Cooper v Phibbs [1867]

Court: House of Lords

Facts: Cooper mistakenly rented a fishery from his cousins, believing they had inherited it from his uncle. In reality, the uncle only had a life tenancy, and Cooper, as the remainderman, inherited the fishery after the uncle’s death. Cooper sought to have the contract set aside due to this mistake.

Issue: Could the contract be set aside for common mistake, given that Cooper and his cousins were mistaken about the ownership of the fishery?

Held: The House of Lords held that the contract was voidable due to a common mistake. The mistake pertained to the legal possibility of performing the contract, as Cooper was already the owner of the fishery and therefore had no need to lease it.

Key Judicial Statements:

• Lord Cranworth: Emphasized that the contract was for the lease of property Cooper already owned. The common mistake about ownership warranted relief, making the contract voidable.

• Lord Westbury: Concurred, noting that the mutual mistake regarding ownership rendered the agreement voidable in equity. He stressed that factual errors about ownership could invalidate the contract.

💡 Leveluplaw: This case illustrates that a contract can be voided if both parties are mistaken about a fundamental fact affecting its performance. In cases of mutual mistake regarding property rights, the contract may be set aside to correct the error.