The travaux préparatoires are official documents that record the negotiations, drafts and discussions that took place during the drafting of a treaty. These documents can be consulted and taken into account when interpreting treaties. They are often unpublished or inaccessible and difficult to find even when they have been published in a collected volume. Many bilateral agreements have entered into force without much formal negotiation; in these cases, there are no travaux préparatoires.
Collected Travaux Préparatoires, by the Yale Law School Lillian Goldman Library
A recommended starting point for research. The aim of this page is to collect references and links to travaux préparatoires, either on paper or online.
Where the United Nations has been involved, some travaux préparatoires can be found through the Official Document System of the United Nations. Some interesting documents can also be found on the United Nations Diplomatic Conferences website. Documents relating to the conventions negotiated by the International Law Commission can be found in the ILC Yearbook.
341(06) HEIA 1653 (in English)
341(06) HEIA 1646 (in French)
The archives of the drafting of the International Declaration on Human Rights, the Convention on the Prevention and Punishment of the Crime of Genocide, the Covenants on Civil and Political Rights and on Economic, Social and Cultural Rights are available online, on the website of the UN Office at Geneva.