Treaties as a Source

Two consequences follow immediately, and both have their own provisions.

A party may not plead its own internal law as a reason for failing to perform. That is article 27, and its importance for an Indian student is dealt with in [International Law in Indian Courts].

A treaty binds only the parties. That is the next section.

Third States: the rule and its exceptions

The rule. Article 34 of the Vienna Convention: a treaty does not create either obligations or rights for a third State without its consent. The Latin tag is pacta tertiis nec nocent nec prosunt, agreements neither harm nor benefit third parties.

Obligations for a third State. Article 35 allows one, but on strict terms: the parties must intend the provision to create the obligation, and the third State must expressly accept it in writing.

Rights for a third State. Article 36 is easier: a right arises if the parties intend to accord it and the third State assents, and assent is presumed so long as the contrary is not indicated, unless the treaty provides otherwise.

Revocation. Article 37 provides that an obligation so created may be revoked only with the consent of the parties and of the third State, unless otherwise agreed; a right may generally be revoked by the parties alone, unless it was intended not to be revocable without the third State's consent.

And the exception that swallows the rule. Article 38 preserves the possibility that a rule set out in a treaty becomes binding on a third State as a rule of customary international law. That is the route that matters, and it is the next section.

How a treaty rule becomes binding on non-parties

This is the most heavily examined point in the topic, and the authority is the case worked in [Custom].

Facts. North Sea Continental Shelf Cases (Federal Republic of Germany/Denmark; Federal Republic of Germany/Netherlands), ICJ Reports 1969, page 3, decided 20 February 1969. Germany had signed but never ratified the 1958 Geneva Convention on the Continental Shelf. Denmark and the Netherlands, both parties, argued that the equidistance method in its article 6 bound Germany anyway, either because Germany had by its conduct assumed the obligations of the Convention or because article 6 had become a rule of customary international law.

Held. Neither argument succeeded. On conduct, only a very definite and very consistent course of conduct could justify holding a State bound where it had not carried out the formalities the convention itself laid down for becoming bound, and estoppel would require that Denmark or the Netherlands had detrimentally changed position in reliance, of which there was no evidence. On custom, the Court set out the three conditions: the treaty provision must be, potentially at least, of a norm-creating character; there must be very widespread and representative participation in the convention, including the States whose interests are specially affected; and State practice must have been extensive and virtually uniform in the sense of the provision invoked, and must have occurred in such a way as to show a general recognition that a rule of law or legal obligation was involved. Article 6 satisfied none of them.

Why it matters here. It is the answer to "can a treaty bind a non-party?". The answer is that the treaty cannot, but the rule in it can, if it has become custom, and the three conditions are the test.

The three relationships between a treaty and custom

Writers and tribunals describe three ways a convention and a customary rule can relate, and naming them is worth a mark.

Declaratory, where the treaty writes down a rule that was already custom. Much of the Vienna Convention on the Law of Treaties is declaratory, which is why its rules are applied to States that are not parties to it, and why India, which has not ratified it, is nevertheless governed by most of its content.

Crystallising, where a rule is emerging and the conclusion of the convention settles it.

Generating, where the convention creates a new rule that afterwards passes into custom through the practice of States, parties and non-parties alike. The exclusive economic zone is the standard example: invented in the negotiations that produced the 1982 Convention, and accepted as custom before that Convention entered into force.

Treaties and India

Three facts belong in an Indian answer and they are often missed.

India is not a party to the Vienna Convention on the Law of Treaties. It signed neither. It is nevertheless bound by most of the Convention's content, because those rules are declaratory of custom. So an answer that says "under the Vienna Convention India must..." is loose; the accurate form is that the rule binds India as custom, and the Convention states it.

The power to make treaties is executive, not legislative. Under article 73 of the Constitution the executive power of the Union extends to matters on which Parliament may make laws, and entries 13 and 14 of List I of the Seventh Schedule cover participation in international conferences and the entering into and implementing of treaties and agreements. So the Union executive may conclude a treaty without Parliament.

But implementing it may need legislation. Article 253 gives Parliament power to make any law for implementing any treaty, agreement or convention, notwithstanding the ordinary division of legislative powers. Whether a treaty is enforceable in an Indian court without such a law is the subject of [International Law in Indian Courts].

A worked example

State G, State H and thirty other States conclude the Convention on the Protection of Migratory Fish, which requires coastal States to close their fisheries for two months in the breeding season. State J, a major fishing State, does not sign. Ten years later, most States in the world, including many non-parties, have adopted closed seasons and defend them in the language of legal obligation. State J refuses.

Does the Convention bind State J? No. Article 34: a treaty does not create obligations for a third State without its consent, and State J has consented to nothing.

Has the rule become custom? Apply the North Sea test. Is the provision norm-creating? A flat obligation to close fisheries for a defined period looks norm-creating, unlike article 6 of the 1958 Convention with its priority for agreement and its special-circumstances escape. Is participation widespread and representative, including specially affected States? Thirty-two parties may not be enough by itself, but the relevant question is whether the great fishing States are among them. Has practice been extensive and virtually uniform with opinio juris? The facts say most States, including non-parties, have adopted closed seasons and defend them as legal obligations, which is exactly the evidence required.

Can State J escape as a persistent objector? Only if it objected from the start and has kept objecting. Ten years of silence followed by refusal is not enough, and this is where many answers go wrong.

What if State J had signed but not ratified? Then the North Sea reasoning applies directly: signature without ratification does not bind, and only very definite and consistent conduct, relied on to another State's detriment, could produce an estoppel.

Distinctions table

What it does NOT mean

A treaty is not superior to custom. Between the parties it prevails because it is more specific and usually later, not because treaties outrank custom in some hierarchy. Article 38 states no hierarchy.

Signing is not being bound. Signature usually authenticates the text and, under article 18 of the Vienna Convention, obliges the State not to defeat the treaty's object and purpose pending ratification. It does not make the State a party. Germany's position in the North Sea cases is the classic illustration.

A treaty codifying custom does not extinguish the custom. The customary rule continues in parallel, which is why non-parties remain bound and why a party that denounces the treaty is not released from the rule.

"Convention", "covenant", "protocol", "charter" and "pact" are all treaties. Nothing turns on the name.

Limits and criticism

The consent principle produces uneven law. The most powerful States can decline to join the conventions that would constrain them, and can then argue that the rules have not become custom because their own practice, as specially affected States, points the other way.

The North Sea test is demanding and vague at once. "Norm-creating character" and "extensive and virtually uniform" are not tests that decide a close case, and the Court's reliance on the permissibility of reservations as evidence that a provision was not thought to state emerging custom has been criticised as reading too much into a drafting choice.

Codification can freeze the law. Once a rule is written into a widely ratified convention, developing it through practice becomes harder, because departures now look like breaches of the treaty rather than the beginnings of a new custom.

Quick revision

Article 38(1)(a): international conventions, whether general or particular, establishing rules expressly recognised by the contesting States.

Law-making treaties lay down general rules; treaty contracts settle a particular matter. Only the first is a realistic candidate to pass into custom.

Article 26 VCLT, pacta sunt servanda: every treaty in force is binding on the parties and must be performed in good faith. Article 27: no plea of internal law.

Third States: article 34, no obligations or rights without consent (pacta tertiis nec nocent nec prosunt); article 35, an obligation needs express acceptance in writing; article 36, a right needs assent, which is presumed; article 37, revocation; article 38, the customary-law route is preserved.

North Sea Continental Shelf (ICJ Reports 1969, page 3): a treaty rule binds non-parties only as custom, and needs a norm-creating provision, widespread and representative participation including specially affected States, and extensive and virtually uniform practice with opinio juris. Signature without ratification does not bind, and estoppel requires detrimental reliance.

Three relationships between convention and custom: declaratory, crystallising, generating.

India has not ratified the VCLT but is bound by most of its content as custom. Treaty-making is executive under article 73 and List I entries 13 and 14; article 253 empowers Parliament to legislate to implement.

Test yourself

1. Distinguish law-making treaties from treaty contracts and say why the distinction matters.

A law-making treaty lays down general rules of conduct for a large number of States, such as the Charter or the Convention on the Law of the Sea. A treaty contract settles a particular matter between two or a few States, such as a boundary or an extradition arrangement. Article 38(1)(a) covers both, since it speaks of conventions whether general or particular. The distinction matters because only a law-making treaty contains a rule capable of general application, and so only a law-making treaty is a realistic candidate for passing into customary international law and binding non-parties.

2. Can a treaty bind a State that is not a party to it?

Not as a treaty. Article 34 of the Vienna Convention provides that a treaty does not create either obligations or rights for a third State without its consent, and article 35 requires express acceptance in writing before an obligation can arise. But article 38 preserves the possibility that a rule set out in a treaty becomes binding on a non-party as a rule of customary international law, and the North Sea Continental Shelf cases set the conditions: a norm-creating provision, widespread and representative participation including specially affected States, and extensive and virtually uniform practice accompanied by opinio juris.

3. Germany had signed the 1958 Convention. Why was that not enough?

Because signature is not the act by which a State becomes bound where the convention itself provides for ratification, and Germany never ratified. Denmark and the Netherlands argued that Germany's conduct had nonetheless assumed the obligations, but the Court held that where a convention specifically provides how the intention to be bound is to be manifested, it is not lightly to be presumed that a State which has not carried out those formalities has become bound another way. Only a very definite and consistent course of conduct, on which the other States had detrimentally relied so as to create an estoppel, would have sufficed, and there was no evidence of that.

4. Explain the three relationships a convention can have with custom, with an example of each.

Declaratory: the convention writes down a rule already customary, as much of the Vienna Convention on the Law of Treaties does, which is why its rules bind States that never ratified it, India among them. Crystallising: a rule is emerging and the conclusion of the convention settles it. Generating: the convention creates a new rule which afterwards becomes custom through subsequent practice, the standard example being the exclusive economic zone, which was accepted as customary before the 1982 Convention entered into force.

5. India has not ratified the Vienna Convention on the Law of Treaties. Is India bound by the rule that treaties must be performed in good faith?

Yes, but not by the Convention. Pacta sunt servanda is a rule of customary international law of great antiquity, and article 26 of the Convention is declaratory of it. So India is bound by the rule as custom, and the Convention is the best statement of its content. The correct way to put it in an answer is that the rule binds India as custom and the Convention states it, not that the Convention binds India.

6. Who in India has power to make a treaty, and can a treaty be enforced in an Indian court?

The power is executive. Article 73 of the Constitution extends the executive power of the Union to matters on which Parliament may legislate, and entries 13 and 14 of List I of the Seventh Schedule cover participation in international conferences and the entering into and implementing of treaties and agreements, so the Union executive may conclude a treaty without Parliament. Whether it can be enforced in a court is a separate question: article 253 empowers Parliament to legislate to implement any treaty notwithstanding the ordinary distribution of legislative powers, and the general position, worked out in [International Law in Indian Courts], is that a treaty affecting private rights or requiring a change in the law needs implementing legislation before a court will give effect to it.