Ratio Decidendi
A voluntary disposition can be set aside for mistake only if the mistake is sufficiently grave. It is not enough that the claimant would not have entered the transaction but for the mistake; the mistake must make it unconscionable for the donee to retain the property.
Hechos
Two appeals were heard together. Both involved transactions by trustees that had unintended adverse tax consequences.
Resumen de la sentencia
The Supreme Court reformulated the law of mistake in relation to voluntary dispositions. Lord Walker held that the test is whether the mistake was of so serious a character as to render it unjust for the donee to retain the property.
Citas clave
"The true requirement is for there to be a causative mistake of sufficient gravity."
— Lord Walker
Tratamiento posterior
The leading authority on setting aside voluntary dispositions for mistake.