Start Your Research

A basic introduction to international legal research in the Peace Palace Library. Your road map for approaching an international legal research problem. Step 1-11.

For thorough and complete public international legal research, six sources of law must be consulted. Please, be aware that these sources are categorized as either primary sources, subsidiary sources of law, or peremptory norms. Start by following the structure of Article 38 of the Statute of the International Court of Justice: (1) treaties, (2) custom, and (3) general principles of law. Subsidiary sources include (4) judicial decisions and the (5) writings of highly qualified publicists. And last, you should consider (6) peremptory norms of international law (jus cogens) which are so fundamental as no derogation from them is permitted.

Continue your search with (7) resolutions and decisions of international organizations. Although they cannot themselves constitute international law or serve as conclusive evidence of a rule of customary law, such resolutions do have value in providing evidence of existing or emerging law. Focus your research on the actions of the United Nations and its various organs. The concept of (8) soft law presents another opportunity for further research as it plays a role in the development of international law. It may become binding when it is incorporated explicitly into an international treaty or otherwise hardens into customary international law.

Once you’ve finished your research on the sources of law, it is time to consult (9) secondary sources for background information and context. Secondary sources are resources that explain, analyze, synthesize, critique or comment on the law. There are a variety of types of secondary sources, including: books, essays, journal articles, dictionaries, legal encyclopedias, law reports, legal treatises, practice materials, blogs, and newspapers.

You should consider the extensive (10) library services the Peace Palace Library has to offer. With so much information available, we are committed to assisting and facilitating your research in public international law, through the website, and with a personal touch. Our (11) law librarians are at your service. They will use innovative search strategies to take knowledge where it’s needed: You!