Interpretation of Treaties

Supplementary means: article 32

Recourse may be had to supplementary means of interpretation, including the preparatory work of the treaty and the circumstances of its conclusion, in order to:

confirm the meaning resulting from article 31; or

determine the meaning when interpretation under article 31 leaves the meaning ambiguous or obscure, or leads to a result which is manifestly absurd or unreasonable.

Note the hierarchy, and note its limits. Article 32 is supplementary, not alternative. But confirmation is always permitted, so in practice a tribunal may look at the travaux to check a conclusion it reached without them, and it need not first find any ambiguity to do so. It is only when the travaux are used to determine meaning against the article 31 result that the two gateways of ambiguity or absurdity must be crossed.

Why preparatory work is demoted. Records of negotiation are incomplete, self-serving and often inaccessible to States that acceded later and never took part. A rule that made them primary would give original negotiators an advantage over later parties, which is unacceptable in an open multilateral convention.

Circumstances of conclusion covers the historical setting, which is why the abuses that produced a treaty are legitimate material for reading it.

Several languages: article 33

Article 33(1). Where a treaty is authenticated in two or more languages, the text is equally authoritative in each language, unless the treaty provides or the parties agree that a particular text prevails in case of divergence.

Article 33(2). A version in a language other than one of those authenticated is an authentic text only if the treaty so provides or the parties so agree.

Article 33(3). The terms are presumed to have the same meaning in each authentic text.

Article 33(4). Except where a particular text prevails, when comparison discloses a difference of meaning which articles 31 and 32 do not remove, the meaning which best reconciles the texts, having regard to the object and purpose, shall be adopted.

The Charter of the United Nations is authenticated in Chinese, French, Russian, English and Spanish, all equally authentic, so article 33 is not an exotic provision but the ordinary case for the instruments in this module.

The principles the articles absorb

Older textbooks list maxims of interpretation. They are not displaced by articles 31 to 33; they are absorbed into them, and it is worth naming them with the article that carries them.

Effectiveness, ut res magis valeat quam pereat. A treaty should be read so that its provisions have effect rather than none. This is object and purpose in article 31(1), and there is a limit: effectiveness may not be used to write in an obligation the parties did not accept.

Implied powers, the institutional form of effectiveness. In Reparation for Injuries the Court held that the United Nations had capacity to bring an international claim although the Charter said nothing about it, because the Charter conferred rights and obligations different from those of its Members and entrusted the Organization with the maintenance of international peace and security. Its agents must be assured of effective protection, and the powers necessary to that end must be regarded as a necessary implication arising from the Charter. The reasoning is article 31(1) applied to a constituent instrument: what does the object and purpose require the text to be understood as conferring?

Contemporaneity and evolutive interpretation. A term is ordinarily read with the meaning it had when the treaty was concluded. But where the parties used a generic term whose content was expected to change, the term takes its meaning at the time of application. Which of the two applies is a question of the parties' intention, drawn from the text.

Expressio unius est exclusio alterius, and ejusdem generis, do the same work as in statutes. They belong to context under article 31(2).

Contra proferentem, that ambiguity is read against the party that proposed the text, survives at most as a supplementary consideration, since article 32 does not list it and multilateral texts rarely have a single proponent.

Restrictive interpretation in favour of sovereignty. The old maxim in dubio mitius, that where a text is ambiguous the obligation less burdensome on sovereignty should be preferred, is not in the Convention. It is best treated as a discredited presumption rather than a rule, and an answer that offers it as a rule of the Vienna Convention is wrong.

A worked example

The Convention on GG, authenticated in English and French, provides in article 4 that each party shall take "appropriate measures" to protect "natural resources" within its jurisdiction. Its preamble recites the parties' resolve to conserve the environment for future generations. The French text of article 4 uses a word that, State AA argues, is narrower than "resources". At the negotiating conference State BB proposed a text listing minerals only, which was rejected without recorded reasons. After twenty years, all parties have consistently applied article 4 to living resources as well as minerals. State AA now says article 4 covers minerals only.

Start with article 31(1). The ordinary meaning of natural resources in context and in the light of object and purpose. The preamble is part of the text under article 31(2) and it speaks of conserving the environment for future generations, which points against confining the article to minerals.

Then article 31(3)(b). Twenty years of consistent application by all parties to living resources is subsequent practice establishing the agreement of the parties regarding interpretation. This is the strongest material in the problem and it is decisive against State AA.

Then article 33. Both texts are equally authoritative and the terms are presumed to have the same meaning. If a real difference of meaning remains after articles 31 and 32, article 33(4) requires the meaning which best reconciles the texts having regard to object and purpose, which again favours the broader reading.

Only then article 32. The rejected proposal to list minerals is preparatory work. It may be used to confirm the article 31 result, and it confirms it, since a proposal to confine the article to minerals was rejected. Had the travaux pointed the other way, they could displace the article 31 result only if the meaning were ambiguous or obscure or the result manifestly absurd or unreasonable, and neither is the case here.

Change one fact: only three of the twelve parties applied article 4 to living resources. Then article 31(3)(b) is not satisfied, because the practice does not establish the agreement of the parties, and the answer turns on ordinary meaning, context and purpose alone.

Distinctions table

What it does NOT mean

There are not three schools to choose between. Article 31 is a single general rule with four elements applied together.

Preparatory work is not forbidden. It may always be used to confirm, and may determine meaning on the two article 32 gateways.

Subsequent practice is not any practice. Article 31(3)(b) requires practice establishing the agreement of the parties.

A treaty is not read in isolation. Article 31(3)(c) brings in relevant rules of international law applicable between the parties.

Equally authentic does not mean identical. Article 33(3) presumes the same meaning, and article 33(4) supplies the rule when comparison shows it is not so.

Effectiveness does not permit writing in obligations. It requires that what the parties did agree should work.

Limits and criticism

The single-rule structure conceals real choices. Object and purpose can be stated broadly or narrowly, and how it is stated frequently decides the case, so the appearance of a mechanical operation flatters what is in truth a judgment.

Article 31(3)(b) is hard to satisfy and easy to assert, especially in conventions with a hundred and more parties, where establishing the agreement of all of them from practice is close to impossible, so tribunals in fact rely on the practice of the actively engaged.

Article 32 does less work than it appears to. Because confirmation needs no threshold, travaux are cited constantly, and the distinction between confirming a meaning and determining it is not always observed.

Evolutive interpretation is contested. Reading a generic term with its meaning at the time of application respects the parties' likely intention in some treaties and defeats it in others, and the Convention gives no test for telling them apart.

Quick revision

Article 31(1): good faith, ordinary meaning, context, object and purpose. One rule, four elements.

Article 31(2), context: text including preamble and annexes; agreements made between all the parties in connection with conclusion; instruments made by one or more and accepted by the others as related.

Article 31(3), taken into account: subsequent agreement; subsequent practice establishing the agreement of the parties; relevant rules of international law between the parties.

Article 31(4): a special meaning if it is established the parties so intended.

Article 32: preparatory work and circumstances of conclusion, to confirm always, or to determine where meaning is ambiguous or obscure or the result manifestly absurd or unreasonable.

Article 33: authentic texts equally authoritative; other versions authentic only if provided or agreed; terms presumed to have the same meaning; unresolved differences resolved by the meaning that best reconciles the texts having regard to object and purpose.

Maxims absorbed: effectiveness (ut res magis valeat quam pereat), implied powers (Reparation for Injuries), contemporaneity and evolutive reading, expressio unius, ejusdem generis.

Test yourself

1. State the general rule of interpretation and explain why it is called a rule rather than rules.

Article 31(1) provides that a treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to its terms in their context and in the light of its object and purpose. It is one rule because its four elements, good faith, ordinary meaning, context, and object and purpose, are applied together in a single combined operation and not as alternatives among which the interpreter chooses. The International Law Commission used the singular deliberately, to reject the idea that textual, contextual and teleological interpretation are competing schools with the interpreter free to pick one.

2. What counts as context, and what is merely taken into account with it?

Context, under article 31(2), comprises the text including its preamble and annexes, together with any agreement relating to the treaty made between all the parties in connection with its conclusion, and any instrument made by one or more parties in connection with the conclusion and accepted by the others as an instrument related to the treaty. Taken into account together with the context, under article 31(3), are any subsequent agreement between the parties on interpretation or application, any subsequent practice in the application of the treaty establishing the agreement of the parties on its interpretation, and any relevant rules of international law applicable in the relations between the parties.

3. When may preparatory work be used?

Article 32 permits recourse to supplementary means, including the preparatory work and the circumstances of conclusion, for two purposes. To confirm the meaning resulting from the application of article 31, which may be done at any time and requires no threshold. And to determine the meaning where interpretation under article 31 leaves it ambiguous or obscure, or leads to a result which is manifestly absurd or unreasonable. Preparatory work is therefore supplementary and not alternative, and the reason for its lower status is that negotiating records are incomplete, self-serving, and often unknown to States that acceded later and never took part.

4. A treaty is authenticated in five equally authentic languages and two of them differ. How is the difference resolved?

By article 33(3) the terms are presumed to have the same meaning in each authentic text, so the first step is to see whether the difference survives interpretation under articles 31 and 32. If it does, and if the treaty does not provide and the parties have not agreed that a particular text prevails, article 33(4) requires the adoption of the meaning which best reconciles the texts, having regard to the object and purpose of the treaty. A version in a language that was not authenticated is not an authentic text at all unless the treaty so provides or the parties so agree.

5. Explain the doctrine of implied powers with the case that established it.

In Reparation for Injuries Suffered in the Service of the United Nations the General Assembly asked the Court whether the Organization could bring an international claim for injury to its agent. The Charter said nothing about it. The Court reasoned that the Charter conferred on the Organization rights and obligations different from those of its Members and entrusted it with the maintenance of international peace and security, that its agents are sent on important missions to disturbed parts of the world and must be assured of effective protection, and that the powers necessary to that end must be regarded as a necessary implication arising from the Charter. So the Organization had capacity to bring a claim, and to exercise functional protection resting not on nationality but on the breach of an obligation owed to itself. The reasoning is the principle of effectiveness applied to a constituent instrument.

6. Why is article 31(3)(c) important?

Because it prevents a treaty from being read as though it were the only law between the parties. It directs that any relevant rules of international law applicable in the relations between the parties be taken into account together with the context, which means custom, general principles and other treaties binding on the same States all bear on the meaning of the instrument being interpreted. The provision is the textual basis for what is called systemic integration, and it is what allows a trade or investment treaty to be read consistently with the human rights and environmental obligations of the same parties, rather than as a self-contained regime.