The House of Lords (Lord Nicholls and Lord Hope dissenting) dismissed the appeal of Malcolm Gregg against the decision of the Court of Appeal that his claim against Dr Scott had been rightly dismissed.
Dr Scott negligently diagnosed as innocuous a lump under Mr Gregg's left arm, when in fact it was cancerous (non-Hodgkin's lymphoma). That led to nine months' delay in Mr Gregg's receiving treatment. During that period his condition deteriorated by the disease spreading elsewhere. The deterioration in his condition reduced his prospects of disease-free survival for 10 years from 42 per cent, when he had first consulted Dr Scott, to 25 per cent at the date of the trial.
The judge found that, if treated promptly, Mr Gregg's initial treatment would probably have achieved remission without an immediate need for high dose chemotherapy. Prompt treatment would, at least initially, have prevented the cancer spreading to the left pectoral region.
However, the judge also found that, although Mr Gregg's condition had deteriorated and in consequence his prospects had been reduced in that way, a better outcome had never been a probability.
Before the negligence Mr Gregg had had a less than evens chance (45 per cent) of avoiding the deterioration in his condition which had ultimately occurred. The delay had not extinguished that chance, but had reduced it by roughly half. The judge assessed that reduction at 20 per cent. That was the extent to which the negligence reduced Mr Gregg's prospects of avoiding the deterioration in his condition which ultimately occurred. On those findings the judge dismissed the claim.
On appeal to the Court of Appeal, the claimant argued, inter alia, that quite apart from any other injury, the reduction in his chances of survival, or loss of a chance, was itself a compensatable head of damage. The Court of Appeal rejected that argument, and the claimant appealed.
Simeon Maskrey QC and Julian Matthews (Sharpe Pritchard) for the claimant; Philip Havers QC, William Edis and David Mankell (Medical Defence Union) for the defendant.
Lord Hoffmann said that there were certainly cases in which loss of a chance was a recoverable head of damage, of which Chaplin v Hicks  2 KB 786 was a well-known example. The question was whether the principle of that case could apply to a case of clinical negligence such as the present.
The answer can be derived from three cases in the House of Lords: Hotson v East Berkshire Area Health Authority  2 All ER 909, Wilsher v Essex Area Health Authority  1 All ER 871 and Fairchild v Glenhaven Funeral Services Ltd  3 All ER 305.
It should be noted that the rule which Mr Gregg advocated would involve abandoning a good deal of authority. It was the very rule which had been rejected in Wilsher. Yet Wilsher had been expressly approved in Fairchild. Hotson too would have to be overruled. Furthermore, it would mean dismantling all the qualifications and restrictions with which the House of Lords had so recently hedged the exception in Fairchild.
A wholesale adoption of possible rather than probable causation as the criterion of liability would be so radical a change in the law as to amount to a legislative act. Any such changes should be left to Parliament.