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

• international custom, as evidence of a gen- eral practice accepted as law;

• the general principles of law recognized by civilized nations;

• subject to the provisions of Article 59, judicial decisions and the teachings of the most highly qualified publicists of the vari- ous nations, as subsidiary means for the determination of rules of law.

The ICJ will resort to the following sources for deciding a dispute before it: treaties (conventions); custom; general principles of law; judicial decisions; juristic work on international law (the teachings of publicists); principles of equity and ex aequo et bono; General Assembly and Security Council resolutions and practices.

Ex aequo et bono means what is just and fair or according to equity and good conscience. Something to be decided ex aequo et bono is something that is to be decided by principles of what is fair and just. A decision-maker who is authorized to decide ex aequo et bono is not bound by legal rules but may take account of what is just and fair.

Treaties, custom, and general principles of law are the main sources of international law.

Judicial decisions and juristic work on international law fall into the category ofsubsidiary sources.

There are two requirements for a custom to be accepted as law: (i) there should be sufficiently uniform general practice accepted as law, and (ii) the belief that such a practice is obligatory.

State practice can be categorized into three groups as evidenced: (a) in the mutual relations among States, (b) in the practice of international organizations, and (c) the unilateral practices of States.

A convention (treaty) may be general either because of the number of parties (as being accepted by a large number of States), or because of the nature of its contents (which is of universal importance). It may be particular because of the limited number of parties, or because of the limited character of its subject-matter.

A treaty contract is an agreement between two (or only limited number of ) States on a special matter concerning those States exclusively. Such treaties create obligations for the parties that would not have existed under the general international law or they modify the existing rules as applicable to their mutual relations.

Guidelines of behavior such as those provided by treaties not yet in force, resolutions of the United Nations, or international conferences, that are not binding in themselves but are more than mere statements of political aspiration (they fall into a legal/political limbo between these two states).

Custom is a habitual course of conduct or general practice accepted as law. Custom evolves after a long historical process culminating in its recognition by the community.

Custom may be treated as a source of law if it manifests the attributes of antiquity, certainty, continuity, consistency, and uniformity.

Usages are habits, often repeated but conflicting. They also vary from one State to another. On the other hand, custom is self-consistent and unified. Usage represents the twilight stage of custom. Custom begins where usage ends. However, it is not necessary that a usage should precede a custom or that a usage becomes a custom. Similarly, there is no international rule that determines when usage shall culminate into a custom.

For a practice or usage to become a customary rule of international law, the following two factors are essential:

• A material fact: in similar circumstances States act similarly, in other words, usage has been constantly and uniformly practiced by States.

State practice may include treaties, diplomatic correspondence and relations, opinions of national legal advisers, national legislation, policy statements, press releases, official manuals on legal questions, executive decisions and practices, decisions of international and national courts, and the practices of international organizations.

The importance of treaties is self-evident, because under Article 38(l)(a) of the Statute of the ICJ ‘conventions’ have been mentioned as the first recourse which the Court is directed to resort for settling a dispute between the parties.

The State practice, even though general and consistent, is not customary law unless an opinio juris or “psychological element” is present, i.e., the practice is recognized as obligatory and there is the conviction that its repetition is the result of a compulsory rule.

A treaty will bind the non-parties if they (expressly or by their conduct) manifest their intention to be bound by the provisions of the treaty as general rules of international law.

Non-liquet means “it is not clear.” In law, a non liquet is a situation where there is no applicable law. It refers to a situation in which a competent court or tribunal fails to decide the merits of a case for the absence of suitable law, the vagueness or ambiguity of rules, inconsistencies in law, or the injustice of the legal consequences.