[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).]
8. Non-Performance Caused by Other Party
308. Article 80 sets forth a simple and hardly controversial rule: for clearly, one party may not rely on a failure of the other party to perform to the extent that such failure was caused by the first party's own act or omission. [page 166]
Judging by its placement in Section 4, it seems that Article 80 was intended to serve as an adjunct to the exemptions rule in Article 79, hereunder Article 79(5). For example, a buyer who himself 'frustrates' performance by the seller can neither demand specific performance nor avoid. Then again, Article 80 was hardly needed to reach such an obviously reasonable result.