Common Counts, Common Law and Common Sense
Symposium on Australian Restitution in the 21st Century

7 March 2026

Introduction
	Mr Justice R.P. Meagher of the New South Wales Court of Appeal once said to Professor Peter Birks:
We don’t need a law of restitution. It is no more than a neo-Marxist conspiracy to upset law that has always been perfectly well understood under the familiar headings of the common counts.
(Peter Birks and Robert Chambers, Restitution Research Resource (2nd ed.) [1997] RLR Supp 1). Mr Justice Meagher’s wit reflected his Honour’s artistic taste for appropriate exaggeration, as well as his Honour’s fondness for teasing and playful admonitions  of would-be reformers who showed even mild signs of hubris. The accusations of neo-Marxism should not be taken literally, although those who are attracted by neo-Marxism’s capacity for overly simplistic classification and misuse of language in its attempt to force the real world into conformity with its theory will find much to enjoy in “unjust enrichment” theory. However, Mr Justice Meagher’s remark made an important point about the way in which the familiar headings of the common money counts express crisply what is obscured by the sogginess of unjust enrichment theory. Unsurprisingly, given their basis in the empirical tradition of the common law, the common money counts also reflect what ordinary people would regard as common sense, and were settled and established well before anyone began to conceive theories to try and explain them. It should be emphasised at the outset that the reference to the “familiar headings” of the common counts does not embrace all of the pleading baggage that went with the common counts, such as the allegation that the defendant “not regarding his said promise and undertaking but contriving and fraudulently intending craftily and subtilly to deceive and defraud the [plaintiff] in this behalf, hath not yet paid the said sum of money or any part thereof to the [plaintiff]” (C.H.S. Fifoot, History and Sources of the Common Law: Tort and Contract (London, Stevens & Sons Ltd, 1949), pp 393–4, extracting Stephen on Pleading (1827), p 312). While the cheerful flow of unguarded conversation should never be construed as one would a statute, Mr Justice Meagher’s reference to the “headings” of the common counts was well made.
	What are the familiar headings of the common money counts? The list of eight is now preserved (uniquely) in New South Wales, where r 14.12(1) of the Uniform Civil Procedure Rules 2005 provides as follows:
Subject to this rule, if the plaintiff claims money payable by the defendant to the plaintiff for any of the following:
(a)	goods sold and delivered by the plaintiff to the defendant,
(b)	goods bargained and sold by the plaintiff to the defendant,
(c)	work done or materials provided by the plaintiff for the defendant at the defendant’s request,
(d)	money lent by the plaintiff to the defendant,
(e)	money paid by the plaintiff for the defendant at the defendant's request,
(f)	money had and received by the defendant for the plaintiff’s use,
(g)	interest on money due from the defendant to the plaintiff, and forborne at interest by the plaintiff at the defendant’s request,
(h)	money found to be due from the defendant to the plaintiff on accounts stated between them,
it is sufficient to plead the facts concerned in short form (that is, by using the form of words set out in the relevant paragraph above).
Stephen’s classic treatise on Pleading (2nd ed, 1827) provided six varieties of the “common” or “indebitatus” counts, to which the third edition of Bullen and Leake in 1868 added two more, namely paras (b) and (g) in the above list. Of the eight, paras (c), (e) and (f) provide a succinct statement of what would now be regarded as central aspects of the common law of restitution.
	It may be observed immediately that all but one of the eight common counts concern consensual transactions, namely sales, requests, loans and agreed accounts. It is thus understandable that lawyers came to refer to them as “quasi-contracts”; that is, transactions which were almost, but not really, contracts. The exception, however, is money had and received by the defendant for the plaintiff’s use, which typically concerns transactions which do not even remotely resemble contracts or promises. As Lord Mansfield explained in Moses v Macferlan (1760) 97 ER 676 at 680–1, the remedy of money had and received was “applicable to almost every case where the defendant has received money which ex aequo et bono he ought to refund”, the basis of which was an obligation to refund money arising from “the ties of natural justice and equity”. These dicta have become grossly over-worked in unjust enrichment theory. As Blackstone’s Commentaries (Book III, Chapter 9) expressly made clear, Lord Mansfield’s dictum was concerned only with money had and received, and had nothing to do with the other common counts, such as goods and services provided at the defendant’s request or money paid for the use of another at the defendant’s request. In relation to these other common counts, the defendant’s request itself evidenced a promise by the defendant (whether express or implied from the circumstances) that the defendant would pay. The court then assessed the amount of the payment, but the promise to pay was a real promise by the defendant, not a fictional one imposed by the court.
	That fundamental proposition highlights the obvious fallacy in seeking to treat this area of law as representing a unified and distinct category of legal thought. The common money counts represent a miscellany of interstitial principles which fill gaps in the law concerning contracts and other transactions. They came to be considered together in English law simply because of the historical accident that they all arose out of a common origin in the action of indebitatus assumpsit (see generally, The Varieties of Restitution (2nd ed, 2017, The Federation Press), Chapter 2). Moreover, a familiarity with the headings of the common counts readily resolves many problematic areas of unjust enrichment theory in a way which accords with common sense. 
I will seek to make good those propositions by reference to the three common counts which correspond to the modern law of restitution, namely (1) work done or materials provided by the plaintiff for the defendant at the defendant’s request, (2) money paid by the plaintiff for the defendant at the defendant's request, and (3) money had and received by the defendant for the plaintiff’s use.
Work done or materials provided by the plaintiff for the defendant at the defendant’s request
	There is ample authority for the proposition that a non-contractual claim for payment for goods or services requires proof of circumstances from which the proper inference is that there was a request to provide the goods or services, such that the court can infer that they were provided by the claimant in the expectation of being paid: see Falcke v Scottish Imperial Insurance Company (1886) 34 Ch D 234 at 249 (Bowen LJ), and, to similar effect, 241 (Cotton LJ) and 252 (Fry LJ), confirmed by the unanimous High Court of Australia in Stewart v Atco Controls Pty Ltd (in liq) (2014) 252 CLR 307 at [47]–[48]. (For completeness, in Lumbers v W. Cook Builders Pty Ltd (in liq) (2008) 232 CLR 635 at [80], Gummow, Hayne, Crennan and Kiefel JJ acknowledged limited qualifications, such as salvage in maritime law and cases of necessitous intervention.) A request ordinarily generates an expectation of payment, although one can always think of exceptional cases, such as a person asking a neighbour or friend for a lift home. Ordinarily, the requested party expects to be paid for the requested service, and the requesting party by making the request ordinarily conveys an undertaking or promise to do so. That is the basis of the restitutionary claim on a quantum meruit. 
	As an aside, it has often been suggested that it is sufficient to generate a liability to pay to show that the goods or services were freely accepted by the defendant with an opportunity to reject them. At least on a literal reading, Gordon, Edelman and Steward JJ in Redland City Council v Kozik (2024) 98 ALJR 544 at [208]–[209] appear to have adopted that notion. At [208], their Honours said that “it is not generally a benefit to receive a service that is not requested and is not freely accepted with an opportunity to reject”, and at [209] their Honours spoke of “the absence of any request for, or free acceptance of, a liability to pay for the relevant works” (emphasis added). At [182], their Honours had spoken of claims based on a service performed “at the request of, or freely accepted by, the defendant”, and at [219] said that “there was no finding nor any available inference that any of the [claimants] requested the works or freely accepted the benefit of them”. Justice Edelman, in his book co-authored with Professor Bant, Unjust Enrichment (2nd ed., 2016, Hart Publishing) at pp 74–76, rejected passive receipt as sufficient to overcome individual autonomy and argued that “free acceptance” could be sufficient only where there is a duty on the defendant to reject the benefit or abide the consequences. In any event, as a matter of principle, “free acceptance with an opportunity to reject” cannot be sufficient to generate liability. “Free acceptance” is consistent with complete indifference on the part of the defendant to what is being provided, and even if it were taken to indicate that the defendant subjectively desired the goods or services it would not indicate that they were among the defendant’s expenditure priorities. For example, in November 2024 a conceptual artwork by Maurizio Cattelan entitled “Comedian” sold in New York for US$6.24 million. It consisted of a banana stuck to a wall with duct tape. Louis MacNeice put the point well (“Snow”, 1935):
World is crazier and more of it than we think, 
Incorrigibly plural.
If someone turned up at your front door and handed you a banana, some duct tape, the instructions for installing the work and a certificate of authenticity, you would be well within your moral and legal rights to throw them in the garbage bin and refuse to pay. However, if you had requested those goods to be delivered, you would be liable to pay their reasonable value, recognising of course the scope for highly divergent opinions on that matter.
	Unjust enrichment theorists are at least prepared to accept that it is an elementary principle of justice that people should not be liable for things that they did not choose (J. Edelman and E. Bant, Unjust Enrichment (2nd edn, 2016), p 63). But that only captures part of the way the law respects individual variety and difference. Even if people would choose the thing in question, they do not necessarily choose to pay a reasonable market price for it and to pay that amount there and then. The concept of a request made in circumstances which convey a promise to pay for the goods or services here and now is the only concept which satisfies common sense notions of justice in these circumstances. The common law caught up with common sense in that regard well over 200 years ago. In unjust enrichment theory, however, the common sense of that position is abandoned, lest the notion of a promissory obligation based on the request might interfere with the taxonomical distinction with contracts. The theory overlooks the fact that promissory obligations are not confined to the taxonomical classification of contracts. Much of the law of debt, trusts, corporations and succession is also based on promises, irrespective of whether there is also a binding contract. 
The centrality of the concept of a request may be seen by taking the problem of so-called “incidental benefits”, where the defendant receives a benefit as an incidental consequence of the claimant’s pursuit of some other objective. For example (as Lord President Dunedin hypothesised in Edinburgh and District Tramways Co. Ltd v Courtenay 1909 SC 99 at 105), let it be supposed that an occupier who heats his downstairs flat claims against his upstairs neighbour for saving him some of the expense of heating. Such a claim would be preposterous (or as President Dunedin said, “absurd”), for the simple and obvious reason that the upstairs neighbour never requested that heating service from the downstairs occupier, and thus never promised (expressly or impliedly) to pay for it. The putative claim would be tenable only in a primitive communist collective which compels an equal sharing of benefits and burdens. 
However, hectolitres of ink have now been consumed on this non-issue in the name of unjust enrichment theory. In the latest edition of Goff and Jones The Law of Unjust Enrichment (10th ed, 2022, para 6–115), now in the hands of Charles Mitchell, Paul Mitchell and Stephen Watterson, many imaginative explanations for denying such a claim are given, except for the obvious and traditional one based on common sense that liability depends on a request by the defendant to the plaintiff for such a service. Those explanations include that:
(a)	the incidental benefit is not something to which the claimant is exclusively entitled or which is attributed by the law to the claimant;
(b)	the incidental benefit is something which the claimant can be regarded as having abandoned; 
(c)	certain benefits must be attributed to the defendant, either because they are a specific incident of the defendant’s ownership of property, or because some benefits fall to be attributed to the very existence of society;
(d)	the defendant’s incidental benefit caused the claimant no additional correlative loss, or that time, effort or expenditure is only a liability-supporting expense by reference to some benefit which it is expended to produce (whatever that means); and
(e)	a defendant’s enrichment will not be unjust if a claimant chooses to pursue a course of action for his own purposes that he knows must incidentally benefit the defendant, on the basis that he intends the outcome, even though it is not his primary motivation.
To adopt Horatio’s expression to Hamlet: “These are but wild and whirling words” (I.v. 132). The learned authors have charitably now given up any reference to the truly bizarre explanation proffered by Professor Peter Birks, oddly enough an avowed opponent of legal fictions, that the lower flat-dweller is intentionally making a gift of his heating to the upstairs neighbour (Unjust Enrichment, 2nd ed, 2005, OUP), pp 158–9. A misconceived theory can easily descend into an indulgent madness and a release from reality.
	Appellate courts in the United Kingdom have surprisingly taken this issue seriously, with the Supreme Court adopting a principle that incidental benefits fall outside the scope of restitutionary claims on the basis that a benefit conferred on a defendant as an incidental consequence of the claimant’s pursuit of some other objective will not qualify as a benefit received “at the claimant’s expense” because a loss was not incurred directly through provision of the benefit: see Investment Trust Companies v Revenue & Customs Commissioners [2018] AC 275 at [46]–[58] (Lord Reed); Swynson Ltd v Lowick Rose llp [2018] AC 313 at [88]–[89] (Lord Mance); [115] (Lord Neuberger with whom Lord Clarke agreed); and see [20] (Lord Sumption). All this theorising is unnecessary if one focuses on the well-established formulation of the relevant common money count rather than the artifice of “unjust enrichment”. In the absence of a request by the defendant for the services in question, the claim is missing the ingredient which centuries of common law precedent insists is essential.
	To turn to a different problem, what happens in jurisdictions which have adopted unjust enrichment theory when the defendant actually refuses the services which the claimant seeks to foist upon it? No sensible lay person would ever think that could generate a liability to pay for the services. In Chief Constable of Greater Manchester Police v Wigan Athletic AFC Ltd [2009] 1 WLR 1580, the Chief Constable proposed to provide a higher level of policing to a soccer club than in previous seasons, in view of the club’s promotion to a higher division. The club objected and refused to pay for policing over and above the levels previously received. The Chief Constable nevertheless provided policing at the higher level and the club refused to pay for the increase. Anyone familiar with the law as it existed before the advent of “unjust enrichment” theorising would readily have said that, in the absence of a request from the club for the extra policing, the Chief Constable’s claim was hopeless. But the claim actually succeeded at first instance, and attracted a dissentient in the Court of Appeal, the majority of which reversed the original decision. All four judges simply made direct recourse to whether there had been an enrichment of the defendant at the plaintiff’s expense which was “unjust”, and the absence of an applicable defence. None of the judges even referred to the unbroken history of centuries of authority which indicates that a request for the services provided by the defendant (in contrast here with an express refusal) was an essential ingredient in the action. A mature body of clear and predictable legal principles was thus abandoned by the English judiciary, and replaced by a primitive regime of palm-tree justice, in the application of which the four judges were (as one might expect) evenly divided.
	As these illustrations show, there is something seriously wrong with unjust enrichment theory, even if it often happens coincidentally to produce the right outcome. That provides as much comfort as knowing that a broken watch will tell the correct time twice a day. But to drive a stake through the heart of unjust enrichment theory, we need to take a further step and judge it according to its own criterion for success, namely the elimination of legal fictions. If liability for goods or services provided by the plaintiff to the defendant is based on unjust enrichment of the defendant at the plaintiff’s expense, then liability would depend on the defendant being enriched. In the English language, enrichment means being made rich or richer. That is, the word refers to someone or something being made materially better off. In the law of restitutionary liability for goods and services that is simply a fiction. Liability does not depend in any way on establishing an enhancement of the defendant’s wealth. As Gordon, Edelman and Steward JJ said in Redland City Council v Kozik at [182], in the case of services performed at the defendant’s request, the relevant prima facie benefit to the defendant is generally the value of the service performed rather than the enhancement of the defendant’s wealth that the service generates for the defendant. The authorities make it absolutely clear that the question of any actual enrichment of the defendant is completely irrelevant. At the very least, unjust enrichment theorists are using the wrong word and the wrong concept for what they are trying to express.
The point is most clearly demonstrated in cases where the defendant abandoned the project for which the claimant’s services had been requested, thereby rendering the claimant’s services a waste of time and effort. In Planché v Colburn (1831) 131 ER 305, the defendants engaged Mr Planché to write a volume on costume and ancient armour for their periodical publication known as “The Juvenile Library”, which Mr Planché had commenced when the defendants abandoned the publication. Mr Planché did not tender or deliver any of his work, but succeeded on a quantum meruit on the common count for work and labour done at the defendant’s request. The first edition of Goff and Jones, then known as The Law of Restitution (London, Sweet & Maxwell, 1966), expressed no difficulty with that position (see pp 340–41). But in the 10th edition, now known as Goff and Jones The Law of Unjust Enrichment (Thomson Reuters, 2022), the authors doubt the correctness of Planché v Colburn on the basis that the defendants were not enriched at all. That stance idiosyncratically prefers theory to both common sense and a long and unbroken phalanx of authority.
In Brooks Robinson Pty Ltd v Rothfield [1951] VR 405, Mrs Rothfield, with the authority of her husband, asked the plaintiff to construct a cocktail cabinet designed by an architect to be installed in a particular curved wall in their home. The plaintiff built the cabinet, almost to the point of completion, when Mrs Rothfield grew impatient and cancelled the project. The constructed cabinet remained on the plaintiff’s premises and was found to be of no value for any other purpose, yet the plaintiff succeeded on the common count for work done and materials supplied for payment on a quantum meruit. 
In Sabemo Ltd v North Sydney Municipal Council [1977] 2 NSWLR 880, the plaintiff won a tender for building work, and at the Council’s request, began work on the architectural plans in anticipation of a building contract being entered into when the plans were agreed, but the Council later abandoned the project for its own reasons. The fact that the architectural plans were completely wasted was no obstacle to the plaintiff’s success in what Sheppard J described as a claim which arises “quasi ex contractu” (at 882G).
In Leading Edge Events Australia Pty Ltd v Te Kanawa [2007] NSWSC 228, the renowned opera singer, Dame Kiri Te Kanawa, requested a promoter to do specific preparatory work for a planned series of concerts with the pop singer, Johnny Farnham, on the shared expectation that a contract would be entered into in due course and the promoter would be paid. Dame Kiri then changed her mind for personal reasons and cancelled the planned concerts. Justice Bergin, a trial judge well-known for her abundant endowment of common sense, found Dame Kiri liable to pay on a quantum meruit basis a reasonable amount for the work which was set out in what her Honour candidly referred to as a “Schedule of Wasted Expenditure” (at [271]).
Any non-lawyer would readily agree with the justice of these decisions: the circumstances of the defendant’s request in each case gave rise to an actual, though implied, promise to pay for the claimant’s services, and the defendant should therefore pay a reasonable amount for the services, irrespective of whether they have turned out to be useful or a complete waste of time and effort. An unjust enrichment theorist, however, is left in a quandary: either (1) these cases stretching back almost 200 years must all be treated as wrongly decided; or (2) some contrived and fictional meaning must be given to the term “enrichment”; or (3) the “unjust enrichment” theory must be jettisoned. The second of those alternatives was adopted by the UK Supreme Court in Barnes v Eastenders Cash & Carry plc [2015] AC 1 at [100], expressed euphemistically by describing the word “enrichment” as “a term of art”. That is a polite way of referring to leaden academic jargon. The third of those alternatives is the only sensible course. Even if one substitutes the word “benefit” for “enrichment”, it has been rightly recognised that, in the context of claim based on a quantum meruit, the notion of benefit to the defendant is irrelevant or fictional: The Batis [1990] 1 Lloyd’s Rep 345 at 353 (Hobhouse J); Coleman Engineering Company Inc v North American Aviation Inc 420 P 2d 713 (1966) at 729 (Traynor CJ); Earhart v William Low Co 600 P 2d 1344 (1979) at 1349–52 (Tobriner J, with whom Bird CJ and Mosk and Newman JJ agreed); MacKenzie v Thompson [2005] 3 NZLR 285 at [10] (Rodney Hansen J).
There is a recent innovation by several High Court judges of seeking to explain restitution for goods or services which have been voluntarily provided as based on the concept of total failure of consideration. A minority in Mann v Paterson Constructions Pty Ltd (2019) 267 CLR 560 at [169] and [189], comprising Nettle, Gordon and Edelman JJ, advanced that view, but it was criticised by Gageler J as suffering from the overgeneralisation inherent in attributing hegemonic status to one Very Big Idea (at [77]–[81]), and finds no support in the dissenting judgment of Kiefel CJ, Bell and Keane JJ (see [25]–[32]). In Redland City Council v Kozik (2024) 98 ALJR 544 at [185], Gordon, Edelman and Steward JJ appear to say that what their Honours conceptualise as “failure of basis” might be applicable not only to claims for the repayment of money but also to claims to be paid the reasonable value of goods or services. That is inconsistent with centuries of authority which have confined total failure of consideration to claims for money had and received (that is, claim for the repayment of money), rather than deploying total failure of consideration as a ground for restitution for goods or services. One might therefore expect some explanation as to why this innovation is sought to be made.
Total failure of consideration cannot provide a sufficient basis for a claim for the reasonable value of goods or services, because the claimant must still overcome the common law’s respect for the defendant’s autonomy in being able to choose what goods or services to acquire, and how to accommodate any such desire within his or her budgetary constraints and priorities. Hence, the claimant must still establish that the goods or services were requested in circumstances giving rise to a reasonable expectation (that is, based on an actual promise, express or implied) that they would be paid for. If, as I have sought to demonstrate, the request in those circumstances is itself a sufficient basis for a claim to be paid the reasonable value of goods or services (subject to any applicable contract between the parties), then the concept of total failure of consideration is a wholly unnecessary and pointless distraction. The only conceivable point would be as a means of forcing the law to fit a pre-conceived theory to which it is ill-adapted.
Money paid by the plaintiff for the defendant at the defendant’s request
	In responding to Mr Justice Meagher’s remark with which I began, Professor Birks wrote that his Honour was “probably one of the few lawyers who do now understand that ‘money had and received’ and ‘money paid’ were common money counts and who could tell what the relation was between them” ([1997] RLR Supp 1). That was rather disingenuous. Professor Birks’s widely read and much cited book, An Introduction to the Law of Restitution (Oxford, OUP, 1985), at pp 111–2 gave a succinct and readily comprehensible explanation of that very matter: “money had and received” concerned money received by the defendant irrespective of whether the defendant wanted or chose to have the money, whereas “money paid” concerned money paid to a third party for the sake of the defendant and, crucially, required that the payment be “at the defendant’s special instance and request”. No lawyer who was or is at all familiar with the law of restitution would be ignorant of that distinction.
	In general, the common law leaves parties at liberty to decide who their creditors will be and the terms applicable to when and how their debts are to be paid. The marketing departments of modern financial institutions, such as banks and insurers, thus spend a great deal of money in an effort to persuade potential debtors of the peace of mind and the serene beach-side setting they might enjoy by choosing that particular institution as their creditor. The common law respects the ability of parties to exercise that choice, and will not permit a plaintiff to recover against a defendant merely by reason of the plaintiff having voluntarily paid the defendant’s debt to a third party. It is otherwise if the defendant has requested the plaintiff to do so. As Bowen LJ explained in Falcke v Scottish Imperial Insurance Company (1887) 34 Ch D 234 at 249, the request means that the defendant knew that the plaintiff was laying out his money in the expectation of being repaid, that being the inferred understanding between the parties. That is common sense. The point may be tested by imagining the reaction of the person acting on the request if the person making it were to add to the request an express statement that he would not be prepared to reimburse the requested person for any expense incurred in fulfilling the request. If, as is usual, that additional statement were not made, the requested person would be entitled to assume that a promise to indemnify was simply understood. The position is consistent with the implied indemnity which arises when one person incurs expense in acting at the request of another: Birmingham and District Land Company v London and North Western Railway Company (1887) 34 Ch D 261 at 272 (Cotton LJ) and 274 (Bowen LJ) (a case decided only 19 days after Falcke was decided by the same judges); Eastern Shipping Company Ltd v Quah Beng Kee [1924] AC 177 at 182–3 (Lord Wrenbury); Yeung Kai Yung v Hong Kong and Shanghai Banking Corporation [1981] AC 787 at 796 (Lord Scarman).
	The position is otherwise where the payment by the plaintiff of the defendant’s debt is not truly voluntary, because the plaintiff is legally compelled to pay the defendant’s debt to the third party. That may arise where both the plaintiff and the defendant are personally liable for the debt to the third party, but the defendant is primarily liable for that debt, as in Brook’s Wharf and Bull Wharf Ltd v Goodman Bros [1937] 1 KB 534 at 544 (Lord Wright MR). It may also arise where the plaintiff is not personally liable to pay the debt, but is liable to have his or her property seized if the debt is not paid, as in Edmunds v Wallingford (1884) 14 QBD 811 at 814 (Lindley LJ). Further, there are several principles of equitable subrogation which supplement the common law principles.
	Modern analyses of the implied indemnity for voluntary but requested payments by the plaintiff in the interests of the defendant tend to focus on Owen v Tate [1976] QB 402. In that case, the plaintiff gave a guarantee to the defendant’s banker for the amount of the defendant’s bank loan. The loan had been secured by a mortgage over property owned by a Miss Lightfoot, whom the plaintiff wished to assist by thus obtaining a discharge of the mortgage. After the plaintiff’s guarantee was called on, the plaintiff’s claim was rejected on the basis that he had acted voluntarily, without a request by the defendants to incur that liability, or even a desire to benefit the defendants and without any necessity or compulsion to do so. Indeed, the factual findings included that the plaintiff assumed the obligation of a guarantor behind the back of the defendants, against their will, and despite their protest (per Scarman LJ at 410C–D  and 412B). Professor Birks (An Introduction to the Law of Restitution, pp 311–2 ) and Professor (now Lord) Burrows (The Law of Restitution, 3rd ed, 2011, OUP, pp 450–1) regarded the decision as wrong given that the plaintiff owed a legal obligation to the bank as guarantor to make the payment. But that defies common sense. The plaintiff had assumed that obligation without a request by the defendants and against their protests. Having done so, making a payment to discharge the obligation could not put the plaintiff in any better position. The plaintiff’s payment under the guarantee was just as much the act of an officious volunteer as if the plaintiff had gratuitously paid the debt directly without interposing the liability under the guarantee. As Scarman LJ put the matter, “the defendants are not to be criticised … for having accepted the benefit of a transaction which they neither wanted nor sought” (at 412B).
 Money had and received by the defendant for the plaintiff’s use
As I mentioned at the outset, money had and received typically (but not invariably) concerns transactions in which the obligation by the defendant to repay the plaintiff does not involve anything resembling a promise. Lord Mansfield in Moses v Macferlan (1760) 97 ER 676 at 681 gave as examples:
money paid by mistake; or upon a consideration which happens to fail; or for money got through imposition, (express, or implied;) or extortion; or oppression; or an undue advantage taken of the plaintiff’s situation, contrary to laws made for the protection of persons under those circumstances.
A principle of unjust enrichment at the plaintiff’s expense might superficially appear to be on its strongest ground in the context of money had and received. In the typical case, the defendant has been enriched by the payment of money, that payment is at the plaintiff's expense and the enrichment is unjust because of some element which vitiates the voluntariness of the payment. But does that translate into a principle, or even a concept, of unjust enrichment at the plaintiff’s expense? That theory is a kind of intellectual trompe-l’oeil: a representation which seems real from a certain distance and a certain angle, but on closer inspection proves to be false. Any theory which might look attractive in its generality, but which is false in matters of detail, is simply false.
	Let us take the simplest and most central of all such cases, namely a mistaken payment by the plaintiff to the defendant in respect of which no recognised defence is applicable. The plaintiff who has made the mistaken payment has just as good a right of recovery irrespective of whether, on the one hand, the plaintiff has fully passed on the expense to his or her customers (even without any discernible loss of sales or loss of the time-value of money) or, on the other hand, the plaintiff has had to bear the entire expense alone: Roxborough v Rothmans of Pall Mall Australia Ltd (2001) 208 CLR 516 at [22]–[28] (Gleeson CJ, Gaudron and Hayne JJ), [68]–[69] (Gummow J); Commissioner of State Revenue (Vic) v Royal Insurance Australia Ltd (1994) 182 CLR 51 at 73–78 (Mason CJ), 90–91 (Brennan J, with whom Toohey and McHugh JJ agreed); Mason v New South Wales (1959) 102 CLR 108 at 146 (Windeyer J); Kingstreet Investments Ltd v New Brunswick (Department of Finance) [2007] 1 SCR 3; 276 DLR (4th) 342 at [42]–[51];  Kleinwort Benson Ltd v Birmingham City Council [1997] QB 380. It is thus no part of the plaintiff’s cause of action to prove that the transaction has made him or her worse off and it is not a defence for the defendant to show that the plaintiff has not suffered in any way. But if the law really were concerned with reversing enrichments “at the plaintiff’s expense”, it would require as a necessary ingredient in the cause of action that the plaintiff had actually been made worse off (that is, suffered an “expense”) as a result of the transaction in a real and meaningful way, and not just in the twinkling of an eye between making the payment to the defendant and recouping the amount from his or her customers. Identifying who has really borne the expense, however, is a matter in which the law wisely takes no interest.
	As a matter of ordinary English, the expression “at the plaintiff’s expense” requires that a loss has been caused to the plaintiff or, as the High Court of Australia put it, a “subtraction from the plaintiff’s wealth”: Roxborough v Rothmans of Pall Mall Australia Ltd (2001) 208 CLR 516 at [26] (Gleeson CJ, Gaudron and Hayne JJ), approving Mason CJ in Royal Insurance at 75). Dictionary definitions of the expression invariably require the causation of loss, damage, detriment or harm. But unjust enrichment theorists acknowledge that the way they use the expression “at the expense of” does not require any loss: Andrew Burrows, The Law of Restitution (3rd ed.), p 65 and see pp 31, 196 and 614; Andrew Burrows. A Restatement of the English Law of Unjust Enrichment (OUP, 2012), pp 45–46; James Edelman and Elise Bant, Unjust Enrichment (2nd ed, 2016), pp 89–91. They are therefore once again using the wrong expression for what they are trying to convey. By contrast, the common money counts do not suffer from that shortcoming. The relevant claim is simply to recover money received by the defendant to the use of the plaintiff, a point made by Lord Wright in Fibrosa Spolka Akcyjna v Fairbairn Lawson Combe Barbour Ltd [1943] AC 32 at 65. The ingredient “at the plaintiff’s expense” is no more than a legal fiction. It is not something that the plaintiff needs to prove and it has nothing to do with how the common law treats like cases alike.
Common law and common sense
	The common law is one of the finest practical expressions of British empiricism. It operates by close observation of the facts as they are revealed by actual experience in the real world, and provides an educated response to those facts, reasoning by analogy from other observed circumstances so that like cases are treated alike. In that way, the common law fulfils its purpose of embodying in a relatively predictable way the reasonable expectations of ordinary and honest people. Lord Mansfield expressed the point with characteristic eloquence in Hamilton v Mendes (1761) 97 ER 787 at 795:
The daily negotiations and property of merchants ought not to depend upon subtleties and niceties; but upon rules easily learned and easily retained, because they are the dictates of common sense, drawn from the truth of the case.
As Lord Atkin said in concluding his Lordship’s famous speech in Donoghue v Stevenson [1932] AC 562 at 599, it is useful to consider what people who are not lawyers tend to think in order to assess whether the law is in accordance with sound common sense. Common law principles are not built by spinning theories. The common law lives in a world of reality, not a palace of dreams.
In applying a system of bottom-up empiricism, Friedrich Hayek argued that the chief concern of a common law judge must be the expectations which the parties in a transaction would have reasonably formed on the basis of the general practices that the ongoing order rests on: Law, Legislation and Liberty, vol 1, p 86. In this way, order emerges from our free transactions, not because it is imposed, but because it is implicit in our dealings: ibid.,vol. 2, pp 108–9. In other words, the common law encapsulates what reasonable people already assume when they engage in free transactions. Roger Scruton took up that argument, and said that implicit in Hayek is the thought that free exchange and enduring customs are to be justified in exactly the same terms, both being indispensable distillations of socially necessary knowledge (Roger Scruton, How to be a Conservative, p 56). Scruton and Hayek both drew a legal analogy with Adam Smith’s “invisible hand” in economics, and the notion that order may emerge from consensual dealings without someone having imposed it (ibid., p 67; Law, Legislation and Liberty, vol 1, pp 37–38). As Scruton said, the common law contains information dispersed through the record of the law that could not be contained in a legislative program. That includes information about conflicts and their resolution, about the sense of justice in action, and about human expectations (Mark Dooley (ed.), The Roger Scruton Reader (Continuum, 2009), p 48).
One upshot of the methodology of the common law is that it has no need for classification, or “taxonomy” or “mapping” as it is more fashionably termed. Those techniques are fundamental to the tasks of postage stamp collectors and field botanists, but they only get in the way of proper common law reasoning. They are better suited to the top-down deductive reasoning of civil law systems. By contrast, the common law technique is to make close observation of the facts as they arise and to draw analogies and distinctions with how other factual scenarios have been treated, identifying in that way central cases and peripheral cases. If the received principle does not apply directly to a new factual scenario, it might still apply analogically. In terms of common law reasoning, if there is a socially agreed solution by custom, convention and the operation of the market, all the common law has to do is recognise and adopt it. In that way, the common law is simultaneously both facilitative and reflective: it states rules which one can pick up and use, and those rules in turn reflect modes of actual observed practice. On this point, I part company slightly with Hayek, who praised the common law as preserving a Middle Ages tradition whereby the law was discovered, not made (Hayek, op.cit., vol 1, pp 83–84). I do not see those concepts as dichotomous, but as occurring simultaneously in common law reasoning.
Another upshot of common law methodology is that the language in which common law principles are expressed should correspond as closely as possible to the ordinary and natural meaning of those words. Language is based on convention, a concept that is sadly much deprecated in modern political and social discourse. The word comes from the Latin convenire, meaning to agree or come together. The noun “convention” is best understood as based on that verb. It is very difficult for lawyers to come together in discussing a branch of the law, such as restitution, and to express the expectations of ordinary, honest and reasonable people, if some of them are using words in an idiosyncratic way, rather than according to their ordinary meaning. The proper use of the English language leads to clearer and better analysis. As George Orwell remarked more generally about modern standards of English expression, the English language:
becomes ugly and inaccurate because our thoughts are foolish, but the slovenliness of our language makes it easier for us to have foolish thoughts. The point is that the process is reversible. Modern English is full of bad habits which spread by imitation and which can be avoided if one is willing to take the necessary trouble. If one gets rid of these habits one can think more clearly.
(“Politics and the English Language”, in George Orwell, Essays (Penguin, London, 2000), p 349). To bring the point closer to home, Sir Victor Windeyer praised the generation of Arts graduates from The University of Sydney in the 1860s, which included Sir Samuel Griffith and Sir Edmund Barton, as bringing to their tasks an appreciation of the meaning of words, saying “They liked to be masters of words and as masters to keep them in their proper places and to make each do its proper work” (“The Faculty of Arts and the Community”, in Bruce Debelle (ed.), Victor Windeyer’s Legacy: Legal and Military Papers (The Federation Press, Sydney, 2019), p 27). Academic discussion of the law of restitution suffers badly from what the Germans call Gesprächsgemetzel: moments when, for no good reason, a conversation suddenly goes awry. A good starting-point for restitution lawyers would be to abandon the contrived usage of words such as “enrichment” and “expense”. Indeed, it is doubtful whether “unjust enrichment” theory would have happened at all in the common law world if people had only been more careful about the use of the English language, the common law’s  most important raw material.
	Finally, the empiricism of the common law makes historical cases and historical statements of principle vitally important. Very few legal problems are entirely new. In treating like cases alike, according to the reasonable expectations of ordinary and honest people, one must look to how such cases have been dealt with in past centuries. The familiar headings of the common money counts enable us to do just that. There is much to admire in the way that previous generations distilled the essence of legal principles which are still operative. We should view the common law as a geologist views a landscape: different eras co-exist irrespective of their chronological order.