Article 1729 C.c.Q.: Presumption of Defect Against a Professional Seller

In a sale by a professional seller, a defect is presumed to have existed at the time of the sale if the property malfunctions or deteriorates prematurely in comparison with identical property or property of the same type; such a presumption is rebutted if the defect is due to improper use of the property by the buyer.

Civil Code of Québec, art. 1729 C.c.Q.

What this article means

Article 1729 lightens the burden of proof for a buyer dealing with a professional seller: a merchant, dealer, manufacturer or retailer. Normally, the buyer must prove the defect already existed at the time of the sale, which is often difficult months later. Against a professional seller, that existence is presumed as soon as the property malfunctions or deteriorates prematurely compared with identical property or property of the same type.

The benchmark is objective: a vehicle whose engine fails at 60,000 km, an appliance that dies after two years, a redone roof that leaks in its third season all deteriorate prematurely compared with what is normal for similar property. The buyer then does not have to identify the technical cause of the defect or prove it predated the sale: the presumption does that work.

The presumption is not absolute, however: the seller can rebut it by showing the defect results from the buyer's improper use of the property (neglected maintenance, abusive use, modification). This article is at the heart of disputes over used vehicles sold by merchants and combines with the presumption that a professional seller knows the defects: together they open the door both to claiming the cost of the defect and to damages (article 1728). The process starts with the written denunciation required by article 1739.

What it means for you

If you are the buyer

If property bought from a merchant fails prematurely, article 1729 works in your favour: you do not have to technically prove the defect existed at the time of the sale. Document the failure (photos, a mechanic's or technician's report, invoices) and compare it with the normal lifespan of similar property.

Denounce the defect to the seller in writing within a reasonable time (article 1739) before having it repaired, so the seller can examine it. A demand letter describing the property, the purchase date, the defect and your claim (repair, refund or price reduction), sent with proof of receipt, is the starting point of your remedy, often in small claims court.

If you are the seller

If you sell property in the course of your business, the presumption in article 1729 applies to you. Your main defence is the buyer's improper use of the property: absent maintenance, abnormal use, third-party intervention. Keep the documents establishing the property's condition at the sale (inspection, maintenance history, mileage) and the usage instructions given to the buyer.

Faced with a claim, insist on examining the property before any repairs: that is also your right, protected by the denunciation requirement of article 1739. A prompt written reply, grounded in the facts, avoids many hearings.

Related articles

• Article 1726 C.c.Q.: Warranty Against Latent Defects
• Article 1728 C.c.Q.: Seller Who Knew of the Defect: Damages
• Article 1739 C.c.Q.: Written Notice of a Latent Defect