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International Law

Sources of International Law: Article 38 of the ICJ Statute

International law has no legislature, so the question of where its rules come from is central. The accepted starting point is Article 38 of the Statute of the International Court of Justice, which tells the Court what law to apply. This note sets out Article 38, explains each source and its standing, considers whether the sources rank in a hierarchy, and covers the sources the list does not mention.

1. Article 38

Structure of Article 38

Figure 1: Structure of Article 38

  • Article 38(1). The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall apply (a) international conventions, whether general or particular, establishing rules expressly recognised by the contesting states; (b) international custom, as evidence of a general practice accepted as law; (c) the general principles of law recognised by civilised nations; and (d) subject to Article 59, judicial decisions and the teachings of the most highly qualified publicists of the various nations, as subsidiary means for the determination of rules of law.
  • Article 38(2). This does not prejudice the power of the Court to decide a case ex aequo et bono, if the parties agree.
  • Article 59. A decision of the Court has no binding force except between the parties and in respect of that particular case.
  • Origin. The text comes from Article 38 of the Statute of the Permanent Court of International Justice, drafted in 1920 by an Advisory Committee of Jurists; the words whose function is to decide in accordance with international law were added in 1945.

2. The Sources Explained

  • Formal and material sources. Formal sources give a rule its legal force, such as treaty and custom; material sources show the content of the rule, such as state practice, decisions and writings.
  • Treaties. Bind only the parties (Article 34, VCLT), but may record, crystallise or generate custom; writers distinguish law making treaties, which lay down general rules for many states, from treaty contracts, which settle particular matters between a few (Topic 13)
  • Custom. A general practice accepted as law, binding on all states except a persistent objector (Topic 8)
  • General principles. Principles common to the major legal systems, used to fill gaps and avoid a non liquet, a finding that there is no law on the point (Topic 9)
  • Subsidiary means. Judicial decisions and writings do not create law; they help identify it (Topic 9)

3. Is There a Hierarchy?

  • No formal ranking. Article 38 lists the sources in an order of convenience; treaties, custom and general principles have equal formal authority.
  • In practice. A court first applies a treaty binding the parties, as the more specific and express rule (lex specialis), then custom, then general principles; a later rule generally prevails over an earlier one (lex posterior)
  • Jus cogens. A peremptory norm overrides any conflicting treaty or ordinary custom (Articles 53 and 64, VCLT; Topic 10)
  • Article 103, UN Charter. Obligations under the Charter prevail over obligations under any other international agreement.

4. What Article 38 Leaves Out

Sources outside the list

Figure 2: Sources outside the list

  • Acts of international organisations. Decisions of the Security Council bind members under Article 25 of the Charter; General Assembly resolutions are recommendations but can show opinio juris (Legality of the Threat or Use of Nuclear Weapons, 1996)
  • Unilateral acts. Public declarations made with intent to be bound can create obligations (Nuclear Tests, 1974; Topic 11)
  • Civilised nations. The phrase reflects its 1920 origins and is now read as referring to all states and legal systems.
  • Soft law. Non-binding instruments, such as declarations and codes, influence the formation of binding rules (Topic 11)

⚠ Exam trap

Article 38(1) lists conventions, custom and general principles as primary sources, and judicial decisions and publicists as subsidiary means. Article 59 means there is no binding precedent at the ICJ. Article 38(2) allows decision ex aequo et bono only with the parties' consent, and the ICJ has never used it. There is no formal hierarchy among the primary sources, but jus cogens and Article 103 of the Charter prevail over conflicting rules.

5. Frequently Asked Questions

Are judicial decisions a source of international law?

Not a formal source. Under Article 38(1)(d), they are subsidiary means for determining rules of law, and under Article 59 an ICJ decision binds only the parties to that case. In practice, the Court follows its earlier decisions for consistency.

Are General Assembly resolutions binding?

Generally no, except on internal matters such as the budget. They may, however, provide evidence of state practice and opinio juris and so contribute to custom, as the ICJ noted in the Nuclear Weapons opinion (1996).

What is a decision ex aequo et bono?

A decision based on what is fair and good rather than on legal rules. Under Article 38(2), the ICJ may decide this way only if the parties agree, and it has never done so.

6. Related Topics

  • Topic 8: International Custom. State practice and opinio juris.
  • Topic 9: General Principles, Judicial Decisions and Writers. The other sources and equity.
  • Topic 13: Law of Treaties I. Treaties as a source.