If you were looking for a part of the law bedevilled by well-meaning sloppiness of thought, you could do worse than start with mitigation. This is not surprising. Issues of mitigation, not to mention its close relative avoided loss, arise all too often in the course of litigation, and can raise some seriously complex questions. Unfortunately, busy judges faced with full lists and a constant urge to get their decisions out as quickly as possible often have little time for such things. They can hardly be blamed if on occasion they take an easy way out by reducing a claimant’s duty to mitigate to an amorphous duty to act reasonably in all the circumstances, or by saying slightly vacuously that the question whether some adventitious benefit to the claimant falls to be docked from any damages depends on whether there is a “sufficiently close link” between it and the defendant’s wrong, before proceeding to determine the issue in a measured but still rather impressionistic way. Precision matters, however, here as elsewhere; and Andy Summers’ neat little book on mitigation of loss is a welcome corrective to such intellectual laziness.
The work’s thesis is refreshingly straightforward. Reasonableness, close connection and such-like may, he says, be incidentally relevant to issues of mitigation, but they are essentially side-issues. Nor for that matter is there any magic, as such, in the word “mitigation”. The mitigation and avoided loss doctrines are actually explainable, he argues, as aspects of causation: not dry analytical “but-for” causation, but the nuanced and textured ordinary-language causation analysis given currency by Hart and Honoré in Causation in the Law (Oxford 1959).
Combining this analysis with an emphasis on personal choice as a vital element in our conception of causation, his argument is roughly as follows (see chs. 5–7). First, a person seeking to be made good following a wrong can generally expect compensation for the ordinary costs of replicating, or nearly replicating, their would-be situation had the wrong not been committed, taking all gains and losses into account. Second, however, things are different where that claimant either genuinely and unconstrainedly chooses not to replicate the no-wrong situation, or alternatively elects to replicate it but does so in an unusual, outré or over-costly way. In such a case the causal connection is negatived; it follows that the consequences cannot be charged to the defendant, and conversely any resultant gains or savings enure to the claimant. This way, the thesis continues, the rules about avoidable and avoided loss can be neatly seen as mirror images of each other.
Having made the main point, the book then goes on in Chapter 8 onwards to clear up some further points, dealing with such matters as how far the propositions set forth match the cases (the answer is, quite well), and the relation between mitigation and doctrines such as contributory negligence, remoteness and the effect of betterment on damages.
The exposition is well written, concisely expressed and in many ways very convincing. Bare reasonableness as a criterion for mitigation, however often cited as the basis of the doctrine, has always been very problematical. As Summers observes, not only does it reduce the law to something of a wilderness of single instances coupled with incantations of words such as “fact-sensitive”; more importantly, there are plenty of cases where claimants have acted entirely reasonably and yet still have lost out on compensation on mitigation grounds. And the same goes, conversely, for the “close link” criterion for when avoided loss falls to be deducted. True, it suggests that the more adventitious a gain the less appropriate it is to deduct it from any award but that is still fairly unhelpful.
By contrast, seeing both issues as fundamentally causation-based, and drawing a distinction between actions aimed at replicating the no-breach situation and others, solves a great many problems. In addition, once we recognise that there is no special magic in mitigation, it lets us realise that mitigation can easily and unproblematically overlap with other doctrines, one neat example being novus actus interveniens where a claimant, aware of a breach of duty by a defendant that creates a danger, has nevertheless continued knowingly to court disaster. The only serious difficulty lies with contributory negligence, which since 1945 has muddied the waters. In some cases – think, for example, the facts of the shipping collision case of The Calliope [1970] P. 172, noted at pp. 257–58 – the Law Reform (Contributory Negligence) Act 1945 allows the same situation to be analysed à choix either as two elements of loss with only one caused by the defendant (mitigation), or alternatively as one composite loss all of which is caused jointly by both claimant and defendant but with liability split equitably between them (division of loss). Summers rightly sees the inconsistency: faute de mieux he suggests, also it is suggested correctly, that where this happens mitigation should take precedence.
On one or two matters I am not entirely convinced. With cases such as Coles v Hetherton [2013] EWCA Civ 1704, essentially allowing an owner of damaged property to claim repair costs even for repairs not done, Summers is unhappy with the potential for over-compensation where the failure to repair was not due to the owner’s choice. But it is suggested that there is something to be said for the more traditional idea that any deterioration in property amounts to a direct loss to its proprietor, and that repair costs are as good a measure as any of that loss. If, for example, my car is damaged and then almost immediately destroyed by chance before I can get around to repairing it, there seems no objection to allowing me to recover for the original damage, if only as a kind of retrospective replication cost (as the law currently provides: see The Glenfinlas [1918] P. 363).
Indeed, it may be that the author too easily dismisses the idea of conventional measures of damages as a whole. Although the book manfully struggles to demolish the standardised awards explanation of the Sale of Goods Act 1979 “market rule” and instead to insert it into the mitigation/causation mould (and, to be fair, the vast majority of judges these days do see the rule as based on mitigation), it is not clear he succeeds. In particular, if Summers is right, a buyer of a readily-traded commodity must lose the right to claim market damages for non-delivery if before they find out about the breach and have a chance to decide whether or not to buy against the seller the market price has dipped below the contract price. This seems counter-intuitive, and no case seems clearly to support it.
Third, there could have been a mention of a further exception to the rule that a claimant must, if they have the choice, take steps to mitigate the consequences of a defendant’s wrong. Parallel to the insurance and benevolence principles that qualify the avoided loss rule, and probably also justified by sound policy rather than any sophisticated causation analysis, this is the two-defendant rule. Where a claimant has the right to have a loss replicated from the defendant or from some other source, the defendant cannot argue that recovery should be reduced because the claimant, however voluntarily, failed to tap the other source: see Peters v East Midlands Health Authority [2009] EWCA Civ 145. To that extent the results reached in Walker v Medlicott [1999] 1 W.L.R. 727 and Symrise v Baker [2015] EWHC 912 (Comm), cited on pp. 145–46, are actually highly doubtful.
But these are minor quibbles. This is a good, well-constructed book. Its basic thesis, that mitigation and avoided loss fall to be analysed as merely aspects of causation, and that replication and choice lie at the back of the causation analysis, is in my view fairly unanswerable. This book will deserve extensive citation in future works on damages, and perhaps more importantly, in the courts. Meanwhile, until then academics and practitioners who get hold of a copy have something of a treat in store.
