Treaties, also called conventions, play the role of statutes in international legal research. The websites for most courts will usually have the major treaties and conventions that apply to that court. However, you may need to consult other treaties and conventions depending on the issue you are researching. Multilateral treaties are easy to locate online, especially newer ones. Bilateral and older multilateral treaties may be more difficult to find. For those, you may need to consult one of the treaty collections or a treaty index to locate the treaty. Listed below are some of the better sources for locating major multilateral treaties.
This website provides full text of treaties and international agreements registered or filed with the UN since 1946. The collection currently contains over 50,000 treaties. The database also includes other treaty-related data including Status of Multilateral Treaties Deposited with the Secretary-General (status of more than 500 major treaties).
This website from the World Legal Information Institute provides free access to international treaties from a variety of freely available sources.
This website provides access to the full text of over 100 treaties related to international humanitarian law, commentaries on the Geneva Conventions and late protocols, and information about the current signatories to the conventions and any reservations, declarations, and objections from state parties to the conventions. The database is can be searched by topic, date, and country. According to Professor Garry, the ICRC’s commentaries on the conventions are generally considered highly persuasive authority by international criminal tribunals.
A helpful starting point for researching travaux préparatoires, the drafting history of international agreements.