Customary International Law

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Information about Customary International Law in free legal resources:

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Hello Customary International Law

Customary international law applies in international
law in case of absence of a treaty. J. L. Brierly, in “The Law of
Nations: an Introduction to the International Law of Peace”states that in order to
determine what international customary law is on a particular subject “we must
look at what states do in their relations with one another and attempt to understand
why they do it, and in particular whether they recognize an obligation to adopt a
certain course, or, in the words of Article 38, we must examine whether the alleged
custom shows ‘a general practice accepted as law.'”(1)

Ian Brownlie, in “Principles of Public International Law”lists the following sources
of custom as “diplomatic correspondence, policy statements, press releases, the
opinions of official legal advisers, official manuals on legal questions, e.g.
manuals of military law, executive decisions and practices, orders to naval forces
etc., comments by governments on drafts produced by the International Law
Commission, state legislation, international and national judicial decisions, recitals
in Treaties in the same form, the practice of international organs, and resolutions
relating to legal questions in the United Nations General Assembly.”(2)



PEACE 60 (6th ed. 1963).

See Also

Further Reading

  • Bederman, David J., Custom as a Source of Law. New York: Cambridge University Press, 2010.
  • Customary International Law on the Use of Force: a Methodological Approach. Leiden ; Boston: Martinus Nijhoff, 2005.
  • Chigara, Ben. Legitimacy Deficit in Custom : a Deconstructionist Critique. Aldershot, England; Burlington, VT : Ashgate/Dartmouth, 2001.
  • Commitment and Compliance : the Role of Non-binding Norms in the International Legal System, New York : Oxford University Press, 2000.
  • D’Amato, Anthony A, The Concept of Custom in International Law, Ithaca, N.Y.: Cornell University Press, 1971.
  • The Fundamental Rules of the International Legal Order: Jus Cogens and Obligations Erga Omnes. Leiden; Boston: Martinus Nijhoff Publishers, 2006.
  • Lepard, Brian D., Customary International Law: a New Theory with Practical Applications. New York, N.Y.: Cambridge University Press,2010.
  • The Nature of Customary Law. Cambridge : Cambridge University Press, 2007
  • Schlütter, Birgit, Developments in Customary International Law: Theory and the Practice of the International Court of Justice and the International Ad Hoc Criminal Tribunals for Rwanda and Yugoslavia. Leiden; Boston : Martinus Nijhoff Publishers, 2010.
  • Villiger, Mark Eugen, Customary International Law and Treaties : a Manual on the Theory and Practice of the Interrelation of Sources, 2nd ed., The Hague; Boston: Kluwer Law International, 1997.
  • Tams, Christian J. Enforcing Obligations Erga Omnes in International Law. Cambridge, UK ; New York : Cambridge University Press, 2005


References and Further Reading

About the Author/s and Reviewer/s

Author: international

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Customary International Law and International Trade Economy

In relation to international trade economy, Christopher Mark (1993) provided the following definition of Customary International Law: International law that has arisen from custom and usage, and that is recognized and accepted as binding even though not codified. See also conventional international law.

Definition of Customary International Law

Within the context of international human rights, the following is a brief meaning of customary international law: Law that becomes binding on states although it is not written, but rather adhered to out of custom; when enough states have begun to behave as though something is law, it becomes law “by use”; this is one of the main sources of international law.

International Law Commission: Identification of Customary International Law

In relation to the international law practice and international law commission on customary international law in this world legal Encyclopedia, please see the following section:

International Organizations

About this subject:

ILC’s Work on Reservations to Treaties

Note: there is detailed information and resources under these topics during the year 2013, covered by this entry on international law commission in this law Encyclopedia.

Customary International Law in International Economic Law

This section provides an overview of customary international law within the legal context of Sources of Law in international economic law .


Further Reading

  • Patrick Dumberry, “Customary International Law in International Economic Law,” Elgar Encyclopedia of International Economic Law, Cheltenham Glos (United Kingdom), Northampton, MA (United States)


See Also

  • Human Rights

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