General Principles, Judicial Decisions, Writers and Equity

Treaties and custom do not cover every question that arises between states. Article 38 therefore adds the general principles of law recognised by civilised nations, and allows courts to draw on judicial decisions and the writings of leading jurists to identify the law. Equity also plays a part. This note explains each of these, with the cases that illustrate them.

1. General Principles of Law

• Article 38(1)(c). The general principles of law recognised by civilised nations; the phrase civilised nations is now read as referring to the community of nations generally.
• Purpose. Inserted in 1920 to fill gaps and prevent a non liquet, that is, a refusal to decide because no treaty or custom applies.
• Two kinds. Principles derived from national legal systems and common to the principal systems, and, according to many writers, principles formed within the international legal system itself.
• Adaptation. In his separate opinion in International Status of South West Africa (1950), Lord McNair said that international law borrows principles from private law not lock, stock and barrel, but as indications of policy and principle.
• ILC work. The International Law Commission adopted eleven draft conclusions on general principles of law on first reading in 2023, and work on the second reading continued in 2025.

Figure 1: General principles applied by the World Court

• Other examples. Nobody may be a judge in his own cause, the right to be heard, the abuse of rights, the separate legal personality of a company (Barcelona Traction, 1970), and elementary considerations of humanity (Corfu Channel, 1949)

2. Judicial Decisions

• Subsidiary means. Under Article 38(1)(d), decisions help determine rules of law; they do not formally create them.
• No binding precedent. Under Article 59, an ICJ decision binds only the parties and in respect of that case; there is no doctrine of stare decisis.
• Consistency in practice. The ICJ regularly cites its own and the PCIJ's decisions and departs from them only for good reason; many rules, such as those on reservations and maritime delimitation, were largely developed by the Court.
• Other tribunals. Arbitral awards, such as Alabama Claims (1872), Island of Palmas (1928) and Trail Smelter (1941), decisions of specialised tribunals, and judgments of national courts, such as Pinochet (1999) in the House of Lords, also serve as evidence of the law.

3. Teachings of Publicists

• Role. The teachings of the most highly qualified publicists of the various nations are evidence of the law, not a source; they collect and systematise practice.
• Historical weight. Classical writers such as Grotius, Vattel and Bynkershoek shaped the law; in The Paquete Habana (1900), the US Supreme Court relied on the works of jurists as evidence of custom.
• Today. Individual writers are cited less; collective bodies such as the International Law Commission, the Institut de Droit International (founded 1873) and the International Law Association carry greater weight.

4. Equity

Figure 2: Three forms of equity

• Equity as part of law. In Diversion of Water from the Meuse (1937), Judge Hudson treated principles of equity as part of international law that the Court may apply.
• Infra legem. Equity within the law, choosing among possible interpretations the one that best meets justice; applied in maritime delimitation through equitable principles (North Sea, 1969; Tunisia/Libya, 1982)
• Praeter legem. Equity beside the law, filling gaps; its use is limited and contested.
• Contra legem. Equity against the law, setting aside legal rules for fairness; possible only in a decision ex aequo et bono under Article 38(2), with consent.
• Frontier Dispute (Burkina Faso/Mali), 1986. The Chamber distinguished equity infra legem, which it could apply, from a decision ex aequo et bono, which the parties had not authorised.

5. Frequently Asked Questions

Why were general principles of law added to Article 38?

To ensure that the Court would never have to declare a non liquet for want of an applicable treaty or custom. Principles common to national legal systems give it a further body of law to apply.

Is equity the same as deciding ex aequo et bono?

No. Equity infra legem operates within the law and the Court applies it as part of international law. Deciding ex aequo et bono means setting the law aside in favour of fairness, which requires the parties' agreement under Article 38(2).

6. Related Topics

• Topic 7: Sources of International Law. Article 38 of the ICJ Statute.
• Topic 11: Soft Law, Unilateral Acts and Estoppel. Nuclear Tests and Eastern Greenland.
• Topic 43: State Responsibility. Reparation and Chorzów Factory.