Contents -- List of Abbreviations -- List of Cases and Documents -- Foreword -- Preface -- Acknowledgements -- Introduction -- Chapter One Customary International Law, Theoretical Conceptions and Evidence of its Formation -- I. Introduction -- II. Customary international law -- A. Custom as a source of international law -- 1. Custom -- 2. Sources of international law -- 3. Formal and material sources of international law and further distinctions -- B. Assessment -- III. Introduction to the theory of customary international law -- IV. Scope of the theoretical assessment -- V. Theory of the formation of customary international law -- A. Positivism -- 1. Voluntarist conceptions -- 2. Other opinio juris-based approaches to customary international law -- 3. Ago's theory of spontaneous law -- 4. Practice-based approaches -- 5. Strict normativism: Hans Kelsen's pure theory of international law and neo-Kelsenian approaches -- 6. Assessment -- 7. Later approaches: Haggenmacher, Mendelson and others -- 8. Commentary on the late positivist approaches -- 9. Other practice-based conceptions -- B. Two-element approaches -- C. Two-element conceptions of the formation of customary international criminal law and customary international human rights law -- 1. Different sorts of customary international law -- 2. The deductive approach to custom-formation -- 3. The 'core rights' approach -- 4. Two-element approaches to customary international human rights and humanitarian law: assessment -- D. Naturalist conceptions -- 1. Moral theoretical approaches to the formation of customary international law -- 2. Assessment -- E. Realist Conceptions -- 1. New Haven and similar approaches -- 2. The customary international law game -- 3. Assessment of the New Haven and the game theory concepts of custom -- F. New Approaches to International Law -- 1. The Sliding-Scale Approach.

2. Ascending and descending conceptions of international criminal law -- 3. Evaluation of the sliding-scale approach and subsequent up and down arguments -- 4. Institutionalised law-making: Charney's 'universal international law' and subsequent ideas -- 5. Assessment of institutionalised law-making approaches -- 6. Critical Legal Studies perceptions of the formation of customary norms -- 7. Assessment of the CLS conception of customary international law -- G. Theory of customary international law: tentative conclusions -- H. Evidence -- Chapter Two Customary International Law and its Relationship with other Sources and Methods of Law-Identification -- I. Introduction -- II. The relationship of customary international law with other sources of international law: general principles of international law and customary international law -- III. General principles of law in accordance with Article 38 (c) and other general principles -- A. Preliminary considerations -- B. General principles of national or international origin -- 1. General principles of national origin -- 2. General principles of a genuine international origin -- 3. A third category? -- 4. General principles of international law originating from any source of international law -- 5. Preliminary Conclusion -- C. General principles of law as a source of international human rights and international criminal law -- 1. Simma's and Alston's approach to international human rights law -- 2. Kolb, Henkin and Yasuaki -- 3. Simma's and Paulus' approach to international criminal law -- 4. Discussion of a general principles approach to international human rights and international criminal law -- D. Concluding remarks on the relationship of custom and the general principles of law -- IV. Interpretative methods and their relationship with the finding of customary international law -- A. Interpretation.

1. The notion of interpretation -- 2. Underlying concepts -- B. Particular methods: Articles 31-33 VCT -- 1. Article 31 (1) and (2) VCT -- 2. Article 31 (3) (c) VCT -- 3. Article 31 (3) (c) and the Oil Platforms Case -- 4. Further interpretative rules of the VCT -- 5. Subsidiary means of interpretation -- C. Interpretation of treaties by the ICJ, the ICTY and the ICTR -- 1. Grammatical interpretation, supporting elements and systematic interpretation -- 2. Object and purpose, effectiveness and other circumstances -- 3. Customary international law -- 4. Assessment -- D. Analogy -- 1. Introduction -- 2. Notion and theoretical underpinnings -- 3. Analogy in the jurisprudence of ICJ and ICTY -- 4. Final considerations on the relationship between analogy and custom -- E. Final assessment of the relationship between interpretation and analogy and the discovery of new customary international law -- Chapter Three Visions of Development -- I. Introduction -- II. Theoretical conceptions of the development of customary international (criminal) law -- A. The humanisation of humanitarian law -- B. A communitarian vision -- C. Increasing fragmentation -- III. Assessment -- Chapter Four Practical Developments (Part One): Customary International Law in the Case Law of the PCIJ and the ICJ -- I. Introduction -- II. Strict Voluntarism -- A. The PICJ's Lotus Case -- B. Discussion of the Lotus findings in the light of the formation of customary international law -- III. Two-element approaches to custom: the customary law on the continental shelf and further cases -- A. The Asylum Case, the Fisheries Case and further judgements -- B. The North Sea Continental Shelf Cases -- C. Discussion of the impact of the North Sea Continental Shelf findings on the methodology of customary international law -- D. Continental Shelf Case I (Tunisia v Libya).

E. Continental Shelf Case II (Libya v Malta) -- F. The Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons -- G. The importance of the conclusions of the Nuclear Weapons advisory opinion for the formation of customary international law -- IV. Deductive reasoning -- A. The Corfu Channel Case -- B. The Advisory Opinion on the Reservations on the United Nations Convention on the Prevention and Prohibition of the Crime of Genocide -- C. Relevance of the findings in the Advisory Opinion on the Genocide Convention and further developments: the Barcelona Traction Case and the Genocide Case (Bosnia Herzegovina v. Serbia Montenegro) -- V. A first drawback for the deductive approach: the South-West Africa Cases -- VI. Deduction affirmed? The Gulf of Maine Case -- VII. Deductive and empirical approaches side by side: the Nicaragua Case -- A. The Court's findings -- B. Further assessment of the Nicaragua Judgment -- VIII. Resumption of the deductive method: the Yerodia Case -- A. The ICJ's findings -- B. Assessment of the Yerodia judgment -- C. Compararison: the discussions at the Institut de Droit International on the immunities from execution and jurisdiction of Heads of State and Government in international law -- IX. The importance of 'elementary considerations of humanity': the Advisory Opinion on the Construction of a Wall in the Palestinian Territories and further cases -- A. Advisory Opinion on the Construction of a Wall in the Palestinian Territories -- B. The 2002 Congo Case and the Srebrenica judgement -- X. Conclusions on the analysis of the case law of the ICJ -- A. The evidence assessed -- B. The methods applied -- Chapter Five Practical Developments (Part Two): The Case Law of the International Ad Hoc Criminal Tribunals on Customary International Criminal Law -- I. Introduction.

II. Preliminary considerations: the definition of international criminal law -- III. The different approaches of the ICTY and the ICTR to customary international law -- A. Differences in the scope of ratione materiae jurisdiction -- B. The applicability of the Geneva Conventions of 1949 and its Additional Protocols to the conflict in Rwanda and the former Yugoslavia -- C. The succession situation in the SFRY and the applicable treaty law -- D. The existence of an international or non-international armed conflict on the territory of Yugoslavia -- IV. The case law of the ICTY and the ICTR on customary international law -- V. The findings of the ICTY on the evolution of new customary international criminal law -- A. The 'sources based approach': international legal instruments and international jurisprudence as evidence of new customary international law -- 1. Nuremberg Jurisprudence and the military trials following World War II -- 2. Risks ensuing from utilizing the Nuremberg jurisprudence and similar case law as evidence of new customary law -- 3. Other international and domestic case law on matters of international humanitarian law -- 4. International humanitarian law instruments -- 5. International human rights instruments -- 6. The ILC Draft Code of Crimes -- 7. The influence of the Rome Statute -- 8. The ICRC Study on Customary International Humanitarian Law and ICRC opinions -- B. Deductive approach / core-rights approach -- 1. Prerequisites for the application of Articles 2 and 3 ICTY Statute / Article 4 ICTR Statute: The Tadić case -- 2. Conclusions on the Tadić Interlocutory Appeal -- 3. Affirmation of the findings of the Tadić Interlocutory Appeal judgment: the Martic Case, the Čelebići Case and subsequent judgments.

4. The 'customs of war' in Article 3 ICTY Statute / Article 4 ICTR Statute: the Kupreškić Trial Chamber judgment and subsequent decisions.