UK Supreme Court's 12 Propositions on the Law of Damages

"(1) Damages assessed by reference to the value of the use wrongfully made of property (sometimes termed “user damages”) are readily awarded at common law for the invasion of rights to tangible moveable or immoveable property (by detinue, conversion or trespass). The rationale of such awards is that the person who makes wrongful use of property, where its use is commercially valuable, prevents the owner from exercising a valuable right to control its use, and should therefore compensate him for the loss of the value of the exercise of that right. He takes something for nothing, for which the owner was entitled to require payment.

(2) Damages are also available on a similar basis for patent infringement and breaches of other intellectual property rights.

(3) Damages can be awarded under Lord Cairns’ Act in substitution for specific performance or an injunction, where the court had jurisdiction to entertain an application for such relief at the time when the proceedings were commenced. Such damages are a monetary substitute for what is lost by the withholding of such relief.

(4) One possible method of quantifying damages under this head is on the basis of the economic value of the right which the court has declined to enforce, and which it has consequently rendered worthless. Such a valuation can be arrived at by reference to the amount which the claimant might reasonably have demanded as a quid pro quo for the relaxation of the obligation in question. The rationale is that, since the withholding of specific relief has the same practical effect as requiring the claimant to permit the infringement of his rights, his loss can be measured by reference to the economic value of such permission.

(5) That is not, however, the only approach to assessing damages under Lord Cairns’ Act. It is for the court to judge what method of quantification, in the circumstances of the case before it, will give a fair equivalent for what is lost by the refusal of the injunction.

(6) Common law damages for breach of contract are intended to compensate the claimant for loss or damage resulting from the non-performance of the obligation in question. They are therefore normally based on the difference between the effect of performance and non-performance upon the claimant’s situation.

(7) Where damages are sought at common law for breach of contract, it is for the claimant to establish that a loss has been incurred, in the sense that he is in a less favourable situation, either economically or in some other respect, than he would have been in if the contract had been performed.

(8) Where the breach of a contractual obligation has caused the claimant to suffer economic loss, that loss should be measured or estimated as accurately and reliably as the nature of the case permits. The law is tolerant of imprecision where the loss is incapable of precise measurement, and there are also a variety of legal principles which can assist the claimant in cases where there is a paucity of evidence.

(9) Where the claimant’s interest in the performance of a contract is purely economic, and he cannot establish that any economic loss has resulted from its breach, the normal inference is that he has not suffered any loss. In that event, he cannot be awarded more than nominal damages.

(10) Negotiating damages can be awarded for breach of contract where the loss suffered by the claimant is appropriately measured by reference to the economic value of the right which has been breached, considered as an asset. That may be the position where the breach of contract results in the loss of a valuable asset created or protected by the right which was infringed. The rationale is that the claimant has in substance been deprived of a valuable asset, and his loss can therefore be measured by determining the economic value of the right in question, considered as an asset. The defendant has taken something for nothing, for which the claimant was entitled to require payment.

(11) Common law damages for breach of contract cannot be awarded merely for the purpose of depriving the defendant of profits made as a result of the breach, other than in exceptional circumstances, following Attorney General v Blake [2001] 1 AC 268.

(12) Common law damages for breach of contract are not a matter of discretion. They are claimed as of right, and they are awarded or refused on the basis of legal principle."

(Morris-Garner v One Step (Support) Ltd [2018] UKSC 20, per Lord Reed (with whom Lady Hale, Lord Wilson and Lord Carnwath agreed) at para 95)