Book Symposium: Comparative Reasoning in International Courts and Tribunals

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Daniel Peat’s excellent study Comparative Reasoning in International Courts and Tribunals covers important issues in the interpretation of treaties. Its examination of how certain international courts and tribunals have used domestic law and principles or concepts derived from domestic law in reasoning leading to interpretation of treaties provides a useful stimulus to consideration of such materials in treaty interpretation. While the book is about interpretation on the international plane, it will also furnish guidance for courts within national systems. Such courts are increasingly encountering legal issues arising from treaties, as treaties come to provide new rules to be given effect within the law of states parties to them, harmonize laws, and provide rules on jurisdiction.

One issue, which is considered in the early part of the book, is how use of reasoning from domestic laws fits with the provisions of interpretation in the 1969 Vienna Convention on the Law of Treaties (‘the Vienna rules’). The flexibility and wide scope of these rules for the discretion of the interpreter has not always been well understood. The book suggests that the Vienna rules ‘set the outer limits of the interpretative enquiry by prescribing the materials that should be taken into account by the interpreter, where those materials are present’ (p 21). While this is explained as meaning that the rules do not give a framework against which it can be judged whether an interpretation is ‘correct’, the Vienna rules are not generally limiting. They provide the essential minimum of identifiable materials or interpretative elements, some indicators of a method, and a springboard or necessary starting point for interpretation of a treaty.

The ‘open’ character of the rules, which is clear from their content and formulation, can also be shown by the way the International Law Commission treated the so-called canons or maxims often expressed by their Latin tags (expressio unius, eiusdem generis etc). Not readily reducible to firm principles (and hence to ‘rules’), these were not included in the draft or final Vienna rules. This was not because they were never to be used, but rather because circumstances for their deployment were too variable and they were only, for the most part, to be regarded as principles of logic and good sense rather than principles constituting rules. (They are exhaustively studied in another recent book: Klingler et al (Eds). Between the Lines of the Vienna Convention? Canons and Other Principles of Interpretation in Public International Law, Kluwer, 2019).

It could reasonably be said that in the right circumstances, use of domestic laws can fulfil a similar role. Where not indicative of practice pursuant to a treaty to show an agreed interpretation (which is already covered by the rules), use of domestic laws may clarify the selection of the appropriate ordinary meaning of terms used or act as supplementary means of interpretation. ‘Supplementary’ means envisaged by the Vienna rules are just that. They supplement the general rule by adding to it or make good any lack of effectiveness in that rule. ‘Supplementary’ means are not exclusively preparatory work and the circumstances of conclusion of a treaty, and are not properly viewed as invariably subordinate to the general rule. This is clearly shown by the fact that recourse to them can be determinative when the prescribed criteria (ambiguity, obscurity etc) apply. ‘Determining’ the meaning is the very antithesis of acting in a subordinate role, which is the reason for prescribing gateways for use of supplementary means for this purpose. Other use of supplementary means is as an adjunct to the general rule in confirming a meaning achieved by its application.

The valuable part which domestic law can play in treaty interpretation is not novel, although such an extensive study of its use as Daniel Peat’s is new. An example from long ago is a case before the US Supreme Court in 1901: Tucker v Alexandroff (183 US 424). Alexandroff was sent to Philadelphia as one of a detachment of Russian sailors who were to man a named warship being built there, with a fuller complement of sailors to be sent out later when it was ready to sail away. After the ship was launched but before it was finished, fitted out, commissioned and put through acceptance trials, Alexandroff left for New York where he found a job and applied for US citizenship. Arrested there as a deserter, he sought release on the ground that he did not come within the provisions of an 1832 bilateral US–Russia treaty requiring local authorities of each party to arrest deserters from the crews of ships of war and merchant vessels of the other party and to assist in their return.

Alexandroff claimed that as the vessel had not been commissioned it was not a warship, and as neither he nor his colleagues had at the time of his departure for New York been on board it, he was not a member of a ‘crew’. Hence he could not be a ‘deserter’. The clinching factor for the majority of the judges seems to have been a detailed study of the domestic law of many states which had a merchant navy, under which anyone who had signed on as crew was to be treated as a deserter if they failed to turn up for duty at the appointed time, whether they previously had been on board or not. The rationale for this was that if once signed on for a ship a sailor could just bunk off, the master or commander could find himself without a complete crew at the time of sailing. The equivalent applied, it was argued, in the naval situation once a sailor had been assigned to a ship. This factor, combined with the cooperative aims of the treaty, determined for the majority that Alexandroff was a member of a crew of the unfinished ship and thus a deserter. Only a very literal reading and somewhat blinkered approach to giving meaning to the terms ‘warship’, ‘crew’ and ‘deserter’ could found reasoning for the dissent.

This case was long before the 1969 Vienna Convention on the Law of Treaties. Would the current Vienna rules afford such weight, or allow any function, to comparison of domestic law to give meaning to the term ‘crew’? If the dissenters’ approach were the proper application of the Vienna rules, this would perhaps give some support for Professor McDougal’s criticism of the Vienna rules as highly restrictive, with an ‘insistent emphasis upon an impossible, conformity-imposing textuality’. However, the presence in the Vienna rules of a role for context, object and purpose, subsequent practice and supplementary means shows emphatically that McDougal’s view on textuality was unfounded, and extensive practice further confirms this.

Textual elements in the treaty could only have a partial role here. There would be limited value in looking at a dictionary to select the ordinary meaning  of ‘crew’ because there are so many possibilities, the dozen or so given by the Oxford English Dictionary potentially providing some support for arguments on either side, with further difficulties attendant upon the change indicated there in nautical usage over the years. A dictionary definition was never offered as a solution by the International Law Commission in its commentary on the draft articles that became the Vienna rules, even though a definition may sometimes provide a starting point. The Commission viewed selection of the ordinary meaning to be guided by the context and object and purpose of the treaty. Supplementary means, including the circumstances leading to inclusion of the provision could confirm the selection or determine the meaning if ambiguity, obscurity etc persisted. The legal skills of the interpreter would be required to reason out the interpretation using these elements.

Without the evidence in Peat’s book some might question whether use of national laws showing the start of a merchant sailor’s service to be before actually joining the ship would be evidence admissible in the interpretative process. The dissenters in the US Supreme Court dismissed it as irrelevant to the terms of service of naval personnel and also because their main focus was on the different topic of when a vessel under construction became a warship. Nevertheless, in this latter quest, the dissenters looked to extensive practice outside treaties for evidence as to when a ship becomes commissioned as a warship, so that they too took in a broad range of materials in seeking to interpret and apply the treaty. Further, the treaty context points to assimilation of sailors from warships and merchant ships in the phrase deserters ‘from ships of war and merchant vessels’.

Perhaps it does not matter too much whether one finds use of domestic law’s relevance to treaty interpretation an adjunct to identifying the ordinary meaning that is particularly apt in a given situation or as a supplementary means of interpretation. In the helpful listing of categories of uses of domestic law in the book’s final chapter, when describing one such use as an auxiliary means of interpretation, Daniel Peat notes that domestic law is rarely determinative of a particular interpretation, but (paraphrasing) can be a good part of the reasoning or confirmation of an interpretative argument when other interpretative sources are thin (pp 218–9). The copious examples throughout the work also demonstrate well what is most aptly described as ‘the irreducibly context-dependent nature of the interpretative process’ (p 221). 

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