United Kingdom Journals

Ten questions for 'unjust enrichment' theorists.

Steve Hedley*

Fellow in Law
Christ's College
Cambridge CB2 3BU
<steve.hedley@law.cam.ac.uk>

Copyright © 1997 Steve Hedley.
First Published in Web Journal of Current Legal Issues in association with Blackstone Press Ltd.

* I am grateful for remarks on an earlier draft from Elisabeth Peden.

Summary

The debate on the 'unjust enrichment' theory as a framework for understanding restitution has so far been inconclusive, not least because it has been poorly focused. This article proposes an alternative view: that while the need for study of restitution is clear, and the importance of many of the topics within it is undisputed, nonetheless those topics have little to do with one another, the area being essentially miscellaneous. The author suggests a number of questions which are relevant to the choice between this 'miscellany' view and the 'unjust enrichment' view.

Contents

Introduction

The overall coherence of restitution

The structure of 'unjust enrichment' theory

Support in authority

Conclusion

Bibliography

Introduction

Restitution is now well established as a modern legal discipline. It has it own texts, a substantial journal literature, even a modicum of recognition from the courts. Yet the nature of restitution eludes consensus. The pioneers of the subject, eager to promote their vision of 'restitution as unjust enrichment', rely primarily on clarity of exposition, though also with occasional asides against the many they see as their enemies (see for example Birks 1985a, p 6; Burrows 1993, pp 2-6; Tettenborn 1996, pp 2-8). Their ultimate argument against all criticisms is through progressive refinement and redefinition of their 'unjust enrichment' theory, a strategy which has resulted in more and more precise notions, but also in a smaller and smaller ambit for their subject, as unpromising material is excluded.

Now that the dust has settled a bit, I hope to focus the argument a little more, by suggesting that 'restitution' is essentially a miscellaneous category, its various constituents united only by the fact that they have all been rejected from inclusion in other theories. Restitution consists of the left-overs of the law. Attempts to unite the material by reference to 'unjust enrichment' are therefore misguided. It does not follow, of course, that none of these left-overs is of any value. What one set of theorists throws away, another may treasure: and such areas as subrogation and mistaken payments (to name but two) are, I believe, of considerable importance. Rather, the importance of 'restitution' is no more than the importance of its parts. Of course, it does not logically follow from the miscellaneous nature of restitution that there are no common themes, or underlying forms of order. Rather, there is no a priori reason to expect such order, and it would be rather surprising if it were present. Arguments that there is some sort of order must be considered on their merits; but arguments that there must be some sort of order may be discounted. It is rather like the difference between a rubbish bin and a bottle bank. We might find order and value in either; it cannot be ruled out. But there is better reason to expect it in the latter. With the former, we know that those who put the stuff there thought it miscellaneous and valueless. They may have been wrong. But careful enquiry is needed.

Feeling themselves attacked on all sides, 'unjust enrichment' theorists have yet to give a very principled answer to any particular opposing point of view. There is a dim recognition that the 'restitution as miscellany' view is one which must be reckoned with. Burrows reacts to it with something approaching incredulity, accurately noting that restitution does not include everything which is not part of contract and tort, and protesting against rendering restitution pointless: he queries 'how, without a guiding principle, one could seriously decide what fell outside contract and tort and hence within the residual category' (Burrows 1993, p 6). Yet no-one argues that restitution does or should include every residual form of liability (Birks 1985a, p 74)(1), though the principle of selection is somewhat obscure. It is not for the 'miscellany' school to explain the 'point' of restitution, especially since they doubt whether there is one. The existence of an academic subject called 'restitution' is a fact. But it is not for a school which doubts its bona fides to be told to explain its 'point'. The question needs to be turned around, and directed back at the unjust enrichment theorists: If restitution has a point, what is it?

What divides the two schools? They are united in believing that the topics conventionally regarded as within restitution have positive value, and amply merit the academic attention paid to them. They are united in their use of induction and generalisation as essential legal techniques. And they are agreed that talk of 'unjust enrichment' is a valuable part of legal and moral discourse. In an attempt to define how we differ, I have identified ten issues where the merits of 'unjust enrichment' approach, at least as currently practised, seem particularly in doubt.

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The overall coherence of restitution

Question One: If the 'unjust enrichment' theory is the answer, what was the question?

The subject-matter of restitution is very diverse. There is little factually in common between marine salvage, undue influence, and over-payment of taxes. The question is, therefore, what links these diverse issues together. The 'miscellany' conception of restitution gives the answer that nothing does. The boundaries of restitution are set by history and by convenience. In asking how the 'unjust enrichment' school would answer, we immediately see how their subject differs from many others: its coherence, if such it is, derives from theory only. It is the last subject without a social context. This is not, in itself, an argument against the 'unjust enrichment' school, but it points a sharp finger at where its justification must be found, if it exists at all - it places an awful weight on the theory of the subject. This is not so in other legal disciplines. For example, employment is a social phenomenon of some importance; accordingly, 'employment law' is safe as a discipline, and is likely to remain so whether the legal theory of employment relations is clear, confused or of indifferent quality.

Of all the 'unjust enrichment' theorists, only Birks has attempted to address the point. He admits that the clarity of theory to which 'unjust enrichment' aspires is not the norm. Most subjects make no such attempts; they are 'contextual' subjects with no high theory. 'There is nothing wrong with categories of that kind ... It is the function and virtue of these contextual categories that they collect together bits and pieces which are kept apart in other ways of dividing up the law' (Birks 1985a, p 74). There can therefore be no pretence that a theory of the sort urged is essential for a legal discipline. If restitution is based on such a theory, it is pretty unusual. The question is, whether there is any precedent for a subject so distant from society, and endowed with so fine a theory, that it can get by with only the latter. Do many such subjects exist? They are rare. Tort hardly fits the bill, for tort too is very diverse; what little theory the various torts share is small (really only some common rules about damages and about limitation, most of which apply also to contract and to breach of trust). Tort, indeed, is a rather good example of a 'miscellaneous' subject, the bounds of which are set by evolution and convention rather than a precise theory. That really only leaves Contract. Is Contract a worth-while model for restitution to emulate? Contract is not without its critics. Are all the critics wrong? Or are their criticisms irrelevant in the case of restitution? These are questions which 'unjust enrichment' theorists should attempt an answer.

Question Two: If there is an ethical principle against 'unjust enrichment', why have ethical theorists not heard of it?

The 'miscellany' school have a clear answer to this. Whenever lawyers reduce moral and social issues to rules, inevitably the result is not quite right. The results are almost bound to be either over-inclusive or under-inclusive. So as well as standard instances of liability, there will also be cases where standard rules leave some classes of person 'unjustly enriched' at the expense of others. So the existence of such cases is no surprise. But it would be surprising if these instances of liability, which are only there at all because of the failure of general theories, could themselves be reduced to a standard principle. It is because they have already resisted treatment by general rules that the prospect of generalising them seems remote.

The problem for 'unjust enrichment' theorists is to describe some moral principle which underlies these cases - to introduce system where none is apparent. And in doing so, it appears that they can expect no help from standard ethical sources. Ethical theorists have much to say on the subject of enriching oneself, but there is no very obvious connection between what they have to say and current 'unjust enrichment' theory. Indeed, restitution is not for the most part concerned with those who set out to enrich themselves, but with those who achieved this by accident. Burrows sees the difficulty, and admits that it is no good making a 'vague reference to individual morality'; but maintains that he is 'not primarily concerned with what any one individual or commentator may think is unjust enrichment but rather with what the law regards as unjust enrichment' (Burrows 1993, p 1). Thus he seeks to maintain a moral backing for the subject, while placing a considerable distance between the morals and the law. But what is this moral backing? If there is no such moral principle, then it is misleading indeed for 'unjust enrichment' theorists to claim its support, even at several removes.

Question Three: Is there any liability at all which could not be described as an example of 'unjust enrichment'?

The trouble with 'unjust enrichment' is not that it does not exist, but on the contrary that it is everywhere. Whenever X declines to pay Y a sum which justice demands X should pay, we can straightforwardly say that X is 'unjustly enriched' to the extent of the payment. Where, then, do we find limits to restitution? To the 'miscellany' school, the only limits we should expect to find are those posed by the presence of established areas of law. If I decline to pay you for goods you have sold me, there is no reason why my liability cannot be described as one for 'unjust enrichment'. I have obviously been unjustly enriched, and only my handing over the price can render that enrichment just. We chose not to describe the case this way, but that is because this question is dealt with by the law of contract (compare Atiyah 1979, pp 149-150). The limits of 'restitution' are therefore conventional only.

What limits can 'unjust enrichment' theorists place on their subject, other than that 'the recognition that the beast is free does not preclude the assertion that it should be respectful of its neighbours' (Barker 1995a, p 459)? 'Unjust enrichment' theorists have not exercised any particular restraint in the way they have used their concepts, and so are poorly-defended from the charge that they could include anything. They do not confine themselves to cases where the defendant is still in profit by the time of the action, for it seems that a defendant may be 'unjustly enriched' even though he is not a penny better off.(2) Again, a defendant may (in the opinion of most writers) be 'enriched' by the receipt of worthless services (see for example Tettenborn 1996, p 6). Indeed, an incompetent trustee who contracts debts he cannot pay apparently 'enriches' his beneficiaries by so doing (Burrows 1993, pp 83-84)! The flexibility of the concepts being used is manifest; and indeed, some 'unjust enrichment' theorists would go still further, arguing that so long as the defendant is in some sense enriched, the liability need not take the form of removing the enrichment, but can consist of some other just response (McBride and McGrath 1995). Plainly, this theory could grow to embrace everything. Either 'enrichment' needs more careful definition, or the idea that it can police the outer boundary of restitution must be abandoned.

Of course, some liabilities are a great deal easier to regard as examples of 'unjust enrichment' than are others. I kill my grandmother, my object being to secure the benefits she apportioned to me under her will. The law deprives me of this benefit (see in bonis Crippen [1911] P 108; Forfeiture Act 1982). Is this 'the principle of unjust enrichment' in action? No, says Burrows: this is property law, not 'unjust enrichment' (Burrows 1993, p 380). The problem is that, having allowed the definition of 'unjust enrichment' theory to grow, yet also demanding a precise definition of liability, it is clear that something has to give. Much of property law could easily be described as concerned to remove 'unjust enrichment'. Indeed, if we take the law's allocation of property rights as settled and unchallengable (as law books tend to do), then most departures from that allocation produces an enrichment that is unjust. But this is not how the 'unjust enrichment' theorists want it, for they seek to separate out their own area; and their cases cannot be 'property' cases, for if they were, they would not need an explanation by means of 'unjust enrichment'. So the most promising examples of liability for unjust enrichment are ruthlessly discarded by the 'unjust enrichment' school.

Question Four: Various proponents of 'unjust enrichment' have claimed that it is as important as Contract and Tort. What criteria of importance do they have in mind?

These claims have become popular, almost routine. So Burrows insists that it 'cannot now seriously be denied that the subject is as important and central as, say, contract and tort' (Burrows 1993, p vii). These claims are, I feel, too imprecise to be dismissed as wrong. It is hard to see how restitution is important to practitioners, the vast bulk of whom have never heard of it. There are doubtless a few specialists to whom it is vital, but that hardly marks restitution out from the rest of the law: each bit of the law is important to someone. The steady trickle of cases is still just that, a steady trickle. As for universities, only a tiny proportion of the average student's time will be spent on it - a notable contrast with contract and tort. It is very hard to see what criteria of importance the 'unjust enrichment' theorists have in mind, if their statement is not to be obvious nonsense. It may well be that their point is a subtly different one, that while restitution is in fact insignificant, it is unjustly neglected and should be treated as on a par with contract and tort. To sustain this, some serious critique of the state of English law in the universities and in the courts is necessary. Many topics cry out for further attention, and it is impossible that they should all receive it. No serious claim along these lines has yet been made. Can it be made?

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The structure of 'unjust enrichment' theory

Turning to the detail of the 'unjust enrichment' theory, we have a problem not merely in assessing what has been introduced, but also of determining what it is reasonable to expect. No theory of liability is perfect, and it is unreasonable to criticise a theory merely for failing to achieve perfection. And generalisation about liability may often be valuable and useful even where it is only partially true, or admits of major exceptions. On the other hand, where particular deficiencies in a theory are significant and have persisted over a period, despite concentrated attempts to resolve them, they certainly detract from the merits of the theory, and may even constitute grounds for rejecting it entirely. In this spirit, I suggest that certain difficulties in 'unjust enrichment' theory have become more than mere anomalies, and should make reasonable people doubt the utility of the theory.

Question Five: Do 'unjust' and 'enrichment' have any clear meaning?

Current theory gives a plethora of meanings. For example, Burrows, lists 5 possible measures of 'enrichment' (Burrows 1993, pp 8-16) and 11 'unjust factors' (Burrows 1993, p 21), leading to 55 different possibilities. Each writer seems to have their own distinct version of this. The real question is, where these theories are heading. The 'miscellany' theory would say that they are heading nowhere. The idea that restitution is about a single thing, namely 'unjust enrichment', can only be sustained by giving 'unjust enrichment' a different meaning in each different context in which it is encountered. The 'unity' of the subject therefore appears to be merely a semantic trick, taking all the various diverse things within restitution but announcing that they all bear the same label. It is as if we collected a variety of dogs and then announced that they must all be essentially the same, because we have called them all 'Gromit'. The question must be, how the 'unjust enrichment' theorists see the argument developing from here, if it can. Perhaps, for example, they envisage that courts should in future use 'unjust enrichment' theory as a menu of choices, reviewing the range of things which 'unjust enrichment' could mean, and deciding which one best suits the case at hand. This method is open to objection, not least for its great uncertainty; but might there not be corresponding advantages? The current state of 'unjust enrichment' theory is vague indeed: a diverse set of factors, with no clear rationale; one commentator, with admirable restraint, suggests that it is 'not very tidy' (Zimmermann 1995, p 416). Is this it? Or do the 'unjust enrichment' theorists mean to develop it further, and if so how?

Question Six: Why are the core cases of restitution treated as examples of 'enrichment' rather than cases of 'loss', or a combination of the two?

The acknowledged core of restitution is the recovery of money paid by the plaintiff and 'had and received' by the defendant. It is very important for 'unjust enrichment' theorists to insist that unjust enrichment is of the essence of this situation. This gives them their core case of liability, their key example, of which all others are only slight variants. The obvious retort is that 'unjust benefit' is only one aspect of the situation described. Loss is also of the essence. The defendant has unjustly gained something, the plaintiff has unjustly lost something.

The point has not yet adequately been dealt with by 'unjust enrichment' theorists. Some have misunderstood it. So Tettenborn argues that the remedy is 'plaintiff-centred' rather than 'defendant-centred': the fact that there is a gain is more important than the fact that there is a loss (Tettenborn 1996, p 7). But both gain and loss are implicit in the situation. If Tettenborn argues that, as to doughnuts, it is the dough which is important and not the hole, whereas I dispute this, I am unlikely to be arguing the merits of holes. Rather, I would be arguing that, without both dough and hole, we are dealing with a different phenomenon. It is hard, indeed, to see what it means to argue about the relative importance of 'loss' and 'gain' in a case where both are necessarily present. The argument assumes an angels-on-pinheads quality.

The point is addressed more directly by Burrows, but ultimately he seeks to divert attention from it. There is nothing wrong with regarding the loss as definitive as the gain, or at least Burrows suggests no reason for so believing; rather, he says, there are other examples of restitution where gain is present and loss is not, which shows that it is really the gain that is important in restitution (Burrows 1993, pp 4-6). But who is to say what forms part of restitution, and what does not? There are indeed a few examples of restitutionary liability where the defendant gains while the plaintiff suffers no loss, though not many. But the same is true of tort liability, too. I carelessly burn down your house. Your loss is immediately made good to you by a wealthy relative, or by your insurer. Yet the fact that you have suffered no loss does not stop you suing as if you had.(3) Do these cases show that tort is 'really' about recovery of benefits? If not, how is restitution different? The truth seems to be that common law doctrine is very strong on compensating for losses caused, but very weak on compelling those who have earned profits to disgorge them to someone else; which is perhaps, in a capitalist legal system, exactly what we should expect. To expect the law to be enthusiastic about removing profits from those who have earned them by their own efforts is to mistake the political and economic system under which we work. The removal of a fair proportion of gains is not the function of restitution, but of taxation.

Question Seven: Is there such a thing as 'restitution for services'?

Considerations of the sort just mentioned have persuaded some that restitution is simply about the protection of property. If I lose my property, and its proceeds end up with you, then it is unsurprising that I have a remedy, and this remedy should properly be regarded as protecting my property rights. 'Unjust benefit' is neither necessary nor complete to describe it: to the limited extent that property rights guard against 'unjust benefit', every property rule protects against unjust enrichment, not just the narrow band which 'unjust enrichment' theorists treat as their own.(4)

'Unjust enrichment' theorists have many answers to this, but a major one is to assert that remedies are available not merely for the protection of property, but also for services unjustly appropriated or at least not paid for. It is of course possible to treat services as a variant of property,(5) but this involves extreme artificiality. The question is, therefore, whether there is such a thing as 'restitution for services' and if so whether it can be treated as part of 'unjust enrichment' theory.

There is great confusion amongst 'unjust enrichment' theorists as to how to conceptualise services, or to say when they are 'enriching' (Hedley 1995, p 596ff). But is there, in fact, any case-law to explain? There are of course many examples of marine salvage, but it now seems to be accepted by the theorists that these are not really reducible to any 'unjust enrichment' theory, or at least not the same one as is promoted generally (Birks 1985a, pp 307-308). As I have described elsewhere (Hedley 1997), there are about a dozen other reported instances of restitution for services. They are of a highly miscellaneous nature; it has proved very difficult indeed to fit them into the structure of 'unjust enrichment', a point which the theorists have acknowledged, even though they tend to blame the judges themselves rather than the theory. It is far from obvious that there is anything here that needs explanation, or that 'unjust enrichment' is the tool to do it with. The status of 'restitution for services', then, remains unclear; indeed, some theorists are retreating altogether from the idea that liability for services needs an explanation in terms of unjust enrichment (Watts 1995).

Question Eight: What benefits have flowed from the establishment of the 'unjust enrichment' theory, and do they outweigh the costs?

'Unjust enrichment' theorists have not spoken much on this question, preferring to argue that their theory is descriptively accurate. No doubt they feel that their theory is true, and so need not argue over whether it is useful. To one less convinced of the truth of the theory, however, the question of benefits is central. Even an over-simple theory can have a useful role to play, if the simplicity can count as a virtue. Yet it appears, on a cursory reading, that the balance-sheet is well into the red. The 'unjust enrichment' theory has brought much complexity, with no very obvious corresponding advantages. I have already adverted to the difficulties in defining 'unjust' and 'enrichment'. Various supplementary notions have been introduced to solve the definitional problems, each of which has spawned, hydra-like, a fresh set of problems: 'objective benefit', 'subjective devaluation', 'free acceptance', 'incontrovertible enrichment' (!), 'bargained-for enrichment'. Burrows has recently defended this jargon in strong terms, insisting that it is 'precise and modern', as contrasted with more traditional terminology, which he calls 'the language of the club, nonsensical to outsiders' (Burrows 1997). This is strange indeed. Firstly, to contrast old and new terminology tells us little, for in a case-based system we are stuck with the old terminology whether or not we adopt the new. We have to know the old terminology to understand the cases; so the question whether the new terminology is better than the old is moot, unless we mean to amend the law reports themselves. Secondly, the meaning of the new terminology has been the subject of frantic debates, in which Burrows himself has been a leading participant. If the traditional language is that of a snobbish coterie, then the new language is that of a frenzied caucus indeed, who in public give speeches about their own excellence but in private engage in internecine warfare over the meaning of their own constitution. Plainly, there is much here on the debit side. What is there on the credit side, and does it compensate for the debit balance?

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Support in authority

Support for 'unjust enrichment' theory in the cases is weak. While there are occasional judicial statements in support, they are rather miscellaneous and non-specific. This is of course just what the 'miscellany' point of view would lead us to expect: the established rules of other disciplines lead to occasional instances of unfairness, driving the judges to assert that, while they do not dispute the general merits of the established areas, they will not allow them to be used as an instrument to secure benefits unjustly. Is there any evidence, then, of any acceptance of a systematic theory of 'unjust enrichment'?

Question Nine: Is there any judicial support at all for an 'unjust enrichment' theory?

Much of what is claimed as support for 'unjust enrichment' is palpably no such thing. A clear example is the grand old case of Moses v Macferlan (1760) 2 Burr 1005, 97 ER 676, in which Lord Mansfield CJ waxed lyrical on the common law action for money had and received, and its potential for the correction of injustice. Yet nowhere did he say that 'unjust enrichment' had anything to do with the matter. The emphasis was on the flexibility of the action: every case where fixed rules of law conflicted with morality, in ways which called for a response from the law, was within the doctrine. Mansfield did not generalise about the basis of the law's intervention, beyond remarking that the liability was such as 'ties of natural justice and equity' demanded (2 Burr 1012, 97 ER 681). All things considered, Mansfield's statement is rather a good authority for the 'residuary' point of view. It is marred only by its insistence on the procedural advantages of the action for money had and received, which have little relevance in the twentieth century. But this again is what we should expect. The institutions of the law change over time; accordingly, devices which fill in the gaps between those institutions will have to address very different concerns over time. Therefore, restitution will, over the course of centuries, not merely give different solutions to the problems it addresses, but also address different problems entirely.

Moving to more modern cases, there is now a significant body of support for restitution considered as unjust enrichment. But if we dig deeper and ask whether these statements truly support the sort of theory that 'unjust enrichment' supporters recommend, or whether they are not simply endorsement of the 'miscellaneous' point of view, they turn out to be largely equivocal (for more detailed treatment see Hedley 1995, pp 580-585). They accept some new ideas from the theorists, but do not repudiate the ideas which the theorists say are heresies. They adopt some of the new terminology, but do not discard the old, despite the theorists' urgings. They qualify their support for 'unjust enrichment' by saying that they mean only to endorse whatever the law happens to regard as 'unjust enrichment' - in this they follow the theorists, but they do not take what the theorists regard as the next step, which is to endorse a rather precise conception of what the law demands. There is a sense, therefore, in which significant numbers of judges have accepted that restitution is based on unjust enrichment, but it is clear that they have not committed themselves to very much. We are quite some way from any endorsement of the theory promoted by the 'unjust enrichment' theorists.

To sum up, the claims by 'unjust enrichment' theorists that they have authority for their view contains elements of equivocation. There are many judges who speak of 'unjust enrichment', but much more is needed. Again, there are many academics, especially in the area of contracts, who are open to ideas of 'unjust enrichment' as a corrective to many of the problems of their disciplines; yet, very far from welcoming such writers as allies, they have been rebuffed. Contract text writers who have added chapters on restitution have been brusquely told not to waste their time (see Birks 1985b, Barker 1995b). And from the responses to the more innovative contractual theorists, it is clear that they are not welcome at all: 'unjust enrichment' theory asserts that there is a sharp line between liabilities voluntarily accepted and those involuntarily imposed, and so those who would bring unjust enrichment into contract are letting the side down by blurring this line. So yet again, what looks like strong support for the 'unjust enrichment' approach seems to be unwelcome to the proponents of the theory.

Relations between the 'unjust enrichment' theorists and the courts become a little clearer when we consider the converse question, of what the theorists think of the precedents themselves. Commentary on recent decisions in restitution is typically argumentative, as the commentators find that their theory is not adhered to. Typically, the leading cases contain some material which fits in well with the 'unjust enrichment' theory, and some which does not. Usually the material which does fit is taken as proof that the judge subscribes to the theory, and the conflicting material is regarded as a series of errors which the judge would not have made had she or he been paying proper attention. This prompts my final question.

Question Ten: Is there any significant modern restitution case which all 'unjust enrichment' theorists would unequivocally endorse?

Certainly none of the leading House of Lords authorities will do. Lipkin Gorman v Karpnale [1991] 2 AC 548 is praised for its acceptance of unjust enrichment, but attacked because it also supports a 'property' theory which is incompatible with it. Woolwich Building Society v IRC (No. 2) [1992] 3 All ER 737 is praised for its general 'unjust enrichment' approach but attacked for its application of the theory, which departs considerably from the theorists' notions. This stream of abusive commentary casts the claim that the judges have truly accepted 'unjust enrichment' into considerable doubt.

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Conclusion

The defences offered by the 'unjust enrichment' school for their position have been rather random. Fearing attack from all sides, they have shot in all directions. In fact, published criticisms of the doctrine have been few and remarkably consistent: that while talk of 'unjust enrichment' is far from meaningless, nonetheless the precision affected by the theorists is entirely spurious. The 'problem' of disorder within restitution is not resolvable by the techniques the 'unjust enrichment' school have adopted, and indeed may not, rightly viewed, be a problem at all. It is to be hoped that better focusing of the issues will lead to a more refined statement of the theory, and hence to a more informed argument over its utility or otherwise.

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Bibliography

Atiyah, PS (1979) Rise and Fall of freedom of Contract (Oxford: Oxford University Press).

Barker, K (1995a) 'Unjust enrichment: Containing the beast' 15 Oxford Journal of Legal Studies 457.

Barker, K (1995b) Review of AG Guest (General Editor) Chitty on Contracts (London: Sweet and Maxwell, 27th edition, 1994 ) Restitution Law Review 290.

Birks, P (1984) 'English and Roman learning in Moses v Macferlan' Current Legal Problems 1.

Birks, P (1985a) Introduction to the law of restitution (Oxford: Oxford University Press).

Birks, P (1985b) 'Six questions in search of a subject: Unjust enrichment in a crisis of identity' 30 Juridical Review 227.

Burrows, A (1987) Remedies for torts and breach of contract (London: Butterworths, 1st ed).

Burrows, A (1993) The law of restitution (London: Butterworths).

Burrows, A (1997) 'Restitution: Where do we go from here?', public lecture at the University of London, 13 March 1997.

Hedley, S (1995) '"Unjust enrichment"' Cambridge Law Journal 578.

Hedley, S (1997) 'Restitution: contract's twin?' in F Rose (ed), Papers from the 1996 SPTL Restitution Conference (Oxford: Hart Publishing, forthcoming).

McBride, N and McGrath, P (1995) 'The nature of restitution' 15 Oxford Journal of Legal Studies 33.

Stoljar, S (1989) Law of quasi-contract (North Ryde, New South Wales: Law Book Company, 2nd ed).

Tettenborn, A (1996) Law of restitution in England and Wales (London: Cavendish Publishing, 2nd ed).

Watts, P (1995) 'Restitution: A property principle and a services principle' Restitution Law Review 49.

Zimmermann, R (1995) 'Unjustified enrichment: The modern civilian approach' 15 Oxford Journal of Legal Studies 403.

Footnotes

1. It appears that various Roman jurists argued precisely this: see Birks 1984. In view of the breadth of modern legal liability, it is plainly unarguable today. Back to text.

2. This is clear from discussions of the extent of the 'change of position' defence. See for example Burrows 1993, pp 423-424. Back to text.

3. See generally Burrows 1987, p 109ff. Anyone uncomfortable at regarding this as an example of 'benefit' to the defendant is in disagreement with all major 'unjust enrichment' scholars, who are unanimous in regarding insurer subrogation as an example of unjust enrichment liability. See for example Burrows 1993, p 78. Back to text.

4. See especially Stoljar 1989. Restitution would of course look rather different if Stoljar decided its limits. Back to text.

5. Perhaps through Nozickean ideas of 'self-ownership': see for example McBride and McGrath 1995, p 37. Back to text.