The Changing Nature of Customary International Law

Methods of Interpreting the Concept of Custom in International Criminal Tribunals

Noora Arajärvi

• Publisher: Routledge
• Year: 2014
• ISBN:
  9781134067343
• Edition: 1
• Topic: Jura
• Subtopic: Rechtstheorie & -praxis

This book examines the evolution of customary international law (CIL) as a source of international law. Using the International Criminal Tribunal for the former Yugoslavia (ICTY) as a key case study, the book explores the importance of CIL in the development of international criminal law and focuses on the ways in which international criminal tribunals can be said to change the ways in which CIL is formed and identified. In doing so, the book surveys the process and substance of CIL, as well as the problematic distinction between the elements of state practice and opinio juris.

By applying an inclusive positivist approach, Noora Arajärvi analyses the methodologies of identification of CIL in selected cases of the ICTY, and their normative foundations. Through examination of the case-law and the reasoning of courts and tribunals, Arajärvi demonstrates to what extent the court's chosen method of identification of CIL affects the process of custom formation and the resulting system of norms in general.

The book will be of great value to researchers and scholars of international law, international relations, and practitioners with interests in customary international law.

1 Genesis of customary international law and international criminal law

1.1. Introduction

This chapter introduces the concept of custom and its varying interpretations in the doctrine and in the case-law. It aims to provide an historical background of the formation of the concept; it discusses the two elements of CIL, and provides examples of CIL in human rights law, humanitarian law, and finally, in international criminal law prior to the establishment of the ad hoc tribunals (ICTY and ICTR).

According to Article 38(1)(b) of the Statute of the International Court of Justice CIL is ‘evidence of a general practice accepted as law’. Although the Statute sets out the particular sources applicable in the ICJ, it also forms the basis of the formulation of CIL in general. It translates into two elements required for CIL to emerge: state practice (‘usus’) and opinio juris sive necessitatis (‘opinio juris’), in other words, the physical practice and the belief that the practice is required by law. These elements are also referred to as the objective and subjective elements of custom: the practice can be observed by external onlookers, whereas the belief arises from the subjective viewpoint of the actor, traditionally actors being the states.¹ In international law, all actions of a state do not automatically contribute to the development of a customary rule – some practice is performed merely out of comity, courtesy or habit, and thus lacks the normative authority needed to transcend practice to become a legal rule. In order to understand the concept of CIL, it is necessary first to look into the historical roots of that concept, followed by an analysis of case-law that has further shaped the concept and which also illustrates the influence of the judicial bodies in the development of CIL. The definitions of state practice and opinio juris are discussed in separate sections, while addressing possible overlapping features shared by these two elements. The final part of the chapter identifies the elements of custom as reflected in human rights law, humanitarian law and international criminal law – prior to the establishment of the ad hoc tribunals in the 1990s. In general, this chapter provides an analytical and conceptual understanding of the concept of CIL.

1.2. Development of customary international law and article 38(1)(b) of the statute of the ICJ

The first reference to custom as a source of law in the doctrine can be traced to the writings of Francisco Suarez. In De legibus ac cleo legislatore, he lists the two elements from which customary law can be deduced, namely consensus and compliance with reason.² Although these two elements were understood by Suarez in a context other than what has eventually developed to be comprised of state practice and opinio juris – for Suarez, consensus meant the consent of the sovereign instead of that of the nation, and reason referring to God’s will revealed to man³ – he did contribute to the essence of CIL in its traditional form. After Suarez, Hugo Grotius described CIL as quintessence to practice that is tacitly accepted as binding by the community.⁴ This implies some amalgamation of state practice and opino juris in the formation of CIL, and provides for the ‘tacit-consent’-theory of CIL.⁵

The first formal written articulation of custom as a source of international law can be found in international humanitarian law instruments. The Conference of Brussels on the Laws and Customs of War in 1874 and The Hague Conferences of 1899 and 1907, conscribed that warfare must be conducted in accordance with ‘the laws and customs of war’. Notably though, already in The Hague Convention with Respect to the Laws and Customs of War on Land (1899) some confusion can be detected as to the separation of CIL and the general principles of law. The Preamble of the Convention, repeating the Martens Clause, declares that in situations which are not covered by the treaty provisions, ‘populations and belligerents remain under the protection and empire of the principles of international law, as they result from the usages established between civilised nations, from the laws of humanity, and the requirements of the public conscience’.⁶ This relaxed approach – bringing non-legal normative issues into CIL – has been occasionally embraced in subsequent case-law and scholarly writings, as discussed below.

In 1920, the Council of the League of Nations established the Advisory Committee of Jurists, in order to produce a draft treaty for the creation of the Permanent Court of International Justice and to list the sources of law applicable by the Court. The Advisory Committee largely relied on the language and approach of the Hague Conferences. The draft treaty defines ‘international custom, being practice between nations accepted by them as law’.⁷ In the final version of the treaty, the concept of ‘nations’ is no longer included but the scope of custom is rather broadened by encompassing ‘international custom as evidence of a general practice accepted as law’. Interestingly, the initial draft also lists ‘international jurisprudence as a means for the application and development of law’ as a source of applicable law⁸ whereas the subsequent Statutes – Statute of the Permanent Court of International Justice and the Statute of the International Court of Justice – only contain a reference to ‘judicial decisions […] of the various nations, as subsidiary means for the determination of rules of law’.⁹ Thus, it seems the Advisory Committee struggled to strike the balance between the impact of national practices and case-law on international law on one hand, and international practice and international jurisprudence on the other.¹⁰

Article 38 of the Statute of the International Court of Justice¹¹ reproduces the list of sources of international law, which the court must adhere to in its determination of applicable law. The Article is identical to that codified already in the Statute of the Permanent Court of International Justice in 1920.¹² Article 38(1)(b) defines international custom as ‘evidence of a general practice accepted as law’, consisting of the two elements: state practice and opinio juris. The paragraph 38(1)(b) does not make an explicit reference to states or nations, unlike two other paragraphs of the same Article.¹³ Therefore, even when adapting a strictly textual interpretation of that paragraph, the court is not bound to limit its analysis only on the practice of states but could extend the scope of the analysis to the practice of other actors who may contribute to the development of law. Also, some subsequent developments in the doctrine imply that the distinction between the two elements of CIL is too simplistic and artificial.¹⁴ For instance, the General Assembly of the United Nations, as well as other international bodies, do affect the formation of CIL, without it being clear if their actions fall in the realm of practice or opinio juris.

The International Law Commission (ILC) was established by the United Nations General Assembly in 1948 for the purpose of restating existing rules of international law, and for promoting ‘the progressive development of international law and its codification’.¹⁵ The ILC has contributed to the formation of CIL on both procedural (the determination of the elements of CIL) and substantive (providing for definitions of specific customary rules) levels. The first ILC report on CIL was produced in 1950, titled ‘Ways and means for making the evidence of customary international law more readily available’.¹⁶ It was drafted on the basis of a working paper by Manley O. Hudson. Notably, in the Report of 1950, judicial decisions, which address the issues of international law – whether by national or international courts – are included as corroborating the rules of CIL.¹⁷ Inclusion of national and international judicial decisions as evidence of CIL can be traced to Article 24 of the Statute of the ILC, which reads as follows: ‘The Commission shall consider ways and means for making the evidence of customary international law more readily available, such as the collection and publication of documents concerning State practice and of the decisions of national and international courts on questions of international law, and shall make a report to the General Assembly on this matter.’¹⁸ This can be understood as one of the earliest departures from the traditional model of CIL formation. Also, according to the ILC, the practice of international organisations may be regarded as evidence of CIL.¹⁹ The Report suggests that the elements composing CIL should be documented and available for consultation, usually through the publication of materials. In the area of customary international humanitarian law, such a task was later carried out by the International Committee of the Red Cross, which produced an extensive study on the substantive customary rules of humanitarian law.²⁰ The ILC has continued its work on CIL, and in 2012 it placed the topic ‘Formation and evidence of customary international law’ on its current programme of work, and named Sir Michael Wood as a Special Rapporteur. The topic was discussed and endorsed at the Sixth Committee of the UN General Assembly,²¹ and the ILC then requested States to ‘provide information on their practice relating to the formation of customary international law and the types of evidence suitable for establishing such law in a given situation, as set out in: (a) Official statements before legislatures, courts and international organizations; and (b) Decisions of national, regional and subregional courts.’²² The first introductory Report was released in May 2013, setting out the scope and outcome, materials to be consulted, and the future work to be carried out on the topic: the subsequent Reports will discuss the two elements of CIL, the effects of treaties and international organisations on CIL, and some particular issues, such as the notion of ‘persistent objector’. The final Report is to be released in 2016 with commentaries and conclusions.²³

1.3. Developments in case-law

One of the earliest cases in which a national court articulated CIL was Paquette Habana,²⁴ in the United States Supreme Court in 1900. The court held that fishing vessels were exempt from capture as prizes of war under a rule of CIL, evidenced by earlier treaties, national orders and instruction of many states and works of jurists and scholars. Importantly, Justice Gray stated in the decision that ‘international law is part of our law, and must be ascertained and administered by the courts of justice of appropriate jurisdiction. […] For this purpose, where there is no treaty, and no controlling executive or legislative act of judicial decision, resort must be had to the customs and usages of civilized nations’.²⁵

The two elements of the CIL, state practice and opinio juris were further elaborated upon in subsequent cases; in the Lotus case (1927) by the Permanent Court of International Justice,²⁶ and in the Asylum case (1950) by the ICJ.²⁷ In relation to the Lotus case, it has been noted that “[d]uring this time, neither the legislation nor the practice of states, save for few exceptions, included extraterritorial criminal jurisdiction except with respect to the conduct of their citizens under the theory of “active personality”’.²⁸ In other words, in the 1920s the notion of extra-territorial jurisdiction had not come to exist under CIL and could n...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Acknowledgements
• Table of cases
• Table of statutes
• Introduction
• 1. Genesis of customary international law and international criminal law
• 2. New concept of customary international law – the role of the international criminal judge
• 3. Customary international law in the decisions of the ICTY
• 4. The principle of legality and customary international law
• 5. The need for a new conceptual framework for the sources in international law
• General conclusion
• Bibliography
• Index