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Max Planck Encyclopedia of Public International Law [MPEPIL]

Treaties, Validity

Meinhard Schröder

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved.date: 22 July 2019

Vienna Convention on the Law of Treaties — Good faith — Treaties, application — Treaties, effect for third states — Treaties, invalidity, termination, suspension, withdrawal — State practice — Codification — Peremptory norms / ius cogens

Published under the auspices of the Max Planck Foundation for International Peace and the Rule of Law under the direction of Rüdiger Wolfrum.

A.  Concept

The term validity of treaties designates in a comprehensive manner the conditions a treaty must fulfil in order to produce a legal effect and the consequences in case of non-compliance (Compliance). These conditions concern (a) the power to conclude an international treaty (Treaties, Conclusion and Entry into Force; Treaty Making Power); (b) the consent of the parties; (c) the legality of treaties; and (d) requirements for registration and publication (Treaties, Registration and Publication). Conflicts between treaties (Treaties, Conflicts between), though occasionally included in the subject, should not be treated as a problem of validity but rather as one of determining which of the conflicting treaties is applicable in a given situation (see also Treaties, Conflict Clauses). This point of view seems to reflect State practice (State), which does not contest the validity of conflicting treaties, and the jurisprudence of international courts (see, however, The Oscar Chinn Case [United Kingdom of Great Britain and Northern Ireland v Belgium] [opinion individuelle de W Schücking]; ‘The Oscar Chinn Case [opinion individuelle Schücking]Oscar Chinn Case; International Courts and Tribunals; Judicial Settlement of International Disputes). Art. 30 Vienna Convention on the Law of Treaties (1969) (‘VCLT’) codifies this practice (Codification and Progressive Development of International Law).

B.  Evolution of Rules

It is only with difficulty that a concise history of the rules governing the validity of treaties can be traced. State practice and decisions of international courts are scarce and inconsistent. International law still shows a distinct tendency to recognize situations even when illegal (see paras 5–7 below). More particularly, deficiencies related to the treaty-making power or the reality of consent and involving the validity of a treaty are normally eliminated during a careful process of negotiation. Thus it should seldom be possible to prove that a party has been the victim of ignorance or error. Other grounds of invalidity have only reluctantly been accepted, due to the fact that they restrict the use of force (Use of Force, Prohibition of) against a party or the freedom of contract by reference to the concept of ius cogens. Further, the traditional lack of an appropriate procedure has been a sensible obstacle to the invalidation of treaties. For all these reasons relevant customary international law is confined to a fairly small area and the doctrine dealing with the subject has been to some extent inclined to borrow principles from domestic law (see also General Principles of Law; International Law and Domestic [Municipal] Law). To clarify matters States have therefore repeatedly concluded special agreements declaring that a certain treaty would be held invalid. Moreover initial efforts have begun to codify rules of invalidity in the context of the law of treaties. They succeeded only after lengthy discussion at the United Nations Conference on the Law of Treaties.

C.  Current Legal Situation

1.  Treaties between States

The VCLT does not set up conditions for the validity of treaties. To achieve a maximum of stability, it rather presumes in its Art. 42 (1) the validity of a treaty and provides in its Arts 46 to 53, 64 to 69 and 71 for exhaustive rules under which treaties may be invalidated. State Parties invoking one of the grounds of invalidity, therefore, have the burden of proof.

(a)  Grounds of Invalidity

The VCLT draws a distinction between absolute and relative grounds of invalidity. In cases covered by Arts 8 and 51 to 53 VCLT, the treaty is void, or the expression of consent to be bound by the treaty is ‘without legal effect’, which leads to the same result. If one of these grounds is established, the treaty is null and void ex tunc, ie from the moment it was concluded. In cases covered by Arts 46 to 50 VCLT, however, the VCLT says that a State may merely invoke the vitiating factor as invalidating the treaty, the effect of this formula being that the treaty is probably voidable rather than void; the treaty is valid until a State claims that it is invalid.

The vitiating factors mentioned in Arts 8 and 51 to 53 VCLT are more serious than those mentioned in Arts 46 to 50 VCLT, so this distinction is logical; but it is doubtful whether this distinction is as clearly established in customary law as the VCLT may suggest.

(i)  Voidability

Grounds of voidability include manifest violation of internal law or of the restrictions of the powers of the State representative who has concluded the treaty (Representatives of States in International Relations), as well as error, fraud and corruption (see also Corruption, Fight against).

A first category of these grounds covers situations in which the representative of a State either violated domestic law or exceeded his powers when expressing the consent of the State to be bound by a treaty. The relevant Arts 46 and 47 VCLT are conceived so restrictively that practical cases in which they could be invoked are rare. Thus, pursuant to Art. 46 VCLT an alleged violation of domestic law may concern only fundamental provisions which pertain to the treaty-making power. ‘Fundamental’ means the provisions should have substantive importance for the constitutional order of the State independent of their formal qualification as constitutional law (in this sense: Land and Maritime Boundary between Cameroon and Nigeria [2002] ICJ Rep 303 para. 266). Secondly, the violation must be evident to any State acting by normal practice and in good faith (Bona fide). The reluctance of tribunals to look behind the ostensible authority of a foreign minister to commit his State was already evidenced, for example, in the Eastern Greenland Case decided by the Permanent Court of International Justice (PCIJ) in 1933 (Legal Status in Eastern Greenland [Denmark v Norway] PCIJ Series A/B No 53). The court decided that the oral statement of the Norwegian Minister of Foreign Affairs exceeding his constitutional limitations of power was valid and binding on Norway. It was sufficient that the Norwegian Minister of Foreign Affairs had made his declaration on behalf of the Norwegian government in a matter which fell within his portfolio as Minister of Foreign Affairs and in answer to a question addressed to him by the Danish diplomatic representative (Heads of Governments and Other Senior Officials). The International Court of Justice (ICJ) held that the limitation of a Head of Stat’ capacity to conclude treaties is not manifest in the sense of Art. 46 (2) VCLT unless it is at least properly publicized. Heads of State are therefore considered as representing their State for the purpose of performing all acts relating to the conclusion of a treaty (Case concerning the Land and Maritime Boundary between Cameroon and Nigeria [Cameroon v Nigeria: Equatorial Guinea intervening] [2002] ICJ Rep 303 para. 265; Land and Maritime Boundary between Cameroon and Nigeria Case [Cameroon v Nigeria]).

In the broader context, the judgment of the European Court of Justice in French Republic v Commission of the European Communities (Case C–327/91 [1994] ECR I–3641; European Communities, Court of Justice [ECJ] and Court of First Instance [CFI]) is instructive. The court held that the European Community (‘EC’) had concluded a treaty with the United States of America in contravention of internal EC rules governing the competence of various EC organs to conclude treaties (European Community and Union, Party to International Agreements; see also European Community and Union, Actor in International Relations). However, the court decided that the treaty was binding on the EC in international law (European Community and Union Law and International Law). Given the complexity of EC internal rules, if the EC enters into a treaty in breach of those rules any internal irregularity is most unlikely to be manifest. It is therefore unlikely that the EC could invoke any rule of customary international law which might be reflected in Art. 46 VCLT, or rather the equivalent article in the Vienna Convention on the Law of Treaties between States and International Organizations or between International Organizations (‘VCLT-IO’) of 1986 (International Organizations or Institutions, External Relations and Co-operation).

As seen from the case law, the violation of internal law on the competence to conclude treaties in recent times seems to have the most relevance. That may explain the qualification of Art. 46 VCLT as representing customary law though the customary law situation is uncertain owing to the infrequent and inconsistent practice (Land and Maritime Boundary between Cameroon and Nigeria [2002] ICJ Rep 303 para. 263; Determination of the Maritime Boundary [Guinea-Bissau v Senegal] [1989] ILR 1989 1 para. 55).

10  Art. 47 VCLT provides that if the authority of a representative to express the consent of the State to be bound by a particular treaty has been made subject to a specific restriction, his omission to observe the restriction may not be invoked as a ground of invalidity unless the restriction was previously notified to the other negotiating State. This seems also acceptable for treaties concluded by States which are not party to the VCLT.

11  A second category of rules is concerned with the reality of consent as affected by error, fraud or corruption. In dealing with error, Art. 48 VCLT follows a practice that has been established mainly in cases of confusion over the mapping of boundaries (Maps). The wording of Art. 48 (2) VCLT is taken almost literally from the judgment of the ICJ in the Temple of Preah Vihear Case. The restrictions under which error has been accepted in these and some other instances leave only narrow opportunity for invalidation. Thus an error—unilateral or mutual—may relate neither to questions of law nor to the agreed text, but only to a fact or situation which was assumed at the time when the treaty was concluded and formed an essential basis of consent and a condition for it (see Mavromatis Jerusalem Concessions [1925] PCIJ Series A No 5, 30; Kasiliki/Seduku Island [Declaration of Judge Higgins] [1999] ICJ Rep 1114). In no case can there be an error if the parties have contributed to it by their own conduct or if the circumstances were such as to put parties on notice of its possibility (see Art. 48 (2) VCLT).

12  Fraud and corruption, dealt with in Arts 49 and 50 VCLT, are of even less importance. International practice does not furnish recent or significant instances.

(ii)  Voidness

13  Grounds of ‘absolute’ invalidity (voidness or nullity) are coercion and inconsistency with ius cogens.

14  Coercion may occur in two forms, either that of the representative negotiating a treaty or expressing consent to be bound, or that of the State itself. Arts 51 and 52 VCLT accept both as invalidating the treaty. Concerning the coercion of a representative, the acts of threat must affect the representative as an individual, not as the representative of his State. The concept of personal coercion extends to blackmailing threats and threats against the representative’s family. There have been a few cases of personal coercion, such as the extreme pressure put on the President and Foreign Minister of Czechoslovakia in 1939 to force them to sign the treaty creating a German protectorate over Bohemia and Moravia (see also Munich Agreement [1938]).

15  Coercion of a State raises some difficulties. The first problem relates to the notion of force used in Art. 52 VCLT. The wording would include not only unjustified physical and political pressure, but also economic and political pressure. Such a broad concept, however, was defined expressly only in the Declaration on the Prohibition of Military Political or Economic Coercion in the Conclusion of Treaties (Economic Coercion) as included in the Final Act of the United Nations Conference on the Law of Treaties. However, the International Law Commission (ILC) did not deem it necessary to change the formulation of Art. 52 VCLT, which is considered sufficient to cover all developments in international law.

16  Secondly, it would be difficult in some cases to establish precisely the close connection between coercion and the conclusion of a treaty. For discussions of a specific case, see United States–Iran Agreement of the American Hostages Executive Order 12284 of 19 January 1981 (Hostages).

17  The Agreement concerning the restoration of the Government of President Aristide, signed in Port au Prince on 18 September 1994, is considered to have been obtained by the threat of force; because at the time an American military action against Haiti was imminent (Haiti, Conflict). However, on 16 October 1993 the United Nations Security Council (United Nations, Security Council) adopted a resolution which authorized the use of force to restore the legitimate government of Haiti. Art. 52 VCLT does not apply to the threat or use of lawful force.

18  Occasionally, contra bonos mores was applied as a standard of validity, in the sense of a general principle of law recognized by civilized nations in the sense of Art. 38 (c) Statute of the ICJ (Sources of International Law). See in this respect The Oscar Chinn Case (opinion individuelle Schücking) 88–89: ‘Jamais … la Cour n’ appliquerait une convention dont le contenu serait contraire aux bonos mores’ (‘The Court would never … apply a convention the terms of which were contrary to public morality’; The Oscar Chinn Case [opinion individuelle Schücking] 88–89, translation by the PCIJ) and also The Krupp Case, which concerned an agreement between France and Germany on the use of French prisoners of war in German armament production (The Krupp Case [The United States of America v Krupp von Bohlen und Halbach] [1950] IX Trials of War Criminals before the Nuernberg Military Tribunals 1395; International Military Tribunals). Today, however, only the higher-ranking standard of ius cogens, which entails the invalidation of a contract, ought to be used. The imprecise standard set by bonos mores has not become generally accepted, but rather, through the use of ius cogens has become entirely obsolete.

19  Taking up this recent tendency in international law, Art. 53 VCLT provides that a treaty conflicting with ius cogens at the time of its conclusion is void. According to Art. 64 VCLT, in the case of conflict with a norm of ius cogens emerging after their conclusion, existing treaties also become void and terminate (Treaties, Termination). There is no agreement on the criteria for identifying which norms of general international law have a peremptory character. Whether a norm of general international law is of a respective quality depends on the particular nature of the subject-matter. The prohibition of the use of force as laid down in the United Nations Charter (‘UN Charter’) is a generally accepted example. The prohibitions of genocide, slavery and torture (Torture, Prohibition of) may also be regarded to be ius cogens.

20  It has been argued by Socialist States and States of the ‘Third World’ (Developing Countries) that treaties concluded on a basis of inequality of the parties (Unequal Treaties) ought to be held invalid. Unequal treaties are those which are said to have been forced upon a weaker State by a stronger one. The VCLT does not mention unequal treaties as a ground of invalidity. The problem of unequal treaties arose in the 19th century during the era of colonialism and was primarily associated with the establishment of a series of treaty regimes between a number of Western powers on the one hand and States in East Asia including Japan (eg The Treaty of Amity and Commerce Between the United States and Japan—The Harris Treaty of 1858—and the Anglo–Japanese Treaty of Amity and Commerce of 1858), Siam (eg The Bowring Treaties of 1855), and China (eg The Treaty of Nanking of 1842 and the Treaty of Tientsin of 1858) on the other (Treaties of Friendship, Commerce and Navigation). The doctrine has been invoked again by the renegotiation of the Panama Canal in 1977 and its return to Panamian sovereignty in 2000. Based on the same doctrine, the United Kingdom returned Hong Kong to China in 1997 and Portugal returned Macau to China in 1999. Nevertheless, the general view is that the principle does not form a part of positive law (Positivism). No two States are ever equal and to allow a State to avoid its treaty obligations on this ground could undermine the stability of treaty relations. But in some instances this may apply under the rules of coercion against a party or under the clausula rebus sic stantibus (Treaties, Fundamental Change of Circumstances).

(iii)  Secret Treaties

21  Customary law does not prohibit secret treaties (Treaties, Secret). In conformity with that, the duty for registration and publication of treaties as provided for in Art. 80 VCLT is not construed as a condition of validity. The same should be true for unregistered treaties and agreements under Art. 102 (2) UN Charter. Genesis and wording different from that of Art. 18 Covenant of the League of Nations (League of Nations) does not give much support to the view that unregistered treaties are invalid within the sphere of the United Nations (UN).

(b)  Procedure and Consequences of Invalidity

22  In providing for a procedure to be followed with respect to the invalidity of treaties, Arts 65 to 68 VCLT break new ground and make an attempt to stress the pacta sunt servanda rule. Each of the grounds which may give rise to a claim of invalidity must be established under this procedure. The request of a party is restricted in Art. 45 VCLT, if it has expressly accepted the continuing validity of the treaty or by reason of its conduct acquiesced in the validity (Acquiescence; Estoppel). The conduct has to be appreciated by the other parties of the treaty, and no presumption exists that the conduct constitutes acquiescence. The request for invalidity, the measure proposed to be taken with respect to the treaty, and the reasons must be notified to the other parties in writing. Any act declaring a treaty invalid is carried out through an instrument communicated to the other parties. If an objection has been raised, the parties shall seek a solution through the means indicated in Art. 33 UN Charter. Should such a solution fail, the parties to a dispute concerning a rule of ius cogens may submit it to the ICJ unless they have agreed to arbitration. In all other cases involving the validity of treaties the parties may set in motion the conciliation procedure provided for in an annex to the VCLT (Conciliation; Mediation).

23  Uncertainties and differences of opinion arise in legal literature dealing with the question whether Arts 65 to 68 VCLT concern all causes of invalidity, ie even the absolute grounds of invalidity which seem to be automatic in nature. The prevailing opinion in literature approves of the condition to notify the other party in all cases of invalidity arguing that otherwise there is no way to explain why Art. 66 VCLT explicitly mentions ius cogens, the cause of invalidity and termination which, by the tenor of Arts 53 and 64 VCLT, ought, more than any case, to operate automatically.

24  Customary law has not developed precise rules as to the legal consequences of invalidity (see also Nullity in International Law). The provisions laid down in Arts 44, 69 and 71 VCLT are of a pioneering character. Usually invalidity operates ab initio. It encompasses the treaty as a whole concept when limited to separable clauses under the conditions of Art. 44 VCLT. The parties may require each other—with some restrictions—to re-establish the status quo ante as far as possible but only in their mutual relations, ie respecting the rights of third States and of individuals (Treaties, Third-Party Effect; Individuals in International Law). Special rules apply to treaties conflicting with ius cogens. If the peremptory rule existed at the time when the treaty was concluded the latter becomes invalid ab initio. The parties are bound to restore themselves as far as possible to a position in full conformity with the principle. Ius cogens superveniens invalidates the treaty pro futuro. Acquired rights and legal relationships are maintained to the extent that they do not conflict with the new rule.

2.  Treaties between International Organizations or between States and International Organizations

25  The rules of validity applicable to treaties concluded between international organizations or between States and international organizations have been excluded from the ambit of the VCLT. Practice is scarce, doctrine only marginal. The VCLT-IO has reproduced to a large extent the provisions of the VCLT. The only substantial exception concerns the access of international organizations to the ICJ in the case of a dispute with respect to ius cogens, foreseen in Art. 66 (2) and (3) VCLT-IO. However, the VCLT-IO, as of the end of 2014, has not yet entered into force. Presumably many States and international organizations feel no need to become parties because the rules of the VCTL-IO are close to those of the VCTL, thus allowing their analogous application.

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