[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).]
294. In domestic sales law and under the CISG: a plaintiff cannot recover for those harms that he could have avoided by reasonable action. Within the Convention context, Article 77 applies:
There is no Convention 'duty' to mitigate as such. However, a party who fails to take reasonable measures to mitigate loss cannot recover for the loss which could have been mitigated, and the principle should apply even as regards a prospective failure to perform: once a party has reason to know that performance by the other party will not be forthcoming, he is expected to take such affirmative steps as are [page 157] appropriate in the circumstances to avoid loss. And as in domestic law, so under the CISG: the avoidability principle determines the point in time at which we calculate the contract-cover and contract-market price differentials.
Also losses otherwise recoverable under the more general Article 74 rule are limited by the mitigation principle. If, for example, the seller delays delivery of goods intended to serve as a key ingredient or tool in buyer's production, and the buyer makes no reasonable efforts to secure a substitute, any profits lost will not have been suffered solely 'in consequence' of seller's breach. Of course, the extent of avoidability will depend on the buyer's ingenuity, experience, and financial resources (ability to obtain credit quickly, etc.), and what is 'reasonable' mitigation will depend on the court's evaluation of the concrete case.
295. Sometimes, a given buyer's loss may seem (at least partIy) caused by her own pre-breach, negligent act.[l] And although CISG Article 75 seems designed mainly to post-breach mitigation, the Convention does not bar recognition of the pre-breach (prevention) aspect of avoidability. For example, where the harm caused by seller's delayed delivery of a simple standard part is aggravated by the fact that buyer keeps no such spares on hand, such a failure to take precautionary measures, if judged unreasonable, will prevent the recovery of compensation for avoidable loss.