(p. 415) 18 Unilateral Acts; Estoppel
States are corporate entities that necessarily operate under a regime of representation. In order to hold them bound by consensual obligations, the normal rules of authorization under treaty law apply; in order to attribute conduct to them for the purposes of determining their compliance with such obligations, the normal rules of attribution for the purposes of state responsibility apply. In addition to these normal rules, there are other cases where states’ consent is given, assumed or implied.
With respect to the rules of representation in treaty law, the organs authorized to represent the state include the head of state, head of government, and minister of foreign affairs, but may also include heads of executive departments and diplomatic representatives, depending on the circumstances.1 But the legal boundaries of the state are not to be defined in simple terms. Specific authority may be given to individuals constituting delegations to conferences or special missions to foreign governments. The existence of authority in a particular instance may be a matter regulated in part by international law. Thus, in treaty-making and in the making of unilateral declarations a foreign minister is presumed to have authority to bind the state.2 Moreover, the quality of ‘the state’ varies on a functional basis: thus ‘sovereign immunity’ from other state jurisdictions extends to the agents of the state, including its armed forces and warships, and state property in public use.
References(p. 416) 2. Unilateral Acts
(A) In General
The conduct of governments may not be directed towards the formation of agreements but still be capable of creating legal effects. The formation of customary rules and the law of recognition are two of the more prominent (though very different) categories concerned with the ‘unilateral’ acts of states. Some authors have been prepared to bring unilateral acts (including protest, promise, renunciation, and recognition) within a general concept of ‘legal acts’, either contractual or unilateral, based upon the manifestation of will by a legal person.3 This approach may provide a framework for the discussion, but it may also obscure the variety of legal relations involved.4 Analysis in terms of categories of ‘promise’, ‘protest’, and the like tends to confuse conditioning facts and legal consequences. Much will depend on the context in which a ‘promise’ or ‘protest’ occurs, including the surrounding circumstances and the effect of relevant rules of law.5
It is true that treaties can be very different one from another yet the category ‘law of treaties’ makes practical as well as analytical sense. It is possible that the same is true of unilateral acts, understood not just as any act of a single state but in some narrower (still to be determined) sense of ‘acts implicating the good faith of the state’, or more simply as ‘commitments and representations implying commitment’. Yet while at some level the principle of good faith undoubtedly applies to unilateral acts as well as to bilateral or multilateral ones, the question which commitments or which representations engage the good faith of the state can only be decided situationally. It has never been the case that they all did, still less can this be true in the age of the twice-daily press conference and the internet.
A state may evidence a clear intention to accept obligations vis-à-vis certain other states by a public declaration which is not an offer or otherwise dependent on reciprocal (p. 417) undertakings from its addressees.6 Apparently the terms of such a declaration will determine the conditions under which it can be revoked.7 In 1957 the Egyptian government made a Declaration on the Suez Canal and the Arrangements for its Operation in which certain obligations were accepted. The Declaration was communicated to the UN Secretary-General together with a letter which explained that the Declaration was to be considered as an ‘international instrument’ and it was registered as such by the Secretariat.8 Such a declaration may implicitly or otherwise require acceptance by other states as a condition of its validity or at least of its effectiveness.9 In short, it seems that while a bare (unaccepted) declaration may be valid, it can produce its intended effects only if accepted (expressly or implicitly).
In the Nuclear Tests cases the International Court held that France was legally bound by publicly given undertakings, made at the highest level of government, to cease carrying out atmospheric nuclear tests.10 The criteria of obligation were: the intention of the state making the declaration that it should be bound according to its terms; and that the undertaking be given publicly. There was no requirement of a quid pro quo or of any subsequent acceptance or response.11 As a result of the FrenchReferences(p. 418) undertaking, so interpreted by the Court, the dispute, it held, had disappeared and ‘the claim advanced…no longer has any object’. While the principle applied—that a unilateral declaration may have certain legal effects—is not new, when the declaration is not directed to a specific state or states but is expressed erga omnes, as here, the detection of an intention to be legally bound, and of the structure of such intention, involves very careful appreciation of the facts. In any event the principle recognized in the Nuclear Tests cases was applied by the Court in Nicaragua12 and also by the Chamber in Frontier Dispute (Burkina Faso/Mali).13
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:…
(b) The extent to which those to whom the obligations are owed have relied on such obligations…14
Unilateral declarations may reflect commitments but they are not treaties, and are not subject to the relatively strict VCLT regime for termination or withdrawal.
Unilateral declarations involve, in principle at least, concessions which are intentional, public, coherent, and conclusive of the issues. However, acts of acquiescence and official statements may have probative value as admissions of rights inconsistent with the claims of the declarant, such acts individually not being conclusive. In Eastern Greenland the Court, as a subsidiary matter, attached significance to the fact that Norway had become a party to several treaties which referred to Danish sovereignty over Greenland as a whole, Norway having contended that Danish sovereignty had not been extended over the whole of Greenland.15
Once a dispute is already known to exist, the other party may damage its case seriously by recognition or acquiescence. Consent by way of acquiescence, recognition, or implied consent may have the result of conceding as lawful the rights claimed.References(p. 419) A similar role appears when a state is claiming rights on a basis which is plausible to some extent, and yet rests either on ambiguous facts, or on a contention that the law has changed or provides an exception in its favour. Here acquiescence involves an acceptance of the legal basis of the opponent’s claim, which can perhaps be more readily proved than in the case of a state faced by an undoubted usurper.16
As a substantive legal concept, acquiescence has its origins in the common law, although the civil law has a similar procedural notion. It crystallized in the system of international law through international adjudication.18