Gregg v Scott

This appeal concerned whether diminution in a patient's prospect of a favourable medical outcome (a "loss of chance") caused by negligent delay in diagnosis is actionable and compensable where the prospect, before the negligence, was itself less than 50%. The key legal issues were causation on the balance of probabilities, the role of statistical evidence in medical prognosis, and whether the law should recognise and value a proved diminution in prospects rather than require proof of a worsened outcome on the balance of probabilities.

The House was split. A majority upheld the conventional requirement that causation of the adverse outcome must be proved on the balance of probabilities and were unwilling to extend a general right to proportionate recovery for loss of chance in clinical negligence beyond narrow and established exceptions. A minority would have recognised diminution of prospects as actionable damage in this class of case and remitted quantum for assessment.

Authoritative authorities discussed included Hotson v East Berkshire (treatment of past facts and hypothetical outcomes), Wilsher (multiple potential causes), Fairchild (limited exception on causation), and established loss-of-chance authorities such as Chaplin v Hicks and Kitchen v RAF.

The claimant, Mr Gregg, consulted his general practitioner about an axillary lump which was negligently misdiagnosed as benign. Diagnosis and appropriate treatment were delayed by approximately nine months. At the date of the first consultation his chance of ten-year disease-free survival was assessed statistically at about 42%; by trial the chance had fallen to about 25%. The trial judge (Judge Inglis) found negligence and found that the delay caused spread of the tumour, but concluded that the claimant had not proved on the balance of probabilities that, absent the negligence, his overall long-term outcome would have been better; the claim was dismissed. The Court of Appeal [2002] EWCA Civ 1471 dismissed the appeal by majority.

The House considered whether a diminution in the claimant's prospects of a favourable outcome (a "loss of chance") caused by negligent delay is actionable where causation of the ultimate adverse outcome cannot be proved more likely than not. Central issues were:

1. the nature of actionable damage in clinical negligence (outcome loss v diminution in prospects);
2. whether statistical evidence of changed probabilities can be used to quantify a lost chance; and
3. whether established causation rules (balance of probabilities) must be retained or adapted to allow proportionate awards for lost chances.

The majority of the House concluded that the conventional causation approach should not be displaced generally. They stressed coherence with precedent (Wilsher, Hotson) and practical and policy difficulties of converting many clinical-neglect disputes into percentage-based claims, and were not prepared to expand the exceptional Fairchild reasoning into a general rule of proportional recovery for lost medical prospects. The minority would have recognised actionable diminution of prospects where (as found here) the claimant had a significant though less than evens chance which was materially reduced by the defendant's negligence, and would have remitted the case for assessment on a loss-of-chance basis.

(i) Nature of claim: damages for personal injury and loss of expectation of life were claimed; the pleadings focused on loss of the prospect of a cure (ten-year disease-free survival). (ii) Issues framed: breach (accepted), causation (whether the negligence caused a worse outcome or a substantial diminution of prospects), and quantum/valuation (use of statistics to assess lost chance). (iii) Reasoning: majority retained the balance of probabilities test for causation and declined to create a general proportional-loss-of-chance remedy in clinical negligence; minority favoured recognising diminution of prospects where medical uncertainty makes only percentage assessment possible and where the duty breached was to protect prospects of recovery.

Appeal dismissed by majority. The majority held that the conventional balance of probabilities test for causation remains fundamental in clinical negligence and that the courts should not generally convert proved diminution in statistical prospects into proportionate damages; established authorities such as Hotson and Wilsher require that causation of the physical outcome be proved on the balance of probabilities except in narrowly defined exceptions (e.g. Fairchild). The minority would have allowed the appeal, holding that a significant diminution in prospects caused by negligent delay is actionable and should be compensable by reference to the percentage reduction in chance.

First instance: trial before Judge Inglis (Queen's Bench Division) — claimant's negligence established but causation and quantum dismissed by the trial judge (3 August 2001). Court of Appeal: appeal dismissed by majority ([2002] EWCA Civ 1471) with Latham LJ dissenting. House of Lords: appeal heard and dismissed by majority ([2005] UKHL 2).