Promises in equity and at law: proprietary estoppel after Guest v Guest

Under the doctrine of proprietary estoppel, a promise made to another that they will acquire a right in the promisor's land can give rise to a legal remedy, if the promisee has detrimentally relied on that promise. In Guest v Guest, the Supreme Court was asked to settle a long-running debate about how judges should go about fashioning that remedy. The Court held that the claimant's award should be whatever is required to alleviate the unconscionability constituted by the promisor's repudiation of their promise. How that is to be determined will vary from case to case, but Guest v Guest makes clear that the starting assumption is that the promise will be enforced. This note sets out the approaches of the majority and the minority, and then discusses a number of issues raised by this decision.