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.
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.
ContractA contract is an agreement that specifies certain legally enforceable rights and obligations pertaining to two or more mutually agreeing parties. A contract typically involves the transfer of goods, services, money, or a promise to transfer any of those at a future date. In the event of a breach of contract, the injured party may seek judicial remedies such as damages or rescission. A binding agreement between actors in international law is known as a treaty.
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.
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.
Money had and receivedAn action for money had and received to the plaintiff's use is the name for a common law claim derived from the form of action known as indebitatus assumpsit. The action enabled one person to recover money which has been received by another: for example, where a plaintiff paid money to the defendant while labouring under a mistake of fact or where there was a total failure of consideration. The action was a personal action only available in respect of money, rather than other benefits.
Quantum meruitQuantum meruit is a Latin phrase meaning "what one has earned". In the context of contract law, it means something along the lines of "reasonable value of services". In the United States, the elements of quantum meruit are determined by state common law. For example, to state a claim for unjust enrichment in New York, a plaintiff must allege that (1) defendant was enriched; (2) the enrichment was at plaintiff's expense; and (3) the circumstances were such that equity and good conscience require defendants to make restitution.
Private lawPrivate law is that part of a civil law legal system which is part of the jus commune that involves relationships between individuals, such as the law of contracts and torts (as it is called in the common law), and the law of obligations (as it is called in civil legal systems). It is to be distinguished from public law, which deals with relationships between both natural and artificial persons (i.e., organizations) and the state, including regulatory statutes, penal law and other law that affects the public order.
