a. The right to claim interest on amounts due and not paid by a contractual party under the CISG is governed by Articles 78 and 84(1). The issue of interest was one of the topics on which no real consensus could be reached in the drafting of the CISG. One commentator has remarked that “Art. 78 is more conspicuous for the questions it fails to answer than the questions it answers.” The fact that such a right was included at all represents a compromise reached by the various interests groups that held incompatible views on interest. This compromise was achieved with great difficulty in the final phases of the Conference.

b. Article 78 is formulated in general terms, leaving the following issues open or unresolved: the rate of interest, whether interest is payable when the breach of the defaulting party is excused under Article 79, whether the amount due needs to be liquidated before interest accrues, whether interest is payable on any amount of damages due, and whether compound interest may be claimed. The determination of the rate of interest was intentionally left open in the drafting process of the CISG as no agreement could be reached on the approach to be adopted.

c. Because of the controversies and uncertainties that surround Article 78 the provisions of the UNIDROIT Principles must be considered as one appropriate way of solving these issues.