Introduction 1
Chapter One Customary International Law, Theoretical Conceptions and Evidence of its Formation 9
Ⅰ. Introduction 9
Ⅱ. Customary international law 9
A. Custom as a source of international law 9
1. Custom 10
2. Sources of international law 11
3. Formal and material sources of international law and further distinctions 11
B. Assessment 13
Ⅲ. Introduction to the theory of customary international law 13
Ⅳ. Scope of the theoretical assessment 14
Ⅴ. Theory of the formation of customary international law 15
A. Positivism 16
1. Voluntarist conceptions 18
2. Other opinio juris-based approaches to customary international law 24
3. Ago's theory of spontaneous law 25
4. Practice-based approaches 26
5. Strict normativism: Hans Kelsen's pure theory of international law and neo-Kelsenian approaches 27
6. Assessment 29
7. Later approaches: Haggenmacher, Mendelson and others 29
8. Commentary on the late positivist approaches 32
9. Other practice-based conceptions 33
B. Two-element approaches 33
C. Two-element conceptions of the formation of customary international criminal law and customary international human rights law 36
1. Different sorts of customary international law 37
2. The deductive approach to custom-formation 39
3. The 'core rights' approach 42
4. Two-element approaches to customary international human rights and humanitarian law: assessment 44
D. Naturalist conceptions 46
1. Moral theoretical approaches to the formation of customary international law 47
2. Assessment 48
E. Realist Conceptions 49
1. New Haven and similar approaches 50
2. The customary international law game 52
3. Assessment of the New Haven and the game theory concepts of custom 54
F. New Approaches to International Law 55
1. The Sliding-Scale Approach 55
2. Ascending and descending conceptions of international criminal law 57
3. Evaluation of the sliding-scale approach and subsequent up and down arguments 58
4. Institutionalised law-making: Charney's 'universal international law' and subsequent ideas 59
5. Assessment of institutionalised law-making approaches 60
6. Critical Legal Studies perceptions of the formation of customary norms 61
7. Assessment of the CLS conception of customary international law 64
G. Theory of customary international law: tentative conclusions 65
H. Evidence 67
Chapter Two Customary International Law and its Relationship with other Sources and Methods of Law-Identification 71
Ⅰ. Introduction 71
Ⅱ. The relationship of customary international law with other sources of international law: general principles of international law and customary international law 71
Ⅲ. General principles of law in accordance with Article 38 (c) and other general principles 73
A. Preliminary considerations 73
B. General principles of national or international origin 74
1. General principles of national origin 75
2. General principles of a genuine international origin 75
3. A third category? 76
4. General principles of international law originating from any source of international law 11
5. Preliminary Conclusion 79
C. General principles of law as a source of international human rights and international criminal law 80
1. Simma's and Alston's approach to international human rights law 81
2. Kolb, Henkin and Yasuaki 81
3. Simma's and Paulus' approach to international criminal law 82
4. Discussion of a general principles approach to international human rights and international criminal law 83
D. Concluding remarks on the relationship of custom and the general principles of law 85
Ⅳ. Interpretative methods and their relationship with the finding of customary international law 86
A. Interpretation 88
1. The notion of interpretation 88
2. Underlying concepts 90
B. Particular methods: Articles 31-33 VCT 92
1. Article 31 (1) and (2) VCT 92
2. Article 31 (3) (c) VCT 93
3. Article 31 (3) (c) and the Oil Platforms Case 94
4. Further interpretative rules of the VCT 95
5. Subsidiary means of interpretation 96
C. Interpretation of treaties by the ICJ, the ICTY and the ICTR 97
1. Grammatical interpretation, supporting elements and systemic interpretation 98
2. Object and purpose, effectiveness and other circumstances 99
3. Customary international law 101
4. Assessment 101
D. Analogy 102
1. Introduction 102
2. Notion and theoretical underpinnings 102
3. Analogy in the jurisprudence of ICJ and ICTY 104
4. Final considerations on the relationship between analogy and custom 106
E. Final assessment of the relationship between interpretation and analogy and the discovery of new customary international law 108
Chapter Three Visions of Development 111
Ⅰ. Introduction 111
Ⅱ. Theoretical conceptions of the development of customary international (criminal) law 111
A. The humanisation of humanitarian law 112
B. A communitarian vision 113
C. Increasing fragmentation 116
Ⅲ. Assessment 117
Chapter Four Practical Developments (Part One): Customary International Law in the Case Law of the PCIJ and the ICJ 121
Ⅰ. Introduction 121
Ⅱ. Strict Voluntarism 122
A. The PICJ's Lotus Case 122
B. Discussion of the Lotus findings in the light of the formation of customary international law 125
Ⅲ. Two-element approaches to custom: The customary law on the continental shelf and further cases 126
A. The Asylum Case, the Fisheries Case and further judgements 127
B. The North Sea Continental Shelf Cases 129
C. Discussion of the impact of the North Sea Continental Shelf findings on the methodology of customary international law 131
D. Continental Shelf Case I (Tunisia v Libya) 132
E. Continental Shelf Case II (Libya v Malta) 134
F. The Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons 137
G. The importance of the conclusions of the Nuclear Weapons advisory opinion for the formation of customary international law 139
Ⅳ. Deductive reasoning 140
A. The Corfu Channel Case 140
B. The Advisory Opinion on the Reservations on the United Nations Convention on the Prevention and Prohibition of the Crime of Genocide 142
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) 145
Ⅴ. A first drawback for the deductive approach: the South-West Africa Cases 147
Ⅵ. Deduction affirmed? The Gulf of Maine Case 150
Ⅶ. Deductive and empirical approaches side by side: the Nicaragua Case 151
A. The Court's findings 151
B. Further assessment of the Nicaragua Judgment 155
Ⅷ. Resumption of the deductive method: The Yerodia Case 157
A. The ICJ's findings 157
B. Assessment of the Yerodia judgment 161
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 162
Ⅸ. The importance of 'elementary considerations of humanity': the Advisory Opinion on the Construction of a Wall in the Palestinian Territories and further cases 164
A. Advisory Opinion on the Construction of a Wall in the Palestinian Territories 164
B. The 2002 Congo Case and the Srebrenica judgement 167
Ⅹ. Conclusions on the analysis of the case law of the ICJ 168
A. The evidence assessed 168
B. The methods applied 170
Chapter Five Practical Developments (Part Two): The Case Law of the International Ad Hoc Criminal Tribunals on Customary International Criminal Law 175
Ⅰ. Introduction 175
Ⅱ. Preliminary considerations: the definition of international criminal law 176
Ⅲ. The different approaches of the ICTY and the ICTR to customary international law 177
A. Differences in the scope of ratione materiae jurisdiction 177
B. The applicability of the Geneva Conventions of 1949 and its Additional Protocols to the conflict in Rwanda and the former Yugoslavia 181
C. The succession situation in the SFRY and the applicable treaty law 182
D. The existence of an international or non-international armed conflict on the territory of Yugoslavia 184
Ⅳ. The case law of the ICTY and the ICTR on customary international law 186
Ⅴ. The findings of the ICTY on the evolution of new customary international criminal law 187
A. The 'sources based approach': international legal instruments and international jurisprudence as evidence of new customary international law 187
1. Nuremberg Jurisprudence and the military trials following World War II 188
2. Risks ensuing from utilizing the Nuremberg jurisprudence and similar case law as evidence of new customary law 195
3. Other international and domestic case law on matters of international humanitarian law 200
4. International humanitarian law instruments 202
5. International human rights instruments 205
6. The ILC Draft Code of Crimes 214
7. The influence of the Rome Statute 216
8. The ICRC Study on Customary International Humanitarian Law and ICRC opinions 218
B. Deductive approach / core-rights approach 220
1. Prerequisites for the application of Articles 2 and 3 ICTY Statute/Article 4 ICTR Statute: The Tadic case 220
2. Conclusions on the Tadic Interlocutory Appeal 224
3. Affirmation of the findings of the Tadic Interlocutory Appeal judgment: the Martic Case, the Celebici Case and subsequent judgments 226
4. The 'customs of war' in Article 3 ICTY Statute / Article 4 ICTR Statute: the Kupreskic Trial Chamber judgment and subsequent decisions 230
5. Assessment of the findings of the Kupreskic Trial Chamber 234
6. The prohibition on destroying civilian property 236
7. Murder 237
8. Outrages upon personal dignity 237
9. Terrorisation of a civilian population: the Galic appeal judgment 238
10. Assessment 241
11. Rape 242
12. The Hadzihasanovic Decision on Interlocutory Appeal Challenging Jurisdiction in Relation to Command Responsibility and subsequent case law 243
13. Drawbacks to the deductive approach: the Ojdanic Interlocutory Appeal on Joint Criminal Enterprise Liability and further judgments 247
C. Mixed methodologies 249
1. Blurring of different sources of international law (general principles of international law and customary international law) 250
2. The need for a differentiation between methodologies: the case law of the ICTY on the customary criminality of co-perpetratorship 253
3. Blurring of customary international law and interpretation 254
4. No differentiation between customary international law and analogy 258
Ⅵ. The case law of the ICTR 259
A. International legal instruments approach 259
1. Crimes against humanity and the fair trial principle 260
2. Widespread and systematic attack 260
B. Blurring of interpretation and custom 262
1. Discriminatory intent requirement 262
2. Murder 263
3. Rape 264
4. Complicity in genocide 265
5. Command responsibility 266
C. Common sense approach 267
1. Extermination 268
2. Other inhumane acts 269
D. Deductive approach 270
1. The customary international law character of the prohibition of genocide, acts of complicity and public incitement to genocide 270
2. Individual criminal responsibility 271
3. Joint criminal enterprise liability 272
Ⅶ. Conclusions on the jurisprudence of the ICTY and the ICTR on customary international law 273
A. Determining agencies 273
1. The Nuremberg trials, the case law of the ICJ, and the case law of the ICTY and ICTR 274
2. The case law of the military tribunals established after World War II and national case law concerning international crimes 275
3. The ILC Draft Code of Crimes 275
4. International treaties and UNGA resolutions 275
5. Military manuals 276
6. ICRC opinions 276
7. Assessment 277
B. A hierarchy of determining agencies for customary international criminal law? 278
C. The methodologies applied when identifying new customary international law 279
1. Different approaches to custom 280
2. Relationship between the four approaches 281
D. Merging of different methods and sources of international (criminal) law 283
Ⅷ. The approaches of the ICTY and the ICTR compared 285
Chapter Six Evolution of New Customary International Criminal Law: Further Implications 287
Ⅰ. Introduction 287
Ⅱ. Article 21 (1) (b) of the ICC Statute: further development of customary international criminal law? 288
A. Preliminary issues 289
B. Article 21 (1) (b) ICC Statute: controversies 291
C. Travaux preparatories 293
D. Conclusion 295
Ⅲ. Clash of custom with aspects of legality? - The nullum crimen sine lege principle and its implications for the formation of new customary international criminal law 296
A. The principle nullum crimen sine lege in national and international law: overview 297
B. Scope of the principle in international law 299
1. International human rights instruments: Article 11 UDHR 300
2. Article 7 (1) ECHR and Article 15 (1) ICCPR 301
3. Article 7 (2) ECHR and Article 15 (2) ICCPR 303
4. Other provisions 305
5. The ILC Draft Code against Peace and Security of Mankind and the interpretation of nullum crimen sine lege in international legal scholarship 305
C. The nullum crimen sine lege principle in the case law of the international ad hoc criminal tribunals 308
1. Nullum crimen as a principle of justice: the Tadic Interlocutory Appeal 308
2. Individual requirements of the principle of legality: the Celebici Trial Chamber judgement 309
3. Assessment 311
4. The Hadzihasanovic Interlocutory Appeal decision 311
5. No creation of new law: the Aleksovski Appeals Chamber judgment 312
6. Limitations on the methodology of customary international criminal law: The Vasiljevic Trial Chamber judgment and the Ojdanic Appeals Chamber decision 313
7. Custom, interpretation and the nullum crimen principle: the Stakic Trial Chamber judgment 316
8. ICTR Cases 316
D. Conclusions on the interpretation of the nullum crimen principle by the ICTY and ICTR 317
E. Further development of nullum crimen sine lege Article 22 of the ICC Statute 318
1. The prohibition of retroactivity 319
2. The rule of strict construction and prohibition of interpretation in malam partem 319
3. The prohibition of analogy 320
4. Article 22 (3) ICC Statute 321
F. Conclusion on the nullum crimen principle in Article 22 ICC Statute 322
Ⅳ. Overall conclusion on the impact of the nullum crimen sine lege principle on the finding of new customary international law 322
Chapter Seven Developments in Customary International (Criminal) Law: Implications from the Case Law of the ICJ, the ICTY and the ICTR 325
Ⅰ. Introduction 325
Ⅱ. The conclusions from the case law of the ICJ, the ICTY and the ICTR 325
A. Lessons from the ICJ's case law 326
1. Concerning the evidence of new customary international law 326
2. The different methods of determining new customary international law 328
B. Lessons from the case law of the ICTY and the ICTR 329
1. Considering the relevant evidence of a new customary rule 329
2. Considering the methodologies applied 330
C. Implications for the theory of international law 333
D. Conclusions 335
Ⅲ. An evaluation scheme for the determination of new customary international (criminal) law 337
A. Introduction 337
B. Evaluation scheme for discovering new customary international (criminal) law 338
1. Preliminary considerations - the importance of interpretation 338
2. The classical two element approach to customary international law 338
3. Application of the international legal instruments approach 339
4. The core rights approach 340
5. Analogy 341
6. General principles of law 341
C. Conclusion 342
Bibliography 343
Index 363