Customary International Law

Introduction

Updated: January 8, 2019 (Bibliography).

According to Article 38 of its Statute, the International Court of Justice 'whose function is to decide in accordance with international law such disputes as are submitted to it,' has to apply, inter alia, 'international custom.' This source of public international law is described, in the same Article, as 'evidence of a general practice accepted as law.' This description of international custom, even though it has been criticized for its exact formulation, at least makes clear that international custom generally refers to a description of State practice, but only such practice as is accepted by the States themselves as legally required. Once a certain practice is understood to be customary law, States are obliged to act as the rule of customary international law prescribes. International customary law is probably the most disputed and discussed source of international law. For example, it is not clear when a particular State practice becomes a legally binding State practice. It is also unclear how one can identify a rule of international custom, or how one can prove its existence.

The International Law Commission appointed Sir Micheal Wood as Special Rapporteur concerning the issue of Customary International Law. His reports and recommendations are available in the bibliography under documents.

This Research Guide is intended as a starting point for research on Customary International Law. It provides the basic legal materials available in the Peace Palace Library, both in print and electronic format. Handbooks, leading articles, bibliographies, periodicals, serial publications and documents of interest are presented in the Selective Bibliography section. Links to the PPL Catalogue are inserted. The Library’s systematic classification → Customary international law and subject heading (keyword) Customary International Law are instrumental for searching through the Catalogue. Special attention is given to our subscriptions on databases, e-journals, e-books and other electronic resources. Finally, this Research Guide features links to relevant websites and other online resources of particular interest.

 

Bibliography

Reference works

Books

Articles

2018

2017

2016 and before

Documents

Bibliographies

Systematic classification → Customary international law

New titles

As we are right in the middle of moving to a new library system, it is not yet possible to automatically collect new titles for this Research Guide.

Librarian's choice

  • Rauter, T., Judicial Practice, Customary International Criminal Law and Nullum Crimen Sine Lege, Cham, Springer, 2017.

    Rauter, T., Judicial Practice, Customary International Criminal Law and Nullum Crimen Sine Lege, Cham, Springer, 2017.

    This study analyzes the methods used by international criminal tribunals when determining customary international criminal law and to consider the compatibility of these approaches with the nullum crimen sine lege principle. In this context, the following research questions are of particular importance: Is there one approach common to all international criminal tribunals when determining customary international law? Do international criminal tribunals regard both traditional elements of customary international law - State practice and opinio iuris - as necessary elements for the establishment of customary international law? Do international criminal tribunals argue along the lines of the International Court of Justice (ICJ), requiring a high frequency and consistency of State practice that is both "extensive and virtually uniform"? In addition, the book analyzes the evidence used by international criminal tribunals in order to establish the constituent elements of customary international. It then poses the question: Do international criminal tribunals distinguish, as defined by Schwarzenberger, between the "law-creating processes" of public international law on the one hand, and the "law-determining agencies" as a subsidiary means of determining rule of law on the other? Assuming that they exist, how can different methodological approaches to determine customary international law be assessed in light of the nullum crimen sine lege principle? Does the principle require judges to apply the traditional method to establish customary international law as being based on extensive, uniform and enduring State practice accompanied by opinio iuris? Can the principle balance the desire for justice and the specificities of law creation of the international legal order with fairness for the accused? How can the law be accessible and criminal punishment foreseeable, when the underlying legal basis for criminal convictions, namely customary international criminal law, is unwritten in nature?

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  • Lepard, B.D. (ed.), Reexamining Customary International Law, Cambridge, Cambridge University Press, 2017.

    Lepard, B.D. (ed.), Reexamining Customary International Law, Cambridge, Cambridge University Press, 2017.

    Tis book takes on the complex issues and controversies surrounding the history, theory, and practice of customary international law as it reexamines customary law's increasingly important role in world affairs. It incorporates the expertise of distinguished authors to probe many difficult issues that remain unresolved concerning the doctrine of customary law. At the same time, this book engages in a profound exploration of the practical role of customary international law in a variety of important fields, including humanitarian law, human rights law, and air and space law.

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Database

Blogs

  • Happy Retirement Ingrid!

    [On the retirement of our curator Ingrid Kost; blog in Dutch] Vandaag 15 januari 2015 is een memorabele dag voor de bibliotheek van het Vredespaleis. Wij nemen na 39 jaar afscheid van onze collega Ingrid Kost. Zij zal genieten van een welverdiend pensioen. Tijd om andere dingen te gaan doen, zoals oppassen op de kleinkinderen en bijenhouden. Wij zullen haar deerlijk missen als collega en als mens. Alvorens vandaag afscheid te nemen, spraken wij met haar en haalden herinneringen op.

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  • Conference about ICJ's judgment in the case between Nicaragua and the USA

    In 1986, the International Court of Justice issued its judgment on the merits in a dispute between Nicaragua and the United States of America. Twenty-five years later, members of the legal teams of both Nicaragua and the United States faced each other once again in the Peace Palace.

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See also

More Research guides on Public International Law

Other suggestions

Systematic classification → Customary international law