Restitution principles require return or compensation for unjust enrichment, with recovery shaped by fault and agreed risks. Restitution encompasses return of a specific thing, disgorgement of benefits unjustly derived, and reparation for loss; it rests on principles of unjust enrichment and unjust impoverishment and may be awarded independently of contract. The measure of recovery is flexible in contexts like non-tortious misrepresentation, with courts weighing relative fault, agreed risks, and fairness of alternative risk allocations when determining restitutionary relief.