The answer is not simple. In 2007, I submitted to the Commission`s working group on the long-term programme of work an informal working paper entitled “Subsequent Treaty Agreements and Practices”.1 The preliminary part of this (unpublished) working paper set out the reasons for the proposal to work on this topic. It refers not only to Article 31(1) as a general rule, but it makes little mention of subsequent practice. However, the resulting practice is rarely used and is used only in a subsidiary manner and only by certain participants. 4. International law has a particularity in ensuring that developments in circumstances are taken into account in a manner consistent with the agreement of the parties. This characteristic is mentioned in Article 31(3)(a) and (b) of the VCLT and consists in recognising the role played by subsequent agreements and subsequent practices in the interpretation of a contract. . . .
