Which principle of law requires subcontractors to uphold promises that the prime contractor has relied upon?

Promissory Estoppel is the principle of law that ensures that subcontractors must uphold promises made in situations where the prime contractor has relied on those promises to their detriment. This legal doctrine prevents a party from withdrawing a promise if the other party has reasonably relied on that promise and acted on it, resulting in a change to their position.

In the context of subcontractors and prime contractors, if a prime contractor depends on a subcontractor's promise for the successful completion of a project, and subsequently suffers a loss because the subcontractor fails to fulfill that promise, the principle of promissory estoppel may apply. This means that the subcontractor could be held liable to fulfill their commitment because the prime contractor took action based on the reasonable expectation that the promise would be honored.

The other principles listed do not specifically address the obligation of subcontractors in the same way. The Universal Commercial Code primarily governs commercial transactions and does not directly relate to subcontractor agreements. Contract Law encompasses a wider range of agreements but does not specifically address reliance-based promises. Civil Liability refers more broadly to the legal responsibility for actions that cause harm and is not confined to the obligations arising from promises made in a contractual context.