#16803 - Sources Of International Law - Public International Law

Sources of International Law

The starting point is Article 38(1) of the Statute of the International Court of Justice, 1945:

‘The Court, whose function is to decide in accordance with international law such disputes as are submitted to it shall apply:

international conventions, whether general or particular, establishing rules expressly recognised by the contesting States;

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

the general principles of law recognised by civilised nations;

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 the rules of law.”

But this does not provide a complete list of the sources of international law — it is a direction to the Court authorising it to consider various materials when deciding disputes. GA resolutions, acts of international organisations, diplomatic correspondence etc. often influence the Court’s decisions, but are not listed as sources. The reason for this may be that they are not formally accepted sources of international law per se, but are evidence of state practice which may be submused under customary international law.

A distinction is sometimes made between formal, material and evidentiary sources of international law. Formal sources are those that explain the procedures by which rules become legally binding, for example, in the UK, the passage of Bill through Parliament is a formal source of law; in international law the formation of custom/Treaty is a formal source of law. Material sources, on the other hand, are concerned with the content of the obligation, and perform the function of enabling subjects of international law to be reasonably certain about rights and obligations prescribed by the law. Examples are state practice, judicial decisions, GA resolutions, etc. — because they all indicate what a state’s obligations actually are, rather than the method by which those obligations become legally binding. Finally, an evidentiary source includes the precise content of legal obligations that bind the states, and are substance related. Things that form evidence of state practice, for example, can be diplomatic correspondence, actual state activity, etc. I don’t think this is a very useful categorisation. Dixon also says that this distinction ‘distorts the function of the sources of international law because all ‘sources’ are, in some way, both law creating and law identifying…’ (see page 27).

Let’s look at the individual categories of the sources of international law. These are:

Custom

Treaties

General principles of law;

and those not included in the statute:

Judicial decisions

Resolutions of international organisations? (see Higgins)

Writers

Soft law

1. Custom = state practice + opinio juris

Law evolved from the practice/customs of states. The activities of states in the international arena may give rise to binding law. Eg: if all maritime nations declare territorial sea 12 miles seaward from the coastline, a customary law to this effect may develop. Some factors that can be identified as elements of customary international law, such as the consistency, generality and duration of state practice, as well as opinio juris.

State practice must be reasonably consistent. In the Lotus Case, the Permanent Court said that it must be ‘constant and uniform’. However, the more fundamental the customary rule, the more consistent any contrary state practice must be before a change in that rule could be recognised (for example, alleged change to jus cogens should be supported by almost universal state practice). So the degree of consistency required will change depending on the subject matter.

State practice must be general, or in other words, common to a significant number of states. However, special weight may be given to the practice of those states whose interests are specifically affected by the subject matter of the rule, such as the maritime states in the North Sea Continental Shelf Cases. On the other hand, if a state initially and sustainably objects to a customary rule, this may prevent that state from being bound from it (the persistent objector): the Court in the Anglo-Norwegian Fisheries Cases said that Norway’s persistent objection to any attempt to apply the ten-mile rule to the Norwegian coast had rendered customary law to that effect inapplicable to Norway. This was because there was an initial objection by a Norwegian minister in his statement, and sustained objection, following principles of delimitation that it considered part of its system in a consistent and uninterrupted manner. Furthermore, the ‘general tolerance’ of other States with regard to Norway’s practice showed that such objection on Norway’s part was not contrary to international law. (NB: in this case, the Court did not think that the 10-mile rule had acquired customary law status, but considered the above questions anyway).

This is important as it may later have effect on the practice of other states (acquiescing in deviation from the customary law); if deviations become so widespread, the previous rule will be destroyed and replaced.

In the Asylum case (Colombia v Peru), the Court recognised that local or regional custom could be binding among a group of states, though did not find that such existed on the facts. In that case, the Colombian government had invoked ‘American international law in general’, alleging local custom peculiar to Latin American states. The party alleging the existence of local custom must prove constant and uniform practice within the locality, which Colombia could not in this case: ‘the facts disclose so much uncertainty and contradiction, fluctuation and discrepancy in the exercise of asylum and official views expressed’.

General, uniform and consistent state practice must be supplemented by opinio juris — states’ recognition that the rule is binding upon them as law, a belief that the practice is obligatory. It is obviously difficult to ascertain whether there is opinio juris or not, as states rarely explicitly state why they have taken a certain course of conduct. Opinio juris that a certain proposition is law may sometimes be found in General Assembly resolutions or in the process by which such resolutions are adopted (cf but see Legality of the Threat or Use of Nuclear Weapons, below). The Court in the North Sea Continental Shelf Cases said that ‘the frequency or even habitual character’ of a practice is not enough to establish opinio juris.

In the Legality of the Threat or Use of Nuclear Weapons case, the Court considered whether a rule of customary international law prohibiting the threat or use of nuclear weapons existed, and stated that the substance of the rule must be looked for in actual state practice and opinio juris. The Court said that ‘the members of the international community are profoundly divided on the matter of whether non-recourse to nuclear weapons over the past 50 years constitutes the expression o fan opinio juris’, and therefore was unable to find such opinio juris. However, the Court noted that GA resolutions, although not binding, may sometimes have normative value in evidencing opinio juris, but said that the resolutions on the use of nuclear weapons fell short of establishing OJ, because ‘several resolutions have been adopted with substantial numbers of negative votes and abstentions’. No customary rule on the prohibition of the threat or use of nuclear weapons existed.

The North Sea Continental Shelf Cases initially set out the dual requirement of state practice + opinio juris to form customary law. In these cases, theCourtexplained the criteria necessary to establish State practice – widespread and representative participation. Ithighlightedthat the practicesof those States whose interests were specially affected by the custom were especially relevant in the formation of customary law. It also heldthat uniform andconsistent practice was necessary to demonstrateopiniojuris – the belief that Statepractice amounts to a legal obligation. In this case, the parties disagreed as to the rules of international law applicable to delimitation of the territorial sea. The Court had to consider whether Germany, who had not ratified the Geneva Convention which included the equidistant principle, would nevertheless be bound by it provisions so far as they reflected customary international law. This was, in principle, possible (for example see the Nicaragua case below), however it was held that the Treaty had neither crystallised existing customary international law at the time it was drafted, nor did it acquire customary status afterwards. Number of ratifications were not adequately widespread, and there was not sufficient opinio juris. For the latter, the Court examined cases where states had indeed delimited their boundaries according to the equidistance rule, but could not deduct any OJ from state practice, which was essential for the formation of customary law. The Court concluded that the equidistance principle was not binding on Germany by way of treaty or customary international law. Inthe case of the latter, the principle had not attained a customary international law status at thetime of the entry into force of the Geneva Convention or thereafter. As such, the Court held that theuse of the equidistance method is not obligatory for the delimitation of the areas concerned in the present proceedings. However, Judges Tanaka and Sorensen stated that OJ was difficult to discover, and...