A good research guide that can help you identify sources and methods for finding or compiling the travaux préparatoire for a treaty is Jonathan Pratter’s, UPDATE: À la Recherche des Travaux Préparatoires: An Approach to Researching the Drafting History of International Agreements.
The drafting history of a treaty (travaux préparatoires) can be a significant supplement aid to interpret treaties. The 1969 Vienna Convention on the Law of Treaties is a treaty about how to interpret treaties. Article 32 states that when treaty terms are ambiguous or leads to an unreasonable result, you may consult supplementary means of interpretation, including the preparatory work of the treaty. Although the United States has not ratified acceptance of this convention, it is a signatory. And, the United States Supreme Court has taken a liberal approach on using the drafting history of a treaty to aid interpretation.
In the United States, the U.S. Supreme Court characterized treaty negotiations and drafting history as aids to treaty interpretation. Medellin v. Texas, 128 S.Ct. 1346, 1357 (2008), quoting Zicherman v. Korean Air Lines Co., 516 U.S. 217, 226 (1996).
There are two types of travaux préparatoire.
1. The first type consists of a collection of all the underlying documentation that led up to the international agreement. This type is most useful when it is cross referenced to each article of the treaty; however, you may find this type of publication to exist as a chronological compilation of documents which is not useful unless you are looking for specific documents.
2. The second type of travaux préparatoire is an article-by-article commentary by a scholar or specialist who is knowledgeable about the subject matter. In this type of publication, the underlying documents are references or abstracted.
Listed below are Commentaries for key treaties. To find out if a Commentary has been published on a treaty, you should conduct a title or keyword search with the formal name of the treaty AND the word 'commentary." Commentaries are highly regarded secondary sources that review the language of a treaty article by article.
Commentaries on Key Treaties
Commentaries on the Vienna Convention
Collected Works of Drafting Documents/Travaux Preparatoire:
Collected Travaux Préparatoire, Ryan Harrington, ed., Yale Law School – This ongoing project provides access to the full text and the table of contents to the drafting documents of selected treaties.
United Nations Diplomatic Conferences - The United Nations has a searchable database of official records from eight UN-sponsored treaty conferences.
If you are trying to find the drafting history or a treaty that might already be published in book or article form (print or online), use the following combinations of words in the title fields of PRIMO or WorldCat, or in the keyword field using Legal Trac:
[combine words from the title of the treaty with the words]
AND
history or travaux préparatoires or commentary
Example: using search terms: “university declaration on human rights and travaux préparatoire” in the PRIMO title field will yield the 2013 title by William Schabas, The Universal Declaration of Human Rights: the travaux préparatoire.