B. The Facts

The San Juan river runs from Lake Nicaragua to the Caribbean Sea. Part of the border between Costa Rica and Nicaragua runs along the right bank—ie the Costa Rican side—of the San Juan river. An 1858 Treaty of Limits [the Treaty] fixed the course of the boundary between Costa Rica and Nicaragua from the Pacific Ocean to the Caribbean Sea. Article VI of the Treaty established Nicaragua's dominion and sovereign jurisdiction over the waters of the river. At the same time, however, it affirmed Costa Rica's navigational rights on the course of the river which serves as a border between the two States. In the Treaty, the sole authoritative version of which was drafted in Spanish, Costa Rica was given navigational rights ‘con objetos de comercio’. It was the interpretation of this term which was the primary focus of dispute in the ICJ proceedings.

C. ‘Con Objetos de Comercio’: The Court's Evolutive Interpretation

In setting out to determine the precise extent of the contested term, ‘con objetos de comercio’, the Court first had recourse to article VI of the Treaty, which in the translation of the Court read as follows:

Nicaragua argued that ‘con objetos de comercio’ must be translated into English as ‘with articles of trade’ and into French as ‘avec des marchandises de commerce’: the ‘objetos’ in issue were understood to be objects in the concrete and material sense of the term. According to Nicaragua, therefore, the freedom of navigation guaranteed to Costa Rica by article VI consequently relates only to transport of goods intended to be sold in commercial exchange. Conversely, for Costa Rica, the contested term meant in English ‘for the purposes of commerce’ and in French ‘à des fins de commerce’: the ‘objetos’ in issue were understood to be objects in the abstract sense of ends and purposes. According to Costa Rica the freedom of navigation given to it by the Treaty must, therefore, be given the broadest possible scope; at all events it encompasses not only the transport of goods but also of passengers, including tourists.Footnote ⁶ Before addressing the twofold question at hand—what was to be understood by ‘con objetos’ and then by ‘comercio’—the Court made two important observations of a more general nature.

The first of these preliminary observations was to say that as it was for the Court in the present case to interpret the provisions of a treaty, it would do so ‘in terms of customary international law on the subject, as reflected in Articles 31 and 32 of the 1969 Vienna Convention on the Law of Treaties’.Footnote ⁷ The fact, therefore, that Nicaragua was not a party to the Vienna Convention and the fact the that the Treaty to be interpreted considerably pre-dated the drafting of the Vienna Convention did not have the effect of preventing the Court from having recourse to the principles set forth in articles 31 and 32 of the Convention.

Secondly the Court was not convinced by the argument set forth by Nicaragua that Costa Rica's right of free navigation should be interpreted narrowly because it represented a limitation of the sovereignty over the river conferred by the Treaty on Nicaragua, which sovereignty was said to be the most important principle set forth by Article VI. Significantly the Court said that:

In the Court's view, a simple reading of article VI showed that the Parties had not intended to establish any hierarchy as between Nicaragua's sovereignty over the river and Costa Rica's ‘perpetual’ right of free navigation. Instead each of these two affirmations should be seen as ‘counter-balancing the other’.Footnote ⁹ Nicaragua's sovereignty, therefore, is affirmed only to the extent that it does not prejudice the counter-balancing right of Costa Rica to free navigation in its domain; though the right to free navigation is ‘perpetual’, it is granted only on condition that it does not prejudice the key prerogatives of the territorial sovereignty of Nicaragua. There were thus no grounds for an a priori proposition that the words ‘libre navegación … con objetos de comercio’ be given a specially restrictive interpretation, any more than an extensive one, the Court said.Footnote ¹⁰

Moving on to look at the meaning of the phrase ‘con objetos’, the Court first observed that the Spanish word ‘objetos’ can, depending on the context, have either of the two meanings put forward. The context must therefore be examined to ascertain the meaning to be ascribed in the question which was in issue: the two meanings were sufficiently different that examination of the context would generally allow for a firm conclusion to be reached. On the background of such an examination, the Court was of the view that the interpretation advocated by Nicaragua could not be upheld. The main reason for this was that ascribing the meaning ‘with goods’ or ‘with articles’ to the phrase in issue would result in rendering meaningless the entire sentence in which the phrase appears. The relevant part of article VI reads: ‘Costa Rica tendrá … los derechos perpetuos de libre navegación …, con objetos de comercio, ya sea con Nicaragua ó al interior de Costa Rica.’ Had the Court accepted Nicaragua's interpretation, there would be no intelligible relationship between the clause following the phrase ‘con objetos de comercio’—ie ‘ya sea con Nicaragua ó al interior de Costa Rica’ (‘whether with Nicaragua or with the interior of Costa Rica’)—and the preceding part of the sentence. Costa Rica's interpretation, by contrast, would allow the entire sentence to be given a coherent meaning. If the phrase were to mean ‘purposes of commerce’ then the immediately following clause—‘ya sea con Nicaragua…’—clearly relates to ‘comercio’; the sentence then conveys a perfectly comprehensible idea. Thus, the Court went on to say, ‘in the present instance a literal analysis of the sentence containing the words requiring interpretation leads to one of the proposed meanings being preferred over the other’.Footnote ¹¹ This finding, the Court said, was supported by three additional arguments, all of which pointed to the same conclusion.

First, the Court pointed out that ‘objetos’ had been used in another article of the Treaty, that is, article VIII. There it could only have the abstract meaning of ‘purposes’ and ‘subjects’: ‘Nicaragua se compromete á no concluir otro (contrato) sobre los expresados objetos …’ (‘Nicaragua undertakes not to conclude any other contract for those purposes…’). It was therefore reasonable to infer that the Parties tended to understand ‘objetos’ in its abstract sense; at least this meaning was familiar to them in their treaty practice.Footnote ¹²

Second, the Court deduced a further indication from the ‘Cañas–Martinez’ Peace Treaty, signed by the Parties on 8 December 1857, but which was never ratified and therefore did not enter into force. In this instrument the Parties tended to use the expression ‘artículos de comercio’, which indubitably translates as ‘articles’ or ‘goods’ of commerce. This, the Court said, would tend to show that when the Parties at the time wished to refer to physical property giving rise to commercial transactions, they did not make use of the term ‘objetos de comercio’, opting instead for an unambiguous term. The Court further noted that it is reasonable to assume that the Parties' replacement of one word with another in two successive instruments, the second of which was drafted shortly after the first, indicated that the Parties wished in the second to refer to something different from that in the first, and that the two terms used must not be taken to mean the same thing.Footnote ¹³

The Court thirdly considered it significant that the two Parties had agreed on the meaning of the phrase ‘con objetos de comercio’ as ‘for the purposes of commerce’ in 1887, when the two Parties each submitted an English translation of the 1858 Treaty to President Cleveland for use in the arbitration proceedings he had been asked to conduct. This argument by itself was undoubtedly not conclusive, as the only authoritative version of the instrument was the Spanish one, and at the time the Parties might have made the same mistake in translation. Furthermore, in submitting the 1877 translation, Nicaragua might have paid insufficient attention to the meaning of the term ‘objetos de comercio’, which was not at issue in the question submitted to the arbitrator. Nevertheless, it remained the case that this concurrence was a significant indication that, at the time, both Parties understood ‘con objetos de comercio’ to mean ‘for the purposes of commerce’. This therefore was the meaning accepted by the Court.Footnote ¹⁴

Having solved the first part of the problem, the Court moved on to finding the meaning to be ascribed to the word ‘commerce’ in the context of Article VI, so that the exact extent of the right of free navigation could be defined. Nicaragua argued that, for the purposes of the Treaty, ‘commerce’ covered solely the purchase and sale of merchandise, of physical goods, excluding all services, such as passenger transport. In line with this, Nicaragua contended that it was important to give the words used in the Treaty the meaning they possessed at the time the Treaty was concluded. Nicaragua averred that determining the intent of the drafters is the main task of interpretation and that identifying the meaning given to the words at the time the Treaty was concluded was the only way to remain true to the intent of the drafters of the Treaty.Footnote ¹⁵ On the other hand, Costa Rica argued that ‘commerce’ as used in the Treaty took in any activity in pursuit of commercial purposes; it therefore must include, inter alia, the transport of passengers, tourists among them, as well as of goods. In this regard Costa Rica added that ‘commerce’ must be conceived of as a broad concept extending even beyond for-profit activities. Costa Rica in this regard cited the 19^th century editions of the Dictionary of the Royal Spanish Academy, in which the word ‘comercio’ is given the second meaning of ‘comunicación y trato de unas gentes ó pueblos con otros’, or communication and dealings of some persons with others. It must follow, argued Costa Rica, that ‘commerce’ includes movement and contact between inhabitants of the villages on the Costa Rican bank of the San Juan river, as well as the use of the river for purposes of navigation by Costa Rican public officials providing the local population with essential services.Footnote ¹⁶

The Court agreed with neither the ‘particularly broad interpretation advocated by osta Rica nor the excessively narrow one put forward by Nicaragua’.Footnote ¹⁷ With respect to the former the Court observed that, were it to be accepted, the result would be to bring within the ambit of ‘navigation for the purposes of commerce’ virtually all forms of navigation on the river. Had that been the intent of the Parties to the Treaty, it would be difficult to see why they went to the trouble of specifying in the first place that the right of free navigation was guaranteed ‘for the purposes of commerce’, as this language would have had virtually no effect. With respect to the narrow interpretation advanced by Nicaragua, the Court observed that it was supported mainly by two arguments: the first one is based on Nicaragua's interpretation of the phrase ‘con objetos’, which the Court rejected; the second was based on the assertion that ‘commerce’ should be given the narrow meaning it had when the Treaty was entered into. The Court chartered a middle course between the interpretations put forward by the Parties.

The Court said that it was true that the terms used in a treaty must be interpreted in light of what is determined to have been the common intention of the parties, which is perforce contemporaneous with the treaty's conclusion. A court seised of a dispute, or the parties themselves, may then, in the determination of the meaning of a treaty for purposes of good-faith compliance with it, set out to ascertain the meaning a term had when the treaty was drafted, as doing so can shed light on the parties' common intention. The Court reiterated that it has so proceeded in certain cases which required it to interpret a term whose meaning had evolved since the conclusion of the treaty at issue, and in those cases the Court adhered to the original meaning. In this regard the Court cited its judgment in the case concerning Rights of Nationals of the United States of America in Morocco (France v United States of America),Footnote ¹⁸ on the question of the meaning to be given to ‘dispute’ in the context of a treaty concluded in 1836, the Court having determined the meaning of this term in Morocco when the Treaty was concluded. It further cited its judgment in the case concerning Kasikili/Sedudu Island (Botswana/Namibia),Footnote ¹⁹ in respect of the meaning of ‘centre of the main channel’ and ‘thalweg’ when the Anglo–German Agreement of 1890 was concluded.Footnote ²⁰ To this the Court added the following caveat:

On the one hand, said the Court, the subsequent practice of the parties, within the meaning of article 31 (3) (b) of the Vienna Convention, may 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 intent of the parties upon conclusion of a treaty was, or may be presumed to have been, to give the terms used, or some of them, a meaning or content capable of evolving—not one fixed once and for all, so as to make allowance for developments in international law. In such instances, the Court continued, it is indeed possible, in order to respect the parties' common intention at the time of conclusion, that account be taken ‘of the meaning acquired by the terms in issue upon each occasion on which the treaty is to be applied.’Footnote ²² This the Court illustrated by reference to the reasoning in Aegean Sea Continental Shelf (Greece v Turkey).Footnote ²³ The Court was called upon in that case to interpret a State's reservation to a treaty excluding from the Court's jurisdiction ‘disputes relating to territorial status’ of Greece. The meaning of ‘territorial status’ was contested. The Court in Aegean Sea said:

Commenting on its 1978 judgment, the Court said that though it had been adopted in connection with the interpretation of a reservation to a treaty, the Court's reasoning in that case was fully transposable for purposes of interpreting the terms of a treaty themselves. As adumbrated above,Footnote ²⁵ the Court in the Decision went on to say that where the parties have used generic terms in a treaty, the parties necessarily having been aware that the meaning of the terms was likely to evolve over time, and where the treaty is one of continuing duration, the parties as a general rule must be presumed to have intended those terms to have an ‘evolving meaning’.Footnote ²⁶

This, the Court said, was the case in respect of the term ‘comercio’ as used in article VI of the 1858 Treaty. First it was a generic term. Second, the 1858 Treaty was entered into for an unlimited duration: it was intended from the outset to create a legal regime characterized by its perpetuity. The last observation was supported, in the view of the Court, by the object itself of the Treaty—to achieve a permanent settlement between the Parties of their territorial disputes. Territorial rules laid down in this type of treaty are, by their nature, particularly marked in their performance; ‘it is a principle of international law that a territorial régime established by treaty “achieves a permanence which the treaty itself does not necessarily enjoy” and the continued existence of that régime is not dependent upon the continuing life of the treaty under which the régime is agreed’. In the view of the Court, this was true as well of the right of free navigation guaranteed to Costa Rica by article VI. The Court concluded from this that ‘the terms by which the extent of Costa Rica's right of free navigation has been defined, including, in particular, the term “comercio”, must be understood to have the meaning they bear on each occasion on which the Treaty is to be applied, and not necessarily their original meaning’.Footnote ²⁷ Therefore, even assuming that the notion of ‘commerce’ does not have the same meaning today as it did when the Treaty was concluded, ‘it is the present meaning which must be accepted for purposes of applying the Treaty’.Footnote ²⁸ The Court found that the right of free navigation in issue applied to the transport of persons as well as the transport of goods, as nowadays the activity of transporting persons can be commercial in nature. If a price—other than a token one—was paid to the carrier by the passengers or on their behalf, the Court saw no persuasive reason by which to exclude the transport of tourist from this category. Any navigation not carried out either to transport goods intended to form the subject of commercial transactions or to transport passengers in exchange for money paid by them or on their behalf could not, however, be regarded as falling within the ‘purposes of commerce’ under article VI. This would be the case in particular of navigation by vessels used in the performance of governmental activities or to provide public services which are not commercial in nature.Footnote ²⁹

D. Conclusion

The evolutive interpretation adopted by the Court in the Decision is in line with a general rule in public international law, as evidenced particularly by the Namibia, Aegean Sea, and Gabčíkovo–Nagymaros Project decisions of the Court.Footnote ³⁰ This needs explaining.

The Court in the last of those decisions held that ‘newly developed norms of environmental law are relevant for the implementation’ of the Treaty in issue.Footnote ³¹ The articles of the Treaty did not contain ‘specific obligations of performance but require[d] the parties, in carrying out their obligations to ensure that the quality of water in the Danube is not impaired and that nature is protected, to take new environmental norms into consideration’.Footnote ³² The Court referred to the articles in issue as ‘evolving provisions’, whose inclusion into the Treaty had the effect that ‘the Treaty is not static, and is open to adapt to emerging norms of international law’.Footnote ³³ This conclusion the Court based on the Parties' intentions. The Court's interpretation in Gabčíkovo–Nagymaros Project has been criticized. Duncan French has taken issue with the Court over the latter's statement that the Parties ‘[b]y inserting these evolving provisions into the Treaty, […] recognized the potential necessity to adapt the Project’.Footnote ³⁴ The gist of French's argument is that ‘[r]ecognition alone is usually not sufficient to generate intent’.Footnote ³⁵ It is precisely this contentious issue the Court clarified when it said in the Decision that

This seems to be the seamless continuation of what, almost 15 years ago, Rosalyn Higgins argued in these pages: ‘that intention of the parties is often to be deduced from the object and purpose of the agreement’.Footnote ³⁷ By underscoring the existence of such ‘a general rule’, the Court brings out that evolutive interpretation is as much a concomitant of treaties where the parties have used generic terms or clauses—the parties necessarily having been aware that the meaning of the terms or clauses, of a treaty characterized by its perpetuity, was likely to evolve—as it is to human rights treaties like the ECHR. This is an expression of the fact that the so-called inter-temporal principle of international law—that the rules of law contemporaneous with the treaty in the past, and not present rules of law, control the legal significance of the treaty—does not apply in the interpretation of human rights obligations and of what Higgins refers to as ‘generic clauses’ treaties.Footnote ³⁸ (It may be, however, that these two categories are not as discrete as they seem at first glance; perhaps the terse and generic provisions of the ECHR, too, should be conceived of as ‘generic clauses’. Because of the nested quality of the two categories, therefore, where the ECHR system is concerned there is a double set of reasons for which the provisions must be evolutionary.) The apposite question is, in any event, whether it has been the intention of the parties, in settling out their obligations, that those obligations be determined by reference to the law as it then stood or as it might stand at the time when any controversy later surfaced.

This was neatly put into system by Higgins when she said that ‘“generic clauses” and human rights provisions are not really random exceptions to a general rule. They are an application of a wider principle—intention of the parties, reflected by reference to the objects and purpose—that guides the law of treaties’.Footnote ³⁹ What Namibia, Aegean Sea, Gabčíkovo–Nagymaros, this Decision—and the many judgments by the European Court of Human Rights which evince use of evolutive interpretation—have in common is a loyal focus on the intention of the parties. The Decision is, therefore, the latest stage in a series of important clarifications by the International Court as to what, in this regard, are the general rules of interpretation in the law of treaties. As such the Decision, unequivocal on this question, seems to soften the brunt of statements put forward by some commentators which paint the evolutive interpretation used in the regime of the ECHR as ‘controversial’ and ‘not always conform[ing] to the classical rules on interpretation’.Footnote ⁴⁰ The Decision, in other words, is a welcome clarification to those concerned with methods of interpretation by international courts and with the implications for the issue of ‘fragmentation of international law’.Footnote ⁴¹