He held that where the "but for" test of causation cannot be satisfied because of some uncertainty, it is relaxed and a claimant will succeed in getting compensation if the defendant materially contributed to the cause of the injury.
Mr Gibson QC, for the claimant, submitted that the authorities showed that the correct question was whether the negligence had "caused or materially contributed to" the injury.
Mr Sweeting submitted that the proper basis was not "contribution to risk or occurrence"; the right test was what he termed "the normal unmodified requirement that the alleged failure should have caused the harm, so that without it the damage would not have occurred."
9 Wilsher was a case where a premature baby negligently received an excessive concentration of oxygen and suffered retrolental fibroplasia leading to blindness.
However the medical evidence demonstrated that this can occur in premature babies who have not been given excessive oxygen, and there were four other distinct conditions which could also have been causative of the fibroplasia.
In the Court of Appeal the claim had succeeded; the majority in their judgments placing some reliance on the House of Lords decision in McGhee.
The defendants failed to take reasonable precautions to prevent one of the possible causative agents (e.g. excess oxygen) from causing RLF.
In such a case, I can see the common sense, if not the logic, of holding that, in the absence of any other evidence, the failure to take the precaution caused or contributed to the dermatitis.
To the extent that certain members of the House of Lords decided the question on inferences from evidence or presumptions, I do not consider that the present case falls within their reasoning.
The judge quoted Lord Bridge in Hotson v East Berkshire Area Health Authority [1987] AC 750 at page 783 where he said this:- "As I have said, there was in this case an inescapable issue of causation first to be resolved.
But if the plaintiff had proved on a balance of probabilities that the authority's negligent failure to diagnose and treat his injury promptly had materially contributed to the development of avascular necrosis, I know of no principle of English law which would have entitled the authority to a discount from the full measure of damage to reflect the chance that, even given prompt treatment, avascular necrosis might well still have developed.
The decisions of this House in Bonnington Casting Ltd v Wardlaw [1956] AC 613 and McGhee v National Coal Board [1973] 1 WLR 1 give no support to such a view."
13 The judge then said this:- "My attention has not been drawn to any subsequent authority that has cast doubt on the formulation of the burden on the Claimant as set out in that passage.
If this approach to causation is permitted it does, of course, mean that the 'but for' test is not being applied: see Fairchild v Glenhaven, etc, at paragraph 129 per Lord Rodger of Earlsferry."
Since it is enough that the defendant's wrongful act materially contributed to the claimant's injury, the law is not applying the causa sine qua non or 'but for' test of causation.
All he needed to prove was that the dust from the swing hammers contributed materially to the dusty atmosphere which he breathed and which caused his illness.
15 The judge, having cited Wilsher and the passage already quoted in the judgment of Sir Nicholas Browne-Wilkinson VC, concluded that the correct question was whether the negligence had "caused or materially contributed to" the injury.
16 As to what is a "material contribution" the judge did not quote any authority but in Mr Gibson's submission Lord Reid's formulation in Wardlaw provides the answer:- "The medical evidence was that pneumoconiosis is caused by a gradual accumulation in the lungs of minute particles of silica inhaled over a period of years.
Fairchild was a case where the claimant had contracted mesothelioma; he had been employed by various employers who had all in breach of duty exposed him to asbestos fibres; the evidence established that one fibre actually caused mesothelioma as opposed to all contributing so to do; it followed that as a fact only one defendant would have caused the injury but the claimant could not because of the inadequacies of medical science establish which.
The House of Lords introduced an exception to traditional principles so as to render liable all who "contributed to the risk" even if as was bound to be the case only one defendant would actually have caused the injury.
The medical evidence is to the effect that the fact that the man had to cycle home caked with grime and sweat added materially to the risk that this disease might develop.
40 If one goes to the speech of Lord Keith in Wardlaw it seems to me that his language could be said to support a 'but for' approach appreciating that in the context of the facts he was dealing with it was because the defendant could not establish that his breach of duty did not cause the injury that the 'but for' test was complied with.
Examples are Lord Hoffmann in Gregg v Scott paragraph 77 in dealing with Wilsher, where he said that "The defendant was only liable if the lack of oxygen caused or substantially (my italics) contributed to the injury."
43 It seems to me thus respectfully that Lord Rodger in Fairchild accurately summarises the position when he says in paragraph 129 that in the cumulative cause case such as Wardlaw the 'but for' test is modified.
It was the inadequacies of medical science that put the claimant in the position of not being able to establish the probability of one cause as against the other but the House of Lords were not prepared to place the case in an exceptional category.
47 The instant case involved cumulative causes acting so as to create a weakness and thus the judge in my view applied the right test, and was entitled to reach the conclusion he did.
She wrote, The exceptional approach to the causal inquiry which derives from McGhee and Fairchild does not apply to the Wardlaw/Bailey situation because there was in the former cases a need to modify the “but for” test because no “but for” causation could otherwise be established.
It is to be hoped, however, that the reasoning therein, and particularly the misleading assertion that it constitutes a modified application of the “but for” test, will not be misinterpreted in future decisions in this notoriously thorny area.
By contrast Marc Staunch has been critical of "hairline distinctions" that the case law has given rise to, but focused some of his criticism on Waller LJ's universal approach, saying, despite Waller LJ's assertion to the contrary, there are, with respect, significant differences between industrial disease and medical negligence claims, justifying a more claimant-friendly approach in the former.
Even though the claim in Bailey was not ultimately against the NHS, and notwithstanding that the case was a very sad one, it is submitted that the Court of Appeal's approach to resolving it is not sustainable.