When parties to a contract make promises to perform their obligations, and one party reasonably relies on the other party’s promise—but the party making the promise fails to perform, causing harm or loss to the party who relied on the promise—the party who relied on the promise to perform is said to have relied to its detriment.

This legal concept is called detrimental reliance. Detrimental reliance may serve as a substitute for consideration, and make an otherwise unenforceable contract enforceable.

Thus, detrimental reliance is a legal concept based on fairness (known as equity or equitable), and is equivalent to contractual promissory estoppel (due to the other party’s reliance, the party who did not keep its promise is prohibited from challenging the enforceability of its promise).

Detrimental reliance is not a separate tort cause of action.

In Florida, detrimental reliance, also known as promissory estoppel, is a legal doctrine that can make an otherwise unenforceable contract enforceable when one party relies on the promise of the other to their detriment. This concept is grounded in principles of equity, aiming to prevent injustice that arises from one party's reasonable reliance on a promise that is not fulfilled. For a claim of promissory estoppel to succeed in Florida, the party asserting it must generally show that a promise was made, they relied on that promise reasonably and to their detriment, and that it would be unjust not to enforce the promise. Detrimental reliance is not an independent tort but rather a principle that can affect the enforceability of contractual obligations. It is important to note that the specifics of how this doctrine is applied can vary based on the circumstances of each case, and an attorney can provide guidance on its applicability to a particular situation.