Unjust Enrichment

"The word restitution means restoration. Restitution is a return or restoration of what the defendant has gained in a transaction. It may be a return of a specific thing or it may be a "return" of a money substitute for that thing." Chapter 4, Restitution

"The underlying policy of restitution is to prevent the unjust enrichment of a party who has received a benefit that in equity and good conscience should not be retained." Chapter 16, Unjust Enrichment

"Restitution is the law of nonconsensual and nonbargained benefits in the same way that torts is the law of nonconsensual and nonlicensed harms. Both subjects deal with the consequences of transactions in which the parties have not specified for themselves what the consequences of their interaction should be. The law of torts identifies those circumstances in which a person is liable for injury inflicted, measuring liability by the extent of the harm; the law of restitution identifies those circumstances in which a person is liable for benefits received, measuring liability by the extent of the benefit." Chapter 1, General Principles

"Unjust enrichment and restitution are .... terms of some indeterminancy and open-endedness. And while both exist outside tort and contract, they also exist within those harm-based doctrines." Chapter 5, General Principles Governing Restitution.