Hartog v Colin & Shields [1939]

Hartog v Colin & Shields [1939] 3 All ER 566 is a notable English contract law case that addresses the issue of unilateral mistake in contractual agreements. The key principle established in this case is that if it is evident that one party has made a mistake in the terms of an offer, the other party cannot simply take advantage of the error and enforce the agreement.

The factual background of the case involves the defendants, Colin & Shields, who were London hide merchants, and Mr Louis-Levie Hartog, a Belgian furrier residing in Brussels. Both parties verbally agreed to the sale of 30,000 Argentinian hare skins at 10d per skin, equating to a total of £1,250. However, when the final written offer was sent, it mistakenly stated "10,000 skins at 10d per lb" and the remaining 20,000 skins similarly per pound, rather than the standard unit of per piece, which was the industry norm. This error substantially altered the agreed-upon price.

Mr Hartog sought to enforce the written offer, claiming loss of profit or, alternatively, the difference between the contract price and the market price at the time of the breach. In response, Colin & Shields argued that the offer was mistakenly expressed, maintaining their intention to offer the goods per piece and not per pound. They further asserted that Hartog was aware of this mistake and fraudulently accepted an offer that the defendants never intended to make.

The judgment favoured Colin & Shields, with the judge determining that the plaintiff must have realised the defendants' error, rendering the contract void due to a mistake in its terms. The judgment emphasised that Hartog had effectively taken advantage of the mistake, referred to as "snapping up the offer," and thus, no binding contract was entered into.

The judge's decision was based on the understanding that the prices of Argentine hare skins had consistently been discussed per piece in verbal negotiations and correspondence. The written offer deviating from this established norm should have raised suspicions, and the judge found it difficult to believe that Hartog did not recognise the mistake. The judgment concluded that the offer was wrongly expressed, and the plaintiff could not reasonably have believed it reflected the offerers' true intention.

In summary, this case reinforces the principle that unilateral mistakes in contractual terms can render a contract void, particularly when the party accepting the offer is aware or should be aware of the mistake and attempts to take advantage of it. The case underscores the importance of upholding the genuine intentions of the parties in contractual agreements.