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 Ohio, the doctrine of unjust enrichment is recognized and applied by courts when one party has received a benefit that would be unjust for them to retain without paying for it, and there is no enforceable contract covering the transaction. This doctrine is based on principles of equity, aiming to prevent one party from being unjustly enriched at the expense of another. Ohio courts will consider factors such as whether a benefit was conferred, whether the recipient appreciated or knew of the benefit, and whether it would be inequitable for the recipient to retain the benefit without payment. The remedy for unjust enrichment is typically restitution, which is the return of the benefit or its value to the party who provided it. This remedy is not based on the existence of wrongdoing but on the equitable principle that it is unfair for one party to benefit at another's expense without compensation. The claim for unjust enrichment is thus a way for the courts to impose a duty to make restitution in the absence of a formal agreement, based on the broader principles of justice and fairness.