III. QUASI-CONTRACT

The basis of this category, though unsatisfactory, is at least clear. There remained a certain number of obligations which could not be said to arise ex contractu, since there had been no agree­ment, and could even less well be said to arise ex delicto, since the person obliged had done no wrongful act (and was amenable not to a penal but to a reipersecutory action).

Some of these obligations are merely incidental to the law of persons, things, or succession, and therefore need not be further discussed here. They are the obligations between tutor and pupillus, between joint-owners or joint-heirs, and between heir and legatee. The others, however, are of considerable impor­tance, and are among the most characteristic of the Roman contributions to modern Civil law.

Negotiorum gestio. The history and classical form of this institution are in many respects obscure, and it is therefore possible here ¹ See above, p. 224, n. 2.

only to give an outline of it as it appears in the Corpus luris. It is the voluntary and unauthorized ‘management of the affairs’ of another, and it creates an imperfectly bilateral relationship^[101] akin to that resulting from mandate. The primary duty is that of the ‘manager’ [gestor) to carry through what he has under­taken, and in doing so to show the care of a bonus paterfamilias, and to account for any proceeds.

The term ‘management of affairs’ can be misleading. Even an isolated act will constitute a gestio. The gestor may, for example, have shored up a building which was in danger of collapse, or have treated a sick slave; he may have collected a debt owing to the principal, or made himself surety for a debt which the principal owed; or he may in any other way have cared for the principal’s property or protected his rights.

But more is needed than simply a voluntary and unauthorized gestio. The law does not require the principal to pay the cost of every unauthorized service he receives. The gestio must have been ‘useful’, in the sense of being something which the principal himself would have done, and the principal must have been absent, or at least incapable of expressing his wishes. (If he was both present and capable, and made no objection, this will amount to a tacit mandate.) But if the gestio was ‘useful’ when first undertaken, the principal could not object that he had nevertheless derived no benefit from it (e.g. because the slave who was treated nevertheless died, or because the building which was shored up caught fire and was destroyed). For the underlying purpose of the law was to encourage the protection of absentees’ interests by indemnifying those who undertook neighbourly acts.

The state of mind of the gestor is relevant in two ways. In the first place, he must have been aware that the ‘affair’ was that of another. The man who, for example, has made repairs to a building in the erroneous belief that it is his own, cannot claim to have ‘managed an affair’ of the owner.¹ On the other hand, it will be no obstacle that he thought the building belonged to A, whereas in fact it belonged to B.

The kinship with mandate is close, so that if the principal, when he becomes aware of the gestio, accepts it, this will con­stitute a ratification so as to make him liable to an actio mandati and, what is more important, to debar him from subsequently questioning the ‘usefulness’ of the gestio.

Negotiorum gestio, with some alterations and extensions, has passed into all Civil law systems, and constitutes one of the most marked divergences, though a minor one, between the Civil law and the Common law. The latter insists on the individualistic principle that a man should not be required to pay for a service for which he has not asked, and holds that to encourage the rendering of such services would be to encourage the ‘officious intermeddler’. The requirements of negotiorum gestio, however, and in particular that of ‘usefulness’ coupled with the restric­tion of the action to the recovery of expenses, offer in fact little scope for such officiousness.

The condictio. We have already encountered this remedy more than once. It was a stricti iuris action claiming a certain sum of money or a certain thing, and it was unique in that its formula stated no cause or ground; it simply alleged that the defendant was under a duty to convey to the plaintiff a certain sum or a certain thing.^{[102] [103]} Its scope was therefore wider than that of other actions. Its applications, as far as we know, were three. It lay to enforce the obligation arising from a stipulation (provided, of course, that it was for a certain sum or thing) or from a literal contract, and any obligation created re, in the older and more restricted sense of the term.

We have seen that, in the classification which Gaius eventually rejected, the obligations arising both from mutuum and from the receipt of what was not owing were classed together, as being sanctioned by the condictio and as arising from a transfer of ownership by the plaintiff to the defendant. In both cases the defendant owned what the plaintiff ought to own, and there­fore he was bound to make restitution. This is the basis of the condictio in this context. Mutuum was, as we have seen, eventually isolated as contract, leaving the receipt of what was not owing to fall into the category of quasi-contract. This was, however, only one example of the quasi-contractual applications of the condictio. There were others also. Since the formula of the condictio was the same in all cases the classical law had no clear-cut classification, but the treatment in the Corpus luris adopted certain headings which passed into the language of the Civil law and are still often used, particularly in German law.

The condictio indebiti lay in the case of a payment or conveyance of what was not owing. The condictio ob causam datorum or causa data causa non secuta applied principally to the situation eventually classified as an innominate contract, and it has been considered in that context,¹ but it applied also where there was no con­tractual element. This was the case of donatio sub modo, i.e. a gift to be applied in a certain way. If A gives B property to be held as dos on his expected marriage to C, and the marriage does not take place, A can claim restitution. The condictio ob turpem vel iniustam causam lay where the payment or conveyance had been made for an immoral or illegal purpose (e.g. to induce the recipient not to commit a crime, or to return what he had borrowed and was wrongfully refusing to return).

In all these cases the basis of the claim was that there was no justification (causa) for the defendant’s retaining what he had received. Justinian, however, added the further heading of con­dictio sine causa. This, if taken literally, would embrace all the preceding cases, but it seems to have been intended merely as a residual category, to accommodate cases which might not fall precisely under any of the other headings, and, in particular, ’ Above, pp. 189 ff.

the case where there had initially been a caiwa for the defendant’s retaining what he had received, but that causa had subsequently ceased to exist (e.g. where he retained the plaintiff’s written acknowledgement of a debt after the debt had been paid).¹

Thus far the condictio enforces restitution only where the defendant unjustifiably retains a certain sum or thing which has been conveyed to him by the plaintiff. This duty of restitution is, however, declared to be founded on a much wider principle of ‘natural justice’, that no one should be enriched at the expense of another. This principle of ‘unjust enrichment’ is one of the entirely original Roman contributions to legal thought. It has become a part of all Civil law systems, but was rejected by English law until very recently.² It deserves therefore further examination.

Unjust enrichment. The hostility which the principle arouses and the difficulties which it encounters derive from the fact that it claims to correct the law by an appeal to justice. Thus, where A has conveyed a thing to B in the mistaken belief that it is owing, the conveyance is valid, but the injustice is rectified by allowing A a condictio.

¹ Civilians call the remedy in this type of case condictio ob causam finitam.

¹ Its fortune has been different in the United States.

The law has accorded B the right in rem, but cannot A assert a right in personam to the extent of B’s enrichment?¹ And, if so, could it not be said that where B has acquired A’s property by prescription the law likewise intends only to determine the question of the right in rem, leaving open that of the right in personam?

In cases such as these—and the list could be almost endless— the simple principle that a man should not be unjustly enriched at the expense of another is an uncertain guide, and unless settled rules of law are to be freely subverted, the principle requires restriction and definition. The classical law met this need by allowing the condictio only where there had been a direct conveyance of a certain sum or thing by the plaintiff to the defendant. All the cases suggested above were thus arbitrarily excluded. In the later law recovery was allowed even where the benefit conferred on the defendant did not result from the con­veyance of a certain sum or thing [condictio incerti), but, here as elsewhere, the extension was made by piecemeal alterations of classical texts, and the limits of the remedy are therefore not clear. It was left to the Civilians, and especially to the German jurists of the nineteenth century, whose work is embodied in the German Civil Code, to make the condictio a workable general remedy for unjust enrichment.

But there have also been other routes within the Civil law tradition by which the principle of unjust enrichment has entered modern systems. We have seen that negotiorum gestio was excluded where the person claiming to be gestor had mistakenly thought that the ‘affair’ was his own, and also where, though he knew that the ‘affair’ was that of another, he had acted entirely in his own interest. In these cases some Roman texts allowed an action to the extent of the principal’s enrichment only. In later centuries many civilians were prepared to extend this negotiorum gestio utilis even to the case where the principal had forbidden the gestio. The language is still that of negotiorum gestio, but so flat a rejection of a fundamental principle makes it obvious that what has in fact emerged is a general remedy for unjust enrichment.

Elsewhere, notably in French law, the remedy has taken a different, though still ostensibly Roman, form, but whatever ¹ See above, p. 135. Specificatio presents the same problem (p. 137). the form taken, it has usually been kept within bounds by an insistence on the Roman requirements of directness or of lack of cause or by a close definition of enrichment. This is reflected in a preference for the term ‘unjustified’ rather than ‘unjust’ enrichment.