2. Where does international law come from?

The rules of international law come from two main sources: treaties and customary international law, both of which are created by States. States are bound by the rules with which they have chosen to bind themselves—rules to which they have consented. ‘Where does international law come from?’ explains how international law works and considers the nature of customary international law and of treaties. Systems of customary law, including customary international law, are rooted in the regularity of an identified practice, whereas a treaty is an agreement between States that is legally binding. Often the broad principles set out in laws have to be mediated through detailed technical rules and standards.

5. Sovereignty inside the State

Limitations on the right to use force are a key element among the principles by which international law secures the sovereign equality and independence of States against external threats. ‘Sovereignty inside the State’ examines the principles of international law that spell out in positive terms the content of that equality and independence. Each State has the sovereign right to decide upon its social and economic structures, and to lay down laws that will influence the national character of the State and of life within it. The legal concept of jurisdiction determines the reach and priority of those laws. That freedom is not unlimited: it is constrained by obligations of the State under international law.

7. What international law does badly (or not at all)

International law cannot manufacture agreement where none exists. For this reason, international law is not well suited to the promotion of innovative solutions to international problems where the interests of States are radically divergent. ‘What international law does badly (or not at all)’ considers this in relation to climate change and to the protection of commercial interests in proprietary drugs. Also, international law cannot itself deliver international justice. While the law is an invaluable instrument for the implementation of policies that aim to make the world more just—the special preferential treatment given to developing States within the World Trade Organization, for example—it will not miraculously produce justice and fairness of its own force.

4. Freedom from external interference

‘Freedom from external interference’ focuses on one aspect of the assurance of the sovereign equality and independence of States and the freedom that it entails for each of them: the freedom from external interference and from forcible coercion by other States. In what circumstances may force be used? What weapons and methods of waging war may be used? Who is entitled to use force? The rules of international law relating to war are traditionally divided into the jus in bello, which governs matters such as prohibitions on certain weapons and ways of waging war against other nations, and the jus ad bellum, which limits the circumstances on the right to go to war.

3. Implementing international law

States tend to comply with international law, but what happens if a State breaks a rule of international law? ‘Implementing international law’ considers the different ways in which international law is implemented—diplomatic protest through acts of retorsion, counter-measures, litigation, arbitration, and mediation. If litigation is necessary, most cases in which international law is applied arise in municipal courts and tribunals. Only a small proportion of cases that are decided by the application of rules of international law are taken to the International Court. Despite the increasing engagement between international law and individuals, the particular focus of international law remains fixed upon States and State responsibility.

1. Nations under law

The most basic function of international law is to secure the coexistence of the world’s almost 200 sovereign States. ‘Nations under law’ explains the essential conditions of statehood under international law: having a permanent population; an effective government; a physical territory; the capacity to enter into relations with other States; and legitimacy as an independent State. International law provides for the security of States’ borders, and for their right to be free from invasion and coercion by neighbouring States. It underpins the right of each State to choose its political, economic, and social structures.

6. What international law does well

States cooperate in making and applying international law in circumstances where they are agreed upon the goals to be pursued, so that the law is employed to express a willing cooperation between them rather than to force rules upon them. ‘What international law does well’ considers the mechanisms of why and how States cooperate. Some arrangements are designed to facilitate transactions rather than to prescribe rules or standards. Examples include cooperation between legal systems and the United Nations. Key areas where international law has had success are in the international economy, through the World Trade Organization; humanitarian law and human rights; environmental protection; and the repression of criminal activity.