Cooper v Phibbs [1867] UKHL 1

Key Point

Where the buyer buys what he already owns, the contract is void for common mistake.


  • Cooper mistakenly rented a fishery from his cousins, believing them to have inherited the fishery from his uncle.
  • In actual fact, his uncle only had a life tenancy of the fishery (a now defunct ownership interest lasting for one’s lifetime) while he held the residual interest, and thus inherited the fishery after the uncle’s death.
  • Cooper sought to have the contract set aside for mistake.

Held (House of Lords)

The contract was voidable and set aside for common mistake.


Note that although the House of Lords held that the contract was voidable instead of void, it was held in Bell v Lever Bros [1932] AC 161 that common mistakes render contracts void in common law.