Acta Sunt Servanda? A Regime for Regulating the Unilateral Acts of States at International Law Camille Goodman Australian Yearbook of International Law, 47 (2006)

I. Introduction Does a written or verbal declaration, made by a state official without any reciprocal commitment, response or acceptance, outside the context of formal negotiations, and to the world at large, give rise to a binding legal obligation? Since the 1974 judgment of the International Court of Justice (ICJ) in the Nuclear Tests Cases,1 this question can be answered in the affirmative. Whilst doctrine has long been in conflict over whether or not to assign any legal effect to such 'unilateral acts', they have been in constant usage by states in the conduct of their day-to-day relations, and in the development of customary international law. International law has expanded and developed rapidly since 1945 and continues to do so, particularly as the burgeoning pool of actors recognised as subjects of international law, and modem methods of travel and communication, increase the ties connecting the subjects of the international system. Unilateral acts have expanded and developed accordingly, both as a common means by which states conduct international relations, and as an accepted practice recognised in doctrine and jurisprudence. The International Law Commission (ILC) identified unilateral acts of states as a topic suitable for codification and progressive development at its 48th session in 1996. The Commission noted that although the topic was well delimited and had been the subject of academic writing, it had never been studied by any official international body; that states had abundant recourse to unilateral acts and there was state practice to draw upon in deducing legal principles in relation to them; that although several judgments of the ICJ had considered unilateral acts, there were uncertainties and questions in the dicta; and that the law of treaties could provide a point of departure for the work. Unilateral acts were accorded little or no binding effect at international law prior to the 1960s, but their existence and effect was increasingly acknowledged such that the ICJ could state in 1974 that 'interested States may take cognizance of unilateral declarations and place confidence in them and are entitled to require that the obligation thus created be respected'. The importance of states being able to place trust and confidence in the declarations of other subjects of international law is obvious. Franck has observed: [O]n this shared mutual expectation rests the element of predictability that prevents relations between states in the nuclear era ... from being chaotic and far more dangerous than they usually are.2 Although conventional agreements are the normal way of acquiring rights and obligations at international law, as they permit states to reconcile divergent interests by negotiation and agreement, unilateral acts are an important addition to this system, indispensable when negotiation appears impossible. Whilst states are obliged to co-operate, due to close social and economic links, the ideological divide can at times be wide, and the utility of the unilateral path becomes evident when a solution is needed, but negotiation is not forthcoming. During the tension aggravated by the Suez Canal affair of 1957, for example, the Egyptian declaration on the 24 April regarding free circulation in the Canal was helpful in re-establishing international confidence and security at a time when a treaty on the matter was not possible. In this regard, it is also worth noting that the acceptance of the jurisdiction of the ICJ, under article 36 of the Court's Statute, is undertaken by an engagement that is unilateral in form, and which by avoiding the necessity for a convergence of wills in fact encourages it. Unilateral acts play an important role of their own in a modern system characterised by both decentralisation and ever-increasing globalisation. Modern communication techniques have helped to

1 Nuclear Tests (Australia v France) [1974] ICJ Rep 253 and Nuclear Tests (New Zealand v France) [1974] ICJ Rep 457. The judgments in the two cases are essentially the same, and page references in this paper will be to the Australian case. 2 T Franck and E Weisband, World Politics: Verbal Strategy Among the Superpowers (1971) 120-21. make unilateral acts one of the most frequently used tools of state interaction, and 'they weave, so to speak, the daily web of international relations'. Unilateral acts occur frequently, and often go unnoticed and undisputed amongst the daily mill of international relations: actions such as recognition of states, governments or situations; pledges of voluntary contributions to other states or international organisations; and cancellations of external debts are all recognisable examples of accepted unilateral action occurring routinely in international law.3 Conduct of states involving trade, security, investment, and innumerable other matters takes place in many forms and under varying circumstances, and is conducted by representatives ranging from the head of state, to bureaucrats or local diplomatic staff. Unilateral statements of government policy regarding future intentions114 often are made to foreign government officials or diplomatic representatives, to the local or world media, or within the domestic political context. Yet, although the existence of a rule of international law giving binding force to such unilateral declarations of a state's intention has been confirmed in international jurisprudence, the contents of the rule have not been delimited. Statespersons considering issuing declarations on behalf of their country are now on notice that they are 'not merely expressing a passing fancy, but pledging the good faith and credit of their nations'.5 It is important that the parameters of this legal norm are established pragmatically, considering the nature, elements and legal basis of unilateral acts, in order to formulate a legal regime to which states may refer when considering issuing a statement of future policy. Described as 'informal transactions of states' in as much as they occur outside the formal boundaries of the treaty-making regime, unilateral acts are in no way of lesser significance than conventional agreements, and the realities of international relations reflect this. No less than conventional acts, unilateral acts consist in the conduct of states, created and underscored by the principle of autonomy of will of sovereign states, binding and interpreted in accordance with the fundamental principle of good faith. This paper provides an overview of the subject, analysing the nature, elements and basis of the unilateral act in accordance with general principles of law in order to formulate a suitable regime to regulate them. This will allow unilateral acts to take their place as a formal, legitimate source of international obligations, producing universally understood and recognised legal effects, and contributing to the stability and predictability that is the aim of regulation at international law.

II. The Nature of Unilateral Acts of States At international law states can acquire legal rights and obligations through an expression of will. International agreements, treaties and conventions feature prominently amongst the sources of law cited in article 38 of the ICJ Statute, however unilateral acts are not mentioned, and indeed, no 'all encompassing, uniform and precise definition of unilateral acts exists'. Yet it is well-recognised that states can acquire obligations over and above those assumed in treaty relationships, through informal conduct and transactions involving unilateral expressions of will. The ILC has defined a unilateral act as 'an unequivocal expression of will which is formulated by a State with the intention of producing legal effects in relation to one or more other States or international organizations, and which is known

3 Other examples of unilateral acts provided by states to the ILC include: declarations concerning the delimitation of maritime boundaries (The Netherlands); declarations concerning use of natural resources, and involvement in military operations outside borders (Israel); declarations concerning the protection of property in Latvia and Lithuania (Estonia); protests over the Timor Gap Treaty, and the recognition of East Timor's right to independence (Portugal); See Replies from Governments to the Questionnaire, ILC 52nd Session, UN Doc A/CN.4/511 (2000). Australia has also expressed concern that unilateral acts should be binding, giving the specific instance of a state requesting extradition promising that the death penalty would not be applied to the extradited individual (Statement by Kym Taylor to the Sixth Committee of the UN, New York, 5 November 2002). 4 The term 'policy' is used throughout this essay to indicate a course of action or principle adopted or proposed by a government as an act or statement indicating legal intention. 5 T Franck, 'Word Made Law: The Decision of the ICJ in the Nuclear Test Cases', (1975) 69 American Journal of International Law 612, 620. to that State or international organization'. Unilateral acts are thus a particular form of manifestation of the will of a state, apt to produce legal effects in the same way as any other conduct of a state. The fundamental conditions for validity of a legal act apply at least as much to unilateral acts as to any other: the act must be imputable to a subject of the law, the object must be legal and the rules relating to will and form must be observed. However, unilateral acts broadly defined constitute a complicated and extremely varied source of obligations that require some preliminary observations. First, the strictly unilateral nature of the act in question must be delimited, to ensure that the only acts under consideration are those that are unilateral both in form and in substance. Second, it is necessary to consider the various categories of unilateral acts that have come to be recognised in international law, and any ramifications these classifications may have for a legal schema regulating unilateral acts. (a) The autonomous unilateral act The etymology of the word 'unilateral' (from the latin unus; one, latus; side) reveals that the unilaterality of an act is characterised not by the number of authors of the act, but by their position in relation to the norm created. In bilateral or multilateral treaties, the authors of the acts will equally be their subjects, but in the case of a unilateral engagement, the authors of the act will find themselves the promisors of obligations undertaken in favour of the promisees of the norm. For example, a joint declaration issued by the Presidents of Venezuela and Mexico, at San Jose, Costa Rica, on 3 August 1980, creating an energy cooperation program for the countries of Central America and the Caribbean, involved the assumption of legal obligations on the part of the declarant states for the benefit of third states that had not participated in the formulation of the declaration. Unilateral acts, like other legal acts, consist of two elements: the legal declaration, or formal undertaking (the instrumentum) and the substance of that obligation (the negotium). Legal acts can thus be unilateral in form alone, emanating from a single manifestation of will, or they can be unilateral in both form and substance, not only emanating but also operating independently of any expressions of will made by other subjects of international law. A declaration that is unilateral in form, such as those accepting the jurisdiction of the ICJ under article 36 of the Statute, or notifying other parties to a treaty of a reservation, may well be bi- or multi-lateral in substance, requiring some degree of interdependence with another document. For an act to be an autonomous unilateral act, however, it must be independent in form and substance, such that it is sufficient to achieve legal effect without the intervention of any other manifestation of will. The difficulty in distinguishing strictly unilateral acts from legal acts made as part of an agreement is demonstrated by the Legal Status of Eastern Greenland Case, which is often cited as an example of a unilateral act. The Permanent Court of International Justice (PCIJ) found that a declaration by the Norwegian Minister for Foreign Affairs (known as the Ihlen Declaration), to the effect that Norway would make no difficulty over the plans of the Danish government for Eastern Greenland was binding upon Norway 'beyond all dispute'. Whilst many commentators consider that this was not actually a unilateral act, stating that the binding effect of this declaration was simply the result of the negotiating circumstances in which it was made - that is, as a 'response to a request by a diplomatic representative of a foreign Power' - it could in fact have produced legal effects by itself, and thus falls within the definition of an autonomous unilateral act offered above. The analysis used to find the Ihlen Declaration part of a bilateral agreement can be misleading, for if one goes past the formal text of the declaration itself, it is often possible to find other texts that can be combined with that at hand, such that the concept of 'external reciprocity' can be used to find an agreement or bilateral nature in almost any seemingly unilateral engagement. At the other extreme, multilateral treaties can be conceived of as a process of unilateral acts expressing consent to be bound, such as signature, ratification, or accession. It is therefore necessary to retain sensible criteria, ensuring that all conduct of states tending to have legal effect is subject to a legal regime, and using logical analysis to avoid any attempt to bring into the conventional regime acts that do not belong there. If the act analysed could produce legal effect by itself, it does not need to be excluded from the category of autonomous unilateral acts sought to be regulated here. (b) Classification of unilateral acts The variety of conduct falling within this definition still leads some \commentators to question whether any universally applicable regime can be found for unilateral acts, in view of the widely- spread and varying nature of the obligations that they produce. Such varied conduct as a declaration of war or neutrality, recognition of a state or government, a declaration ceding territory, and a promise to act or not act in a specified manner, all constitute unilateral conduct, yet produce very different legal effects. Various attempts have been made to systematise these acts according to the legal effects they produce. Some unilateral acts, including recognition, protest, notification and waiver, are generally seen to have acquired the status of customary norms of their own volition, whilst others such as promises, declarations and assurances are more difficult to classify and remain subject to debate. A short survey of generally recognised unilateral acts highlights the difficulties posed by attempts to render their validity and legal effects dependent on classification in a specific category. Recognition is 'a unilateral declaration of will whereby a subject of international law acknowledges the existence of a fact, a situation or a claim and expresses its will to consider them legitimate'. Whilst acts of recognition are 'unilateral in the strict sense of the term and are perhaps the most important type of unilateral act', they have characteristics in common with waiver and promise, as can be seen in cases such as Eastern Greenland. Whilst the Ihlen Declaration recognised a legal situation (Denmark's sovereignty over Eastern Greenland), it also contained a promise (not to interfere with Denmark's activities in this territory) and even a waiver (of any title to the territory). The declaration of the government of Colombia recognising the sovereignty of Venezuela over the Archipelago of Los Monjes can similarly be construed as recognition, promise or waiver. Waiver, or renunciation, 56is the abandonment or relinquishment of rights. Declarations of neutrality could be classified as waiver, if not promise or notification. Similarly, negative security guarantees given by nuclear states to non-nuclear states, stating their intention not to use nuclear weapons against them, could be classified as waiver as well as promise. 57 Protest, by which a state communicates to another subject of law its objection to, or non-recognition of, an act formulated by the latter, has sometimes been seen as the corollary of waiver, and failure to protest has been found to constitute waiver, as in the Temple of Preah Vihear Case. The controversial question of 'promise' is yet another example of the difficulties presented by any attempt to put universal acts into formalistic categories. The cases described above have already demonstrated the frequency with which unilateral acts can be found to constitute promises, and yet more examples can be added to this list. Such diverse conduct as the Italian Law of Guarantees of 1871, recognising the inviolability of the Pope and promising him specific rights, the Declaration of the Government of Egypt on the Suez Canal, and declarations of the French government relating to the cessation of atmospheric nuclear testing (which were the subject of the Nuclear Tests Cases) have been considered to constitute promises. A perusal of the jurisprudence and doctrine on the subject thus shows the difficulty, and, it is submitted, futility, of attempting such formalistic classifications. As has already been established, unilateral acts are a manifestation of the will of states, the conventional rubric for conduct of states occurring outside a treaty regime. Accordingly, it is the instrumentum, or formal criteria, of the legal act that must be used to classify it, and on the basis of which it will have legal effects, not the negotium, or contents, which are too varied and produce overlapping classifications. To this end, a 'top-down' approach to legal acts, assigning conduct of a state to its correct place in the international legal system and then deducing any legal effect, is more logical than a 'bottom-up' approach, attempting to classify the conduct as being within a certain category of act, and to assign it legal effects on that basis. Using this approach, the place of unilateral acts in the international legal system can be established, and their effects more readily understood. (c) The place of unilateral acts in the international legal system Legal effects are produced at international law by international legal facts, to which international legal norms attach effects that create, modify or extinguish rights and obligations of subjects of the international system. While everything that happens in the world is a fact or event, some of these are so important that they are taken into consideration by a legal norm, and these are legal facts. Legal facts can be divided into facts of nature that create legal consequences (such as an earthquake producing a new island), facts caused by individuals but not imputable to a state (such as birth and death, or publication of a book), and facts caused by individuals that international law ascribes to a state. The latter, which are international legal facts, can be divided into lawful and unlawful acts. Unlawful acts will either be refused any effect, or will entail the international responsibility of the state concerned. Lawful acts are the 'manifestations of the will of States in the domain of international relations' and produce legal effects in so far as the international legal order provides. Anzilotti points out that it is not the manifestation of will that produces the legal effect, but rather the legal norm, which attaches legal effects to the legal fact when the conditions of validity are fulfilled. The four conditions of validity are those that the law generally considers as necessary for the validity of legal acts: a capable subject; an appropriate object; the requisite intention, free from vice; and the correct form. When international legal facts fulfil these criteria, they can be considered 'international legal acts' with legal consequences. This approach provides the same conditions for validity of unilateral acts as for bilateral or multilateral treaties, consisting of general principles of law that are found in all the legal systems of the world. It requires an analysis of the instrumentum of the act to determine its classification as an international legal act entailing legal effects at international law, and allows the applicable legal norms to attach such effect in accordance with the nature of the act. It is thus necessary to review the elements required for the existence of a valid unilateral act, and the methods of interpretation to be applied to the instrumentum creating them, in order to progress toward the conception of a legal regime governing unilateral acts.

Ill. The Elements and Interpretation of a Unilateral Act Unilateral acts may be the most frequent tool of state interaction, but if a state were to incur binding obligations as a result of every action, statement or conduct, state practice would be severely restricted and the international system paralysed. Accordingly, certain strict conditions must be fulfilled before a legal fact is regarded as a legal act, producing binding obligations for the declarant. In the case of conduct occurring in the context of bilateral and multilateral treaties, these conditions are extensively codified by the 1969 Vienna Convention on the Law of Treaties (VCLT), and this text is a suitable source, methodology and even substance when considering unilateral acts. By considering the general conditions of validity individually, and using the VCLT as a point of reference, the peculiarities and requisite elements of unilateral acts can be established, allowing the development of some basic principles governing their interpretation. (a) A capable subject In order to be recognised in international law, an obligation must be undertaken by a subject of public international law, acting through an organ competent to engage the state. In the context of unilateral acts, the state assuming the obligation is the sole participant in the formulation of the act adopting it, and the particularities resulting from this must be taken into account in considering the capacity of an organ to represent the state. The provision in article 7(2)(a) of the VCLT, confirming the capacity of the Head of State, Head of Government, and Minister for Foreign Affairs, to undertake binding obligations in the name of the state seems to be generally accepted in doctrine, practice, and jurisprudence as being equally applicable to unilateral acts. It can be seen that the general principles encompassed by the provisions of the VCLT relating to capacity to bind the state are to a large degree capable of being used analogously in interpreting unilateral acts. Keeping in mind the restrictive approach referred to above, the principles of articles 8, 46 and 47 are also applicable in this context. (b) An appropriate object The second condition is an appropriate object of the unilateral act, for no manifestation of will can make good an object or purpose that is materially impossible, or forbidden by law. The object of a unilateral act should not conflict with that of another international engagement contracted by the state, or it may attract the international responsibility of the state. (c) The requisite intention The classical definition of a legal act, as a manifestation of will to which a juridical norm attaches legal effects, clearly demonstrates the importance that the doctrine of state sovereignty has accorded to the role of intention in determining international legal acts.90 A unilateral declaration is binding if 'clearly intended to have that effect, and held out ... as an instrument on which others may rely and under which the declarant purports to assume such obligations' .91 International jurisprudence has shown intention, and communication of that intention to the intended recipient, to be the decisive element making a unilateral act binding: When it is the intention of the State making the declaration that it should become bound according to its terms, that intention confers on the declaration the character of a legal undertaking, the State being thenceforth legally required to follow a course of conduct consistent with the declaration. An undertaking of this kind, if given publicly and with an intent to be bound, even though not made within the context of international negotiations, is binding.6 In this formulation, unilateral acts are binding if they express subjective intent. This was the element by which the Court in Nuclear Tests distinguished them from non-binding obligations. Yet the Court went on to state that the French statements had to be: considered within the general framework of the security of international intercourse, and the confidence and trust which are so essential in the relations of states. It is from the actual substance of these statements and the circumstances attending their making, that the legal implications of these acts must be deduced7. This statement appears to introduce an objective standard, whereby the decisive intent is not that of the French authorities, but that deducible from good faith, trust, confidence, and the circumstances in which the declarations were made. It is thus necessary to decide whether it is the real or the declared intention that is to govern interpretation of a unilateral act: whether construction of the declarant's intent is to be made on a subjective or objective basis. The VCLT provides a largely objective system for conventional agreements, stating that 'a treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose'. This objectivity can be taken further in the case of unilateral acts, for two reasons. First, unilateral acts are generally the expression of will of just one subject of law, of which it alone is cognisant, and is capable of expressing orally or in writing as explicitly as desired. Other states taking notice of this declaration can only rely on the declared intent, as they are not involved in the expression and communication of intention as they would be in a conventional process. Inversely, it may become important for the declarant state to be able to retreat behind the declared intention in limiting their obligation to that explicitly undertaken. Another important facet of interpretation is the distinction between political and legal intent, or between the intention to create a binding obligation and a mere declaration of intention: for only declarations by which a state intends to become bound acquire the character of a legal undertaking. In the Military and Paramilitary Activities Case, for example, the ICJ stated that the intention of the Nicaraguan Junta to hold free elections arose as part of its political program of government, and refused to accord it any legal intent. The precision with which the intention is stated is of great relevance to its interpretation. The manifestation of will must be made in a clear and unequivocal manner, such that any conduct that contravenes the obligation undertaken will be identifiable. It is also necessary to consider the presumption at international law against the renunciation of rights by a state. As has already been discussed, the negotium of unilateral acts may result in a waiver, or renunciation, of rights, and as the ICJ pointed out in the Nuclear Tests Case, 'when States make statements by which their freedom of action is to be limited, a restrictive interpretation is to be called for'.8 112 In addition, any manifestation of will that is not made freely and without defects may be nullified in the same way as will is vitiated in a conventional situation: the provisions in articles 48 to 52 of the VCLT are a suitable source of reference in this regard. 113 Unilateral acts that are made as a result of error, fraud, corruption or coercion may be void ab initio, and the articles referred to above can be applied almost mutatis mutandis to unilateral acts. This overall system of interpretation largely retains the principles set out in articles 31 and 32 of the VCLT, which have been held to be general rules under international law for the interpretation of any legal instrument, from a treaty or unilateral act to an arbitral award or resolution of an international organisation.1

6 Nuclear Tests Cases [1974] ICJ Rep 253, [43]. 7 Ibid. 8 [1974] ICJ Rep 253, [44]. (d) The question of form The final condition of validity prescribed by general principles of law is the form of unilateral declarations. First, as the ICJ pointed out in Nuclear Tests, international law imposes no special or strict requirements in this domain. The variety of forms that unilateral declarations have taken in practice demonstrates this. The Ihlen Declaration was made orally, whilst the Suez Declaration was registered with the United Nations (UN) Secretariat. The French declarations in Nuclear Tests were made in a variety of circumstances including a statement by the French President at a press conference, and a declaration by the Foreign Minister at the UN General Assembly, and the Austrian declaration of neutrality was contained in a statutory document. When international law does not prescribe a particular form, the parties are free to choose what form an act will take, providing that the intention is clear, because as international law is not in principle formalistic, it uses intention, rather than form, as the central element in the theory of a legal act. In the case of unilateral acts, however, one crucial element of form has been retained: for a unilateral act to be valid, and opposable, it must have been adequately communicated to its intended audience. This is a common-sense ingredient, for unless an act is known, it is of no legal value, and may be modified at will by the author. Once such an engagement is made public, it acquires a definitive form and legal effect, and can be invoked against the declarant state by all interested states, if made publicly erga omnes, or by the pre-determined states to which it was communicated in private. Publication, notification or communication of a unilateral act is thus of considerable importance, and can be compared to signature, ratification or adhesion to a conventional agreement. These conditions of validity and rules of interpretation consist of general principles of law, applicable to all conduct of states, but adapted to accommodate the peculiarities of unilateral conduct. This system of construction limits the circumstances under which a unilateral act creates a binding obligation, in order to implement the intent of the declarant, and avoid the confusion, chaos and paralysis that would result in international relations if states were to become bound on an unregulated basis. Having deduced the conditions of formation of a unilateral legal act, however, it remains important to discover what legal norm attaches to the act and gives it legal effect, or in other words why a unilateral act creates an enforceable duty in international law.

IV. The Legal Basis of a Unilateral Obligation The juridical rationale for unilateral acts has long been a point of dissension amongst publicists, and despite a clear indication from the ICJ on this matter in Nuclear Tests, it continues to be a source of controversy. The Court stated explicitly that '[j]ust as the very rule of pacta sunt servanda in the law of treaties is based on good faith, so also is the binding character of an international obligation assumed by unilateral declaration'. The subjective explanations offered range from a view that unilateral acts have no independent status or binding legal effect at international law, to theories that presumed consent, third-party beneficiaries of contract, estoppel and autonomous expressions of will found the obligation. These theories warrant exploration, for they cast light on various aspects of unilateral acts and highlight, by apposition, the truly objective basis of the obligation. (a) No legal effect The most restrictive view holds that unilateral acts have no independent legal status at international law, and that whatever their political value may be, they create no obligations in law. The French jurist Kiss stated categorically that a unilateral act does not engage the state from which it emanates, although he acknowledged the existence of certain unilateral acts such as notification and renunciation, which he said give rise to pre-determined effects. These theories not only give pre- eminence to consent, but make it a criterion of the legal act, in so much as unilateral acts only become valid when they are quasi-treaties. State practice and jurisprudence have shown the weakness of this theory and doctrine has accordingly 'undergone a slow, yet significant, change'. The theory that unilateral acts create binding obligations has experienced a steady increase in support. (b) Presumed consent founds the obligation Even those supporting the binding nature of a unilateral obligation still seemed to feel constrained to discover its basis in a conventional context, and the theory of presumed consent was a popular one. By construing the behaviour of the addressee subsequent to the communication of the act as active or even tacit consent, a binding contractual relationship was implied. This reasoning is unsatisfactory for several reasons. First, the question arises whether silence or passivity is to be interpreted as amounting to consent, or to no more than indifference or forbearance. Alternatively, equivocal reaction to a unilateral act may be construed as acquiescence, or absence of protest, and thus constitutive of an abandonment of a right. Furthermore, it is clear that the intention of the addressee is of no import in the formation or validity of a unilateral act: the only necessary intent is that of the declarant. (c) Third-party beneficiaries of contract Another explanation for the binding obligation of the unilateral declaration is drawn from an analogy between rights conferred on third parties by a treaty, and unilateral declarations benefiting a second party. In the case of third-party benefis stemming from a treaty provision, however, the rights rest on a binding conventional relationship, rather than providing the basis for the obligation. Accordingly, acceptance by the third party adds nothing to the obligation already undertaken. The analogy with unilateral acts is self-evident: the theory of third-party benefit adds nothing to the obligation already contained in the unilateral act, and the binding nature of this obligation must be sought elsewhere. (d) Unilateral acts enforced through estoppel The municipal law concept of estoppel has often been invoked to support the legal effects produced by certain state conduct, and has been said to be the typical minimum effect of a unilateral act. As a doctrine that prevents a party from acting inconsistently with a prior statement or conduct on the same matter, the effects of estoppel would appear to be identical to those of a unilateral promise. Estoppel accords with ideas of stability of international legal relations, confidence in and protection of expectations, and will often produce the same effect as a unilateral promise, but the concepts of unilateral act and estoppel must still be seen to be distinct. This distinction is to be found in the way the obligation is created. A unilateral obligation is created by a legal act, an expression of will by which the declarant unilaterally decides to be bound. Estoppel, however, results not from the intention of the declarant, but from the expectation or behaviour of the addressee of the act. Whether international law estoppel requires reliance or detriment in a manner analogous to municipal law, or only that the addressee believed in good faith in the reality of the obligation undertaken, the conduct of the third party adds nothing to the intention of the declarant, and the fundamental norm must be sought elsewhere. (e) From subjective expressions of will to the objective foundation of good faith Unilateral acts, like bilateral and multilateral engagements, consist in conduct of states, and are thus susceptible to regulation in much the same way as conventional acts. Just as the ultimate source of law in a treaty is the agreement behind it - or the convergent expression of will of two or more sovereign states - so the principle creative of a unilateral act is the manifestation of will. This is reflected in the famous dictum of the PCIJ in the Wimbledon Case that 'the capacity to undertake international engagements is precisely an attribute of state sovereignty', and applies equally to unilateral and conventional engagements. The argument put forward in support of this theory is that, while the principles of good faith or pacta sunt servanda may govern the execution of the obligation in question, they are insufficient to found the obligatory character of the engagement at its conception. It is submitted, however, that it is precisely within the execution of the obligation that the basis of its obligatory nature resides, and that the manifestation of will creative of it is an important condition of validity, but no more. It is in the objective principle of good faith, and its more precise expression in other principles stemming from it, that the binding nature of engagements undertaken can be found. The decentralised character of international law, the increasing number of rights, obligations, and international actors, and the diminution in formalities accompanying international transactions, make good faith not only necessary, but more than ever an essential element in international engagements. As formal treaties and multilateral conferences are replaced to some extent by electronic communications, it is necessary to be able to extrapolate the extent of rights and obligations that are created but not exhaustively delimited in these more informal situations. Evidently, this applies just as much to unilateral acts as to conventional agreements. The questions thus arising are what is the content of good faith, how does it manifest itself within the area of international legal acts, and how does it operate in unilateral acts to allow states to draw such 'proper conclusions'? (f) Analogies with the law of treaties: the relationship between good faith and pacta sunt servanda Good faith is consecrated in the law of treaties within article 26 of the VCLT, which is entitled pacta sunt servanda. The relationship between pacta sunt servanda and good faith is rarely clearly explained, however, and the principles are often placed on the same plan of generality. The rule pacta sunt servanda, which has constituted 'since times immemorial the axiom, postulate and categorical imperative of the science of international law', is generally understood as meaning that valid treaties are binding on the parties to them; in other words, it is a command to execute an obligation, but does not actually determine the contents of that obligation. Good faith, on the other hand, has a broader, but more removed role. It serves to delimit the contents of the obligation, to correct defects of will or formality where fairness demands it, and to enlarge the domain of obligatory acts in international law. Good faith is the over-arching and reconciling principle of law that founds and legitimises other rules including pacta sunt servanda, rebus sic stantibus and estoppel. It is possible to imagine the intervention of good faith to reconcile a collision of norms such as pacta sunt servanda and rebus sic stantibus, or to apply article 18 of the VCLT and decide whether or not a party's behaviour was intended to defeat the object and purpose of a treaty. The obligatory nature of an international engagement can thus be seen to gain its binding force from pacta sunt servanda, which can be conceptualised as a specific enunciation of the application of good faith in the domain of international legal acts, with a fundamental importance of its own, but with its basis in the over-arching principle of good faith. Good faith has been determined to be the ultimate legal basis of not only the conventional but also the unilateral act, the question of whether its more specific application in the form of pacta sunt servanda is similarly applicable to both has produced dissent. The importance of the principle pacta sunt servanda has been recognised in doctrine in no uncertain terms: it is the basic principle of the law of treaties, ensuring that every treaty is binding on the parties to it, and must be performed in good faith. Such a principle is equally necessary to ensure reliability and predictability in all forms of conduct of states, and thus it is suggested that the meaning of the term pactum should be extended in today's international law to apply not only to bilateral and multilateral agreements freely arrived at, but also to unilateral acts of a legal nature. If this norm, according to which engagements must be respected, is key to international legal relations, then to consider conventional agreements obligatory because they are founded on the concordant will of two or more states, while refusing to ascribe the same value to unilateral acts because the will is not met by another will, is a rigid and formalistic approach that does away with the very aim of regulation: the security and harmony of international relations.

V. A Legal Regime Governing Unilateral Acts Having established the nature, elements and binding force of unilateral acts, a framework governing the creation and validity of a unilateral act emerges, which can be applied by states in considering whether and how to undertake a unilateral act, or in interpreting such an act. (a) Regulating the creation and validity of a unilateral act The similarity between conventional and unilateral acts, both in terms of the objective basis creating and regulating the obligation undertaken, and the general principles of law governing validity, have been highlighted throughout this paper, and analogies have been drawn with many parts of the VCLT. Whilst the principles of the VCLT are obviously not applicable mutatis mutandis to the unilateral regime, due to the distinctive characteristics of unilateral acts, many of those related to assessing the valid creation of a legal act are based on general principles of law, easily translated to the unilateral sphere. It is thus possible to begin by assessing the conduct in question according to general principles of law, to determine whether or not it is in fact creative of a legal act. The act in question must first be determined to be an international legal fact, that is, an act imputable to a state, of a lawful nature, to which international law ascribes consequences in accordance with its norms. The norm in this case is acta sunt servanda, which will apply only if the international legal fact fulfills the conditions of validity for an international legal act - those of object, subject, intention and form - and produces legal effects autonomously, without the need for the intervention of any other legal act. Once determined to be a valid unilateral act, it will be a binding unilateral obligation, to be executed in good faith in accordance with acta sunt servanda. The conditions of validity are largely the same as those for a conventional act, although somewhat narrowed in order to accommodate the autonomous nature of the act, and to maintain an interpretation of state conduct consistent with the rule against restricting the freedom of sovereign states. It is important, however, to maintain an objective approach, interpreting the declared intention of the state in good faith, in order to achieve the security and stability of international relations, which is the purpose of the regime. To this end, the political and other circumstances surrounding the act may aid good faith interpretation. Intention to create legal relations is the key element to a binding unilateral act, but it is often difficult to distinguish between legal and political intent. In such a situation, the necessary intent may be inferred as a legal fiction if it appears that the act objectively gave rise to belief in a legal undertaking. (b) The continued existence and execution of a unilateral act Questions of revocation, suspension and termination require significant investigation, for the effects of unilateral acts are many and varied, and may certainly differ substantially from those of a conventional agreement. In this regard, once the instrumentum of a unilateral act has been assessed, and has been found to be binding in accordance with the principle acta sunt servanda, it may be necessary to look at the negotium or material substance of each act separately, and identify the legal effect it produces. As no state can create an obligation for another state without its consent, the legal effects of a unilateral act could .only be such that a state affirms a pre-existing right, undertakes an obligation, or, exceptionally, acquires a new right. The latter may only occur if it does not result in an obligation for other states, in cases such as acquisition of sovereignty over a newly discovered territory, for example. An act of protest constitutes the affirmation of a pre-existing right, and seeks to prevent another state from acquiring or abridging it, while waiver of a right results in the acquisition of an obligation to no longer contest the right against the party to whom it has been waived. Similarly, recognition produces an obligation on the part of the recognising state to conduct itself in accordance with the situation, claim or competence recognised, and promise is an obvious example of an acquisition of obligations. Whilst the classification of state conduct into formalistic categories is not a useful approach, a practical assessment of the legal effects of the act may allow rules to be developed governing the negotium. On such a basis, it is possible to imagine the development of applicable rules similar to those in the VCLT governing modification, termination, suspension and revocation. Unilateral obligations are more easily undertaken than conventional agreements, which require conciliation and concession, and thus they should perhaps be more difficult to alter or retract than their conventional cousins, in pursuit of the good faith co-operation that allows the international system to operate - although the reverse could also be argued. In any case, the maker of the unilateral declaration has the opportunity to insert conditions of revocation or modification into the original act, providing for an alteration of the obligation undertaken should stated events occur, or circumstances arise. The over-arching principle of good faith is just as applicable to the unilateral regime as to its conventional counterpart, and thus nothing would prevent such norms as rebus sic stantibus, supervening impossibility of performance, or the emergence of a new peremptory norm of international law from affecting the continued existence of the obligation in much the same way as under the VCLT. The VCLT provisions regarding internal law, territorial scope and non-retroactivity are also susceptible to translation into the unilateral regime. Whilst the elaborate system governing reservation that exists under the conventional regime will not be applicable to unilateral acts, the formulation of reservations or conditions as part of the instrumentum at the time the act is created will need to be carefully enunciated. A unilateral act should not be subject to arbitrary revision, and whilst this may be seen to limit the freedom of action of states, it is a consequence of the unilateral nature of the act undertaken. Furthermore, rebus sic stantibus, supervening impossibility and the emergence of a new peremptory norm would all produce determinable effects: for example, were international law to develop such that the use of nuclear weapons was considered contrary to a principle of jus cogens, then the 1974 Declaration of France would be invalid in any case.

VI. Conclusion It is anomalous that while bilateral and multilateral conduct have been regulated, and unlawful unilateral acts have been recognised and codified within the area of state responsibility, lawful unilateral acts remain unregulated at international law. The codification of unilateral acts would be a significant progression towards the achievement of the general topic of 'sources of international law', which was identified as a global topic of codification by the UN Secretariat in 1949. The importance of unilateral acts is likely to increase. Unilateral acts constitute the conduct of states of an autonomous unilateral nature, and they are thus susceptible to regulation in much the same way as bilateral or multilateral agreements. Unilateral acts can be identified and isolated from acts performed under the umbrella of a conventional relationship, the conditions that govern their validity can be deduced from general principles of law, and their binding nature discovered in the over-arching concept of good faith as governed from day to day by the principle acta sunt servanda. Using the existing law of treaties as a point of departure, taking a pragmatic approach based on general principles of law, and reviewing the significant state practice that exists in this regard, a set of draft articles codifying the law of unilateral acts should be a priority for the international legal community. Clear exposition in draft articles, or codification in a conventional instrument, would allow unilateral acts recognition as a source of international obligations, and provide certainty for states by giving unilateral conduct determinable effects.