Proprietary estoppel - The remedy

In Guest v Guest [2022] UKSC 27, the Supreme Court held that the aim of the remedy granted by a court in a proprietary estoppel case is to prevent the unconscionable repudiation of promises or assurances about property upon which the promisee has relied to its detriment, so that the normal and natural remedy is to hold the promisor to its promise rather than to compensate the promisee in respect of its detrimental reliance. However, given that the remedy lies in the discretion of the court, in the case where the promisor can prove that specific enforcement of the full promise, or its monetary equivalent, would be out of all proportion to the cost of the detriment to the promisee, then the court may be constrained to limit the extent of the remedy. Lord Leggatt and Lord Stephens dissented and held that the aim of the remedy should be to ensure that the promisee does not suffer detriment as a result of the promisee's reliance on the promise. When considering the role that proprietary estoppel plays in construction cases, it is important to remember that the jurisdiction of the court is most likely to be invoked in cases where the relationship between the parties is a familial one or is characterised by a degree of informality. Where the relationship between the parties is a formal, arm's length relationship, it is far less likely that a party who acts to its detriment on the basis of a promise that is unsupported by consideration will be able to invoke proprietary estoppel in order to obtain relief from the promisor.