars to the exercise of that jurisdiction: diplomatic immunity and state immunity; these are covered in Sections 6.3 and 6.4. Two other bars to jurisdiction, namely special mission immunity and the foreign act of state doctrine, are also briefly covered in Sections 6.6 and 6.7.

International humanitarian law (‘IHL’), also known as the law of armed conflict (‘LOAC’), is a branch of international law that regulates the behaviour of participants in armed conflicts and encompasses rules on the military targeting of persons and objects, the means and methods of warfare, the protection of persons and objects, and the implementation and enforcement of the law. International humanitarian law is also one of the most highly codified fields of international law, with numerous treaties adopted over the last 150 years; many of these have also attained customary status. In developing IHL, states have recognised that, while the ultimate aim of society should be to strive to prevent war, wars will nonetheless occur, and that while ‘war will always constitute suffering and personal tragedy … rules of warfare are intended to prevent unnecessary suffering that yields little or no military advantage’. This balance between humanitarian aims and military objectives serves as the basic underpinning of all the modern laws of armed conflict.

The Australian legal system is not an island, and Australian law has felt the influence of law and legal ideas from other jurisdictions, particularly other common law countries. Australian law has also been shaped by public international law both directly and indirectly and this interaction has become increasingly important as the scope and content of international law have grown. The relationship between Australian law and international law is mediated by Australia’s constitutional framework in which the separation of powers between the executive, legislature and the courts holds central place. Unlike the constitutions in many other legal systems, the Australian Constitution does not address the relationship between international and domestic law, and most of the relevant legal principles are to be found in the common law. This chapter examines how each arm of government in Australia has engaged with international law, identifying areas where the relationship is well settled (as it is in relation to treaties) and areas where there remains some uncertainty (as in relation to customary international law).

States often need to cooperate with each another to address legal and other issues of common concern across many fields in an interdependent world. International organisations (‘IOs’) emerged in the 19th century as a means of intensifying and permanently institutionalising international cooperation, through bodies with an international legal personality, and functions and powers, separate from their member states. While the earliest IOs had a narrow technical focus, the League of Nations (1919–46) and United Nations (since 1945) reflect a more ambitious global agenda of broad-spectrum cooperation. The proliferation of IOs has generated some key legal issues which this chapter explores: how to define IOs; the nature, extent and consequences of their international legal personality; their powers, immunities and privileges; and the scope of their legal responsibility for their conduct. There is a special focus on the United Nations, as a universal IO with competence in many areas of international life and human activity, and from whose establishment and practice much of the international law of IOs has emerged.

This chapter covers the international law governing the use of force between states – the jus ad bellum. This is in contrast to the jus in bello – the law of armed conflict, or international humanitarian law – which regulates the conduct of hostilities once under way (see Chapter 11). Since at least 1945 the use of force by states has been prohibited, except in self-defence or when authorised by the United Nations Security Council. This chapter analyses the prohibition, the two exceptions, and the controversial issue of humanitarian intervention and its close relative, the ‘responsibility to protect’.

Public international law is a worldwide legal system which regulates the conduct of states (countries) and other actors, both in their international relations and within states’ territories. It governs many areas, such as sovereignty over territory; rights and responsibilities at sea; environmental protection; human rights and the suppression of international crimes; trade and investment; the use of military force; responsibility for breaches of the law; and the settlement of disputes. This chapter introduces the main features of public international law, including its history, sources and purposes. It outlines what the law regulates, who has rights and bears obligations under it, and how it is implemented and enforced. The chapter then considers jurisprudential debates about the nature of public international law as ‘law’ and the reasons for compliance with it, and concludes with discussion of some key critical theories.

All states have an obligation to settle disputes peacefully in accordance with arts 2(3) and 33 of the Charter of the United Nations (‘UN Charter’), and the purpose of this chapter is to provide an introduction to the methods for the settlement of international disputes. It begins with an overview of international dispute settlement, including a discussion of the concept of a ‘dispute’, and the distinction between political and legal disputes. It then traces the evolution of the obligation to settle disputes peacefully through its broad phases: the 1899 and 1907 Hague Conventions for the peaceful settlement of international disputes, and the creation of the Permanent Court of Arbitration; the Covenant of the League of Nations of 1919, and the creation of the Permanent Court of International Justice (‘PCIJ’); and the Kellogg–Briand Pact of 1928, and the UN Charter of 1945. The chapter then considers the various methods of international dispute settlement, beginning with the diplomatic methods (negotiation, fact-finding and inquiry, the use of ‘good offices’, mediation, and conciliation) before turning to the adjudicatory forms of dispute settlement.

International environmental law (‘IEL’) began to emerge as a distinct subdiscipline of international law in the 1970s. Since then, it has assumed critical importance in helping to maintain the ecological systems upon which all life on planet Earth depends. It is continuing to develop and is relevant to all states and communities, affecting a wide range of human activities and concerns. This chapter briefly traces the history of IEL and sets out some recent institutional and policy developments, including the United Nations Environment Assembly and the UN Sustainable Development Goals. It also looks at concerted attempts to fill gaps in the field. Given the vastness of the subject matter, the chapter does not purport to be a comprehensive or in-depth analysis. It addresses the main organising principles of IEL, both established and emerging. It provides an overview of treaties (also referred to as multilateral environmental agreements or ‘MEAs’) in several key subfields, including regimes addressing the atmosphere, transboundary pollution, chemicals and wastes, biodiversity, and land degradation. It also includes a case study on world heritage and its implementation in Australia.

International economic law is an umbrella term with no fixed meaning. At its broadest, it covers all aspects of economic relations between states, including regulation of the conduct of individuals, corporations and international organisations. A narrower meaning is ‘the segment of public international law directly governing – rather than merely affecting – economic relations between States or international organizations’. The field also embraces governance arrangements, such as the World Bank, International Monetary Fund, and World Trade Organization, as well as the many UN and regional bodies that advance economic development. As space does not permit a discussion of all these aspects, this chapter focuses on two important areas: international trade law and international investment law. International trade law is the body of law, mainly treaty based, that governs the terms on which states permit the trade in goods and services across their borders.

To explain the law of state responsibility and diplomatic protection, it helps to distinguish between primary rules and secondary rules. The primary rules of international law provide that certain acts or omissions are unlawful – for example, the law on the use of force would be considered primary rules of international law, a breach of which would be an internationally wrongful act. When those primary rules are breached, it is the secondary rules – the law of state responsibility – that come into play, to determine inter alia the consequences of that initial wrongful act, whether the wrongful act was committed by a state (thereby entailing that state’s responsibility), and what action the ‘wronged state’ may take in reply. The rules on state responsibility cover wrongful acts committed against another state, as well as certain wrongful acts committed against nationals of the state, including corporations; the law of diplomatic protection solely concerns how a state may raise a claim against another state for a wrong committed against one of its nationals, rather than against the state itself.

The law of the sea, one of the oldest areas of international law, is now substantially codified in the 1982 United Nations Convention on the Law of the Sea (‘UNCLOS’), the ‘constitution for the oceans’. UNCLOS ushered in the modern law of the sea, providing a comprehensive regime for maritime zones, navigational rights and freedoms, fishing and other uses of the world’s oceans that cover approximately 70% of the Earth’s surface. As an island country with extensive maritime zones, Australia has a major stake in the law of the sea and has been actively involved in its development and implementation. Australia was one of the original signatories to UNCLOS and ratified it in 1994, the year it entered into force generally. The central issues of concern for the law of the sea have traditionally been the extent of maritime jurisdiction and navigational rights. However, a much broader range of matters is addressed in contemporary law and practice, from sustainable fisheries management through to mining of the deep seabed beyond national jurisdiction. There are also major new challenges on the horizon – none more so than climate change.

International human rights law (‘IHRL’) provides minimum standards which states must observe in their treatment of individuals under their jurisdiction. In this respect, it differs from many other areas of international law which focus on regulating international relations between states. The human rights recognised in international instruments are considered to be fundamental rights which all human beings are entitled to enjoy, regardless of their personal circumstances or the state in which they reside.

The starting point for discussion and analysis of the sources of international law is almost invariably art 38 of the Statute of the International Court of Justice (‘ICJ Statute’), the International Court of Justice being the primary judicial organ of the United Nations. Article 38 lists the sources of international law as comprising treaties, custom, general principles of law, and – as subsidiary means for determining the law – judicial decisions and academic writing. However, in the 75 years since the adoption of the ICJ Statute, newer sources of legal obligation have emerged for the international community. These often involve non-state and intergovernmental actors in their creation. This chapter explores both the traditional and newer sources of international law and assesses how they are adopted and created.