Does not legally justify its decision

Application pratique:

Under the 1976 ruling, a contractor cannot be partially exonerated merely by alleging the client's interference unless the client is proven "notoriously competent" in construction. The owner, an accountant with no building expertise, should formally reject the builder's claim, demand full repairs under the decennial warranty (garantie décennale), and, if necessary, present evidence of his lack of construction knowledge to prevent any reduction in liability.

Application pratique:

Citing the Court of Cassation decision, the landlord should insist the contractor remains fully liable because the court must first investigate whether the landlord was notoriously competent. As a retired schoolteacher with no construction background, the landlord's interference does not automatically reduce the contractor's liability. He should engage a building surveyor to document defects and send a formal notice (mise en demeure) holding the contractor fully accountable.

Application pratique:

The condominium syndicate (syndicat des copropriétaires) should argue that under the 1976 precedent, the contractor cannot escape liability simply by pointing to the co-owner's interference unless that co-owner is proven notoriously competent in construction. Since the co-owner lacks relevant expertise, the syndicate must demand full rectification of the defects under the construction work guarantee, and if litigation ensues, request the court to verify the co-owner's actual competence as required by the case law.