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 California, the doctrine of unjust enrichment is recognized as a legal principle that allows a party to recover benefits that were unjustly conferred upon another party, even in the absence of a contractual agreement. This doctrine is grounded in the concepts of equity and restitution, and it operates under the premise that it is unjust for one party to retain benefits at the expense of another without providing compensation. California courts have articulated that a claim for unjust enrichment is not based on the commission of a wrongful act, but rather on the notion that equity and good conscience require the return of benefits to prevent one party from being unjustly enriched at the expense of another. The courts will look at the circumstances of each case to determine whether an implied or quasi-contractual obligation exists, and whether restitution is warranted to correct the situation. This equitable remedy is discretionary and seeks to uphold justice and fairness in situations where the law does not provide a clear remedy through contractual terms.