International Law

Part 1

---

Article 38(1) of the Statute of the International Court of Justice is generally recognized as a definitive statement of the sources of international law. It requires the Court to apply, among other things, (a) international conventions "expressly recognized by the contesting states", and (b) "international custom, as evidence of a general practice accepted as law". To avoid the possibility of not having any applicable law (“non liquet”), sub-paragraph (c) added the requirement that the general principles applied by the Court were those that had been "the general principles of the law recognized by civilized nations".

Due to the fact that it is (sovereign) states that, by consent, determine the content of international law, sub-paragraph (d) acknowledges that the Court is entitled to refer to "judicial decisions" and the most highly qualified juristic writings "as subsidiary means for the determination of rules of law".

On the question of preference between sources of international law, rules established by treaty will take preference if such an instrument exists. It is also argued however that international treaties and international custom are sources of international law of equal validity; this is that new custom may supersede older treaties and new treaties may override older custom. Certainly, judicial decisions and juristic writings are regarded as auxiliary sources of international law, whereas it is unclear whether the general principles of law recognized by 'civilized nations' should be recognized as a principal or auxiliary source of international law.

Treaties

(A) Treaties and conventions are the persuasive source of international law and are considered "hard law." Treaties can play the role of contracts between two or more parties, such as an extradition treaty or a defense pact. Treaties can also be legislation to regulate a particular aspect of international relations, or form the constitutions of international organizations. Whether or not all treaties can be regarded as sources of law, they are sources of obligation for the parties to them. Article 38(1)(a) of the ICJ, which uses the term "international conventions", concentrates upon treaties as a source of contractual obligation but also acknowledges the possibility of a state expressly accepting the obligations of a treaty to which it is not formally a party.

For a treaty-based rule to be a source of law, rather than simply a source of obligation, it must either be capable of affecting non-parties or have consequences for parties more extensive than those specifically imposed by the treaty itself.

(B) Treaties and conventions are also a source of recognized international custom. Some treaties are the result of codifying existing customary law, such as laws governing the global commons, and the right to war (“jus ad bellum”). While the purpose is to establish a code of general application, its effectiveness depends upon the number of states that ratify or accede to the particular convention. Relatively few such instruments have a sufficient number of parties to be regarded as international law in their own right. The most obvious examples are the 1949 Geneva Conventions for the Protection of War Victims.

Most multi-lateral treaties fall short of achieving such a near universal degree of formal acceptance, and are dependent upon their provisions being regarded as representing customary international law and, by this indirect route, as binding upon non-parties. This outcome is possible in a number of ways.