to raise a defence against any such claim, though not itself to raise an action founded on the estopped rights. Such an analysis may be com­ pelled in relation to express undertakings if, as in the Common law jurisdictions, there is a requirement of mutual consideration before an enforceable contract of waiver can exist and such consideration is lacking; in jurisdictions allowing gratuitous contracts or unilateral promises, however, it is largely superfluous to use this analysis to deal with express undertakings to waive contractual rights; or

(5)the donation conception: one might conceivably characterise a renun­ ciation of contractual rights as a species of donation, on the basis that what the renouncing party is doing is gifting to the other a release from the latter’s contractual duties. In Roman law, a renunciation of rights was conceived of as a kind of donation, a tradition carried over into some modern legal systems. Under such an approach, the rules on the form of a donation are determinative of the required form for a renunciation.

In cases where there is no express undertaking not to enforce contrac­ tual rights, but merely words or conduct which create a reasonable impres­ sion in the other party’s mind that the rights will not be enforced, which impression is relied upon to that other party’s detriment, then while an express contractual or unilateral promissory explanation is not amenable to describing what has happened, the analysis of personal bar or estoppel can still be used to explain the defence given to the second party.

4.  Express contractual or promissory renunciation of rights

(a)  The Common law

From the sixteenth century onwards, the view was taken by the English courts that a mere agreement to vary a contract was not enforceable, including a variation by which a creditor undertook to renounce some or all of its rights.14 This view was a simple conclusion from the application

14For instance, Comyns, Digest of the Laws of England, cites (p. 127) the case of Lynn v. Bruce 2 H. Bl. 317 (1794), in which a declaration had been made by A that he had, at B’s request, agreed to accept from B a composition of so much in the pound upon a certain sum of money owing by B in full satisfaction and discharge of B’s debt. It was held that B’s promise to pay this composition was not a good consideration to support an assumpsit against B, ‘a mere accord not being a ground of action’.

of the rule requiring mutual consideration.15 It means that, for instance, a bare promise made by a creditor to accept part payment in full settlement of a debt is not contractually enforceable, and the creditor is able to go back on such a promise, it being no argument that he may have received the ‘practical benefit’ of securing some payment rather than none from a financially distressed debtor.16 However, even a change in time or place of performance can constitute valid consideration,17 and, as eighteenthand nineteenth-century courts were increasingly willing to hold, even a slight benefit in the creditor’s favour can count as valid consideration. More recently, it has been held that a variation which may benefit or preju­ dice either party is enforceable,18 though arguments about whether fact­ ually this may or may not be so create undesirable uncertainty about the enforcement of a variation. The decision in Williams v. Roffey Bros.19 that a promise to pay more for services already due is an enforceable variation makes continued insistence on the non-binding nature of a promise to pay a reduced sum in settlement of a debt seem inconsistent. In either case a seriously intended renegotiation of an existing duty is at stake, and the alleged valid consideration in Williams v. Roffey of the acquiral by the promisor of the benefit of the completion of work by a promisee who may have been unable to complete the works without the extra payment20 represents such a fictional manifestation of consideration as seriously to call in to doubt the continued insistence for such consideration when contractual­ duties are renegotiated.21 As Ibbetson has remarked of the basis of liability in the case, the ‘real test of liability was that provided by the Will Theory: so long as the parties had freely agreed, without duress, that the higher sum would be paid, the court would hold them to their agreement.’22 A lot has changed in the thirty years since Fried argued that consideration was still a dominant doctrine within contract law. The decision in Williams v. Roffey surely suggests that it would not be too great a leap for the English courts to continue that development by recognising

15On the historical background, see Ibbetson, A Historical Introduction, p. 240, and cases there cited.

16Foakes v. Beer (1884) 9 App Cas 605 (HL); Selectmove, Re [1995] 1 WLR 474.

17Pinnel’s Case (1602) 5 Co Rep 117a.

18Alan & Co. Ltd v. El Nasr Export & Import Co. [1972] 2 QB 189.

19 [1991] 1 QB 1.    20  Ibid., judgment of Glidewell LJ at 15–16.

21Waddams has remarked of the present, post-Roffey position, that it is now ‘very diffi­ cult to state what principles govern modification of contracts’ (Waddams, ‘Principle in Contract Law’, p. 61). Such uncertainty would seem to be an inevitable effect of the chip­ ping away at the doctrine of consideration without taking the bold step of abolishing it.

22Ibbetson, A Historical Introduction, p. 240.

that all promises seriously intended should, as a matter of principle, be enforceable at law, and to carve out any exceptions from that principle which were thought desirable.

In the absence of any mutual consideration, a valid renunciation could previously be made under seal, or now, since the abolition of the requirement of the seal, in a deed. If, however, neither consideration nor deed routes are available, recourse will have to be had, if available on the facts, to common law forbearance or one of the various forms of estoppel (discussed below), which is the closest English law comes in practice to enforcing, albeit tangentially, a unilateral promise to renounce contrac­ tual rights.

(b)  Mixed legal systems

In Scotland, with its separate obligations of contract and promise, both a contractual and promissory analysis of renunciation of rights is possible, and the renunciation may be either an undertaking not to enforce the right in question pro tem or an outright termination of the right. Thus, parties may either agree by contractual variation or by a new contract to vary previously constituted rights,23 or one party may unilaterally prom­ ise for the future not to enforce its rights against another (either for a spe­ cified period of time or for the entire remaining period of the contract). Alternatively, a contract may contain a clause entitling a party to waive one of the contractual rights in its favour, such a right, though being con­ stituted by contractual agreement, effectively allowing a unilateral renun­ ciation to occur.24

In addition, it is conceivable that, without either party entering into a contract or making a promise, one party may simply, by a unilateral

23Such renunciations have a long pedigree. For instance, some late medieval examples of renunciations of rights are narrated in the Protocol Book of Sir Alexander Gaw, includ­ ing the following: ‘Memorandum narrating that Robert Scot acknowledged that he had granted his permission to Egidia Lesslie and Stephen Arnot, her son, to labour and till two parts of Estir Pitgrugny, and denied that he had given to them right and title of his possession within the bounds of the lands, but promised that he would not cite or pursue them for the permitted labouring of the lands before any judges, because the lands were in dispute between him and a certain Peter Balvard (1st January 1550)’.

24A conceptually tricky case is the right of waiver of a suspensive condition in a contract. If such a right is given to both parties, case law indicates that a unilateral renunciation of the right by either may only be made if the right is designed purely for that party’s benefit and is severable from the rest of the contract: see Manheath Ltd v. Banks & Co. Ltd 1996 SC 42.

declaratory act, immediately renounce its rights in favour of another, such declaration sometimes being referred to as a type of ‘express waiver’.25 Such unilateral acts of renunciation are not just possible in respect of con­ tractual rights, but in relation to other rights too.26

As Scots law lacks a doctrine of mutual consideration, there was no need for Scotland to develop a doctrine of promissory estoppel to deal with cases of gratuitous renunciation of rights: such cases can be dealt with either as gratuitous contracts of renunciation, gratuitous promises to renounce, or simple unilateral declarations of renunciation, depend­ ing on the precise circumstances. There is also, however, a doctrine of personal bar which operates in Scots law, not just in contract but in other fields of law too (for instance, property law), and it is applicable to some of the circumstances that would fall under promissory estoppel or waiver in English law (a fact discussed further below).

Turning to Louisiana law, one encounters no general definition of a renunciation (or ‘remission’ as it is often styled) of contractual rights.27 The Civil Code seems to assume an understanding of the concept when it provides in Article 1888 that a ‘remission of debt by an obligee extin­ guishes the obligation’, adding that the remission ‘may be express or tacit’. Such a remission is most likely to be given gratuitously, though conceiv­ ably some consideration may have been provided by the debtor.28 The terms of Article 1888 tell us nothing of whether the remission is conceived of as a unilateral or bilateral act, or whether it is to be viewed as a contract, a unilateral promise, or in some other way. Article 1890 however tells us that the remission of debt is effective ‘when the obligor receives the com­ munication from the obligee’. This not only makes it clear that commu­ nication of the remission is essential, but it might be thought to suggest,

25Where the waiver is not expressly made, but is arguably to be implied from conduct, then the circumstances are properly described as implied waiver, a species of personal bar discussed later: see further discussion in main text, below at p. 447.

26For instance, the right of ownership in property law may be unilaterally renounced, the effect being that the property concerned is held to be abandoned and ownership passes to the Crown; the benefited proprietor under a real burden may unilaterally renounce it; succession rights may unilaterally be renounced.

27‘The Louisiana Civil Code, which regulates nominate contracts and juridical acts in detail, does not provide definition or regulation for a contract or act of waiver’ (the view of the US Court of Appeals, Fifth Circuit, in its judgment in Shaw Constructors v. ICF Kaiser Engineers 395 F 3d 533).

28A gratuitous release does not, however, constitute a valid contract of compromise in Louisiana law and therefore cannot be founded upon to bar litigation between the par­ ties: Bielkiewicz v. Rudisill 201 So 2d 136 (La 1967).