Binding unilateral declarations

Legal assistance paper

All reasonable efforts have been made to ensure the accuracy of this information at the time the advice was produced (please refer to the date produced below). However, the materials have been prepared for informational purposes only and may have been superseded by more recent developments. They do not constitute formal legal advice or create a lawyer-client relationship. You should seek legal advice to take account of your own interests. To the extent permitted any liability is excluded. Those consulting the database may wish to contact LRI for clarifications and an updated analysis.

Date produced: 09/12/2009

1. Under what circumstances might a unilateral statement by a State or State official be legally binding under international law, particularly when statements are made in the context of an international negotiation? What factors will affect that analysis? 

2. Regarding the same questions, what effect, if any, might reliance by other States (e.g. Providing financing) have on whether a unilateral statement might be legally binding?

3. What steps might a State take to ensure that a unilateral statement by it does not create an international legal obligation?

Executive Summary:

1. What are the circumstance in which a unilateral statement may be legally binding? There is no settled rule, however the following issues are relevant: the intention of the declaring state; the reliance placed on a declaration by other states; any applicable preceding treaty provisions; rules of customary international law; and the extent to which the relevant parties have acted in good faith.

‘The ILC Guiding Principles applicable to unilateral declarations of States capable of creating legal obligations 2006’ (adopted 2006 by International Law Commission) are relevant and support the above. Additional considerations set out in the principles include: the authority of the person making the declaration; and the extent to which the declaration is formulated in clear and specific terms – ambiguity will be construed in a restrictive manner.

2. What is the significance of reliance by states on a declaration? Reliance of third party states will influence the degree to which a declaration may have legal effect provided the reliance benefits the declaring party or is of detriment to the relying party. The length of time of the reliance will be relevant. Legally binding obligations may be created despite the lack of intention by the declaring party to achieve this where reliance, detriment and / or benefit is demonstrated. However, in the context of multilateral treaty negotiations this would be difficult to demonstrate. The ILC Guiding Principles referred to above state that declarations may not be revoked following reliance (Principle 10).

3. How can a State avoid creating legal obligations? A clear statement by the party making the declaration, stating that it is not intended to create legal obligations, will prevent it from doing so.


It is not possible to offer definitive general advice in general terms on the legal effect of unilateral declarations (or declarations made on behalf of more than one state) – all the circumstances, including the language used, the political level of the official making the statement, the treaty context and the response of other states are relevant to a determination of legal effect. However, by applying the criteria set out below it is possible to reach a provisional view as to whether it is likely or not that a declaration will have legal effects on the rights and obligations of other states. It is worth noting that most if not all of the cases where unilateral declarations have been held to be binding have not involved multilateral treaty negotiations and are more likely to involve bilateral disputes between two states, eg over diplomatic immunity, over boundaries, or over compensation for harm to a citizen or company’s rights.

We are happy to comment further on the potential implications of specific texts/statements as the negotiations progress.

1. Unilateral declarations

A leading commentator has summarised the position as follows:

“There is no settled rule for determining which unilateral declarations give rise to legal rights and duties for other states, and which do not. In some cases the fact that particular consequences flow from a declaration is the result of a treaty provision or a rule of customary international law. Apart from such cases, the question whether any particular declaration directly confers rights or imposes obligations on other states will in the first place largely depend upon the intentions of the state making the declaration and the circumstances of any reliance placed on the declaration by other states: as is the case with treaties, so with declarations the imposition of obligations on other states, otherwise than as a condition for the enjoyment of the conferred rights, will usually be difficult to establish.”

There are a number of key points to draw from this:

  • As with the question of whether an instrument or text constitutes a treaty (we have obtained advice on this point – please let us know if you would like to see it), the intention of the state making the declaration is of key importance;
  • The relationship between a unilateral statement and any provision of the UNFCCC or KP is also important in determining its legal effect;
  • It will be necessary to consider the statement in the light of relevant principles of customary international law (if any);
  • It will be very important to analyse whether the statement constitutes the laying down of a ‘condition for the enjoyment of conferred rights’ such as to lead to the imposition of legal obligations on other states;
  • It will be necessary to consider whether other states have acted in reliance on the declaration.

The leading case on the status of unilateral declarations is the ICJ’s judgment in the 1974 Nuclear Tests Cases where the Court held that:

  • When it is the intention of the State making the declaration that it should become bound by it according to its terms, that intention confers on the declaration the character of a legal undertaking;
  • An undertaking of this kind, if given publicly and with an intent to be bound, even though not made in the context of international negotiations, is binding;
  • In these cases nothing in the nature of a quid pro quo or reply or reaction is required from other States for the declaration to take effect;
  • The form of the statement itself is not decisive
  • One of the basic principles governing the creation and performance of legal obligations, whatever their source is good faith;
  • Interested states may place confidence in unilateral declarations and are entitled to require that the obligation thus created be respected.

Also relevant in this regard are the 2006 Guiding Principles that provide guidance on when a unilateral statement by a State or State official may be legally binding under international law. The Principles apply only to formal declarations formulated by a State with the intent to produce obligations under international law and therefore do not resolve the issue of whether unilateral statements which are not clearly intended to have legal effect, may nevertheless do so on the basis that they are linked to treaty obligations and/or an estoppel has been created (see below).

The Guiding Principles were adopted in 2006 by the International Law Commission and were submitted to the General Assembly, so are generally accepted, They are set out at the end of this note. In particular:

Principle 1 provides that:

“Declarations publicly made and manifesting the will to be bound may have the effect of creating legal obligations. When the conditions for this are met, the binding character of such declarations is based on good faith; States concerned may then take them into consideration and rely on them; such States are entitled to require that such obligations be respected”

This makes clear that other States may rely on unilateral statements that meet the stated conditions). Principle 7 makes clear that “a unilateral declaration entails obligations for the formulating State only if it is stated in clear and specific terms”. Principle 10 contains rules against unilateral revocation of statements, when there has been reliance by those to whom the obligations are owed.

Often unilateral declarations by States in international negotiations are to excuse themselves from performance, rather than to commit to performance. Declarations under the ICJ Optional Protocol are a very important example to the contrary, of States voluntarily agreeing an additional commitment . The key point about the Optional Clause is that the unilateral declarations clearly have binding effect because the Statute itself anticipates that effect. Several treaties allow States to make an optional declaration accepting compulsory jurisdiction, ie to make the treaty obligations binding, vis a vis other States who have also accepted jurisdiction. For example, the 1991 Protocol to the Antarctic Treaty on Environmental Protection enables any party to make a declaration accepting as compulsory the jurisdiction of the ICJ or arbitration.

2. Reliance by other states

Even where a statement is not clearly intended to be binding its legal status may be affected by the reliance on it by other states. If reliance causes the statement to be binding this is known as ‘estoppel’. The ICJ has held that the essential elements of estoppel include a statement or representation made by one party to another and reliance upon it by that other party to his detriment or to the advantage of the party making it, El-Salvador Honduras Land, Island and Maritime Frontier case, ICJ Rep 1990 pp 92, 118.

However, it would be difficult in our view to base an estoppel argument to render the relevant declaration binding on the state making the declaration purely on the normal interchange which takes place in multilateral treaty negotiations which essentially consist of offer and counter-offer between states. Such an argument would have to be scrutinised very carefully in the light of the considerations set out at 1 above.

In addition, long-term reliance on a statement by other parties to the negotiations in their conduct, beyond the negotiation of the agreement itself, may affect the status of a unilateral declaration, for example if it can be shown that an estoppel has been created.

3. Avoiding the creation of a legal obligation

In short, quite easily, given the criteria laid down in the case-law of the ICJ and set out in the Guiding Principles. It follows from the 10 Guiding Principles that the best way to ensure a unilateral statement does not create an obligation is to say so in the text. However, public relations may lead a State to want to avoid such an express statement. If there is no such statement, then according to Principle 7 there will only be obligation if the obligation is stated in clear and specific terms, and this will be interpreted restrictively.

The International Law Commission’s 2006 Guiding Principles draw particular attention to the fact that whether or not a State will be bound is dependent upon the individual circumstances in which the statement is made and acknowledges that “in practice, it is often difficult to establish whether the legal effects stemming from the unilateral behaviour of a State are the consequence of the intent that it has expressed or depend on the expectations that its conduct has raised among other subjects in international law.”

“1. Declarations publicly made and manifesting the will to be bound may have the effect of creating legal obligations. When the conditions for this are met, the binding character of such declarations is based on good faith; States concerned may then take them into consideration and rely on them; such States are entitled to require that such obligations be respected;

2. Any State possesses capacity to undertake legal obligations through unilateral declarations;

3. To determine the legal effects of such declarations, it is necessary to take account of their content, of all the factual circumstances in which they were made, and of the reactions to which they gave rise;

4. A unilateral declaration binds the State internationally only if it is made by an authority vested with the power to do so. By virtue of their functions, heads of State, heads of Government and ministers for foreign affairs are competent to formulate such declarations. Other persons representing the State in specified areas may be authorized to bind it, through their declarations, in areas falling within their competence;

5. Unilateral declarations may be formulated orally or in writing;

6. Unilateral declarations may be addressed to the international community as a whole, to one or several States or to other entities;

7. A unilateral declaration entails obligations for the formulating State only if it is stated in clear and specific terms. In the case of doubt as to the scope of the obligations resulting from such a declaration, such obligations must be interpreted in a restrictive manner. In interpreting the content of such obligations, weight shall be given first and foremost to the text of the declaration, together with the context and the circumstances in which it was formulated;

8. A unilateral declaration which is in conflict with a peremptory norm of general international law is void;

9. No obligation may result for other States from the unilateral declaration of a State. However, the other State or States concerned may incur obligations in relation to such a unilateral declaration to the extent that they clearly accepted such a declaration;

10. A unilateral declaration that has created legal obligations for the State making the declaration cannot be revoked arbitrarily. In assessing whether a revocation would be arbitrary, consideration should be given to:

(i) Any specific terms of the declaration relating to revocation;

(ii) The extent to which those to whom the obligations are owed have relied on such obligations;

(iii) The extent to which there has been a fundamental change in the circumstances.”