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Evolutionary Interpretation and Other Developments of the Vienna Convention on the Law of Treaties

Essay 2019 8 Seiten

Jura - Europarecht, Völkerrecht, Internationales Privatrecht


Table of Content

I. Introduction

II. Development of the Vienna Convention on the Law of Treaties – Evolutionary Interpretation
1. What is Evolutionary Interpretation?
2. What Role Does the Evolutionary Interpretation Play within the VCLT?
3. Legal Basis for Evolutionary Development in Article 31 VCLT
4. Does One Size Fit All? - Different Areas of Treaty Law
5. Interim Conclusion

III. Amendments, Modifications, Developments and Clarifications of other Provisions of the VCLT
1. Article 7 VCLT
2. Article 9 (2) VCLT
3. Article 11 VCLT
4. Article 18 VCLT
5. Articles 19-23 VCLT

IV. Conclusion.

I. Introduction

The Vienna Convention on the Law of Treaties (VCLT) constitutes the "bible" of international practitioners. Like the United Nations Charter, the widespread clarity and intelligence of its drafting have enabled States to comply with the rules and adapt their practice without distorting or departing from the VCLT.1 The rules provide an important framework which is flexible enough for States to accommodate alternatives, variations and even developments in their state practice. The provisions of the VCLT leave the states room for individual concretization. Some commentators say the VCLT has had its day and is incapable of dealing with the challenges of the 21st century. However, the VCLT has proved itself to be a most adaptable tool, as it was able to deal with challenges of the past decades.2 In order to do so, the provisions of the VCLT were clarified, modified, developed, or amended. This paper aims at discussing the development of several selected provisions of the VCLT as well as analysing the new types of interpretation, such as the evolutionary interpretation. The difference between the original provisions and the present state of the law will be outlined subsequently.

II. Development of the Vienna Convention on the Law of Treaties – Evolutionary Interpretation

1. What is Evolutionary Interpretation?

Evolutionary interpretation is a type of interpretation, also known as dynamic interpretation. The International Law Commission (ILC) defined it as "a form of purpose-oriented interpretation", it "may be guided by subsequent practice in a narrow and in a broad sense".3 Subsequent conduct in terms of interpretation is closely linked to the question of inter-temporal law. This deals with the issue whether a treaty must be interpreted in light of the circumstances at the time of its conclusion, so-called "contemporaneous interpretation", or rather in the light of the circumstances at the time of its application, so-called "evolutionary interpretation".4 Subsequent conduct has a bigger or smaller role to play for interpretation depending on the resolution of the aforementioned issue.5 The judgement of the ICJ in Navigational Rights6 depicts the relationship between evolutionary interpretation and subsequent practice. This case concretely dealt with the question whether “objetos de comercio” (“for purpose of commerce”) included tourism. The Court considered both approaches: “On the one hand, the subsequent practice of the parties, within the meaning of Article 31 (3) (b) of the Vienna Convention, can result in a departure from the original intent on the basis of a tacit agreement between the parties. On the other hand, there are situations in which the parties' intent upon conclusion of treaty was (…) to give the terms used (…) a meaning or content capable of evolving, not one fixed once and for all, so as to make allowance for, among other things, developments in international law”.7 The Court held that the treaty in question must cover all modern forms of commerce including tourism. As soon as treaty parties decide to use generic terms, it can be assumed that future developments must be included particularly where treaties entered into force for a long period.8 Therefore, the Court concluded that it must be presumed as a general rule that the parties have intended those terms to have an evolving meaning.9 Some cases were decided in favour of the contemporaneous approach, such as the Rights of US Nationals in Morocco, other cases invoked for establishing the legitimacy of an evolutionary interpretation, like in the Namibia Opinion of the ICJ.10 Other judgements argue with the “generic character” of particular terms and the fact that the treaty is designed to be “of continuing duration”.11 In the Iron Rhine case, generic terms were not an issue but rather technical developments were to be interpreted evolutionary.12 The Case concerning the delimitation of maritime boundary between Guinea-Bissau and Senegal demonstrates that contemporaneous and evolutionary interpretation can even coexist.13 A treaty must adapt to new developments and evolutionary interpretation is the most appropriate type of interpretation to do so.

2. What Role Does the Evolutionary Interpretation Play within the VCLT?

Bjorge's answer to the above-mentioned question is that evolutionary interpretation is, in common with other forms of interpretations, the outcome of the process of the general rule of interpretation and is established upon the objective establishment of the intention of the parties.14 The evolution involved in the evolutionary interpretation of treaties can be understood as evolution intended.15 Still, the Articles 31-33 VCLT apply to the evolutionary interpretation of treaties as well as to any other type of interpretative process. Besides the intention of the parties, the principle of good faith is of importance. The good-faith-compliance may steer the interpretation in direction of evolution, Bjorge even states that "evolutionary interpretation may be required by good faith".16 Good faith acts as guarantor of expectations of the parties and treaties must be interpreted in conformity with loyalty and reciprocal confidence.17 Another principle plays a role within the evolutionary interpretation, namely the effet utile, as it is central for treaty interpretation that a convention is interpreted as to be effective in terms of the intention of the parties. This as well applies to every type of interpretation.18 However, if accepting the evolutionary interpretation there must be another form of "border to the new territory". As mentioned earlier, the intention of the parties does play a role within the evolutionary interpretation, as it constitutes a different threshold than the wording. As the ILC stated, treaties are "the embodiments of the common will of their parties", highlighting that the concept of intention is of great importance for the interpretation, if not the essential framework. Consequently, the evolutionary interpretation is built upon the intention of the parties and in order to establish the common intention of the parties, Article 31 VCLT provides, by objective means, the basis and the border for it.19

3. Legal Basis for Evolutionary Development in Article 31 VCLT

Article 31 VCLT is designed to contain the general rule of treaty interpretation, it contains one single rule in para. 1 that consists of the three main elements: wording, context and object and purpose as well as the guiding principle of good faith. Concerning evolutionary interpretation, para. 3 is the most relevant as it rather designates other elements of contexts and lists interpretative means to be used along with the context.20 Article 31 (3) VCLT requires to take account of subsequent developments, agreements between parties and practice in applying the treaty. Thus, it focuses on the current consensus of the parties in understanding the treaty.21 The original provision of Article 31 (3) VCLT does not directly address the temporal issue, namely evolutionary interpretation or the principle of contemporaneity. Both approaches can be found in international judicial practice, as discussed above. As Article 31 (3) takes into account agreements in letter (a) and practice in letter (b), the parties used generic terms which are flexible and allow to fill these words with concrete approaches. The present state of the provision allows for evolving new types of interpretation, such as the evolutionary interpretation, as long as it can be derived from Article 31 (3) VCLT. A particular application of the evolutionary approach lies at the heart of the establishes jurisprudence of the ECtHR which will be presented subsequently.22 Concluding, evolutionary interpretation is embedded in Articles 31 VCLT, particularly para.3, and can be regarded as a development of this Article.

4. Does One Size Fit All? - Different Areas of Treaty Law

Specific treaty regimes, such as the human rights law, might not perfectly fit the size of Articles 31-33 VCLT. Although these Articles do not mention any modification for certain treaties, it is often argued that the general rules of interpretation undergo some modifications when they are applied to these types of treaties.23 Human rights law is one of the most significant areas of treaty law which opts for individual approaches in order to interpret human rights treaties. The ECtHR has established a more autonomous approach, as the human rights regime is considered as special regime which therefore deserves a particular interpretation approach. At the same time, human rights law cannot be interpreted in a vacuum, it must refer to general international law and must be interpreted in harmony with general principles of international law.24 As a consequence of the autonomous approach, the ECtHR developed the “living instrument doctrine” and interpreted it “in light of present-day conditions”.25 This approach provides for an adaption to changing social realities by means of an evolutive and dynamic interpretation in order to keep the human rights standards “up to date”.26 This doctrine symbolises the difference between human rights law and general international law: Human rights treaties are "generic terms" treaties, they protect the fundamental rights of individuals rather than the interests of contracting parties.27 Consequently, this allows for a certain detachment from original provision of Article 31 VCLT, however, still respecting the consensus of the parties as a border of evolutionary interpretation.

Modification was also needed in case of treaties operating as constituent instrument of an international organization according to Article 5 VCLT. This provision already allows for some flexibility as it is stated that the VCLT is applicable to those kinds of treaties "without prejudice to any relevant rules of the organization". The ICJ pointed out in its Advisory Opinion on Nuclear Weapons that there are certain elements "which may deserve special attention when the time comes to interpret constituent treaties".28 Still, the general rules of treaty interpretation according to the VCLT apply, however, three modifications appeared in practice: (1) in interpreting the constituent document of an international organization effectively, particularly in ICJ's jurisprudence with regard to powers of UN organs29 ; (2) the subsequent practice of the organization itself is regarded, rather than that of its Member State in applying the constituent treaties; (3) if an organ has been empowered to interpret the constituent treaty of the organization, there is usually a need for an autonomous interpretation.30 The VCLT provides for certain flexibility due to the use of generic terms. This allows for certain modification in human rights law and treaties constituting international organizations. Since the modifications are still based on the general rules of interpretation according to Articles 31-33 VCLT one can state that one size - with certain flexibilities - fits all.


1 Anthony Aust, “Vienna Convention on the Law of Treaties (1969)“ ( MPEPIL 2006) (accessed 15 January 2019)

2 ibid.

3 ILC, “Report of the International Law Commission on the Work of its 65th Session“ (6 May-7 June and 8 July-9 August 2013) UN Doc A/68/10, 27.

4 Georg Nolte, “Jurisprudence of the International Court of Justice and arbitral tribunals of ad hoc jurisdiction relating to subsequent agreements and subsequent practice“ (Introductory Report for the Study Group on Treaties over Time 2009) 21.

5 ibid.

6 Dispute regarding Navigational and Related Rights (Costa Rica v Nicaragua) ICJ Rep 2009.

7 ibid., 343 para. 64.

8 Ibid., 343 para. 66.

9 ibid.

10 Legal Consequences for States of Continued Presence of South Africa in Namibia (South West Africa) notwithstanding Security Council Resolution 276 (1970) (Advisory Opinion), ICJ Rep 1971 p. 30 para. 51.

11 Supra note 6, 343 para. 66.

12 Arbitration Regarding the Iron Rhine (“Ijzeren Rijn“) Railway (Belgium v. The Netherlands), Permanent Court of Arbitration Award of 24 May 2005, para. 80.

13 Case concerning the delimitation of maritime boundary between Guinea-Bissau and Senegal, Reports of International Arbitral Awards (14 February 1985) 119 et seq. Further example for evolutionary interpretation is the ICJ Aegean Sea Continental Shelf Case (Greece v. Turkey) (1978) ICJ Rep. 1978 p. 33 concerning the ”Territorial status of Greece“ as generic term the meaning of which „was intended to follow the evolution of the law and to correspond with the meaning attached the expression by the law in force at any given time“.

14 Eirik Bjorge, “The Evolutionary Interpretation of Treaties“ (OUP 2014) 188.

15 ibid.

16 ibid., 190.

17 Robert Kolb, “La bonne foi en droit international public: Contribution à l'étude des principes généreaux de droit“(Presses Universitaires de France 2000) 274-275.

18 Lighthouses Case between France and Greece (1934) PCIJ Series A/B No 62 231; Territorial Dispute (Libya/Chad) (1994) ICJ Rep 21 p. 23.

19 Supra note 14, 5.

20 Dörr, “Article 31“ in Vienna Convention on the Law of Treaties, A Commentary“ (Oliver Dörr, Kirsten Schmalenbach eds. 2018) 561 para. 5.

21 ibid., 561 para. 4.

22 For example, ECtHR, Tyrer v United Kingdom (1978) App No 5856/72, Ser A 26, para 31 ; Marckx v Belgium App (1979) No 6833/74, Ser A 32, para 41; Loizidou v Turkey (Preliminary Objections) (1995) App No 15318/89, Ser A 310, para 71.

23 Supra note 20, 575 para. 28.

24 Christina Binder, „The European Court of Human Rights and the Law of Treaties – Sign of Fragmentation or Unity?“ in: Binder/Lachmayer (eds), The European Court of Human Rights and Public International Law - Fragmentation or Unity (2014), 43-66, 47.

25 ibid. 53, 55.

26 ibid. 53, 55.

27 ibid. 55.

28 Legality of the Use by a State of Nuclear Weapons in Armed Conflict (Advisory Opinion) (1996) ICJ Rep 66, para 19.

29 Cf Reparation for Injuries Suffered in the Service of the United Nations (Advisory Opinion) (1949) ICJ Rep 174, 182– 183; Certain Expenses of the United Nations (Advisory Opinion) (1962) ICJ Rep 151, 168 .

30 Supra note 20, 576 para. 30.


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Universität Wien – Institut für Europa- und Völkerrecht
Evolutionary Interpretation Vienna Convention on the Law of Treaties




Titel: Evolutionary Interpretation and Other Developments of the Vienna Convention on the Law of Treaties