Different Ways of Using International Law

The judicial challenges involved in stretching, perhaps even breaking, the common law rules related to use of international law in the domestic sphere are illustrated in the death penalty jurisprudence of the Commonwealth Caribbean.

A. Comparative Uses of All Forms of International Law

Firstly, international law, like any non-national system of law, can be relied upon by a domestic court as non-binding, but perhaps persuasive, comparative authority. Judges may take judicial notice of the rules and principles of public international law, including those established by treaties to which their state is a party, even when they are not embodied in municipal law.^[547] Further, as a result of the presumption that Parliament does not intend to violate its international legal obligations, judges are obliged to consider any relevant rule of public international law and permit the citation of any relevant treaty, including the 1969 Vienna Convention on the Law of Treaties.^[548]

Such comparative uses of public international law cannot be said to be extraordinary. Just as a Commonwealth Caribbean judge can turn to an Australian precedent to help interpret or apply a rule or principle, so too can she or he look to an international legal norm or international judicial decision for guidance. The international source will not be binding, but it can assist the judge by providing a concrete example of legal analysis and legal practice on a particular issue. In this way, the courts in Thomas v Baptiste and Neville Lewis, for example, legitimately could have looked at Inter-American norms to help understand and elaborate common law concepts, such as the right of due process, in relation to domestic procedures — such as whether one has the right to make submissions to the mercy committee.

But such a comparative or illustrative use of international law may only be helpful to clarify or develop an existing domestic legal concept, not to bridge the gap between domestic law and international law. In other words, international jurisprudence could help reveal the full meaning of a right, such as the right to due process; but contrary to Thomas v Baptiste and Neville Lewis, international law could not provide the link between a domestic law right (protection of the law) and a non­domestic process (an Inter-American petition). Only if one were to say that the international legal process somehow became a domestic law one, would it be possible to decide that other domestic processes must await its completion.

Nevertheless such comparative uses of international law can be important and all international norms can be used for such purposes. National judges equally could refer to various forms of international law: (1) binding treaty obligations; (2) �incomplete’ treaty obligations (i.e., where the state has yet to complete the final act required to formally consent to the treaty, and therefore is not yet fully bound);^[549] (3) non­binding treaties, such as treaties concluded between third parties; (4) international judicial decisions; and (5) �soft law’, including non­binding international statements that may shed light on the meaning of a concept or rule. Equally, it is important to note that the strength of the international legal norm as evaluated by international law, either generally or as against the state itself, becomes irrelevant when the norm is merely being relied upon for comparative or illustrative purposes. A non-binding international norm may be equally helpful.

Interestingly, although the use of international law in this illustrative sense may not seem particularly potent, the hard-fought battles at the Privy Council on whether to include, or exclude, international law suggest otherwise.

B. Customary Law as Part of the Law of the Land

Secondly, a domestic tribunal can refer to, and apply, customary international law so long as it is not contradicted by statutory or judicial authority. Customary international law in such cases becomes domestic law and therefore can be applied directly by a domestic court without statutory basis, in the same manner that a judge applies a rule of common law. Interestingly, as established in the Trendtex case, a national judge can even apply customary law that appears to conflict with a prior precedent, if that prior precedent itself adopted and relied upon a rule of customary international law that is no longer in existence.^[550] In other words, domestic judges could use the development of customary international law as a basis for distinguishing prior domestic precedents.

C. As Domestic Statutory Law (Transformation)

Thirdly, international law may affect the domestic sphere when a treaty or customary obligation is transformed by statute. Technically speaking, the international legal obligation is replaced by the domestic law obligation in the incorporating statute, and therefore one might say that international law no longer plays a role here. But this process nevertheless allows a domestic judge to apply national law which closely parallels international law, thereby potentially upholding the state’s international legal obligations.

Importantly, since the judge is applying a domestic statute, the rules of statutory interpretation apply and allow a variety of sources to be examined to ascertain the legislative intention.^[551] One of these sources is the incorporated treaty itself. Francis A.R. Bennion argues that treaties can be looked to in interpreting legislation even where that legislation is unambiguous, and even where the treaty is not referred to in the text of the legislation.^[552] He submits that judicial decisions �suggesting that the court is entitled to consult a relevant treaty only where the enactment is ambiguous can no longer be relied on...

On such grounds, a domestic court therefore may permissibly look to the following sources when interpreting domestic legislation: the treaty which it transforms, its travauxpreparatories, decisions of foreign courts and writings of foreign jurists which point to the correct interpretation of the treaty, and decisions of the organs of international organizations which are entrusted with the task of authoritatively interpreting the treaty (such as the Inter-American Commission on Human Rights and Inter-American Court of Human Rights).^[556]

What may also prove interesting in this context is the question of the manner of transformation. It is easy to recognize express examples of statutory transformation, such as a �Caribbean Court of Justice Act,’ or a �Revised Treaty of Chaguaramas Act.’ But perhaps other, subtler forms of transformation may also exist. This is an area that will be examined below and which could be developed in Commonwealth Caribbean jurisprudence.

D. Interpretation of Ambiguous Domestic Law

Thirdly, it is clear that an unincorporated treaty may be used by courts for the purposes of interpreting ambiguous domestic law. If the domestic statute is ambiguous in the sense of being capable of being read so as to support, or contradict, the treaty obligation, then reference may be made to the unincorporated treaty for interpretive purposes. The �ambiguity’ could be in relation to a number of domestic legal sources including (1) a statute, (2) a constitutional provision, or (3) a common law rule.

What is interesting here is how powerful the interpretive process becomes in such circumstances. The presumption that domestic law should be interpreted so as to comply with international obligations, if not rebutted, has tended to work like a switch: once ambiguity is found, the court will interpret the law so as to conform to the treaty obligation. In other words, ambiguity is followed by conformity with the international rule.

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