Research Guides : International Moot Court Guide: Customary International Law

What is customary international law?

According to Article 38 of the Statute of the International Court of Justice, the second most significant source of international law is international custom. Specifically the ICJ statute states that the court shall apply international custom as “evidence of a general practice accepted as law”. An international lawyer must prove two basic elements for a particular norm to qualify as customary law:

State practice must be generally consistent
Practice must occur out of a sense of legal obligation.

Secondary Sources STATING Custom

ENCYCLOPEDIAS

Max Planck Encyclopedia of Public International Law This link opens in a new window
This online edition of the Max Planck Encyclopedia of Public International Law covers central and essential topics in international law.
Max Planck Encyclopedia of Comparative Constitutional Law This link opens in a new window
The Max Planck Encyclopedia of Comparative Constitutional Law provides analytic coverage of constitutional law topics in a comparative context. The encyclopedia articles address a focused range of topics that seek to provide the best coverage of the essence, character, development, and history of constitutional law from a global perspective.

TOOLS FOR LOCATING TREATISES

Online Catalog
Locates materials at all FSU Libraries.

Oxford Bibliographies This link opens in a new window
Developed cooperatively with scholars and librarians worldwide, Oxford Bibliographies offers exclusive, authoritative research guides.
Oxford Scholarly Authorities on International Law This link opens in a new window
Oxford Scholarly Authorities on International Law contains full-text online editions of market-leading reference works and treatises published by Oxford University Press. Books such as Oppenheim, our Oxford Handbooks in international law, and the Oxford Commentaries on International Law are made available online for the first time, fully searchable and linked by the Oxford Law Citator.

MAJOR SCHOLARLY WORKS

MAJOR INTERNATIONAL JOURNALS

TOOLS FOR LOCATING ARTICLES

HeinOnline - International and Non-US Law Journals

Index to Foreign Legal Periodicals This link opens in a new window

Lexis - All International Law Reviews & Journals Search
- This link opens in a new window
Westlaw - International Journals
- This link opens in a new window

INTERNATIONAL LAW COMMISSION (ILC)

Restatement of the Law, Foreign Relations Law 3d - Official Text
- This link opens in a new window
Restatement of the Law - The Foreign Relations Law of the United States
- This link opens in a new window

Restatement of the Law, Third, Foreign Relations of the United States by Louis Henkin (Editor); American Law Institute Staff
Call Number: RESERVES: KF395.A2F6 1987
ISBN: 0314301380

Digests of US Practice in International Law
US State Department publishes a series of digests covering U.S. state practice in international law. Here you'll find written views, practices and pronouncements of the US government.
Digest of US Practice in International Law
Same as above, but freely available from US State Department, covers U.S. state practice in international law. Here you'll find written views, practices and pronouncements of the US government.
American Journal of International Law
Use this source to update the Digest of US Practice. In the table of contents, look at "Contemporary Practice of the US Relating to International Law."

Primary Sources STATING Custom

Virtually all states have signed the following conventions.

Vienna Convention on the Law of Treaties
Vienna Convention on Consular Relations

General Assembly resolutions, in and of themselves, do not state rules of international law. But, they can result in creating customary international law. Use the following sources to locate resolutions.

Best known resolutions that are in the form of an international agreement are:

Examples of UN General Assembly resolutions that are viewed as customary law are:

To locate judicial opinions that contain a statement that there is a a rule of cutomary international law in effect, consult a well-respected treatise that confirms the statement or consult a database of international opinions.

Treatises

General international law treatises listed here.
International law treatises on specialized topics.

Databases

Oxford Reports on International Law
International Law Reports (JUSTIS)

When using the databases above, possible search terms and strategies include the following:

[rule] AND principle AND custom!
[rule] /p principle /p custom!
[rule] /s principle /s custom!

Sources of Evidence of State Practice & Opinio Juris

Diplomatic Papers of the United States

American State Papers
Foreign Relations of the United States
International Agreements and Diplomatic Documents
Public Papers of the Presidents of the United States

Diplomatic Papers of Other Countries

To access compiled collections of diplomatic records of other countries, you may also want to search your online catalog using a subject search of: