Under article 4(a) of the CISG, domestic law governs if a sales contract's validity is at issue.' One must consult the conflict of laws provisions of private international law to determine which domestic law is applicable.
In contrast to the Convention, the Swiss Code of Obligations as well as relevant Swiss literature and jurisprudence clearly address the issue of contractual validity. Swiss contract law's error provisions are characterized as contract validity rules. If, for instance, a buyer claims that he erred on a certain fact that was a necessary basis for him to enter into an international sales contract under which the parties stipulated that the Convention would provide the applicable law and Zurich would be the forum of litigation, a Zurich court would probably characterize the claim as an issue requiring application of domestic validity rules. In light of the Convention, would this characterization be correct? The interplay between Swiss contract law's approach to a contract's validity and that of the Convention gives rise to this Article's central focus.
Christoph R. Heiz,
Validity of Contracts Under the United Nations Convention on Contracts for the International Sale of Goods,
20 Vanderbilt Law Review
Available at: https://scholarship.law.vanderbilt.edu/vjtl/vol20/iss4/2