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 South Carolina, 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 would result if the promisor were allowed to renege on their promise after the promisee has taken action or refrained from action based on the promise made. For a claim of promissory estoppel to succeed in South Carolina, the promisee must demonstrate that they reasonably relied on the promisor's promise, that the reliance resulted in a detriment, and that enforcement of the promise is necessary to avoid injustice. It is important to note that detrimental reliance is not an independent cause of action for a tort claim; rather, it is a principle applied in the context of contract disputes to enforce promises that lack consideration, which is typically required for contract formation.