James Barr Ames and the Early Modern History of Unjust Enrichment
1 Professor of Law, Boston University; Reporter, Restatement Third, Restitution and Unjust Enrichment (American Law Institute).
The modern conception of unjust enrichment as a source of private obligation, and as the basis of today’s law of restitution, is usually traced to the American Law Institute’s Restatement of Restitution (1937). But the Restatement’s most significant innovation—its unified treatment of law and equity, presenting quasi-contract and constructive trust as alternative responses to the problem of unjust enrichment—merely put the ALI imprimatur on discoveries announced some fifty years earlier by James Barr Ames of the Harvard Law School. Ames’s propositions about unjust enrichment had found steadily increasing acceptance in the intervening decades, and by the time the Restatement was drafted they represented American academic orthodoxy. The law of restitution has been notoriously slow in developing, but its modern era is approximately half a century older than is generally supposed.