Academic journal article University of New Brunswick Law Journal

A Common Law of the World? the Reception of Customary International Law in the Canadian Common Law

Academic journal article University of New Brunswick Law Journal

A Common Law of the World? the Reception of Customary International Law in the Canadian Common Law

Article excerpt


In an increasingly globalized world, the importance of international law to our domestic legal system continues to grow. This growth is both exponential and multidimensional. International law had been traditionally concerned with relations between states and about the status and action of international organizations. But today, not only is international law having a greater impact than ever on the state of domestic law, it also influences more areas of domestic law than ever. These areas include human rights, labour law, commercial law, intellectual property law, immigration and refugee law, and criminal law, to name but a few.

In this paper, I intend to focus on the means by which customary international law exerts its influence on the Canadian domestic legal culture. As will be discussed in greater detail below, customary international law is developed by state practice and the recognition of the legally binding nature of this practice, while other parts of international law are grounded in treaties and other multilateral instruments, which reflect the contractual activities of states and organizations. I will address some intricacies of this process. Before I do so, however, I will use again an analogy which, at least for the classical music lovers, may be of some assistance to understand the issues of interaction of international and domestic law.

A number of years ago, I co-wrote an article describing how the reception of international law into the Canadian legal order could be usefully compared to two distinct classical musical styles. First, there is the "fugue" style, from the Baroque period, in which "one or two themes are repeated or imitated by successively entering and interweaving repetitive elements." (1) The second style is "fusion"--"a merging of diverse, distinct, or separate elements into a unified whole," or "the combination of different styles ... to form a new style." (2)

Metaphorically, these two styles refer to two different approaches to the internalization of international law. Under the fugue approach, the domestic and international legal orders operate independently, and are only interwoven when international law is formally incorporated, or "transformed", into the domestic order. This method may also be termed the dualist approach to reception, under which international law must be expressly received to by some executive and/or legislative action in order for it to be effective domestically.

In contrast stands the fusion approach, which is synonymous with the monist approach to reception. Under this approach, international law is directly incorporated into domestic law and is immediately effective without any additional legislative or executive action. Just like the music created by this style, the fusion approach modifies the domestic law and changes it from what it might otherwise have been.

Subject to certain exceptions, upon which I will elaborate, the Canadian approach to the reception of customary international law has moved decidedly towards the "fusion" end of the spectrum. By and large, customary international law is now directly incorporated into the common law of Canada and is effective immediately without the need for further legislative or executive action. I will first discuss what constitutes custom in international law and how it develops. I will then review the development of the law regarding reception of custom into the domestic legal order, in the U.K. and in Canada. Finally, I will turn to some specific problems and issues raised by the Canadian approach to the reception of customary international law.


A logical starting point is to describe, briefly, what customary international law is and how it gets recognized. Article 38(1) of the Statute of the International Court of Justice identifies the various sources of international law, as follows:

(a) international conventions, whether general or particular, establishing rules expressly recognized by the contesting states;

(b) international custom, as evidence of a general practice accepted as law;

(c) the general principles of law recognized by civilized nations;

(d) subject to the provisions of Article 59, judicial decisions and the teachings of the most highly qualified publicists of the various nations, as subsidiary means for the determination of rules of law. …

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