doctrine of promissory estoppel

The doctrine of promissory estoppel prevents someone from going back on a promise if another person has relied on it to their significant detriment. Essentially, if a person makes a clear promise, and the other person reasonably acts based on that promise, it wouldn't be fair to allow the promisor to renege later. This principle ensures fairness by enforcing promises even without a formal contract, provided that the promisee's reliance was reasonable and caused them harm or loss.