Unjust Enrichment

n. a benefit by chance, mistake or another's misfortune for which the one enriched has not paid or worked and morally and ethically should not keep. If the money or property received rightly should have been delivered or belonged to another, then the party enriched must make restitution to the rightful owner. Usually a court will order such restitution if a lawsuit is brought by the party who should have the money or property.