The Sources of International Law

"Recognized by civilized nations." The phrase is a relic of 1920 and is dealt with in [General Principles of Law Recognised by Civilised Nations].

"Subsidiary means for the determination of rules of law." Paragraph (d) is not a source of law at all. Judicial decisions and writings are ways of finding out what the law is, not ways of making it.

Formal and material sources

This is a distinction the standard textbooks make and examiners ask for.

A formal source is what gives a rule its legal validity, the process that makes it law. In this subject the formal sources are treaty and custom, with general principles a third.

A material source is where you find evidence of the rule's content: judgments, resolutions, treaty collections, diplomatic correspondence, the writings of jurists, the reports of the International Law Commission.

The distinction explains paragraph (d) exactly. Judicial decisions and the teachings of publicists are material sources: they tell you what the law is without making it.

Is there a hierarchy?

Students often assume article 38 lists the sources in order of authority. That is not quite right, and the exact position is worth stating.

There is no formal hierarchy in article 38. The order (a) to (d) is not stated to be an order of precedence, and the words "in the following order" were considered by the 1920 drafters and dropped.

There is a practical order. A court asked to decide a dispute will look first at any treaty binding both parties, because that is the most specific expression of what they agreed. Failing that, custom. Failing that, general principles, which in practice fill gaps rather than decide cases.

Paragraph (d) is expressly subordinate, being described as subsidiary means.

But three ordinary rules of legal reasoning apply, and they cut across the list. Lex specialis derogat legi generali: a special rule prevails over a general one, so a treaty between two States prevails over a general custom on the same point. Lex posterior derogat legi priori: the later rule prevails over the earlier, between the same parties. And jus cogens prevails over everything, so a treaty conflicting with a peremptory norm is void under article 53 of the Vienna Convention, whatever the parties agreed.

So the honest answer is: no hierarchy on the face of article 38, a working order in practice, and one true supremacy, that of peremptory norms.

The seven items MU lists, and where each is dealt with

MU prints topic 1.5 with a heading and then seven items, and each has a chapter.

Custom is [Custom]. The general practice and the belief that law requires it.

Treaties are [Treaties as a Source]. How a treaty binds parties, and how a treaty rule can pass into custom and bind non-parties.

General principles of law recognised by civilised nations are [General Principles of Law Recognised by Civilised Nations]. What the phrase means and which principles have actually been applied.

Judicial decisions and writings of jurists are [Judicial Decisions and the Writings of Jurists], and they are one chapter because article 38(d) treats them together as subsidiary means.

Equity is [Equity], including article 38(2)'s ex aequo et bono.

Resolutions of the General Assembly are [Resolutions of the General Assembly], which is the modern question article 38 does not mention at all.

What article 38 leaves out

This is the sharpest question on the topic and a good answer names four omissions.

Resolutions of international organisations. Article 38 was drafted before organisations produced resolutions in volume. General Assembly resolutions are not binding by themselves under articles 10 to 14 of the Charter, but they can express or crystallise custom, and some Security Council decisions bind all Members under article 25. Neither appears in article 38.

Unilateral acts. A State can bind itself by a public declaration intended to be binding, and no source in article 38 covers it.

Jus cogens. Article 38 is a list of where rules come from; it has nothing to say about a class of rules that outrank others. Article 53 of the Vienna Convention supplied that in 1969.

Soft law. Codes of conduct, guidelines, declarations and standards that are not binding but are widely followed. They are not law, and they are not nothing, and article 38 has no room for them.

A worked example

State A and State B dispute the boundary of their continental shelf. Where does a tribunal look, and in what order?

First, any treaty between them. If they have a delimitation treaty, that governs, because it is the most specific expression of their agreement, and lex specialis applies.

Second, any treaty in force between both on the subject generally. If both are parties to the Convention on the Law of the Sea, articles 76 and 83 govern, which is [The Continental Shelf].

Third, custom, if one of them is not a party. This is precisely the situation in the North Sea Continental Shelf cases, worked in [Delimitation of Maritime Boundaries], where Germany had signed but not ratified the 1958 Convention, so the tribunal had to ask whether the treaty rule had passed into custom.

Fourth, general principles, which here supply the vocabulary of equity but not the boundary.

And throughout, judicial decisions and writings, not as law but as evidence of what the law is. The tribunal will read the earlier delimitation judgments closely, and it is not bound by any of them, because article 59 provides that a decision of the Court has no binding force except between the parties and in respect of that particular case.

Distinctions table

What it does NOT mean

Article 38 is not a statute of the whole world. It is a direction to one court about what that court shall apply. Its authority as a list of sources comes from universal acceptance, not from its own terms.

A source is not the same as a basis of obligation. The basis of obligation is the question in [Theories of the Basis of International Law]. The source is the question of where a particular rule comes from and how to prove it.

Article 38(d) does not make judicial decisions binding precedents. Article 59 says a decision has no binding force except between the parties and for that case. The Court in practice follows itself closely, which is a different thing.

Ex aequo et bono is not equity. It is a power to decide outside the law altogether, and it needs the agreement of both parties. No party has ever given it. That distinction is worked in [Equity].

Limits and criticism

The list is a century old and shows it. It has nothing on resolutions, nothing on soft law, nothing on unilateral acts and nothing on peremptory norms, all of which are now part of any serious account of how international obligations arise.

"Civilized nations" should have been amended at some point in a hundred years and has not been.

The two main sources are becoming harder to tell apart. Multilateral conventions codify custom, custom then develops through the practice of parties to those conventions, and the two feed each other continuously. The North Sea cases had to unpick that relationship and it has only become more tangled since.

Quick revision

Article 38(1) of the Statute of the International Court of Justice is the accepted list: (a) international conventions, (b) international custom as evidence of a general practice accepted as law, (c) the general principles of law recognised by civilised nations, (d) subject to article 59, judicial decisions and the teachings of the most highly qualified publicists, as subsidiary means. Article 38(2): ex aequo et bono with the parties' agreement.

Its authority comes from universal acceptance and from article 93(1) of the Charter making every Member a party to the Statute.

The (b) wording is back to front: practice is evidence of custom, not the other way round.

Formal sources make law: treaty, custom, general principles. Material sources show what the law is: judgments, writings, resolutions, ILC reports.

No formal hierarchy, but a working order, plus lex specialis, lex posterior, and the true supremacy of jus cogens under article 53 of the Vienna Convention.

Omitted from article 38: resolutions of international organisations, unilateral acts, jus cogens, and soft law.

Article 59: a decision of the Court has no binding force except between the parties and in respect of that particular case.

Test yourself

1. Reproduce article 38(1) and identify which of its four heads is not a source of law.

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 recognized by the contesting states; (b) international custom, as evidence of a general practice accepted as law; (c) the general principles of law recognized by civilized nations; and (d) subject to the provisions of 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. Head (d) is not a source: it is expressly a subsidiary means for determining rules of law, that is, a material rather than a formal source.

2. Is there a hierarchy among the sources?

Not on the face of article 38, which does not state an order of precedence and from whose draft the words indicating one were removed. There is a working order: a tribunal looks first to a treaty binding both parties, then to custom, then to general principles, and treats judicial decisions and writings as evidence throughout. Three rules cut across this: lex specialis, so a special rule prevails over a general one; lex posterior, so a later rule prevails over an earlier between the same parties; and the supremacy of jus cogens, which voids any treaty conflicting with it under article 53 of the Vienna Convention.

3. Distinguish formal from material sources with an example of each.

A formal source is the process that makes a rule legally valid: a treaty, or a custom formed by general practice accepted as law. A material source is evidence of the content of a rule: a judgment of the International Court, a report of the International Law Commission, or a treatise. A formal source can create an obligation; a material source can only show that one exists. Article 38(a) to (c) are formal, article 38(d) is material.

4. What does article 38 omit, and does the omission matter?

Resolutions of international organisations, unilateral acts of States, jus cogens, and soft law. It matters in the sense that any complete modern account of how international obligations arise has to deal with all four, and none of them can be fitted into the text without strain. It matters less than it seems, because resolutions and unilateral acts do their work largely through custom and through good faith, and jus cogens was given statutory form in article 53 of the Vienna Convention in 1969, which article 38 does not need to repeat.

5. Why is the wording of article 38(1)(b) criticised?

It says international custom is evidence of a general practice accepted as law, which reverses the logical relationship. Custom is the rule; the general practice accepted as law is the evidence from which the existence of the rule is inferred. Every court and writer reads the provision as though it said custom as evidenced by a general practice accepted as law, and the drafting has never been corrected.

6. State A obtains a judgment of the International Court against State B on a point of law. State C is later in dispute with State D on the same point. Is the earlier judgment binding?

No. Article 59 of the Statute provides that a decision of the Court has no binding force except between the parties and in respect of that particular case, and article 38(1)(d) is expressly made subject to article 59. There is no doctrine of stare decisis in international law. In practice the Court follows its own reasoning closely and departs from it only for good reason, so the earlier judgment will carry very great weight as a subsidiary means for the determination of the rule, but it binds nobody in the later dispute.