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Sources of international law

International law, also known as 'public international law', is the system of law that imposes rights and obligations on States in their dealings with each other.

For more information on legal research, including Australian law, use our Law subject guide

International law sources


For Australian cases see Westlaw Australia cases and CaseBase via Lexis Advance.


A treaty is an agreement involving two or more states that is written in accordance with and governed by international law. Treaties are either bilateral, involving two states, or multilateral, involving three or more states. A “party” is a state that has agreed to be bound by a particular treaty. Treaties are key sources of international law.


Consulting secondary sources provides an overview of the legal principles you are investigating. Researchers in international law often encounter unfamiliar terms, or familiar terms used in unfamiliar ways. When you encounter these terms, avoid confusion by consulting dictionaries and lists of abbreviations. Secondary sources include: textbooks & books discussing specialised legal topics, encyclopaedias & dictionaries, journal articles

Secondary sources will provide you with the broader legal context of an issue, refer you to key primary sources such as cases and treaties and alert you to areas of uncertainty and debate in the law.

Start by consulting textbooks, books and legal encyclopaedias, that discuss legal principles more broadly, before moving to journal articles and commentary for a more critical analysis of a legal issue.


For more secondary sources see the Journals and Legal encyclopedias & dictionaries pages of this guide