(Inter)Temporal Considerations in the Interpretative Process of the VCLT: Do Treaties Endure, Perdure or Exdure?

© T.M.C. Asser Press and the authors 2015
Mónika Ambrus and Ramses A. Wessel (eds.)Netherlands Yearbook of International Law 2014Netherlands Yearbook of International Law4510.1007/978-94-6265-060-2_6

6. (Inter)Temporal Considerations in the Interpretative Process of the VCLT: Do Treaties Endure, Perdure or Exdure?

Panos Merkouris 

Lecturer on International Law, University of Groningen, Groningen, The Netherlands



Panos Merkouris


When interpreted, sometimes treaties have to go through a trial by fire and are found either to be ‘living instruments’ evolving alongside the relevant changes both in law and in facts or to have a ‘fixed’ meaning. The aim of the present article is to examine how intertemporal considerations find their way into the interpretative process and what the effects are on the treaties being interpreted. Do these changes in law and fact actually change the treaty itself, or do they merely trigger a latent quality already existing in the treaty itself? Does time change the treaty, or does it merely ‘unfold’ it? This question will be examined through the lens of the main philosophical theories on identity, persistence, time and change (endurantism, perdurantism and exdurantism), and by focusing on the ‘direct’ (principle of contemporaneity and evolutive interpretation) and ‘indirect’ (Article 31(3)(c) and the intertemporal application of the rules of interpretation) points of entry of intertemporal considerations in the interpretative process. Through this examination the elements that weigh upon the judicial interpretative process and tip the scales either in favour of an evolutive interpretation or in favour of the principle of contemporaneity, will be identified, as well as the limits of any such interpretation. In this manner, an answer will be arrived at as to whether, from an interpretative perspective, treaties endure, perdure or exdure.

InterpretationEvolutive interpretationDynamic interpretationIntertemporal lawContemporaneityLaw of treatiesVienna Convention on the Law of TreatiesEndurantismPerdurantismExdurantism

δὶς ἐς τὸν αὐτὸν ποταμὸν οὐκ ἂν ἐμβαίης.

You cannot enter the same river twice.


6.1 Introduction

In the philosophy of Heraclitus of Ephesus, change was of central importance. In the quote cited above, Heraclitus touches upon the paradox of change and of identity. If you enter a river at one point in time the river will consist of a certain amount of water and of certain droplets. If you enter at a later time what you would perceive as the ‘same’ river, so Heraclitus posits, you will actually be entering a different river. The body of water that surrounded you during your first immersion has now moved on. It has meandered its way towards the delta of the river. The second time around you are entering a qualitatively and quantitatively different river. Various solutions have been offered to reconcile this paradox with our common understanding of time, change and identity, ranging from, on the one hand, it being a false paradox due to the use of ‘same’ as meaning two different things simultaneously to, on the other hand, theories of persistence and viewing words as ‘time-worms’.1

An in-depth analysis of this discourse would fall outside the scope of the present chapter, it helps, however, in highlighting the fact that the passage of time and change go hand in hand, in all manifestations of the cosmos. Law could not be an exception and is subject to the altering effects of time. This topic has been the focal point of seminal academic works.2 In the context of international law one such manifestation can be found in the interpretation of treaties. When interpreted, sometimes treaties have to go through a trial by fire and are found either to be ‘living instruments’ evolving alongside the relevant changes both in law and in facts or to have a ‘fixed’ meaning.

The aim of the present article is to examine how temporal considerations find their way into the interpretative process and what are the effects on the treaties being interpreted. Do these changes in law and fact actually change the treaty, or are they merely a latent quality already existing in the treaty itself? Does time change the treaty, or does it merely ‘unfold’ it as Max Frisch would put it?3 All of these ideas, and the philosophical theories on identity, persistence, time and change connected to them, which explain the terms employed in the soustitre of this chapter (‘Do Treaties Endure, Perdure or Exdure?’), will be addressed in Sect. 6.2.

The necessity of adopting this analytical viewpoint is two-fold. Firstly, the entire system of international law has always been a compromise between two key-functions; providing long-term stability and legal certainty, on the one hand, and ensuring the viability, adaptability and relevance of the system by allowing change, growth and evolution of the relevant legal rules on the other. Second, the overarching theme of the present Volume is that of ‘Temporariness in International Law’. Consequently, it is essential that we first determine the main concepts of identity, persistence and change. If we do not know, what identity, persistence and change are, how could we possible offer any meaningful answer as to whether treaties change in time or remain the same, and what the elements and limits are that affect any such determination.

The theme of the Volume also colours the particular elements of the interpretative process that will be the focus of the analysis. Temporal considerations are almost ubiquitous in Articles 31 and 32 of the 1969 Vienna Convention on the Law of Treaties (VCLT).4 To name but a few instances where temporal considerations play a role in the interpretative process: subsequent practice,5 subsequent agreements and ‘relevant rules’ of Article 31(3)(c).6 As a detailed exposition of all these elements would be impossible within the confines of a single chapter, the analysis will focus mainly on the ‘points of entry’ of temporal considerations, and in particular those which are connected to the notion of inter-temporality.7

There are two main points of entry of (inter)temporal considerations in the interpretative process:

(1) Direct point of entry: Contemporaneity or Dynamic Interpretation. According to Fitzmaurice one of the main principles of interpretation is the principle of contemporaneity, i.e. that ‘[t]he terms of a treaty must be interpreted according to the meaning which they possessed … at the time when the treaty was originally concluded’.8 There is, however, one important caveat: ‘[unless] it was the intention of the parties that the meaning or scope of a term or expression used in the treaty should follow the development of the law.’9

What we will examine is whether international jurisprudence has a tendency to give weight to particular elements in order for it to conclude that a treaty is to follow the principle of contemporaneity or should be interpreted dynamically. Such elements are, indicatively, the intention of the parties, the object and purpose of a treaty and the nature of the words employed in the treaty being interpreted.

(2) Indirect point of entry: Intertemporal Considerations within Article 31(3)(c) and in the Application of the Rules of Interpretation. Article 31(3)(c) of the VCLT states that during the interpretative process account shall be taken of ‘all relevant rules of international law applicable in the relations between the parties’. Although the text itself does not make any explicit reference to temporal considerations, its silence speaks volumes. An analysis of the preparatory work of the VCLT will show that one major point of consideration was again a temporal one. Which rules could be considered as relevant, the rules at the time of the conclusion of the treaty or the rules at the time of the interpretation of the treaty? This connection could also be transposed to the rules of interpretation themselves. When a court interprets a treaty, which rules of interpretation should it apply. The rules of interpretation contemporaneous to the treaty or the rules of interpretation at the time of the interpretation of the treaty?

In order to highlight the ties and overlaps between these two points of entry the present chapter in Sect. 6.2 will clarify certain concepts central to the following analysis. Section 6.3 will provide an overview of the preparatory work of the VCLT on intertemporal law. In Sect. 6.4 the analysis will move on to an examination of both the direct and indirect points of entry of intertemporal considerations in the interpretative process of the VCLT and the elements that factor in opting either in favour of a dynamic/evolutive interpretation or in favour of the principle of contemporaneity. Finally, in Sect. 6.5, we will attempt to map the limits, if any, to which the judges are restricted when engaging in dynamic/evolutive interpretation.

6.2 Definitional Issues

Before embarking on an examination of the manner in which intertemporal considerations infiltrate the interpretative process it is appropriate to first clarify the meaning and content of several of the concepts that will be the crux of the analysis.

6.2.1 Endurantism, Perdurantism, and Exdurantism

The first thing we need to address is the terms used in the soustitre of the article. The ideas of time, change, identity and persistence have ‘persisted’ from ancient Greek philosophy to modern times. The first systematic attempts to tackle these concepts from a logical and philosophical point of view were connected to paradoxes. Paradoxes were a favourite tool of ancient Greek and Roman philosophers in order to highlight either the pitfalls of our own preconceptions or the limits of our quest for true knowledge.10 There is a wide number of paradoxes that relate to the aforementioned concepts. For instance: (i) Heraclitus’ river paradox, according to which one is never able to enter the same river twice; (ii) Theseus’ ship paradox, according to which the question is at which point (if any) the ship stopped being his ship and became a new one due to the replacement of rotten planks to the extent that the entire ship ended up being comprised of newer pieces of wood11; and (iii) Chrysippus’ paradox. Chrysippus, a 3rd century BC Stoic philosopher, posited the following. There is a man called Dion. There is also Theon, who consists of Dion minus his left foot. If Dion’s left foot is amputated then what happens to the relationship between Dion and Theon, are they still two different things that simply occupy the same space, has Dion ceased to exist and been subsumed by Theon, or has the reverse taken place, i.e. Theon being subsumed by the now-amputee Dion?12

An analysis of these paradoxes falls outside the scope of this chapter, nonetheless, all have as a common denominator the aforementioned concepts of time, change, identity and persistence. Consequently, a brief examination of the main philosophical approaches to these concepts will allow us to better understand their function within the sphere of treaty interpretation and also demonstrate firstly what the subtitle selected for this chapter means, and, second, why it was considered to be reflective of the interpretative approaches to the (un)changing nature of treaties.

Various philosophical theories have been proposed throughout history to account for change in time. The two most prominent schools of thought are known as endurantism (endurance theory) and perdurantism (perdurance theory). The main difference between endurantism and perdurantism is the manner in which things persist and how change is accounted for.13 Endurantists hold that things have only spatial elements/parts and are ‘wholly present whenever they exist’.14 This creates some difficulties as to accounting for how things can change.15 Sorensen, gives a great account of the problems that one may face in applying strictly endurantism in conjunction with Leibniz’s Law of Identity.16

The Heracliteans did have a logical argument for the universality of change. If x is identical to y and x has property F, then y has property F [indiscernibility of identicals] … If Socrates when ill is identical to the man who recovered, then every property possessed by the ill Socrates is possessed by the recovered Socrates. But then the healthy Socrates would still be ill. What appears to be a single individual, Socrates enduring through time is actually a succession of individuals. The Heracliteans conclude that our ordinary use of identical is loose talk founded on mere resemblance. Socrates before and after his illness are only identical in the way that distinct grains of salt are identical.17

In order to account for change through time, and avoid the above paradoxes, endurantists have proposed various theories such as presentism,18 temporal-relationism19 and adverbialism,20 none of which however is without its difficulties.

On the other end of the spectrum is perdurantism. Unlike endurantists, perdurantists posit that things not only have spatial parts but temporal parts as well.21 According to them an object at any given moment is never wholly present, as its persistence has to be looked also from the perspective of the fourth dimension, that of time. Hence, an object at a specific ‘time-slice’22 is only partially present. From the perdurantist point of view objects are seen and referred to as ‘space-time worms’.23 As a worm wriggles along the earth, ‘space-time worms’ wriggle along a four-dimensional plane, along both space and time. Similar to a worm that does not exist wholly at a particular point or two-dimensional plane, but exists in space, objects are only partially present at any particular point in time. Their whole presence can be identified only by looking at the span of their existence along the fourth-dimension axis, thus giving the impression of a worm.

Because time and temporal parts are such an important factor in distinguishing between endurantism and perdurantism, the former and its associated theories are referred to as three-dimensionalism (3D-ism), whereas the latter where time considerations are predominant is referred to as four-dimensionalism (4D-ism).

Finally, there are other theories which try to combine elements of both endurantism and perdurantism. The most notable of these is exdurantism, known also as ‘stage theory’. According to exdurantism, objects have temporal parts,24 which are referred to as stages. However, unlike perdurantism, exdurantism argues that an object is wholly present ‘at momentary regions that lack temporal extension’.25 The question then that arises is if an object is wholly present at different ‘time-slices’, how is this different from endurantism and how can this be the same object? With respect to the first question, endurantism does not accept the existence of temporal parts, whereas ‘stage theory’ is actually based on their existence. As to the second question, the key idea is that objects persist through time by exduring, i.e. ‘by standing in temporal counterpart relations to later and earlier object stages’.26 The difference between perdurantism and exdurantism is that whereas the former views an object as a continuity, as a ‘space-time worm’, exdurantism views the object as a compilation of the sum of ‘time-slices’ or ‘stages’, where the object exists wholly in each and every one of them. How does this translate in an example taken from everyday life? Take, for instance, movies. Movies take advantage of the persistence of vision.27 Due to the speed with which the film roll is played we seem to perceive one continuous image, e.g. a train moving. However, if one slows down the film roll, one will easily see that the image previously perceived as ‘moving’ is nothing more than the sum of still images. In the same manner exdurantism posits that objects are the sum of an infinite amount of stages, the ‘still images’ from our previous example, where the object is wholly present at each and every one of them.

In summation:

  • endurantism holds that an object does not have temporal parts and that it exists wholly at every instant;

  • perdurantism holds that an object is a ‘space-time worm’. It has both spatial and temporal parts, and it exists only partially at any given moment; and finally,

  • exdurantism holds that an object has both spatial and temporal parts, but because it is the sum of its various ‘object-stages’ it exists wholly within any given moment.

6.2.2 Intertemporal Law

Connected to these theories of identity and change within the context of international law is the notion of intertemporal law. The most oft-cited quote on intertemporal law is that of Judge Huber in the Island of Palmas case:

a juridical fact must be appreciated in the light of the law contemporary with it … The same principle which subjects the act creative of a right to the law in force at the time the right arises, demands that the existence of the right, in other words its continued manifestation, shall follow the conditions required by the evolution of law. 28

However, pinpointing the exact content of intertemporal law has been somewhat more elusive, so much so in fact that Higgins argued that the quote has been read ‘in the most remarkably extensive fashion, as providing obligatory rules in circumstances that it never addressed, with consequences that it never intended’.29 This uneasiness as to the precise nature, scope and content of intertemporal law is equally reflected in the variety of terms in which it has been employed: ‘international intertemporal law’,30 ‘doctrine of intertemporal law’,31 ‘rule of intertemporal law’,32 ‘intertemporal principle’,33 ‘principle of the inter-temporal law’,34 ‘principle of the intertemporality of law’35 to name but a few.

Due to this uncertainty, it is necessary to determine whether intertemporal law has any connection to the process of interpretation or if it functions on a completely different sphere and thus is irrelevant to the interpretative process. Huber’s dictum consists of two legs, the first relating to the creation of a right, and the second to its continued manifestation. Both legs of Huber’s dictum concern the determination of the existence or non-existence of rights, not the determination of its content. It for this reason that one could get the impression that intertemporal law stricto sensu and interpretation have two very distinct functions and should not be conflated with one another.36

However, the contrary view that accepts some form of linkage between intertemporal law and the process of interpretation is not without its merit. Both doctrine37 and judicial practice38 seem to have no problem in accepting the possibility of transposition of the rationale behind intertemporal law to the interpretative process. Characteristically, Fitzmaurice argued that the principle of contemporaneity,39 can be understood as a ‘particular application of the doctrine of inter-temporal law [within the context of treaty interpretation]’.40

Based on the above, the doctrine of intertemporal law can be transposed to the interpretative process. Nonetheless and in order to avoid the doctrinal uncertainties surrounding intertemporal law, the term that was selected in the title was not ‘intertemporal law’ or ‘doctrine of intertemporal law’ but instead ‘(inter)temporal considerations in the interpretative process of the VCLT’. An additional reason was also that the term ‘considerations’, as well as the inclusion of the prefix ‘inter’ between brackets, was felt to better reflect the dual nature of the evolution of a particular term. Specifically, the meaning of a particular term can change due to the evolution not only of law but of facts as well, whereas intertemporal law as such and based on Huber’s dictum seems to focus only on the evolution of the law.

6.2.3 Principle of Contemporaneity and Evolutive/Dynamic Interpretation

The response to which legal system prevalent at subsequent time-periods should be the one decisive for interpretative purposes is not an easy one and definitely not one to which a clear-cut answer can be given. Prior to the conclusion of the VCLT, Fitzmaurice took it upon himself to try and distill from the jurisprudence of the ICJ the principles of treaty interpretation. In his series of articles in the BYIL he identified several principles of interpretation, one of which was the principle of contemporaneity,41 According to this principle

[t]he terms of a treaty must be interpreted according to the meaning which they possessed, or which would have been attributed to them, and in the light of current linguistic usage, at the time when the treaty was originally concluded.42

Several years later and in the same series of articles, Thirlway reaffirmed this principle but added one requirement:

Provided that, where it can be established that it was the intention of the parties that the meaning or scope of a term or expression used in the treaty should follow the development of the law, the treaty must be interpreted so as to give effect to that intention.43

International jurisprudence has evolved along those lines, with some tribunals recognizing the principle of contemporaneity,44 while others opting for a more ‘evolutive/dynamic’ interpretation.45

Evolutive/dynamic interpretation reveals the present content of a particular term, its ‘current frontier’.46 Various terms have been used to describe this interpretative approach such as ‘evolutionary interpretation’47 ‘evolutive interpretation’48 or ‘dynamic interpretation’.49 Whether these terms differ from one another or whether they can be used interchangeably is a matter of academic debate. International jurisprudence similarly does not offer much assistance in resolving this issue. The terms ‘dynamic’ and ‘evolutive’ have been used in all possible variations. Within one and the same sentence or paragraph one can find reference to these terms: (i) expressed in the alternative, i.e. ‘dynamic or evolutive’50 (ii) cumulatively, i.e. ‘evolutive and dynamic’,51 and (iii) both cumulatively and in the alternative in the same judgment.52 Helgesen, attempts a distinction by using the term ‘“evolutive” as covering the situation where the Court gives answers to new facts, societal changes, an issue which has never been before the Court. While “dynamic” interpretation [on the other hand] … refers primarily to the situation where the Court gives new answers to old facts.’53 Irrespective of whether this distinction is actually reflected in international judicial practice and for reasons of simplicity of this chapter the term that will be used from this point onwards will be ‘evolutive interpretation’ as being more closely linked linguistically to the idea of ‘living instruments’ that need to evolve in order to survive.

The connection of evolutive interpretation with intertemporal law is not only demonstrated by its ties with the principle of contemporaneity but is further substantiated by the fact that it has been referred to as the ‘intertemporal dimension’54 and the ‘temporal issue’55 in treaty interpretation.56

There is an extensive jurisprudence on evolutive interpretation, which is not restricted simply to human rights courts judgments,57 but covers those of other international judicial or quasi-judicial bodies.58

Evolutive interpretation can occur along two main tracks: (i) evolution of fact and (ii) evolution of law.59 Along similar lines, Georgopoulos although analyzing mainly ‘generic terms’60 adopts the terms ‘renvoi mobile’ and ‘ouverture du texte’.61 In the latter case (‘ouverture du texte’), the openness of the terms used in the treaty text allows for the content of the norm to change alongside the factual situation contemplated. This would be a case of ‘evolution of fact’. On the other hand, in the case of ‘renvoi mobile’ the norm reflects at each time it is being interpreted the evolution of the law to which it is connected. As the law changes so does the content of that norm.62 This situation would be one of ‘evolution of law’.

Examples of what international courts and tribunals have considered as evolution of fact are medical and scientific advancements,63 societal and cultural changes,64 moral developments,65 and the socio-economic situation of a State (including current living conditions).66 On the other hand, customary international law,67 international treaties,68 and even domestic law69 have all been considered when determining the content of a term that follows the ‘evolution of law’.

As a final note, it has to be stressed that this tug-of-war between the principle of contemporaneity and evolutive interpretation guided the focus of the title on the three main approaches to explaining persistence and change through time, i.e. endurantism, perdurantism and exdurantism. These philosophical schools of thought were selected as they seem to reflect the same challenges that the different approaches to intertemporal considerations in the interpretative process face. On the one hand, we have the principle of contemporaneity, which argues that the terms of a treaty should be understood as they stood at the time of the conclusion of a treaty, which seems to correspond to endurantism. A treaty is to be understood as being completely there.70 On the other hand, we have evolutive interpretation, which seems to reflect on the interpretative plane either the perdurantist or the exdurantist school of thought, depending on whether one sees the treaty as continuous instrument a ‘space-time worm’ or simply as a collection of interpretative ‘still images’ that are taken each and every time a judicial body is called to interpret the treaty in question.

But before making any premature claims regarding the nature of treaties, let us first examine whether during the preparation of the VCLT the ILC members were aware of the connection of Article 31 with intertemporality, and whether the existing direct and indirect ‘points of entry’ of intertemporal considerations were a conscious choice, with an intended specific content and range of function.

6.3 Silence Can Speak Volumes: The Lack of Explicit References to Intertemporal Considerations in the VCLT

6.3.1 Pre-VCLT Considerations on the Topic

It would be wrong to assume that the Island of Palmas case, that was the first instance where the issue of intertemporal law grabbed the attention of international law practitioners and scholars.

The two patriarchs of international law had already taken position on the issue of time and change on the interpretation of treaties. Both Vattel and Grotius unequivocally came down on the side of the principle of contemporaneity arguing that ‘[l]anguages vary incessantly and the signification and force of words change with time. When an ancient act is to be interpreted, we should then know the common use of the terms at the time when it was written.’71

Originally, the concept of intertemporal considerations within the interpretative process had failed to register a significant impact on the deliberations of the Institut de Droit International (IDI). Only Lauterpacht during the Sienna Session (1952) made passing references to the issue.72 Almost two decades later the IDI returned to the subject of intertemporal law with a vengeance, devoting the Wiesbaden Session on the matter culminating in a Resolution.73 It has to be noted that the discussions attempted to address all aspects of intertemporal law, not just the interpretative ones, yet, the solution at which the members of IDI arrived was almost a verbatim reproduction of Huber’s dictum.74

So what had transpired during these two IDI Sessions that could explain such a shift in focus? The answer can be found in the travaux préparatoires 75 of the VCLT and it is exactly to those that we shall now turn our attention.

6.3.2 Rejection of Explicit Incorporation of the Doctrine of Intertemporal Law in the VCLT: Draft Article 56

In his Third Report on the Law of Treaties Special Rapporteur Waldock proposed an article entitled ‘Inter-temporal Law’. In this he essentially adopted Judge Huber’s structure in his famous Island of Palmas dictum, substituting the terms of ‘appreciation’ and ‘manifestation’ with the terms ‘interpretation’ and ‘application’.76 Paragraph 1 of Draft Article 56 is a statement of the principle of contemporaneity, a principle which, according to Special Rapporteur Waldock, was supported by the international jurisprudence of the time.77 Of import is the fact that Waldock felt the need to elaborate further on the driving force behind this jurisprudence. According to him, the reason why international courts and tribunals in that jurisprudence opted for the principle of contemporaneity was that it was closest to the will of the parties, especially considering that most of these disputes related to boundary treaties and related issues. It is only logical to assume that the parties would have wanted in such instances to resolve the matter once and for all and not for the boundaries to ebb and flow in tandem with the tidal forces of evolving delimitation principles of international law.78

This Draft Article sparked a fiery debate amongst the ILC members on several levels. Some objected to the apparent contradistinction between interpretation and application,79 others that the issue tackled topics that were addressed by or at least co-dependent on other areas of treaty law,80 while others argued whether there was a hierarchical relationship between the two paragraphs.81 Irrespective of this, the common denominator on which all ILC members seemed to agree was that the will of the parties was the decisive criterion for establishing which rules applied to a particular treaty medio tempore.82 This fragmentation of approaches on Draft Article 56 was equally reflected in the comments made by the Governments, with some arguing in favour of a strict adherence to the principle of contemporaneity,83 while others in favour of evolutive interpretation.84 As to what should be the decisive criterion there were two main attractors: intention of the parties85 and good faith.86

Following this, Special Rapporteur Waldock decided to omit Draft Article 56 from his Sixth Report. A critical factor in this decision was probably the fact that the two legs of Draft Article 56 were being dealt with in other parts of the Draft Articles. In more detail, the first paragraph of Draft Article 56, ‘[a] treaty is to be interpreted in the light of law in force at the time when the treaty was drawn up’, was supposed to be reflected in the Draft Articles on interpretation under discussion,87 while the second paragraph, ‘[s]ubject to paragraph 1, the application of a treaty shall be governed by the rules of international law in force at the time when the treaty is applied’, was considered to be regulated by Draft Article 68, which tackled the issue of modification of treaties.

It is perhaps ironic that references to intertemporal considerations in both of these Articles did not survive the scrutiny of future discussions and none of them found their way into the VCLT.88 Nonetheless, during the Vienna Conferences on the Law of Treaties, Waldock reiterated that intertemporal law was fraught with difficulties and that the ILC had made the conscious and tactical choice of abandoning making explicit references to it, since otherwise its members would have gotten bogged down in addressing the highly mercurial relationship between customary law and treaty law.89 The fact that the deletion of Draft Article 56 did not stir up too much controversy among the delegations of the Governments during the Vienna Conference on the Law of Treaties, seems to be a pretty good indication that these concerns also reverberated with the States.

6.3.3 Rejection of Explicit Solutions to Intertemporal Considerations Through the Backdoor of Article 31

Apart from Draft Article 56, intertemporal considerations found their way also into the debates on the rules of treaty interpretation and in particular what would eventually become Article 31(3)(c) VCLT. As with Draft Article 56 the main question was which rules were the ones pertinent for the interpretation of the treaty. Should a treaty be interpreted in the light of the rules in force at the time of the conclusion of the treaty or in force at the time of the interpretation of a treaty? Strong views were expressed in support of both approaches.90 In an attempt to try and find a common ground for negotiation Special Rapporteur Waldock redrafted the text of then Draft Article 70 (later to become Article 31(3)(c) VCLT) to read: ‘1.(b) in the light of the rules of international law [in force at the time of its conclusion]’,91 but the debate continued with even greater fervor.92

For this reason, in his Sixth Report on the Law of Treaties Waldock decided to remove the part that was within brackets. The Draft Article now read: ‘1. A treaty shall be interpreted … in the light of … (b) the rules of international law’.93 This idea of wording the rule of interpretation in a manner that maximized its potential for flexibility,94 seemed to have gained traction. Whereas the ILC members were previously polarized between adopting a solution that would take into account rules either at the time of the conclusion or at the time of the interpretation of a treaty, now they seemed to be rallying around the idea of ensuring a certain flexibility of the rule that would collapse into the proper solution on an ad hoc basis, guided by the intention of the parties.95 It was this approach that was reflected in the final version of Article 31(3)(c) VCLT that was the basis of the discussions of the 1969 Vienna Conference on the Law of Treaties. As with the deletion of Draft Article 56, the delegations of the participating States were in agreement as to the solution adopted by the ILC, i.e. that of opting for a flexible approach rather than a rigid rule. As the delegation of the Netherlands very succinctly put it, since both the doctrine of intertemporal law and the rules on interpretation were essentially manifestations of the principle of good faith, there was no need for an explicit rule. It was the latter’s application that would give the solution in each scenario as to whether the principle of contemporaneity or the evolutive interpretation was the most apposite response.96

6.4 Points of Entry of Intertemporal Considerations in Article 31 VCLT

6.4.1 Direct Point of Entry

The examination of the discussion leading up to the VCLT revealed that although intertemporal considerations and their direct and indirect ‘points of entry’ within Article 31 VCLT, had been spotted by the ILC members, nonetheless the position that prevailed was that the less said the better. Flexibility though silence was considered to best serve the purpose of Article 31 VCLT, rather than explicit solutions incorporated within the text of that Article.

Similarly to the ILC, international jurisprudence seems also to favour a ‘flexible approach’.97 According to this

approach using conventional language, or the “relevant rules of international law”, the interpreter of a treaty will sometimes have to draw upon the language and rules that were in existence when the interpreted treaty was concluded, and sometimes upon the language and rules existing at the time of interpretation.98

The manner in which the interpreter will select one way or the other is reflective of the three mains schools of interpretation. Some argue that this decision is based on the object and purpose of the treaty,99 while others posit that the nature of the terms100 is the critical element. Finally there is another group, which holds that the intention of the parties is not only the critical element,101 but ubiquitous in any kind of justification one might put forward with respect to adopting an evolutive interpretation. Object and Purpose of the Treaty

The object and purpose of a treaty is sometimes used as a building block in order to establish the validity of evolutive interpretation. In the GabčíkovoNagymaros Project case, for instance, the ICJ’s analysis seems to be teetering between the intention of the parties, on the one hand, and the nature of the obligations contained in the treaty and its object and purpose, on the other.102 This reflects a growing trend in international jurisprudence to justify recourse to evolutive interpretation based on the nature of the text being interpreted, i.e. its object and purpose. There are two groups of treaties where this trend is most pronounced: (i) human rights treaties (and to a lesser degree environmental treaties) and (ii) constituent instruments of international organisations.

With respect to human rights (and environmental) treaties, the idea is that because of the uniqueness and importance of the rights protected by these instruments, their existence and continued relevance must be secured in the face of challenges posed by a constantly changing legal and societal environment.103 The extensive jurisprudence, especially of the European Court of Human Rights (ECtHR) and the Inter-American Court of Human Rights (IACtHR), on the matter seems to prima facie support this point.104 However, that is not to say that human rights treaties are an automatic exception to the principle of contemporaneity, and that to them only evolutive interpretation should be applied. If one scrutinizes the relevant cases it becomes readily apparent that the argument based on the object and purpose of the human rights treaties, is not a self-standing one. On the contrary, it is predicated on the intention of the parties. Since ‘[human rights treaties] represent the very archetype of treaty instruments in which the Contracting Parties must have intended that the principles and concepts which they employed should be understood and applied in the light of developing social attitudes’.105 More than a decade earlier, Higgins had arrived at the same conclusion. ‘“[G]eneric clauses” and human rights provisions are not really random exceptions to a general rule … [but] an application of a wider principle—intention of the parties, reflected by reference to the object and purpose—that guides the law of treaties’.106 Consequently, the reason why evolutive interpretation may seem to be more tailored to the needs and particularities of human rights (and environmental) treaty provisions is not simply and solely because of their object and purpose, but because this very object and purpose reflects the intention (explicit or presumed) of the parties. The object and purpose argument in favour of evolutive interpretation is simply a variant of the ‘time-will’ (intention) of the parties.

The same arguments hold true for the second group of treaties for which evolutive interpretation has been argued to be better tailored in lieu of the principle of contemporaneity, i.e. constituent instruments of international organizations. Sands and Klein have argued that ‘[t]here is some authority for the proposition that a treaty of constitutional character should be subject to different rules of interpretation to allow for the “intrinsically evolutionary nature of a constitution”’.107 Based on that it is no big leap to conclude that ‘given the changing nature of the problems and circumstances international organizations have to confront, a degree of evolutionary adaptation is the only realistic approach to realizing the underlying purposes of the organization as laid down in its constituent instrument.’108

However, looking closely at the arguments in support of evolutive interpretation of these instruments by virtue of their ‘intrinsically evolutionary nature’ it is notable that not a single author argues either that constituent instruments of international organisations are an automatic exception to the principle of contemporaneity or that object and purpose is the basic reason for recourse to evolutive interpretation. All of the relevant analysis in doctrine sooner or later comes back to the acknowledgement that for the purposes of evolutive interpretation the nature of the treaty is a reflection of the intention of the parties.109 Of note is Brölmann’s excellent analysis on the topic, who draws attention to the fact that teleological interpretation and evolutive interpretation should not be conflated with one another, and that it is actually teleological rather than evolutive interpretation that features more prominently in the interpretation of these treaties.110

Consequently, object and purpose of a treaty may assist international judges in determining whether a particular provision should be interpreted evolutively or not, but it can never be the sole basis of this determination. Recourse to evolutive interpretation will unerringly be based on the expressed or presumed intention of the parties. By the same token, no automatic exceptions (either of human rights treaties or of constituent instruments of international organisations) to the principle of contemporaneity can be deduced from international jurisprudence. Any exception will, once again, be based on the intention of the parties. ‘Generic Terms’

The text itself and, in particular, the linguistic characteristics of the terms being interpreted may also have a bearing on the intertemporal dimension in the interpretation of treaties. A term, which is ‘generic’ may push an international court or tribunal in the direction of opting for an evolutive interpretation.111 Various attempts have been to define what exactly a ‘generic term’ is. It has been described as a ‘variable concept’,112 a term with ‘evolutionary potential’,113 ‘whose content the parties expected would change through time’,114 and whose ‘meaning was intended to follow the evolution of the law’.115 Despite the fact that a generally accepted definition of ‘generic term’ continues to elude us, an ex ante determination of the ‘generic’ or not nature of a term could prove useful as it may be quite a forceful argument in favour of evolutive interpretation.

Drawing inspiration from linguistics Linderalk and Helmersen attempt such an ex ante determination. The former, identifies three groups of ‘referring expressions’116: (i) ‘definite referring expressions’, which refer to one or more specific phenomena (ii) ‘indefinite referring expressions’, which refer to one or more non-specific phenomena and (iii) ‘generic referring expressions’, which refer to one or more phenomena as they change in time.117 Out of these groups only the ‘generic referring expressions’ are not time-bound since ‘no relationship is established between the time of the utterance and the time when the referent was assumed to exist’.118 Consequently, such expressions by their nature offer ‘stronger reasons for the assumption that the parties expressed their agreement in such a way that (a) the treaty agrees with the conventional language that exists at the moment of interpretation, and that (b) the treaty will have effects consistent with the international law then in force’.119

Helmersen suggests a different taxonomy. According to him, ‘generic terms’ can be characterised as either (i) ‘value driven’ or (ii) ‘non-value driven’ and linguistically as either (i) ‘evolving’ or (ii) ‘non-evolving’.120 Combining these two taxonomies creates a set of four different groups of ‘generic terms: (i) ‘value-driven non-evolving’, (ii) ‘value driven evolving’, (iii) ‘non-value driven non-evolving’ and (iv) ‘non-value driven evolving’. ‘Non evolving terms’, irrespective of whether they are ‘value driven’ or not, are open to evolutive interpretation only on the basis of the terms being given a ‘special meaning’, as per under Article 31(4) VCLT. ‘Value driven evolving’ terms by definition would be assumed to have ‘evolutionary potential’ as that is the presumed intention of the parties for selecting these terms. Finally, for ‘non-value driven evolving’ terms the in casu tribunal would not be able to rest on the previous assumptions but would have to go into a detailed analysis in order to determine the ‘time-will’ of the parties.121 Furthermore, according to Helmersen, in the jurisprudence of the ICJ a presumption seems to be emerging in favour of evolutive interpretation when two conditions are met: (i) when the term is ‘generic’ and (ii) when the treaty is of unlimited duration.122

All the above attempts to linguistically pre-determine whether a term should be interpreted evolutively or not raise many interesting points. However, as in the previous section on ‘Object and Purpose’, the text of the treaty and the ‘generic’ nature of terms cannot and are not the sole basis for opting for evolutive interpretation. First of all, in very few cases are there any indications given as to why some terms are characterized as ‘generic’123 and in no case has this been done on a strictly linguistic basis. Unfortunately, in most cases the judges simply say they are so and therefore they are; post hoc ergo propter hoc. Furthermore, even in the cases where ‘generic terms’ are used to allow recourse to evolutive interpretation, it is not the text which is the sole basis for justifying such recourse, but what is actually hidden behind the text, the ‘time-will’ of the parties, i.e. their intention to allow certain terms to evolve or to force them to remain static in time.124 Judge Higgins, once again, draws our attention that neither the text, nor the object and purpose of a treaty can be the sole basis for evolutive interpretation. These are mere reflections of the true basis. It is always the intention of the parties (specifically, their ‘time-will’) that should be the international judge’s Northern star when examining whether an evolutive interpretation should be opted for.

[The aim] is not to discover a mythical ‘ordinary meaning’ … we must never lose sight of the fact that we are seeking to give flesh to the intention of the parties, expressed in generalized terms in 1890. We must trace a thread back to this point of departure. We should not, as the Court appears at times to be doing, decide what in abstracto the term ‘the main channel’ might today mean, by a mechanistic appreciation of relevant indicia. Rather, our task is to decide what general idea the parties had in mind, and then make reality of that general idea through the use of contemporary knowledge.125 Intention of the Parties

The principle of contemporaneity as identified by Fitzmaurice and elaborated on in the writings of Thirlway, provides that the intention of the parties determines whether the terms of the treaty being interpreted should retain the meaning they had at the conclusion of the treaty or whether they should follow the evolution of fact or law. It is this intention that is the critical element to be considered. Since so far we have talked about ‘time-slices’, and ‘space-time worms’, it is only appropriate to refer to this intention of the parties that determines the temporal destiny of a particular term as the ‘time-will’ of the parties. This ‘time-will’ may be identified by reference to the text of the treaty, the drafting history, the object and purpose of the treaty, state practice, as well as other relevant treaties.126

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