What are the errors in creating the contract?

An error can be by one party (unilateral) or by both parties either common or mutual. However, for the error to affect the validity of the contract, it needs to be ‘substantial’ affecting the fundamentals of the contract, resulting in no consensus in idem.  Morrison v Robertson (1908) this case involved Morrison being approached by a man who wanted to purchase 2 cows on credit. The man told Morrison that he was the son of Wilson, a well-respected, affluent farmer known to Morrison. The man then sold the cows to Robertson. On discovering that the man was not the son of Wilson, but a well-known rogue named Telford, Morrison sought to recover the cows from Robertson.

It was held that given the identity of the man was crucial to the contract, there was no consensus in idem and the contract was void resulting in Morrison reclaiming the cows and Robertson having no contractual rights. It is important to remember errors can make a contract voidable and not automatically void as seen in MacLeod v Kerr 1965, in this case, Kerr sold a car to a man posing as someone else and with a stolen cheque, the man later sold the car to Macleod. Kerr sought to recover the car however it was held that although the contract was voidable due to an induced error, the identity of the man was not crucial to the sale of the car and as Kerr did not raise the action after it was sold to Macleod then the opportunity had passed to have the contract declared void and Macleod had a good title to the car.  As well as errors in identity other substantial errors are in price, quantity, subject matter, nature of contract.