In a very important sense, for the lawyer, each international organization is unique, based as it is on its own constituent document and influenced as its development will be by peculiar political configurations. Thus, labels should never be substituted for analysis, as Brownlie has pointed out. An academic textbook on international organizations is not complete with-out an attempt to classify the various organizations into different types, sorts, forms or categories. Perhaps the main reason for making such classifications resides in the academic psyche: all academic disciplines engage in classification for purposes of organizing knowledge, if nothing else, so legal academics should do the same. We can classify international organization based on different criterions. Some of them are the following.

Classification based on functions

A first point often made by scholars is that organizations may be classified in accordance with their stated functions. Thus, quite few are active in the economic field; others are engaged in peace and security, or can be classified as military alliances. Yet others deal with issues of nutrition, public health, and telecommunication or fisheries conservation, to name just a few possibilities. A distinction based on functions automatically suggests itself, and it is broadly possible to distinguish between the “political” organizations, concerned primarily with the preservation of international peace and security, and the administrative organizations of more limited aims. The distinction is perhaps more accurately stated as one between organizations of comprehensive competence and organizations of limited competence. Prima facie, one should also distinguish the institutions for the judicial settlement of disputes, such as the permanent Court of international justice. As we shall see, no rigid distinction in functions is made in practice. The “political” organization, the United Nations, has amongst its organs the Trusteeship Council, with primarily administrative functions, and the I.CJ., a purely judicial body. The co-ordination achieved by bringing the specialized agencies into relationship with the UN also makes any clear classification by function difficult.

Classification based on Membership

Other classifications point to the membership of organizations as being of distinctive value. This method of classification base itself on the fact that some organizations are” global” whereas others are “regional”. Thus, some organizations aspire to universal or near universal membership, inviting in principle all states to join .The United Nations is a typical example, in principle open to all states as long as they meet certain requirements. Hence, the UN is often referred to as an ‘open’ organization, as are (although their membership does not compare to that of the UN) such organizations as the World Health Organization (WHO) and the World Trade Organization (WTO).

Other organizations however, may rest satisfied with a limited membership, and usually such limitations may derive from their overall purpose. Thus, many regional organizations, aiming to organize activities in a certain geographical region, are open only for states from that region. The European Union is only open for European sates; no Asian state can join the organization of African Unity, and the organization of American sates can only be joined by sates from the Americas. Within Europe at least (because of the diversity of the organizations involved), it has been possible to make the same broad division between organizations of general competence and those of limited competence.

The limitation is not always based on consecrations of geography, though. For instance, the organization of Petroleum Exporting Countries (OPEC) is a limited organization, but its membership spans the globe, including states from the Middle East, Latin America and Africa. Here, the ties are economic. Similarly the organization for Economic Co-operation and Development (OECD) has also, in addition to a large number of west European member-states, members from the Americas, Asia and Oceania, and the North Atlantic Treaty Organization (NATO) does justice to the Atlanticism in its name by including members from western and southern Europe as well as the US and Canada, wereas the French-speaking countries are united in an organization devoted to francophonie^.. Where membership is limited to states from a certain, region such organizations may be referred to as ‘regional’, but the more generic term used is often ‘closed’.

Classification based on the kind of contracting parties

It has also been suggested that there is a fundamental distinction, and therefore a basis for classification, between organizations founded on a treaty between states and a treaty between governments. Jenks has described this distinction as having importance comparable to that of the classical distinction between a confederation and a federation in the evolution of the public law of the principal federal states. The idea is, essentially, that the inter-state treaty form embraces the totality of the state’s institution, its legislative and judicial machinery as well as the administrative, whereas the inter-governmental treaty form embraces only the administrative. It would seem, however, that in practice the distinction is not regarded as having this significant difference in effect. The UN Charter itself refers indiscriminately to “peoples,” “governments” and “states,” so that it is difficult to see who the parties really are. Organizations like the IMF or the newer IMCO are based on inter-governmental treaties, whereas the FAO or WHO are inter-state; yet there is no observable difference in the view that States take as to their commitments according to the form used. The most that might be said is that, from the point of view of drafting technique, these variations leave much to be desired. The only possible justifications for the difference are first that the inter-governmental form would be satisfactory for a non-permanent organization, like UNRRA, and second that some States might find it easier, from their constitutional position, to accept the inter-governmental form. The distinction between inter-governmental and non-governmental organizations is, of course, a quite different matter.

Classification based on Intergovernmental or supranational

It is also possible to distinguish organization “Supranational,” i.e. power to bind member states by their decisions, from those without such powers. But this is often the characteristic of particular organ, rather than the organization as a whole, and whilst the possession of such powers will be pointed out where they exist. As things stand, there is only one organization which is usually held to be supranational in character: the EC. Hence, any description of supranational organizations will inevitably be based on the EC.

In comparison with other organizations, the EC possesses a few features which, in combination, render it distinct from the rest. First, under the constituent treaties, decisions which will bind the member –states can be taken by majority vote. Thus, it is entirely possible that a member – state will have to adopt a certain course of behavior which it itself vehemently opposes. Second, the product of those decisions is EC law which attains supremacy over conflicting domestic law, regardless of what the laws of the member-state stipulate and regardless of which one was enacted later. Third, much of the law promulgated by the EC may be directly effective in the legal orders of the member-states. Thus, much EC law may be invoked not just by one member-state against his or her own government, or in relations with employers or other relations of a private nature. It is in this sense that people often say that the member-states have transferred parts of their sovereignty to the EC, and it is in this sense that the EC. stands, in an almost literal way, above its member –States (hence the term’ supranational).

Some would go further and claim that on occasion, the member-sates are no longer allowed even to attempt to regulate behavior: the doctrine of pre-emption not only holds that member-state action can be overruled, but goes beyond this in saying that member-state action is no longer acceptable in some areas^.

By contrast, the general rule among international organizations is that binding law-making decisions, at least on issues of substantive policy, can usually only be taken by unanimity, or consensus; that such rule does not usually work directly in the domestic legal orders of the member–states, and most assuredly that the member-states are not pre-empted from legislating. Here then, the organization does not rise above its member but remains between its members (intergovernmental)^.