CISG Article 43
1. The buyer loses the right to
rely on the provisions of article
41 or article 42 if he does not
give notice to the seller
specifying the nature of the
right or claim of the third party
within a reasonable time after
he has become aware or ought
to have become aware of the
right or claim.
2. The seller is not entitled to
rely on the provisions of the
preceding paragraph if he knew
of the right or claim of the
third party and the nature
2. The seller is not entitled to rely on the provisions of the preceding paragraph if he knew of the right or claim of the third party and the nature of it.
ULIS Article 52(1) and 52(4)
1. Where the goods are subject to a right or claim of a third person, the buyer, unless he agreed to take the goods subject to such right or claim, shall notify the seller of such right or claim. Unless the seller already knows thereof, and requests that the goods should be freed therefrom within a reasonable time or that other goods free from all rights and claims of third persons be delivered to him by the seller.
4. The buyer shall lose his right to declare the contract avoided if he fails to act in accordance with [the notice requirements of] paragraph 1 of this Article within a a reasonable time from the moment when he became aware of the right or claim of the third person in respect of the goods.