Tumonis, Vitalius

The central question of this dissertation is how much of judicial decision-making depends on legal reasoning. Do judges, after finding the relevant facts of the case, consult legal rules and then arrive at their decision? Or maybe the equation that the decision equals facts plus rules is merely an illusion? This dissertation argues that judges usually can make decisions on other grounds than formal legal rules and then use formal legal rules merely to justify those decisions. Also, judges will have preference for intuitive decision-making over rule-based and logical reasoning. When judges make decisions on other grounds than formal legal rules, judicial creativity is unlikely to be constrained by these formal rules. Also, judges will seldom have trouble justifying their decisions with formal rules because they will almost always find some competing legal rules that will tally their decision; this is largely because public international law is even more ambiguous than common law systems. Specific driving forces behind judicial decisions will be different in each case – it is even possible that in some cases formal legal rules will be the controlling factor. However, international courts will be often swayed by various policy principles, including conciliatory justice. It also means that judicial law-making by international courts is inevitable.

International customary law is traditionally defined as general practice States accepted by them as law. That is, it is composed of two elements – (1) practice of states (so-called objective element), and (2) opinio juris (so-called subjective element, which according divergent views means either belief that State is conforming to existing law, or consent to be subject to emerging law). The present thesis attempts to prove that international organizations may also contribute in their own name to formation of customary international law. It first attempts to establish the existence of secondary rules providing for law-making rules customary law – i.e. by defining subjects capable of forming customary law and establishing modalities. Having not found such rules either as separate set of rules or part of what could be called constitution of international community, it proceeds to prove that States don’t have an exceptional competence in law-making in international community; the concept of sovereignty is analyzed, and it is concluded, that whatever sovereignty means, it has nothing to do with exclusive law-making competence of States. The synopsis of customary international law is then provided. Most importantly, the thesis aims at ascertaining the nature of customary law and then argues that by the very nature of customary international law international organizations possess competence to contribute to formation of customary international law. Yet, this competence is confined by personality of international organizations which possess only those powers that States delegate to them. Nevertheless, the nature of international organizations' powers is the second prong of the argument that international organizations possess competence of customary law formation.