UNIDROIT Principles and CISG: change of circumstances and duty to renegotiate according to the Belgian Supreme Court

The Article addresses the issue of the interpretation and supplementation of international Conventions on uniform law, focusing on the relationship between the UNIDROIT Principles of International Commercial Contracts and the UN Convention on International Sales (CISG). In particular, it deals with the gap-filling role which is attributed to the UNIDROIT Principles according to its Preamble, in conjunction with Art. 7(2) CISG and in the light of a recent controversial decision of the Belgian Supreme Court on change of circumstances. After a discussion of the differing scholarly opinions on the question, the point is made that the direct application of the rules on hardship of the UNIDROIT Principles (Arts 6.2.2-6.2.3) does not appear to be justified, since no general principle concerning judicial intervention in the contractual regulation by parties can be found in CISG. In the Author’s opinion, however, a duty to renegotiate in good faith in a case of supervening circumstances could well be inferred from the application of the general principle of good faith, according to Art. 7(2) CISG. Furthermore, it is argued that a similar result would be reached by applying the UNIDROIT Principles as a means to interpret and/or supplement the applicable national law (in the case at hand, French law, which shows an interesting development from the traditional “Canal de Craponne” case approach to a more nuanced scholarly and judicial acceptance of a duty to renegotiate in good faith in specific circumstances). The UNIDROIT Principles could prove to be a particularly useful tool to solve interpretative issues within national law in favour of the solution which is more convincing for international commercial transactions.[...]