The doctrine of unjust enrichment applies the principles of restitution to disputes that are not governed by a contract between the parties. It characterizes the result of a failure to make restitution under circumstances that give rise to an implied or quasi-contractual obligation to return those benefits.

The courts describe this claim in general principles. For example, courts have stated that a claim for unjust enrichment seeks to restore money where equity and good conscience require restitution; it is not premised on wrongdoing, but seeks to determine to which party, in equity, justice, and law, the money belongs; and it seeks to prevent unconscionable loss to the payor and unjust enrichment to the payee.

Because recovery based on unjust enrichment of another party relies on the court's sense of fairness or equity rather than the law, it is often referred to as the equitable doctrine of unjust enrichment.

In New York, the doctrine of unjust enrichment is recognized as a legal principle that allows a party to recover benefits that were unjustly conferred upon another, even in the absence of an explicit contract. The doctrine is based on the concept of equity, aiming to prevent one party from being unjustly enriched at the expense of another. To establish a claim for unjust enrichment in New York, a plaintiff must demonstrate (1) that the defendant was enriched, (2) at the plaintiff's expense, and (3) that it is against equity and good conscience to permit the defendant to retain what is sought to be recovered. This doctrine is often invoked in situations where there is no enforceable contract but where the circumstances imply a legal obligation to return the benefits received. New York courts will consider factors such as the relationship between the parties and the expectations that arose from their interactions. The remedy for unjust enrichment is typically restitution, which involves returning the plaintiff to the position they would have been in had the unjust enrichment not occurred.