Customary International Law

Introduction

Updated: July 02, 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 provides a starting point for research on Customary International Law. It contains legal materials available in the Peace Palace Library, both in print and electronic format. Books, articles, bibliographies, periodicals, serial publications and documents of interest are presented in the Selective Bibliography section including links to the PPL Catalogue when available. 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

2019

  • Berkes, A., “The Formation of Customary International Law By de Facto Regimes” (February 27, 2019), in S. Droubi and J. d’Aspremont (eds.), International Organizations and Non-State Actors in the Formation of Customary International Law, Manchester University Press, 2019. [PDF]
  • Brölmann, C.M., “Capturing the Juridical Will of International Organisations (February 25, 2019), in S. Droubi and J. d’Aspremont (eds.), International Organizations and Non-State Actors in the Formation of Customary International Law, Manchester University Press, 2019; Amsterdam Law School Research Paper No. 2019-09; Amsterdam Center for International Law No. 2019-02. [PDF]
  • Deplano, R, “The Riddle of Custom: General Assembly Resolutions (November 20, 2018), in S. Droubi and J. d’Aspremont (eds), International Organizations, Non-State Actors, and the Formation of Customary International Law, Manchester University Press, 2019. [PDF]
  • Dodge, W.S., “International Comity in the Restatement (Fourth) of Foreign Relations Law” (January 6, 2019). [PDF]
  • Gradoni, L., “Un-procedural Customary Law”, Journal of International Dispute Settlement, 10 (2019), No. 2, pp. 175-199. [e-article]
  • Nolte, G., “How to Identify Customary International Law?: On the Final Outcome of the Work of the International Law Commission (2018) (June 2019), KFG Working Paper Series, No. 37, Berlin Potsdam Research Group “The International Rule of Law – Rise or Decline?”, June 2019 . [PDF]

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

  • Heieck, J., A Duty to Prevent Genocide : Due Diligence Obligations Among the P5, Cheltenham, Edward Elger, 2018.

    Heieck, J., A Duty to Prevent Genocide : Due Diligence Obligations Among the P5, Cheltenham, Edward Elger, 2018.

    The permanent five (P5) members of the United Nations Security Council have a firm duty to prevent genocide in light of the due diligence standard under conventional, customary, and peremptory international law. This perceptive book explores the positive obligations of these states to act both within and without the Security Council context to prevent or suppress imminent or ongoing genocide. The author successfully argues why the duty to prevent genocide is not only a customary, but also an absolute norm of international law, and analyses the scope of the due diligence standard regarding the duty to prevent genocide. In doing so, he considers the ramifications of this on the actions of the P5 members of the Security Council, both inside and outside of this eminent body. Significantly, Heieck proposes a legal test for identifying jus cogens norms, and explores the effect of these on the actions and omissions of specifically identified members of the United Nations (UN). Topical and insightful, A Duty to Prevent Genocide will be an important read for both academics and students of international law and politics who wish to further understand the legal nature of the duty of the P5 members to prevent genocide. It will also provide valuable insights for policy makers of the P5 Member States.

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  • 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