Principles of authenticity disputes

A warranty of authenticity is an undertaking by the seller as to the author of the work. It may result from an express clause, a catalogue mention or the certificate handed over. Its scope depends on the terms used: "by", "attributed to", "workshop of", "after".

The tribunal interprets these terms according to the customs of the auction house and of the market. A reasonable buyer is presumed to understand the usual meaning of catalogue mentions, unless misled.

Mistake as to substance allows annulment of the sale where authenticity was decisive for the buyer. Fraud assumes that the seller deliberately deceived the buyer. The seller's good faith does not prevent the warranty from applying, but it affects damages.

The tribunal takes account of the state of knowledge at the time of the sale: a work held to be authentic according to the science of the day does not necessarily engage the seller's liability, but the buyer may obtain restitution if the warranty was strict.

The burden of proof lies, in principle, on the person contesting authenticity. The tribunal may reverse it if the seller alone holds the decisive elements. Evidence is free: appraisal, analyses, archives, catalogues raisonnés, testimony.

Limitation runs from discovery of the defect, within the limits of the applicable law. OIMAP recommends acting within two years of the serious doubt, without waiting for the outcome of a lengthy negotiation.

The tribunal takes customs into account: practices of auction houses, usual duration of the warranty (five years), the distinction between catalogues and condition reports, the value of catalogues raisonnés. These customs may be proved by any means, including OIMAP's good-practice guides.

They help fill gaps in the contract and interpret ambiguous clauses, taking account of the buyer's legitimate expectation.