Учебный год 22-23 / The Law of Obligations

the bottom of both the principle that all pacts are actionable and of its limitation there lies the specific significance attributed by canon lawyers and moral theologians alike to the human will.250

(b) The clausula from the 17th century to today

The 17th century was a flowering time for the clausula doctrine (partly, perhaps, in response to the devastating wars of the time)251 and it became part and parcel of the usus modernus as well as of the systematic endeavours of the natural lawyers.252 It attained great prominence in the field of public international law,253 but in the area of private law its star ultimately began to wane. Nineteenth-century legal science was predominantly hostile to it, and the clausula thus disappeared.254 But the underlying idea had only temporarily lost its attraction. Thrown out by the door, as Windscheid put it,255 it will always re-enter through the window. The will of a person usually relates to a certain given set of facts only; it has been formed on the basis of certain suppositions. If these turn out to be wrong, it is not always fair to hold that person by his word. On the other hand, however, the promisor's interest in having the contract set aside must be balanced against the interest of the community at large in certainty of the law. Some kind of criterion is therefore needed to attempt to achieve the balance. Windscheid's own " Voraussetzungslehre" (doctrine of tacit presupposition) was one such attempt,256 but it did not commend itself to the drafters of the BGB.257 The BGB does not, in fact, contain a general rule dealing with the problem of changed circumstances. The modern version of the clausula rebus sic stantibus therefore had to be developed

250Feenstra/Ahsmann, op. cit., note 214, p. 21.

251E.M. Meijers, "Essai historique sur la force majeure", in: Etudes d'histoire du droit, vol.

IV (1966), p. 29.

^2 On Grotius' attitude cf. Feenstra, Daube Noster, pp. 84 sqq.; Beck-Mannagetta, in: La

fomazione storka, vol. Ill, pp. 1270 sqq.

253Cf. e.g. Pfaff. Festschrift Unger, pp. 282 sqq.; Erich Kaufmann, Das Wesen des Votkerrechts und die ctausula rebus sic stantibus (1911).

254Cf. supra, note 237.

255"Die Voraussetzung", (1892) 78 Archiv fur die civilistische Praxis 197.

256Windscheid defined the term "presupposition" in terms of an "undeveloped condition": one party wishes the effects of a transaction to be dependent on a certain state of affairs without, however, elevating such presupposition, by way of an express declaration, to the status of a term of the transaction. Such party may refuse to render performance, if

his contractual opponent was in a position to gauge, from the circumstances of the transaction, that the presupposition in fact formed an element of his intention. Cf. esp.

Bernhard Windscheid, Die Lehre des riimischen Rechts von der Voraussetzung (1850); idem, in: Windscheid/Kipp, §§ 97 sqq. Contra e.g. Otto Lenel, "Nochmals die Lehre von der Voraussetzung", (1892) 79 Archiv fur die civilistische Praxis 49 sqq.; cf. also Gerhard Kegel, "Empfielt es sich, den Einfluss grundlegender Veranderungen des Wirtschaftslebens auf Vertrage gesetzlich zu regeln und in welchem Sinn?", in: Verhandlungen des 40. Deutschen Juristentages (1953), vol. I, pp. 143 sqq; for a recent analysis, cf. Ulrich Falk, Ein Gelehrter w'xe Windscheid (1989), pp. 193 sqq. The notion of "economic" impossibility (cf. e.g. RGZ 100, 129 (130)) may be mentioned as another attempt to cope with the problem of changed circumstances.

257 "Protokolle", in: Mugdan, vol. II, p. 1174. On the clausula cf. "Motive", in: Mugdan, vol. II, pp. 109, 471.

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extra legem by courts and legal writers; it is the doctrine of "Wegfall der Qeschdftsgrundlage" (collapse of the underlying basis of the transaction), which was formulated, initially, in response to the problems posed by the consequences of the First World War on the performance of long-term contracts,258 and which has become part and parcel of the modern German law of contract.259 Its functional equivalent in English law is the doctrine of frustration of contract.260

258Paul Oertmann, Die Geschaftsgrundlage, ein neuer Rechtsbegriff (1921). On the judicial reception of this doctrine since the famous decision of RGZ 103, 328 sqq., see Bernd Riithers, Die unbegrenzte Auslegung (1973), pp. 40 sqq.

259Cf., for example, Karl Larenz, Geschaftsgrundlage und Vertragserfullung (3rd ed., 1963);

Matte Diesselhorst, "Die Geschaftsgrundlage in der neueren Rechtsentwicldung", in: U. Immenga (ed.), Rechtswissenscha.fi und Rechtsentwicklung (1980), pp. 153 sqq.; Giinther H. Roth, in: Munchener Kotnmentar, vol. II (2nd ed., 1985), § 242, nn. 465 sqq.; for a crisp account of the development cf. also Joachim Meinecke, "Frustration in the West German Law of Contract", (1978) 13 The Irish jurist 83 sqq.

260Treitcl, The Law of Contract, pp. 663 sqq.; on its history, see Kegel, op. cit., note 256, pp. 172 sqq.; for a comparison, cf. Stefan Schmiedlin, Frustration of Contract und clausula rebus sic stantibus (1985). The Louisiana Civil Code, interestingly, deals with the problem as being one of an error in motive, which can under certain circumstances constitute a ground for the voidability of contracts: "No error in motive can invalidate a contract, unless the other party was apprised that it was the principal cause of the agreement, or unless from the nature of the transaction it must be presumed that he knew it" (art. 1826). For details, see Timothy Hofi", "Error in the Formation of Contracts in Louisiana: A Comparative Analysis", (1978-79) 53 Tulam LR 358 sqq.

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CHAPTER 19

Error

1.Error and contractual theory

(a)Cotton ex Peerless

Sometime in the 1860s two ships sailed from Bombay to Liverpool. Both were called Peerless. The one had left Bombay in October, the other in December. Meanwhile, back in England, 125 bales of cotton "to arrive ex Peerless from Bombay" had been sold. When the vendor tendered the cotton that had arrived with the December Peerless, the purchaser refused to accept it. He had meant and intended, so he alleged, to buy the cotton from the October Peerless.

We do not know what the (real) reason for the purchaser's reaction was. Possibly the price had fallen below the level of 17^ pence per pound (which was the contract price) during the time between the arrival of the two ships. The court, in any event, gave judgment in his favour.1 Again, we do not know the reasons, since none have been reported. Shortly after counsel for the defendant had risen, the court abruptly stopped him in his argument and announced its judgment. What had he said that so impressed the court? "That being so, there was no consensus ad idem, and therefore no binding contract."

Quite understandably, under these circumstances, the decision in Raffles p. Wichelhaus was taken to lend support to a subjective approach to the formation of contract. What matters is that the minds of the parties are ad idem; if that is not the case, there can be no contract. But there have also been different interpretations. Oliver Wendell Holmes, for instance, tried to "objectify" Raffles v, Wichelhaus and wrote:

"It is commonly said that such a contract is void, because of mutual mistake as to the subject-matter, and because therefore the parties did not consent to the same thing. But this way of putting it seems to me misleading. The law has nothing to do with the actual state of the parties' minds. In contract, as elsewhere, it must go by externals, and judge parties by their conduct. . . . The true ground of the decision was not that each party meant a different thing from the other . . . but that each said a different thing. The plaintiff offered one thing, the defendant expressed his assent to another."3

These words remind us of what has been mentioned very briefly in the previous chapter.3 A contract, in modern analysis, is made up of two

1Raffies v. Wichelhaus (1864) 2 H & С 906. On the rule developed on the basis of this decision cf, in particular, William F. Young, "Equivocation in the Making of Agreements", (1964) 64 Columbia LR 619 sqq.; for a critical evaluation, see also Grant Gilmore, The Death of Contract (1974), pp. 35 sqq.

2The Common Law, p. 309. "Even for Holmes this was an extraordinary tour de force", comments Gilmore (p. 41).

3Supra, pp. 567 sqq.

583

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declarations of will, and each of these, as the term suggests, of two elements: verba and voluntas. As a rule, will and declaration will coincide. According to Holmes, this was the case in Raffles v. Wichelhaus: the vendor meant December Peerless, and though he only said Peerless, his declaration must also be interpreted as referring to the December Peerless. The purchaser, on the other hand, intended to buy his cotton from the October Peerless, and his declaration, too, has to be seen in the light of this intention. Thus, whether we emphasize will or declaration, the result is the same: in either case there is no correspondence, and hence a contract has not been concluded.

(b) Discrepancy between intention and declaration

Things begin to look quite different, though, if one of the parties has declared one thing but meant another. Suppose there had been but one Peerless, and Raffles (or Wichelhaus) had referred to it by mistake, meaning quite a different ship, with quite a different name, which he thought to be the Peerless. It is obvious that both declarations correspond. If this were the deciding factor, both parties would be bound, and the purchaser would have to accept the cotton from Bombay ex Peerless. It is equally obvious, however, that, as to their intentions, both parties are not in fact ad idem. Their minds have not met "in unam sententiam", and hence there is no consent. If this were crucial, a contract could not be said to have come into existence. Which of these two approaches—diametrically opposed as they appear to be—should a legal system adopt?

(c) Private autonomy and protection of expectations engendered

If freedom of contract and private autonomy were our guiding principles (and they are indeed entrenched, for instance, in the German constitution4), then everybody should be able to determine his legal relationships with other people according to his own free will. This will must, of course, be free of vices and thus, for instance, the contracting party must not be labouring under a mistake. A declaration affected by mistake—in terms of "classical" contract theory—is not likely to lead to a result that is substantially fair. Or, put differently (namely in the words of the Louisiana Civil Code): The basis of contract is consensus; and "consent being the concurrence of intention in two or more persons, with regard to a matter understood by all, reciprocally communicated, and resulting in each party from a free and deliberate exercise of the will, it follows that there is no consent, . . . where it has

4 Arr. 2 I GG; cf. e.g. Ludwig Raiser, "Vertragsfreiheit heute", 1958 Juristenzeitung 4 sqq.; Manfred Wolf, RechtsqeschaftUche Entscheidungsfreiheit und t>ertra%licher Interessetutusgleich

(1970), pp. 21 sqq.

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been procured by—Error; Fraud; Violence; Threats".5 On the other hand, it has to be taken into account that freedom (and the exercise thereof) entails responsibility. The individual is free to determine whether he wants to enter into a contract or not. But once he decides to do so and communicates his intention to others, he engenders expectations, which the law has to protect too. This is the reason for the binding nature of a contract, from which, as we have seen,6 the parties cannot be allowed (and are indeed not allowed) to withdraw at will. Hence, one could say that to be bound by one's declarations is the price to be paid for the freedom of will. As a result of this view, the risk of error would always have to be borne by the person making the declaration and not by the addressee.7

(d) Will theory and declaration theory

It is obvious that we are here again8 dealing with a situation where neither of these two fundamentally irreconcilable approaches can sensibly be taken to any extreme. While it may be equitable to stress the individual will and to take into account any kind of mistake, certainty of law will be most detrimentally affected. Sole emphasis on the external manifestation of that intention, in turn, will be conducive to certainty of law, but is bound to lead to harsh and inequitable results. Every developed legal system will therefore have to find some balance between the two positions. If it proceeds from what is usually dubbed the "will theory", it must make some concession to the protection of the other party's reliance, and can therefore not give effect to every type of error. In the same way, the so-called "declaration theory" can serve only as a starting point and must be modified so as to accommodate the reasonable interests of the author of the declaration.

In modern South African case law both approaches have been vying for recognition.9 On the one hand, it has been held that error excludes consensus and thus prevents the formation of a contract.10 But not every kind of error has this effect. It must relate to one of the essential elements of the contract. Furthermore, the will theory is tempered by

3 Art. 1819; cf. further Saul Litvinoff, "'Error' in the Civil Law", in: Joseph Dainow (ed.),

Essays on the Civil Law of Obligations (1969), pp. 222 sqq.

''Supra, pp. 577, 578.

For a recent analysis of the "dynamic that operates in areas of doctrine caught between

the commitment to objectivity, expressed as reliance on 'manifestation', and the commitment to subjectivity expressed as reliance on 'intent'" (p. 1065), cf. Clare Dal ton, "An Essay in the Deconstruction of Contract Doctrine", (1985) 94 Yale LJ 1039 sqq.

я Cf., for example, supra, pp. 87 sqq.

9 For a general discussion, see Konrad M. Kritzinger, "Approach to Contract: A Reconciliation", (100) 1983 SALJ 47 sqq.; De Wet en Yeats, pp. 7 sqq.; Joubert, Contract, pp79 sqq.

10 Cf. e.g. Robinson v. Randfontein Gold Mining Co., Lid. 1925 AD 173; Trollip v, Jordaatt 1961 (1) SA 238 (A); Ocean Cargo Line Ltd- v. F. R. Warm? (Pty.) Ltd. 1963 (4) SA 641 (A).

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the doctrine of assent by estoppel11 or, as many now prefer to say, of quasi-mutual assent:12 a person who has deliberately or negligently13 made a declaration which did not correctly reflect his true intention may be estopped from proving the truth and will thus be forced to proceed as if the misrepresentation had been true.14 On the other hand, there are those who agree with Wessels CJ that "[t]he law does not concern itself with the working of the minds of the parties to a contract, but with the external manifestation of their minds".15 This is an endorsement of the declaration theory, but it, in turn, is modified by the doctrine of iustus error: if a party to a contract has been labouring under a reasonable mistake, he may repudiate the contract (with the effect of in integrum restitutio). But when is a mistake reasonable? Usually it is said that it must relate to one of the vital elements of the agreement and that it must not have been due to inattention or negligence on the part of the mistaken party. But support can also be found for the proposition that an error is iustus when it has been

1 The classic text in this regard is j.C. dc Wet, Estoppel by Representation in die Suid-Afrikaatue Reg (1939).

12Cf. R.H. Christie, "The Doctrine of Quasi-Mutual Assent", 1976 Actafuridica 149 sqq.

13But it is doubtful whether fault is always required: cf. the discussion by Tebbutt J, in

Sonday v. Surrey Estate Modern Meat Market (Pty.) Ltd. 1983 (2) SA 521 (C); he himself answers the question in the negative. Another problem, which has not yet been authoritatively settled, is whether the party relying on estoppel must have acted to his prejudice (on which see e.g. Peri-Urban Areas Health Board v. Breet 1958 (3) SA 783 (T), which answers this question, too, essentially in the negative).

14 The most recent authoritative statements by the Appellate Division are Saambou-

Nasionale Bouvereniging v. Friedman 1979 (3) SA 978 (A); Mondorp Eiendomsagentskap (Edms.) Bpk. v. Kemp en be Beer 1979 (4) SA 74 (A) and Spes Bona Bank Ltd. V Portals Water

Treatment South Africa (Pty.) Ltd. 1983 (1) SA 978 (A). Historically, this modification of the "will theory" dates back to che famous leading English case of Smith v. Hughes (1871} LR 6 QB 597, which contains the following dictum by Blackburn J (at p. 607) : "If, whatever a man's real intention may be, he so conducts himself that a reasonable man would believe that he was assenting to the terms proposed by the other party, and that other party upon that belief enters into the contract with him, the man thus conducting himself would be equally bound as if he had intended to agree to the other party's terms." The dogmatic basis for this reception is unclear. Trollip J in Connoch's (SA) Motor Co. Ltd. v. Sentraal Westelike Ko-operatiewe Maatskappy Bpk. 1964 (2) SA 47 (T) at 49A-B described it thus: "The English doctrine of Estoppel by representation migrated to this country on the authority of a passport that it approximated the exceptio doli mali of Roman Law. However doubtful the validity of that passport might originally have been . . ., the doctrine has now become naturalized and domiciled here as part of our law." "The immigration authority who first stamped the doctrine's passport for entry into the Cape . . . appears to have been Lord de Villiers CJ": Tebbutt J, in Sonday v. Surrey Estate Modem Meat Market 1983 (2) SA 521 (C) at 525C.

15 "Even, therefore, if from a philosophical standpoint the minds of the parties do not meet, yet, if by their acts their minds seem to have met, the law will, where fraud is not alleged, look to their acts and assume that their minds did meet and that they contracted in accordance with what the parties purport to accept as a record of their agreement. This is the only practical way in which courts of law can determine the terms of a contract": South African Railways & Harbours v. National Bank of South Africa Ltd. 1924 AD 704 at 716 sq. Cf. further e.g. Cotlen v. Rietfontein Engineering Works 1948 (1) SA 413 (A) at 431. For a nearly identical formulation of this proposition, see Holmes, The Common Law, p. 309 ("The law has nothing to do with the actual state of the parties' minds. In contract, as elsewhere, it must go by externals, and judge parties by their conduct").

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induced by the wrongful misrepresentation of the other party. Others stress that the mistake must not have induced in that other party a reasonable belief that consensus has in fact been reached.16 Closely related as they are, in actual practice all these approaches usually arrive at the same result as would have been achieved if the will theory and the doctrine of quasi-mutual assent had been applied.17 Thus, South African law provides a good example of how two different theoretical perspectives are able to converge so as to lead to essentially the same solutions. Abstract theorizing in terms of will and declaration theory does not normally affect the direction of the law in action.

2.Basic types of error in Roman law

(a)Verba and voluntas

If we turn our attention to Roman law, the last thing we can expect to find is, of course, a neat and logical theoretical framework for the problem of error. Two things are clear, however.1H In ancient Roman law it was only the declaration that counted. All legal acts were of a strictly formal nature, and whenever the prescribed form was complied with, mancipatio, stipulatio and whatever other legal acts existed were binding and effective. There was an irrebuttable presumption that the will of the parties was correctly and adequately reflected in, for instance, the verba of the old sponsio/stipulatio. Under these circumstances, there was, of course, no room for taking any kind of error into account. According to the law reflected in Justinian's compilation, on the other hand, certain types of mistake exclude consensus, the essential basis for the formation of contract. Ulpianus D. 18, 1, 9 pr. leaves no doubt about that:

lfi For these various meanings of iustus error cf. D.B. Hutchison/B.J. van Heerden, "Mistake in Contract, A Comedy of (Justus) Errors", (1987) 104 SALJ 522 sqq., who also draw attention to the anomaly that the iustus error doctrine is still applied in spite of the fact that the courts now generally appear to adhere to the (subjective) will theory, and no longer to the declaration theory. In fact, in recent years, there has been an unprecedented flood of decisions and case notes on the question of iustus error. Cf, most recently, Horty Investments

(Pty.) Ltd. v. Interior Acoustics (Pty.) Ltd. 1984 (3) SA 537 (W); Osman v. Standard Bank National Credit Corporation Ltd. 1985 (2) SA 378 (C); Du Toil v. Atkinson's Motors Bpk. 1985

(2) SA 893 (A); Spindrifter (Pty.) Ltd. v. Lester Donovan (Pty.) Ltd. 1986 (1) SA 303 (A); Nasionale Behuisingskommissie v. Greyiing 1986 (4) SA 917 (T); Standard Credit Corporation Ltd. v. Naicker 1987 (2) SA 49 (N); Carole Lewis, "Caveat Subscriptor and the Doctrine ofjustus Error" (1987) 104 SALJ 317 sqq.; A.J. Kerr, "Uses and Misuses of the Term Iustus Error. Questions concerning Error in Corpore", (1987) 104 SALJ 377 sqq.;J.S. McLennan, "Justus Error, Snatching of Bargains, and Rectification", (1987) 104 SALJ 382 sqq.

17 For a redefinition of iustus error in terms of quasi-mutual assent (an error is iustus when the other party, due to his unreasonable reliance, cannot uphold the contract on the basis of quasi-mutual assent), cf. M.F.B. Reinecke/Schalk van dcr Merwe, 1984 TSAR 290 sqq.; Hutchison/Van Heerden, (1987) 104 SALJ 522 sqq.

18 Cf, for example, Voci, L'errore (1937); Gian Gualberto Archi, "Dal formalismo negoziale repubblicano al principio giustinianeo 'cum sit iustum voluntates contrahentktm magis quam verborum conceptionem inspicere'", (1980) 46 SDHI 1 sqq.

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"In venditionibus et cmptionibus consensum debere intcrcederc palam est: ceterum sive in ipsa emptione dissentient sivc in pretio sive in quo alio, emptio imperfecta est. si igitur ego me fimdum emere putarem Cornelianum, tu mihi te vendere Sempronianum putasti, quia in corpore disscnsimus, emptio nulla est. idem est, si ego me Stichum, tu Pamphilum absentem vendere putasti: nam cum in corpore dissentiatur, apparet nullam csse emptionem."

For a valid contract (of sale) we need consensus. Such consent is lacking if the parties are not ad idem with regard (particularly) to the sale itself, or to the price, or to the object. For "not being ad idem" the term "dissensus" is used.

(b) Determination of the object of performance

Less clear, and consequently much disputed, is the position in classical Roman law. A variety of authors have argued that the reason why classical authors regarded certain types of error as operative was not the lack of consent, but rather the fact that the object of the performance was not sufficiently determined.19 They claim that what Ulpian really said in D. 18, 1, 9 pr. ran something like this:

"Si cum ego me fimdum emcre putarem Cornelianum, tu mihi te vendere Sempronianum putasti (the sale is invalid, because] nee emptio nee venditio sine re quae veneat potest intellcgi."

A contract of sale requires the determination, by the parties, of two essential matters: object and price. In the example discussed by Ulpian, vendor and purchaser have two different tracts of land in mind. Thus there is no object to which the contract could refer; hence the invalidity of the transaction. This argument sounds plausible enough. But the path to this result is paved with interpolation hypotheses which are as far-reaching and radical as they are unacceptable. According to Joseph Georg Wolf, for instance, the whole of D. 18, 1, 9 pr., apart from the example concerning the sale of land, is spurious.20 But the consensusoriented argument in D. 18, 1, 9 pr. is supported by a variety of other texts.21 In fact, we do not know of any classical discussion of mistake in the formation of contract unrelated to or detached from the consensus problem. Presumably, then (and this does indeed appear to

1 Joseph Georg Wolf, Error im romischen Vertragsrecht (1961); Ugo Zilletti, La dottrina dell' errors nella storia del diritto roinano (1961); Franz Wieacker, "Irrtum, Dissens oder gcgenstandslose Leistungsbestimmung?", in: Melanges Philippe Meylan, vol. I (1963), pp. 383

sqq.

211 Error, pp. 23 sqq., 99 sq., 135 sq.

21 For some more general statements cf. Iul./Ulp. D. 2, 1, 15 ("non consentiant qui errent"); Iul./Ulp. D, 5, 1, 2 pr. ("error . . . non habet consensum"); Pomp. D. 39, 3, 30 ("nulla enim voluntas errantis est"); Diocl. C. 1, 18, 8 ("cum crrantis voluntas nulla sit"); Diocl. C. 1, 18, 9 ("cum nullus sit errantis consensus"). The identification theory is also in direct conflict with Iul. D. 18, 1, 41, 1, a text regarded as genuine even by Wolf (Error, pp. 160 sqq.): cL e.g. Luigi Labruna, (1962) 8 Labeo 138.

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be the prevailing opinion),22 classical law did not differ much in this respect from what we find in the pages of the Digest. Of course, the object of a contract of sale had to be identified. But this identification took place in the agreement of the parties. It was one of the main features of the contractual consent. Without it, a contract could not be said to have been concluded. It is only under this perspective, i.e. from the point of view of the more general problem of impairment of consensus, that the determination of the object of performance, emphasized by Wolf and others, obtains a specific significance for the problem of mistake in contract.

(c) Utp. D. 18, 1, 9 pr. and error in corpore

It must be obvious from what has been said so far that the consideration of error started with the consensual contracts. Not only were they based on the consent of the parties,23 but the actions arising from them were also to be granted ex bona fide. This left the necessary room for the intention of the parties to be taken into account. Not surprisingly, then, the main dissertation on the problem of error contained in the Digest relates to the prototype of the consensual contracts, to emptio venditio. We have cited the first part of it already: it is the fragment D. 18, 1, 9 pr. Of central significance is the example relating to the Cornelian/Sempronian estate. The purchaser assumes that he is buying fundus Cornelianus, the vendor that he is selling fundus Sempronianus. These are the only facts provided by Ulpianus. He does not relate to us what the parties did in fact declare: a matter that would have been of the utmost interest to the modern analyst. Three different situations are conceivable:24

(1)The declarations of the parties were so vague and unclear that a specific fundus is not objectively identifiable—perhaps they referred only to a fundus in general, or they tried to individualize the tract of land by referring to certain features which were (unbeknown to them) common to both. This would be a dissensus

(a hidden lack of agreement) in the narrow, modern sense of the word.25

22Thco Mayer-Maly, "Bemcrkungen zum Aspekt der Konscnsstorung in der klassischen Irrtumslehre", in: Melanges Philippe Meylan, vol. 1 (1%3), pp. 241 sqq.; Wunner, Contractus, pp. 134 sqq., 144 sqq., 193 sqq.; Kaser, RPr I, p. 237; Honsell/Mayer-Maly/Selb, p. 122.

21Gai. Ill, 135.

24 Cf. , in particular, Wunne r, Con trac tu s, pp. 145 sqq.

25 Cf. e.g. § 155 BGB ("If the parties to a contract which they regard as concluded have in fact not agreed upon a point upon which agreement should have been arrived at . . ."). In the terminology of the English common law, we are dealing in this alternative with mutual mistake. For a comparative discussion cf. Dietrich Rothoeft, System der Irrtumslehre (1968), pp. 147 sqq. Earlier in this century, it was argued repeatedly that only a hidden lack of agreement (dissensus in the modern sense) vitiated the contract; texts such as D. 18, 1 , 9 pr. were thus explained solely in terms of alternative (1), and it was argued that unilateral error did not affect the validity of the contract: cf, in particular, Werner Flume, "Irrtum und

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(2)The declarations of the parties related to the fundus Cornelianus; however, the vendor wanted to sell a tract of land which was the fundus Sempronianus, but which he believed to be the fundus Cornelianus. This would be a unilateral mistake on the part of the vendor about the identity of the object of the transaction.

(3)The declarations of the parties related to fundus Sempronianus; however, the purchaser wanted to buy a tract of land which was

fundus Cornelianus, but which he believed to be fundus Sempronianus: unilateral mistake regarding the identity of the object of sale, this time on the part of the purchaser.

For the Roman lawyers these distinctions did not matter. What mattered to Ulpianus was what he described as putare emere and putare vendere: the intentions of the parties. As long as they were not directed at the same thing, a contract could not come into being. This situation is referred to as dissensus. Dissent, in the terminology of Roman law, therefore embraced (unilateral) mistake, in this instance a mistake as to the identity of the thing which was the object of the contract. This type of mistake was material (or operative) in the sense that it excluded consensus.26 It has come to be known as error in corpore.

(d) Error in pretio

Although it features particularly prominently in our sources, error in corpore was not the only material mistake. The identity of the object was but one of the essential elements of a contract of sale. There were other matters on which the parties had to be ad idem. The price was obviously one of them. Hence the statement by Ulpianus: "si in pretio dissentiant, emptio imperfecta est."27 An error in pretio was thus also material. A case relating to locatio conductio deals with this problem: "Si decem tibi locem fundum, tu autem existimes quinque te conducere, nihil agitur."28 This appears to be the rule; no consensus as to the rent has been reached, and thus there is no contract. Interestingly, however, the result is different in the following example: ". . . sed et si ego minoris me locare sensero, tu pluris te conducere, utique non pluris

Rechtsgescbaft im romischen Recht", in: Festschrift fur Fritz Schulz, vol. I (1951), pp. 236 sqq. Contra (e.g.) Wicacker, Melanges Meylan, pp. 389 sqq.; Wunncr, Contractus, pp. 163 sqq.; Frier, (1983) 100 ZSS 262.

"6 This idea found its expression in the maxim "errantis voluntas nulla est" (e.g. Pomp. D. 39, 3, 20 and supra, p. 588). It does, of course, not mean that a person labouring under a mistake does not have a will at all, but only that his will is not his true will and thus a nullum. The idea that mistake excludes consensus can be traced back to Julian and appears to have been well established in high and late classical jurisprudence. Cf Arnold Ehrhardt, "Errantis voluntas nulla est", (1938) 58 ZSS 167 sqq.; idem, "Betrachtungen uber die Lehre vom Error", (1952) 69 ZSS 402 sqq.; Wolf, Error, pp. 1 sqq.; Wunner, Contractus,

pp, 195 sqq.

27 Cf. D. 18, 1, 9 pr.

3H Pomp. D. 19, 2, 52.

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