Combe v Combe  2 KB 215
PROMISSORY ESTOPPEL – CONSIDERATION – LORD DENNING
The case concerns a husband and wife – when the couple became estranged, the husband agreed to make maintenance payments to the wife. The husband then failed to make these promised payments. The wife sought to bring an action asserting the principle of promissory estoppel.
It was for the court to decide whether or not the relationship between the parties at the time of the promise meant that promissory estoppel was available to the wife.
For promissory estoppel be applicable, there must have existed a previous legal relationship between the parties. As there was no such relationship between the husband and wife, the wife’s action failed. Promissory estoppel cannot ‘stand-alone’ – there must have been a previous legal relationship for which there is adequate consideration, see Lord Denning’s judgment:
“The principle, as I understand it, is that, where one party has, by his words or conduct, made to the other a promise or assurance which was intended to affect the legal relations between them and to be acted on accordingly, then, once the other party has taken him at his word and acted on it, the one who gave the promise or assurance cannot afterwards be allowed to revert to the previous legal relations as if no such promise or assurance had been made by him, but he must accept their legal relations subject to the qualification which he himself has so introduced, even though it is not supported in point of law by any consideration but only by his word.”
The judgment famously including the comment that promissory estoppel acts as a shield, and not a sword. This phrase means that promissory estoppel can only be used as a defence for the ‘injured’ party to whom the promise was made, not to create a new cause of action and force the promise into action.