English unjust enrichment lawThe English law of unjust enrichment is part of the English law of obligations, along with the law of contract, tort, and trusts. The law of unjust enrichment deals with circumstances in which one person is required to make restitution of a benefit acquired at the expense of another in circumstances which are unjust. The modern law of unjust enrichment encompasses what was once known as the law of quasi-contract. Its precise scope remains a matter of controversy.
AssumpsitAssumpsit ("he has undertaken", from Latin, assumere), or more fully, action in assumpsit, was a form of action at common law used to enforce what are now called obligations arising in tort and contract; and in some common law jurisdictions, unjust enrichment. The origins of the action can be traced to the 14th century, when litigants seeking justice in the royal courts turned from the writs of covenant and debt to the trespass on the case. In the early days of the English common law, agreements were enforced in local courts.
Form of actionThe forms of action were the different procedures by which a legal claim could be made during much of the history of the English common law. Depending on the court, a plaintiff would purchase a writ in Chancery (or file a bill) which would set in motion a series of events eventually leading to a trial in one of the medieval common law courts. Each writ entailed a different set of procedures and remedies which together amounted to the "form of action". The forms of action were abolished during the 19th century, but they have left an indelible mark on the law.
Quasi-contractA quasi-contract (or implied-in-law contract or constructive contract) is a fictional contract recognised by a court. The notion of a quasi-contract can be traced to Roman law and is still a concept used in some modern legal systems. Quasi contract laws have been deduced from the Latin statement "Nemo debet locupletari ex aliena jactura", which proclaims that no man should grow rich out of another person's loss. It was one of the central doctrines of Roman law.
Restitution and unjust enrichmentRestitution and unjust enrichment is the field of law relating to gains-based recovery. In contrast with damages (the law of compensation), restitution is a claim or remedy requiring a defendant to give up benefits wrongfully obtained. Liability for restitution is primarily governed by the "principle of unjust enrichment": A person who has been unjustly enriched at the expense of another is required to make restitution.
