The travaux préparatoires (French: "preparatory works", in the plural) are the official record of a negotiation. Sometimes published, the "travaux" are often useful in clarifying the intentions of a treaty or other instrument, as is reflected in Article 32 of the Vienna Convention on the Law of Treaties (VCLT).
To interpret treaties, the VCLT places this form of interpretation as secondary to the ordinary meaning (see Articles 31 and 32).
In the Sigurjonsson v. Iceland case the Court noted that the use of the travaux préparatoires in the earlier Young James and Wester case was not decisive but merely provided a working hypothesis. The preparatory work was legitimately invoked by the Commission to show that the provision that "Every shall be free to leave any country, including his own", does not entitle a convicted prisoner to leave the country in which he is lawfully detained.
An example of such interpretation was provided by Lord Diplock in the case Fothergill v Monarch Airlines Ltd 
The most well-known travaux are associated with the drafting of the Genocide Convention.
- Clare Ovey and Robin C.A.White (2002). Jacobs and White: European Convention on Human Rights. Oxford University Press. pp. 29–30. ISBN 0-19-876-5800.
- HL. AC 251 (1981). "Law report". Cite journal requires
- "The Genocide Convention: The Travaux Préparatoires (2 vols) | Brill". www.brill.com. Retrieved 2016-11-04.