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 Colorado, the doctrine of unjust enrichment is recognized and applied by courts when one party has received a benefit at the expense of another in the absence of a contractual agreement. The doctrine is based on principles of equity and restitution, aiming to prevent one party from being unjustly enriched at the expense of another. Colorado courts will consider an unjust enrichment claim when there is no valid contract covering the dispute, but where it would be inequitable for the defendant to retain the benefits without compensating the plaintiff. The claim is not based on the presence of wrongful conduct but rather on the notion that it is unjust for one party to retain benefits without paying for them when fairness dictates otherwise. To succeed in an unjust enrichment claim in Colorado, the plaintiff must typically show that a benefit was conferred upon the defendant, the defendant appreciated or knew of the benefit, and under the circumstances, it would be inequitable for the defendant to retain the benefit without paying its value.