Introduction

Any community is said to function more effectively towards the general welfare of its members if it follows a certain set of rules; the international community of states being no exception. The welfare-superiority of the rule system springs from the fact that the benefits of decreased uncertainty about the threats of the outside world created by rules and their enforcement commonly overweigh the costs of compliance with them (this view is sustainable both from a communitarian as well as an individualistic perspective). In economics, many institutionalists (for example, Douglass C. North) and even libertarians (Friedrich A. Hayek), see these rules as a kind of learning mechanisms of societies embodying knowledge about the desired, but at the same time effective, functioning of the social world.

Sir Humphrey Waldock of the International Law Commission (1963; in Jennings 1995: 1160) defined international law as “the body of rules and principles of action which are binding upon civilized states in their relations with one another”. Identification of these rules is at the core of their proper enforcement. In other words, knowing what the rules are, how they are formed, and when they are breached, lies at the heart of applying sanctions for possible misbehavior. Understanding the sources of international law, set of rules of the international community, is thus vital for an efficient functioning of the world society. The community of states is a very specific community when compared to national societies, however. There is no world government to enact laws “from above” – states have to decide on the guiding principles themselves under the shadow of anarchy. Moreover, the international community also lacks an effective enforcement of law for the same reason. In fact, however, the functioning arrangements of international relations prove that anarchy does not necessarily imply disorder. The one-level tier state environment (of “equals”) closely approximates what extreme libertarians would call the “natural order” in domestic societal context, where agents solve their problems solely on the basis of their interests and capabilities (for example, Hans-Hermann Hoppe; also used by Jean-Jacques Rousseau and other ‘social contract’ theorists as their starting point). Other social scientists warn about the arrangements where all actors enjoy a veto power of behaving purely at their own will. Game theory, and the Prisoner’s Dilemma game in particular, is probably the most famous example of the limitations of individual rational behavior in the achievement of overall welfare. The global climate regime, without the cooperation of the greatest polluter – the United States, seems to come close to this actor constellation. Having these particularities in mind, it is my intention in this essay to examine the sources of law, that is, what gives the rules of behavior among states their legal status. I will first refer to Article 38 of the Statute of the International Court of Justice (also known as the World Court) to investigate what it has to say about the sources of international law. Afterwards, I will follow with describing other possible sources of legalization. In conclusion, I am going to answer the research question of whether the Art. 38 is a correct and complete enumeration of the sources of public international law.