Liability
Figures in brackets are a reference to paragraph numbers in The Law of Damages

Liability (to pay some compensation/damages) is established when the claimant proves, on the balance of probabilities, that the wrongdoer�s fault (breach or breaches of duty) was causative of some/tangible harm/loss/injury.

When the burden of proof has been discharged/the claimant has proved causation of some harm, it gives rise to a right/entitlement to damages and a corresponding duty on the court/tribunal to assess the amount of compensation attributable to the harmful consequences in question (6.8). Where there is a right (liability) the court cannot deny a remedy (damages): Attorney General v Shimizu Corporation [1996] HKCFI 171. See also Palmer v Connecticut Ry & Lighting Co, 311 US 544 (1941) Reed J: "To require proof of rental value approaching mathematical certitude would bar a recovery for an actual injury suffered."

The leading authority for the principle that some harm = liability = duty to assess/some compensation is Chaplin v Hicks [1911] 2 KB 786, CA (6.10). In that case the claimant was one of 50 ladies selected for interview in respect of 12 contracts available to theatre actresses. She was unable to attend on the only day fixed for interview and sought damages in respect of the lost opportunity of being selected for employment. It was held that she had not been afforded a reasonable opportunity of presenting herself for selection and damages were assessed at �100. The defendants appealed alleging amongst other things that the damages were "so contingent as to be incapable of assessment."

So far as the some harm/duty to assess/burden of proof point is concerned, Fletcher Moulton LJ said (at p795) that:

"Where by a contract a man has a right to belong to a limited class of competitors [primary facts/evidential basis], he is possessed of something of value [tangible loss], and it is the duty of the jury to estimate the pecuniary value of that advantage taken from him."

So far as the impossible to assess argument was concerned Vaughan Williams LJ said (at p792) that:

"I do not agree with the contention that, if certainty is impossible of attainment, the damages for a breach of contract are unassessable .. I only wish to deny with emphasis that, because precision [ie certainty/accuracy] cannot be arrived at, the jury has no function in the assessment of damages. ..In such a case ...... [ie difficult to assess/impossible to say exactly how much case] the jury must do the best they can, and it may be that the amount of their verdict will really be a matter of guesswork. But the fact that damages cannot be assessed with certainty does not relieve the wrongdoer of the necessity of paying damages for his breach of contract."

The overriding principle on assessment may be expressed as follows:

Where the claimant has proved some harm then, regardless of the difficulty in question, the duty of the court is to make the best estimate which it can, in the light of the evidence, of the amount which the claimant has, on balance of probabilities, incurred as a result of the breach.

Other cases. Cases applying the best estimate rule which also have the some loss aspect may be found here.

The duty to assess/best estimate rule also applies in relation to the valuation/assessment/ascertainment of the value of something such as work done or variations/changes in work done under a construction contract. It would therefore be wrong not to make some (interim/provisional) assessment/valuation of a known variation/change (liability established) on the ground that the contractor had not provided cost records: eg Mears Construction Ltd v Samuel Williams (Dagenham Docks) Ltd (1977) 16 BLR 49. The effect of providing records/precise evidence is that a better/more reliable (in terms of certainty/accuracy) valuation might be made (the better evidence rule). It is suggested that, in the case of variation/change, liability is established when it is proved that there was some change/variation which had some cost implication: eg Sabemo (Sa) Pty Ltd V. AIW Engineering Pty Ltd File No. SCGRG 92/36 Judgment No. 3630 Number of pages - 15 Arbitration (1992) 9 BCL 280; [1992] SASC 3630 (24 September 1992), Supreme Court of South Australia

In addition to the court having a duty to assess damages there is also a duty on the parties and their legal representatives (lawyers owe the duty to the court and to their clients) with regard to adducing evidence to assist the court in the assessment. Where (quantum) evidence is missing, however, it should not result in no recovery/an assessment should still be made. In Biggin and Co Ltd and Another v Permanite Ltd [1950] 2 All ER 859 at 870 Devlin J said that:

"Where precise evidence is obtainable, the court naturally expects to have it, [but] where it is not, the court must do the best it can."

Where better or precise (quantum) evidence is obtainable but not adduced the court has a number of options.