“the question upon a breach of the contract is, what is the condition in which the plaintiffs would be if the defendant had performed the contract. Generally speaking, where there are several ways in which the contract might be performed, that mode is adopted which is the least profitable to the plaintiff, and the least burthensome to the defendant.” 29. Similarly, in Robinson v Robinson (1851) I De GM & G 247 Lord Cranworth, giving the judgment of the Lords Justices in Chancery, said, at p 257: “Where a man is bound by covenants to do one of two things and does neither, there [is] an action by the covenantee the measure of damages is in general the loss arising by reason of the covenantor having failed to do that which is least, not that which is most, beneficial to the covenantee …” 30. By the time this court came to decide Lavarack[1967] 1 QB 278 more than a century later the rule was well established. In that case Diplock LJ accepted as correct the principle (stated by Scrutton LJ in Abrahams v Herbert Reiach Ltd[1922] 1 KB 477 ) that in an action for breach of contract “a defendant is not liable in damages for not doing that which he is not bound to do”
“The general rule as stated by Scrutton LJ in Abrahams v Reiach, that in an action for breach of contract a defendant is not liable for not doing that which he is not bound to do, has been generally accepted as correct and in my experience at the Bar and on the Bench has been repeatedly applied in subsequent cases. The law is concerned with legal obligations only and the law of contract only with legal obligations created by mutual agreement between contractors—not with the expectations, however reasonable, of one contractor that the other will do something that he has assumed no legal obligation to do. And so if the contract is broken or wrongfully repudiated, the first task of the assessor of damages is to estimate as best he can what the plaintiff would have gained in money or money’s worth if the defendant had fulfilled his legal obligations and had done no more. “Where there is an anticipatory breach by wrongful repudiation, this can at best be an estimate, whatever the date of the hearing. It involves assuming that what has not occurred and never will occur has occurred or will occur, i e that the defendant has since the breach performed his legal obligations under the contract, and if the estimate is made before the contract would otherwise have come to an end, that he will continue to perform his legal obligations thereunder until the due date of its termination. But the assumption to be made is that the defendant has performed or will perform his legal obligations under his contract with the plaintiff and nothing more. What these legal obligations are and what is their value to the plaintiff may depend upon the occurrence of events extraneous to the contract itself and where this is so, the probability of their occurrence is relevant to the estimate.” 32. Russell LJ said at p 298E–G: “A plaintiff in an action for damages for wrongful dismissal can rely only on the fact that the defendant was obliged to carry out the contract sued upon. His prospects in terms of money or money’s worth resulting from the carrying out of the contract may be conditioned by the estimated impact of external events on the results of the carrying out. But it has never been held that the plaintiff can claim any sum on the ground that the defendant might after the repudiation date have voluntarily subjected himself to an additional contractual obligation in favour of the plaintiff. That is not the law nor, with respect, do I think it would be in accord with the sense of the matter so to hold an employer whose attitude to the employee has reached the stage that he is prepared to sack him out of hand is, to say the least, an unlikely source of future generosity.” 33. The least burdensome performance rule has been regularly applied in commercial disputes where contracts of sale or carriage commonly provide for a margin on the quantity of goods at the option of the defaulting party. In such cases it has been regarded as settled principle for over a century (see In re Thornett and Fehr & Yuills Ltd[1921] 1 KB 219 ) and applied as ratio in numerous cases, including at the highest level (see, for example, the cross appeal in Bunge Corpn, New York v Tradax Export SA, Panama[1981] 1 WLR 711 , 731B–C). 34. The rule was cited with approval by Lord Hoffmann in the Judicial Committee of the Privy Council in Lion Nathan Ltd v C-C Bottlers Ltd[1996] 1 WLR 1438 in the following terms, at p 1446: “In order to compensate the plaintiff for what he has lost, the court must in such cases determine what benefits the plaintiff would have derived from the performance by the defendant of his outstanding obligations under the contract. It is well settled that the court will assume that the defendant would have performed those obligations in the way least onerous to himself … All this makes perfectly good sense when damages depend upon a prediction of how the defendant would have performed outstanding contractual obligations which gave him a choice of what to do.” 35. In the Supreme Court in Geys v Société Générale, London Branch[2013] ICR 117 ;[2013] 1 AC 523 Lord Wilson JSC referred, at para 64, to the: “application of the ‘least burdensome’ principle, namely that damages should reflect only the losses sustained by the employer’s decision to repudiate the contract unlawfully rather than by his having hypothetically proceeded, in the manner ‘least profitable to the plaintiff, and the least burthensome to the defendant’, to terminate the contract lawfully: see Cockburn v Alexander (1848) 6 CB 791, 814 (Maule J) , and McGregor on Damages , 18th ed (2009), para 8-093. So, where under the terms of the contract it had been open to the wrongfully repudiating employer to have taken a course which would have terminated the contract quickly as well as lawfully, the damages will be small.” 36. In the present case Mr Mackenzie’s contract of employment with AADL could be terminated in one of three ways, other than by mutual consent: by either side giving the other notice (in this contract 12 months’ notice) to terminate at the end of that period; by immediate termination with a payment in lieu of notice; or by summary dismissal if the facts justified it. In the context of contracts of employment I find it difficult to imagine a clearer case of the application of the rule than where the contract expressly gives the employer a choice between dismissal with a requirement that the employee works out his notice and dismissal with payment in lieu of notice. The whole point of a PILON clause is to give the employer that choice and to avoid the argument that dismissal with pay in lieu is a repudiation. 37. The position is less clear cut where an employer is under a single contractual obligation involving a discretion which the contract requires him to exercise in good faith. This has led to differing outcomes in cases about bonuses. In Lavarack[1967] 1 QB 278 itself there had been a bonus scheme in force at the time of the plaintiff’s dismissal in July 1964. The following year the defendants discontinued the bonus scheme, which they had no contractual obligation to maintain. Diplock LJ said at p 297C: “In the present case if the defendants had continued their bonus scheme, it may well be that upon the true construction of this contract of employment the plaintiff would have been entitled to be recompensed for the loss of the bonus to which he would have been likely to be legally entitled under his service agreement until its expiry. But it is unnecessary to decide this. They were under no contractual obligation to him to continue the scheme and in fact it was discontinued. His legal entitlement under the contract on which he sues would thus have been limited after31 March 1965 to his salary of£4,000 per annum. And there, in my view, is the end of the matter. I know of no principle upon which he can claim as damages for breach of one service agreement compensation for remuneration which might have become due under some imaginary future agreement which the plaintiffs did not make with him but might have done if they wished. If this were right, in every action for damages for wrongful dismissal, the plaintiff would be entitled to recover not only the remuneration he would have received during the currency of his service agreement but also some additional sum for loss of the chance of its being renewed upon its expiry.” 38. Lavarack is to be contrasted with the later decision of this court in Horkulak v Cantor Fitzgerald International[2005] ICR 402 . In that case it was found as a fact by the trial judge ([[2004] ICR 697 , Newman J) that the defendant had repudiated the claimant’s contract of employment and was liable for loss of what was described as a discretionary bonus. On appeal to this court Potter LJ said, at para 68: “Clause 3(b)(ii) embodies a scheme designed to confer a contractual benefit on the employee, … [which] is to be administered rationally and in good faith. The company is not free to choose from a ‘range of reasonable methods’ of performance. There is only one method of arriving at a decision: that is, negotiation, followed (in the absence of mutual agreement) by a decision by the president of the parent body. The fact that the final decision is to be made by someone other than the employing company, or its officers, emphasises the objectivity of the process. It seems to us implicit that the president will pay due regard to the interests of both employer and employee, rather than simply to that of achieving the ‘minimum burden’ for the company. The task of the court is to put itself in his shoes.” 39. In Durham Tees Valley Airport Ltd v bmibaby Ltd [2011] 1 All ER (Comm) 731 it was held that where a contract imposed a single obligation, rather than alternative obligations, and gave a party discretion as to how to perform that obligation, the assessment of damages for the breach of the contract should not be limited strictly to what was the minimum level of performance required by the contract. The court had to conduct a factual inquiry as to how the contract would have been performed had it not been repudiated. Patten LJ, after referring to the judgments in this court in Abrahams v Herbert Reiach Ltd, emphasised at para 69 the difference between “alternative methods of performance” cases and those where “there is only a single obligation to be performed”