Customary International Law

Art. 38 (1) Statute of the International Court of Justice, after saying that the court’s function is ‘to decide in accordance with international law such disputes as are submitted to it’, states, in para. (1) (b), that it shall apply ‘international custom, as evidence of a general practice accepted as law’.

Customary international law, although long recognized as a primary source of international law, remains “replete with enigmas, both conceptual and practical. These include how to determine the existence of opinio juris, the function of the state practice requirement, the definition of jus cogens customary norms, and the relationship between customary international law and ethics.”(1)

Customary International Law and Ethics

Notes

1. Customary International Law. A New Theory with Practical Applications, Brian D. Lepard (2010)

See Also

• Legal Systems
• Comparative Law Contents
• Hindu Law in General
• Chinese Law in General
• Common Law Systems
• Code Law Systems
• Socialist Legal Systems
• English Law System
• English Common Law
• Rules
• Islamic Law
• Legal Pluralism
• Legal Theory
• Philosophy of Law
• Political Science

Further Reading

• Customary International Law. A New Theory with Practical Applications, Brian D. Lepard (2010)
• H Triepel, Vülkerrecht und Landesrecht (Hirschfeld Leipzig 1899).
• H Kelsen, General Theory of Law and State (Harvard University Press Cambridge 1949).
• M Giuliano, La comunità internazionale e il diritto (Cedam Padova 1950).
• R Ago, Scienza giuridica e diritto internazionale (Giuffré Milano 1950).
• H Kelsen, Principles of International Law (Rinehart New York 1952).
• G Barile ‘La rilevazione e l’integrazione del diritto internazionale non scritto e la libertà di apprezzamento del giudice’ (1953) 5 ComuneStudi 141-229.
• HLA Hart, The Concept of Law (Oxford Clarendon Press 1961).
• D Anzilotti, Corso di diritto internazionale (4th ed Cedam Padova 1955).
• B Cheng, ‘United Nations Resolutions on Outer Space: “Instant” International Customary Law?’ (1965) 5 IJIL 23-48.
• G Morelli, Nozioni di diritto internazionale (7th ed Cedam Padova 1967).
• M Virally, ‘The Sources of International Law’ in M Sà¸rensen (ed) Manual of Public International Law (Macmillan London 1968) 116-74.
• RR Baxter, ‘Treaties and Custom’ (1970) 129 RdC 25-105.
• AA D’Amato, The Concept of Custom in International Law (Cornell University Press Ithaca 1971).
• P Reuter, Droit international public (4th ed Presses Universitaires de France Paris 1973).
• R-J Dupuy, ‘Coutume sage et coutume sauvage’ in RJ Dupuy— (ed) Mélanges offerts à Charles Rousseau: La Communauté Internationale (Pedone Paris 1974) 75-87.
• M Akehurst, ‘Custom as a Source of International Law’ (1974-75) 47 BYIL 1-53.
• G de Lacharrière, La politique juridique extérieure (Economica Paris 1983).
• P Weil, ‘Towards Relative Normativity in International Law?’ (1983) 77 AJIL 413-42.
• L Ferrari Bravo, ‘Méthodes de recherche de la coutume internationale dans la pratique des Etats’ (1985) 192 RdC 233-330.
• P Haggenmacher, ‘La doctrine du droit coutumier dans la pratique de la cour internationale’ (1986) 90 RGDIP 5-126.
• M Sahovic, ‘Rapports entre facteurs matériels et facteurs formels dans la formation du droit international’ (1986) 199 RdC 171-232.
• FL Kirgis, ‘Custom on a Sliding Scale’ (1987) 81 AJIL 146-51.
• WM Reisman, ‘The Cult of Custom in the Late 20th Century’ (1987) 17 CalWIntlLJ 133-45.
• G Arangio-Ruiz ‘Consuetudine (consuetudine internazionale)’ in P Spirito (ed) Enciclopedia Giuridica (Istituto della Enciclopedia Italiana Roma 1988) vol 8 Condo-Contratti.
• A Cassese and J Weiler (eds) Change and Stability in International Law-Making: Based on the Proceedings of Two International Colloquia held at the European University Institute (De Gruyter Berlin 1988).
• P-M Dupuy, ‘Le juge et la règle générale’ (1989) 93 RGDIP 569-98.
• T Meron, Human Rights and Humanitarian Norms as Customary Law (Clarendon Press Oxford 1989).
• A Pellet ‘The Normative Dilemma: Will and Consent in International Law-Making’ (1988-89) 12 AustYBIL 22-53.
• O Schachter ‘Entangled Treaty and Custom’ in Y Dinstein (ed) International Law at a Time of Perplexity: Essays in Honor of Shabtai Rosenne (Nijhoff Dordrecht 1989) 717-38.
• T Treves, ‘Codification du droit international et pratique des Etats dans le droit de la mer’ (1990) 223 RdC 9-302.
• L Condorelli ‘La coutume’ in M Bedjaoui (ed) Droit international: Bilan et perspectives (Pedone Paris 1991) 187-221.
• JI Charney, ‘Universal International Law’ (1993) 87 AJIL 529-51.
• G Danilenko, Law-Making in the International Community (Nijhoff Dordrecht 1993).
• K Wolfke, Custom in Present International Law (2nd ed Nijhoff Dordrecht 1993).
• L Doswald-Beck (ed) San Remo Manual on International Law Applicable to Armed Conflicts at Sea (CUP Cambridge 1995).
• ME Villiger, Customary International Law and Treaties: a Manual on the Theory and Practice of the Interrelation of Sources (2nd ed Kluwer The Hague 1997).
• MH Mendelson, ‘The Formation of Customary International Law’ (1998) 272 RdC 155-410.
• M Byers, Custom, Power and the Power of Rules: International Relations and Customary International Law (CUP Cambridge 1999).
• G Cahin, La coutume internationale et les organisations internationales: l’ incidence de la dimension institutionnelle sur le processus coutumier (Pedone Paris 2001).
• B Chigara, Legitimacy Deficit in Custom: A deconstructionist critique (Ashgate Aldershot 2001).
• AE Roberts ‘Traditional and Modern Approaches to Customary Law: A Reconciliation’ (2001) 95 AJIL 757-91.
• A Watts, ‘The International Court and the Continuing Customary International Law of Treaties’ in N Ando (ed) Liber Amicorum Judge Shigeru Oda (Kluwer Law International The Hague 2002) 251-66.
• E Cannizzaro and P Palchetti (eds) Customary International Law and the Use of Force: A Methodological Approach (Nijhoff Leiden 2005).
• AT Guzman, ‘Saving Customary International Law’ (2005) 27 MichJIntlL 115-76.
• JM Henckaerts, ‘Study on Customary International Humanitarian Law: A Contribution to the Understanding and Respect for the Rule of Law in Armed Conflict’ (2005) 87 ICRC 175-212.
• T Meron, ‘Revival of Customary Humanitarian Law’ (2005) 99 AJIL 817-34.

International Law: Customary Law

Introduction to International Customary Law

Customary international law is unwritten and derives from the actual practices of nations over time. To be accepted as law, the custom must be long-standing, widespread, and practiced in a uniform and consistent way among nations. One example of customary international law is a nation’s right to use the high seas for fishing, navigation, overflight, and submarines.

Treaties represent another source of customary law. Although treaties generally bind only those countries that ratify them, customs may be deduced from the rules and statements contained in treaties. These new customs may be considered binding even on those states that did not sign and ratify the original treaty. Whether or not they are embodied in a written treaty, customs become part of international law because of continued acceptance by the great majority of nations.

Some customary international law has been codified in recent years. For example, the Vienna Convention on the Law of Treaties, which was approved in 1969 and took effect in 1980, codified the customary law that treaties between sovereign states are binding on their signatories and must be followed in good faith.” (1)

International Customary Law

Embracing mainstream international law, this section on international customary law explores the context, history and effect of the area of the law covered here.

Resources

Further Reading

• The entry “customary law, international” in the Parry and Grant Encyclopaedic Dictionary of International Law (currently, the Encyclopaedic Dictionary of International Law, 2009), Oxford University Press

Resources

Notes and References

• Information about International Customary Law in the Encarta Online Encyclopedia

Guide to International Customary Law