the creditor is unable to sue. Two such reasons have a very extensive operation, viz.

(1) Insufficiency of form in contracts. We shall see that in Roman law agreements were actionable only if they were clothed in a definite form, or belonged to one or other of certain classes specially favoured; exactly as in English law no promise is legally binding unless made either under seal or for valuable consideration. Agreements which neither belonged to the favoured classes, nor were expressed in the proper form, were nuda pacta, and unactionable, although (according to Savigny and many other writers) they gave rise to a natural obligation enforceable in other ways. This is inferred in particular from Dig. 2. 14. 7. 4 igitur nuda pactio obligationem non parit, sed parit exceptionem,' ib. 1. pr. huius edicti aequitas naturalis est: quid enim tam congruum fidei humanae, quam ea, quae inter eos placuerunt, servari,' Dig. 46. 3. 5. 2 ... puta, quaedam earum [usurarum] ex stipulatione, quaedam ex pacto naturaliter debebantur: . . . et sicut ex pacti conventione datae repeti non possunt;' cf. Dig. ib. 95. 4. On the other hand, the passage last cited is the only one in which the effect of producing natural obligation is directly attributed to a mere pact; and on account of this insufficiency of evidence there are many who hold that Savigny is not justified in affirming natural obligation as an incident of nuda pacta in general. Most directly they are supported by Dig. 45. I. I. 2 si quis ita interroget, dabis? responderit, quidni? et is utique in ea causa est, ut obligetur. Contra si sine verbis adnuisset, non tantum autem civiliter, sed nec naturaliter obligatur, qui ita adnuit: et ideo recte dictum est, non obligari pro eo nec fideiussorem quidem.'

(2) A person's defective capacity of right or disposition. Thus, between pater and filiusfamilias, and between master and slave, there could be natural obligation only, and even to an extranea persona a slave could not be bound civiliter. The SC. Macedonianum (Bk. iv. 7. 7 and notes inf.) affords another example: a disputed case is that of contracts made by a pupillus without his guardian's auctoritas; see on Bk. i. 21. pr. supr.

Sometimes, moreover, an obligation which was originally civilis ceased to be actionable, and became naturalis. (a) In some cases the praetor, on principles of equity, disregarded strict civil law rules so far as to permit the survival, in a 'natural' form, of an obligation which had iure civili ceased altogether to exist, e. g. where a creditor became heir to his debtor, and in capitis deminutio, 'hi qui capite minuuntur, ex his causis, quae capitis deminutionem praecesserunt, manent obli

gati naturaliter' Dig. 4. 5. 2. 2; this, however, ceased to be of importance when in integrum restitutio of the creditors had become usual under such circumstances, see p. 372 supr. (b) Other instances are supplied by the law of procedure. If a judge erroneously decided an action so as to acquit a debtor who, as a fact, was liable, the latter remained bound naturaliter, Dig. 60. 12. 2; 28. 12. 6, though this is denied by some writers. So, too, an obligation continued to exist as naturalis after it had ceased to be actionable through either the rules for the prescription of actions, or the operation of litis contestatio (Gaius iii. 180) or res iudicata, Dig. 12. 6. 60. pr.; 46. 2. 29, Cod. 8. 41. 28.

The legal effects of natural obligation have as yet been defined only negatively; it did not entitle the creditor to sue. As to its positive effects, no general rule can be laid down for all cases: they must be determined for each case individually, for the creditor's right, in one instance, may have a greater or less orbit than in another; in other words, apart from the right of action, a natural obligation may possibly entitle him to all or any of the rights which he would. have were the debitor bound civiliter, or possess all or any of the following properties:

(1) It excludes condictio indebiti (note on Bk. iii. 14. 1), i. e. if money is owed naturaliter only, and is paid, even by mistake, it cannot be recovered on the ground that it is not due: 'naturales obligationes non eo solo aestimantur, si actio aliqua earum nomine competit, verum etiam cum soluta pecunia repeti non potest' Dig. 46. 1. 16. 4.

(2) It can be set off against an actionable claim of the debtor on the creditor, e. g. if A owes B 10l. naturaliter, and B owes A 20%. civiliter, B on being sued by A can set the 10l. off against the 207., though he cannot directly sue for it himself: 'etiam quod natura debetur venit in compensationem' Dig. ib. 26; cf. Bk. iv. 6 39 inf.

(3) It forms a sufficient basis for those other rights which can only come into existence under the condition that there is already an actual obligation in esse, viz. pledge, Dig. 20. 1. 5; guarantee ('at ne illud quidem interest, utrum civilis an naturalis sit obligatio cui adiciatur fideiussor' Bk. iii. 20. 1; so too, with constitutum, for which see on Bk. iii. 20. 9), and novation (Bk. iii. 29. 3, Dig. 39. 5. 19. 4); by constitutum a natural can be converted into a civil obligation by a mere formless second promise by the debtor, Dig. 13. 5. 1. 7.

(4) Deductio de peculio. Contracts between a paterfamilias and his filius, or between a master and his slave, produced natural obliga

tions only, which, if the inferior had a peculium, discharged themselves by their operation on the latter, which was automatically diminished by what he owed the superior, and augmented by what the superior owed him, Dig. 15. 1. 9. 2−4.

In Bk. iii. 29 there is a discussion of the modes in which obligations could be extinguished: but this seems the most convenient place for briefly describing those in which they could be transferred. To this question there are two sides; either the right may be transferred, or the liability. Transference of the liability, if by that we understand a transaction which entirely releases the person who has hitherto been liable, and imposes the debt on some one else, could (apart from universal succession) be effected only by novatio (Bk. iii. 29. 3), which, when employed for this specific purpose, was called expromissio, or by an act of a similar character, defensio. Transference of the right also (except in cases of universal succession) could at first be effected only by novatio. This, however, is not assignment, but substituted agreement; the assent and co-operation of the debtor is required, and the right does not pass from the person entitled to some one else, but is cancelled on condition of a new one being created in favour of the latter. The Romans, in fact, struggled, with a tenacity equalled only by that of the English Common Law, against the assignment of what we call choses in action, i. e. rights in personam; but while the reason alleged for his resistance by the English judge was the evil of 'maintenance,' the Romans, with more lawyer-like instinct, based their opposition on the character of an obligation as an essentially personal relation, the parties to which could not be changed without destroying its existence1.

A rude species of assignment became possible after the introduction of the formulary procedure, under which plaintiffs were generally permitted to conduct their suits through agents (Gaius iv. 82). If A, creditor against B, debitor, wished to assign his right to C, he could make the latter his agent, procurator (in rem suam); C thereby became entitled to accept performance from B, or in default to sue him in A's name, the condemnation being expressed in his own name (Gaius iv. 86, 87). The result, in the Roman view, was no transference of the obligation, for A remained the true and only creditor; all that passed was the right of action, or rather the capacity to exercise another's right of action, and all that C asserted or

1 Cf. Mr. O. W, Holmes' Common Law pp. 239, 341.

Hh

realized was the claim of another person. This cessio nominum or actionum, as it was called, though it dispensed with the necessity of the debtor's assent, was not only rude, but faulty, especially if made for valuable consideration. The appointment of C, as A's procurator, was governed by the usual rules of mandatum, and consequently became void (Bk. iii. 26. 9 and 10) if before action brought either assignor or assignee died, or if the former revoked his commission; there was no legal relation between assignee and debtor until litis contestatio had been reached in proceedings taken by the former. At length this was obviated by the assignee's being allowed to sue, not in the assignor's name, but in his own by actio utilis (Dig. 3. 3. 55, Cod. 4. 15. ult. ; 6. 37. 18), which he was enabled by gradual changes to do not only where he had been expressly appointed agent, but also in cases of a mere alienatory disposition. It is disputed whether the effect of the change was to make the assignee sole creditor, or whether, in relation to the debtor, he did not still legally continue a mere agent, enforcing by action in his own name the right of another; in other words, whether a genuine assignment, by which the assignee simply and actually stepped into the shoes of his assignor, who simultaneously dropped altogether out of the matter, was recognised at any time in Roman law. This, however, is too minute and complicated a question to be entered upon.

For such assignment no form was prescribed. It could be effected (1) by any expression of intention, unless it was of such a legal character as to be invalid unless accompanied by certain solemnities (e.g. donatio, p. 224 supr.); (2) by judicial sentence, e.g. in an actio familiae erciscundae, Dig. 10. 2. 3. If a defendant were ordered to transfer a chose in action, the judge might add that unless the order were obeyed the assignment should be taken to have actually been made; (3) in pursuance of a general rule of law (cessio legis), e.g. a person who procures the rescission of a will by querella inofficiosi can recover legacies paid by the testamentary heir, Dig. 5. 2. 8. 16; 19. I. 13. 25.

The following rules of assignment are deserving of notice, if only for the close parallelism between some of them and those of English law:

(1) Until the debtor has received notice of the assignment, he is at liberty to treat the assignor as his true creditor; thus he is released by payment to him ('ille, cuius nomen tibi pignori datum est, nisi ei cui debuit solvit nondum certior a te de obligatione tua factus,

utilibus actionibus satis tibi facere compelletur, quatenus tamen ipse debet' Cod. 8. 17. 4), and is not prejudiced if (before notice) he allows the creditor to set the claim off against a converse one of his own. Opinions differ as to the necessity of express notice by the assignee himself. Many writers add that successive and competing assignees rank, as against the debtor, in the order, not of the assignments, but of the notice; but this is denied by others, and seems to be unsupported by textual authority.

(2) After notice the debtor is no longer entitled to treat the assignor in any way as his creditor, and, if sued by him, is protected by exceptio, Dig. 2. 14. 6.

(3) The right passes to the assignee with all the defects and all the advantages incident to it while vested in the original creditor. So far as the former are concerned, this may be expressed by saying that the assignment takes place subject to equities,' Cod. 4. 39. 8, i. e. the assignee can be met by the same defences as might have been urged against the original creditor at any moment before notice of the assignment was received, except such as are purely personal (e.g. the exceptio pacti de non petendo, if available only against the releasor). Among the advantages incident to the chose in action which pass with it are rights of security, both real and personal, and unsatisfied claims to interest; the assignee may deal with it as if he himself had been creditor ab initio; e.g. he may assign it afresh, release it, or use it as a set-off.

(4) In respect of certain assignments for valuable consideration, there is an important enactment of Anastasius (lex Anastasiana, Cod. 4. 35. 22), to the effect that no purchaser of a chose in action should be able to recover more from the debtor than what he had paid himself, with ordinary interest, even though it was alleged that the transaction was in part a gift. So far as the actual debt exceeded the purchase money, it was ipso facto cancelled.

The Romans did not carry their theory of assignment beyond the actio utilis; for although it is true that the assignee's right to sue was often, and perhaps usually, attested by a cautio or bond of the debtor, transferred by the assignor for evidentiary purposes, yet this cautio was no embodiment of the right after the fashion of negotiable instruments in modern law, which are exempt from the rules relating to notice and equities. As Mr. Poste remarks (Gaius p. 431), 'the complete transferability of obligations was unknown to jurisprudence until modern legislation gave validity to contracts with an incerta persona, i.e. with a person unascertained except as a member of a