Unjustified enrichment: surveying the landscape
Preliminary questions ‘Unjustified enrichment’. The expression is mysterious. So are the other terms in use for the same subject, ‘unjust enrichment’ and ‘restitution’. What is an enrichment and when is it unjustified? To state that something amounts to unjustified enrichment is merely a conclusion, that because the enrichment is unjustified it should be returned, restored or made over to the person properly entitled to it. That conclusion is in need of supporting normative argument. But what sort of argument? Some time ago the Roman jurist Pomponius wrote the now-famous words nam hoc natura aequum est neminem cum alterius detrimento et iniuria fieri locupletiorem , ‘by the law of nature it is right that nobody should be unjustly enriched at another's expense’. Pomponius's maxim encapsulates the key elements of enrichment liability: enrichment, which is unjust, and which is at the expense of the claimant. But it exemplifies a problem that faces modern legal systems, too: formulating the principles of a law of unjustified enrichment in a way which is clear and yet not excessively broad. There is no doubt that Pomponius's formulation is, as a matter of classical Roman law, much too broad. There were many cases in which unjustified enrichment was simply allowed to rest where it arose. A clear instance is the claim of a possessor in good faith who improved land from which he was later ejected by the true owner.
The Law of Obligations: Roman Foundations of the Civilian Tradition
Part 1 Introduction - the concept of an obligation and its implications: obligatio - conceptual and systematic foundations stipulatio alteri, representation, cession. Part 2 Verbal obligations: stipulatio stipulatio poenae - conventional penalties suretyship. Part 3 Real obligations: mutuum - loan for consumption commodatum, depositum, pignus - loan for use, deposit, pledge. Part 4 Consensual obligations: emptio venditio I - sale (basic requirements) emptio venditio II - sale (main effects) emptio venditio III - sale (warranty of title and of proper quality) locatio conductio I - mainly lease locatio conductio II - contract of employment, contract for work mandatum - mandate excursus - negotiorum gestio societas - partnership. Part 5 Arrangements outside the contractual scheme of classical Roman law: donatio pacta and innominate real contracts. Part 6 General principles of contractual liability: formation of contract error - mistake interpretation of contracts metus and dolus - duress and fraud invalidity and reasons for invalidity condicio and dies - conditions and time clauses termination of obligations breach of contract. Part 7 Obligations arising neither from contract nor from delict: unjustified enrichment. Part 8 The law of delicts: delict in general furtum - theft Lex Aquilia I Lex Aquilia II actio iniuriarum - infringements of personality rights strict liability.
The Doctrine of Unjustified Enrichment
The origin and growth in continental law of the doctrine of unjustified enrichment is not merely an object lesson of the greatest importance to comparative lawyers. It is also of peculiar interest to English lawyers because it affords an admirable illustration of the working of the system of precedent in the continental countries. Moreover, it furnishes abundant proof—if any be needed—of the fact that an elaborate system of rules based on judicial precedent can, and does, exist side by side with the provisions of codes which in their inception were designed to prevent case law from coming into existence.