[For more current case annotated texts by this author, see Bernstein & Lookofsky, Understanding the CISG in Europe, 2d ed. (2003) and Lookofsky, Understanding the CISG in the USA, 2d ed. (2004).]
138. Like Article 25, Article 26 is a general provision relating to the right of either injured party (seller or buyer) to avoid.
Because avoidance can have serious consequences for the party in breach (requiring, e.g. that a breaching seller retake possession of the goods on foreign [page 79] soil), Article 26 provides that a declaration of avoidance of the contract is effective only if made by notice to the other party. It also follows that the contract is avoided as of the point in time when the notice takes effect, i.e. 'upon dispatch'.
On the other hand, assuming the injured party is entitled to avoid, e.g. by reason of a fundamental breach or, e.g. the breaching party's failure to duly comply with a reasonable Nachfrist notice, a single Article 26 notice will suffice: unlike some domestic systems, the Convention does not first require a 'warning' notice which declares in advance the injured party's intention to avoid. [page 80]