The relationship between treaty and customary law in the sources of international law

However, the most important point to be noted is that norms derived from the two sources contribute significantly to the system of the law worldwide. Therefore the rules extracted from the two sources may conflict each other in content or even restrict each other, therefore harboring law incongruity. Investigating the relationship between customary law and treaty law as sources of international law. Treaties are explicit law sources that obtain its legitimacy through signatures while on the other hand, customary laws tend to be implicit based on generally accepted principles and practices among nation states. In determining the relationship that exists between these two sources, it is imperative to develop a concrete understanding of these law sources. A good example is the International Court of Justice (ICJ) made a substantive effort to do this in 1969 North Sea Continental Shelf Cases.

International law refers to generally accepted legal relations among states and nations and is regarded as so by these nations1. These laws and rules act as a universal framework through which stabilized and organized international relations are achieved. Customs and treaties are relied upon for decision making among states because there is no existence of parliament on an international level. International law sources include treaties, custom international laws, scholarly writings, decisions of lower and national courts and the generally regarded international laws. When making legal decisions, the International Court of Justice often examines treaties and customs simultaneously. Customs play a substantive role when it comes to the interpretation of treaties3. Most of the times, treaties cannot be utilised without having a reference to customs.

However, it should be understood that it is possible for a treaty to have a provision that extends beyond customs. When a provision of a treaty has been accepted as a custom and subsequently adopted as international law, a subsequent disregard to this custom does not alter its validity but amounts to a breach of international law4. This drives us to the two main aspects that enables the formation of a custom; first is the legal obligation that must be attached to the custom 8such that the people following a certain practice ensure that they do so in due regard to the law and secondly, is the physical aspect that nations or states must actually follow a certain norm and practice and observe it for it to be widely accepted and adopted as an international law.

Typically, customary laws are binding to all states unless it is a regional customary law. Furthermore, once a custom has been established it is assumed that it has a legal basis to apply to all states unless a nation withdraws using the Doctrine of Persistent Objection. While customary laws remain primary sources of international laws, its shortcomings are due to the fact that it is hard to provide proof as well as determining the stage in which it becomes authoritative9. Treaty laws as well as customary international laws are seen as the key derivations for the international law and therefore International institutions such as ICJ give them a higher priority before those laws that are generally accepted, prior to the court making their decisions, scholarly writings when making legal decisions.

Treaty and customary laws are distinct sources of law and are competitors. Firstly, we will look at the standpoints on their existence. Advocates who favor a liberal approach towards international law could prefer the use and utilisation of the treaty process as a certain and definitive approach of dealing with relationships among states. In respect to this view, there should be an equal basis in the formulation of new norms of international laws among states. On the other hand, Advocates who prefer a more traditional approach to international law would rather utilise the use of customary laws instead of treaties. This often happens when international law is expanding and undergoing transformation through codified state agreements. Comparing Another distinction factor between treaties and customary laws is that it, it can be deduced that treaties are binding only to those states that have accepted its obligations, on the other hand, most theorists have concluded that customary international laws bind states generally regardless of whether they have consented to its rules or not13.

This aspect of the customary law has its support premised on the consensual international theory of the law by the device of “persistent objector” which allows a state to opt out of customary law or norm in the process of its formation. It is assumed that a state has accepted the rule of a customary norm unless it continuously and persistently contests the rules enshrined in the customary norm at its initial phase of formation. Furthermore, it should be noted that objection to a customary law after its formation would not prevent a state from being bound by it. Even in the case of the same content in the both the customary and the treaty norms, it would not stand waters for the court to conclude that instilling customary law to a treaty norm must extract the customary norm of its use as separate as that of the treaty law.

A situation where there are same rules shared enshrined in these two law sources are envisaged and envisioned and therefore recognized by in the North Sea Continental Shelf Cases (the North Sea Continental Shelf Cases, ICJ Reps, 1969, p. 3 at 44). However, largely, those cases only accelerated the question of the rule that is enshrined in a treaty if it also exists in a customary law just because a treaty is a codified custom norm. Overall, though, here is no sufficient base to customary law has identical rules to those found in the treaty law, the latter supersedes the former, and so that implication can be made that customary international law cannot exist on its own. Some courts and commentators have been satisfied to conclude the very existence of rules of customary law that rely solely on the existence of treaties and the resolutions made by the United Nations in the face of much contradictory practice.

However, some commentators seem to have actively denied the existence of relevance between customary law analysis of practice other than treaties and General Assembly resolutions when such exist. In reference to case law in the ICJ’s argumentative Case: (Nicaragua vs. the United States) 16 whose court decision was made in 1996 gives the following as the summary of the relationship between the two sources. The techniques used for enforcement of cooperation between these two sources are radically different. b. In terms of distinctive nature of these two sources, the court expounded this using an instance of a nation that expresses the utilisation of self-defense as highlighted in article 51, in accordance with the UN charter, is obliged to presents its report to the Security Council any attempt of forceful use.

The court determined this was a requirement in the treaty that did not exist in the customary law (para 200, 235). For parties in a treaty, in case of a disparity in the treaty law and customary norms, amongst these parties, the provisions in the treaty apply as lex specialis (Para 180 and 181). a. As mentioned earlier, international laws comprise laws that are generally accepted and are regarded as binding in terms of relations between states and nations thereby forming a framework that underpins legal relations among states. The rules that are contained in this framework are derived from inter-state treaties and customs. While treaties refer to codified legal agreements made between states or organizations which are written and binding, customary laws are unwritten yet binding agreements made between states.