Fairchild v Glenhaven Funeral Services Ltd & Ors [2002] UKHL 22 (20 June 2002)

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URL: http://www.bailii.org/uk/cases/UKHL/2002/22.html
Cite as: [2002] Lloyds Rep Med 361, [2002] 3 All ER 305, [2003] 1 AC 32, [2002] PIQR P28, (2002) 67 BMLR 90, [2002] UKHL 22, [2002] Lloyd's Rep Med 361, [2002] 3 WLR 89, [2002] ICR 798

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JISCBAILII_CASE_TORT


     

    Judgments - Fairchild (suing on her own behalf) etc. v. Glenhaven Funeral Services Ltd and others etc.

    HOUSE OF LORDS
    Lord Bingham of Cornhill Lord Nicholls of Birkenhead Lord Hoffmann Lord Hutton Lord Rodger of Earlsferry
    OPINIONS OF THE LORDS OF APPEAL FOR JUDGMENT
    IN THE CAUSE
    FAIRCHILD (SUING ON HER OWN BEHALF AND ON BEHALF OF THE ESTATE OF AND DEPENDANTS OF ARTHUR ERIC FAIRCHILD (DECEASED)) (APPELLANT) v GLENHAVEN FUNERAL SERVICES LIMITED AND OTHERS (RESPONDENTS) FOX (SUING AS WIDOW AND ADMINISTRATRIX OF THOMAS FOX (DECEASED)) (FC) (APPELLANT) v SPOUSAL (MIDLANDS) LIMITED (RESPONDENTS
    MATTHEWS (FC) (APPELLANT)
    v
    ASSOCIATED PORTLAND CEMENT MANUFACTURERS (1978) LIMITED AND OTHERS (RESPONDENTS)
    ORAL JUDGMENT: 16 MAY 2002
    REASONS: 20 JUNE 2002
    [2002] UKHL 22
    LORD BINGHAM OF CORNHILL
    My Lords,
  1. On 16 May 2002 it was announced that these three appeals would be allowed. I now give my reasons for reaching that decision.
  2. The essential question underlying the appeals may be accurately expressed in this way. If
  3. (1) C was employed at different times and for differing periods by both A and B, and
    (2) A and B were both subject to a duty to take reasonable care or to take all practicable measures to prevent C inhaling asbestos dust because of the known risk that asbestos dust (if inhaled) might cause a mesothelioma, and
    (3) both A and B were in breach of that duty in relation to C during the periods of C's employment by each of them with the result that during both periods C inhaled excessive quantities of asbestos dust, and
    (4) C is found to be suffering from a mesothelioma, and
    (5) any cause of C's mesothelioma other than the inhalation of asbestos dust at work can be effectively discounted, but
    (6) C cannot (because of the current limits of human science) prove, on the balance of probabilities, that his mesothelioma was the result of his inhaling asbestos dust during his employment by A or during his employment by B or during his employment by A and B taken together,
    is C entitled to recover damages against either A or B or against both A and B? To this question (not formulated in these terms) the Court of Appeal (Brooke, Latham and Kay LJJ), in a reserved judgment of the court reported at [2002] 1 WLR 1052, gave a negative answer. It did so because, applying the conventional "but for" test of tortious liability, it could not be held that C had proved against A that his mesothelioma would probably not have occurred but for the breach of duty by A, nor against B that his mesothelioma would probably not have occurred but for the breach of duty by B, nor against A and B that his mesothelioma would probably not have occurred but for the breach of duty by both A and B together. So C failed against both A and B. The crucial issue on appeal is whether, in the special circumstances of such a case, principle, authority or policy requires or justifies a modified approach to proof of causation.

  4. It is common ground that in each of the three cases under appeal conditions numbered (1) to (5) above effectively obtained. During his working life the late Mr Fairchild worked for an employer (whose successor was wrongly identified as the first-named defendant) who carried out sub-contract work for the Leeds City Council in the early 1960s and may have built packing cases for the transportation of industrial ovens lined with asbestos. He also worked for a builder, in whose employment he cut asbestos sheeting both to repair various roofs and while renovating a factory for Waddingtons plc. In the course of his work Mr Fairchild inhaled substantial quantities of asbestos dust containing asbestos fibre which caused him to suffer a mesothelioma of the pleura, from which he died on 18 September 1996 at the age of 60. Waddingtons plc accepted at trial that it had exposed Mr Fairchild to the inhalation of asbestos fibres by a breach of the duty owed to him under section 63 of the Factories Act 1961. (Waddingtons plc was not an employer, but nothing turns on this distinction with the other cases.) It thereby admitted that he had been exposed to a substantial quantity of dust or had been exposed to dust to such an extent as was likely to be injurious to him. After the death of Mr Fairchild his widow brought this action, originally against three defendants (not including the builder). She discontinued proceedings against the first-named defendant, and on 1 February 2001 Curtis J dismissed her claim against Waddingtons plc and the Leeds City Council. The Court of Appeal dismissed her appeal against that decision in the judgment already referred to, finding it unnecessary (because of its decision on causation) to reach a final decision on all aspects of her common law claim against the Leeds City Council. She challenges that causation decision on appeal to the House.
  5. The late Mr Fox was employed as a lagger by Spousal (Midlands) Ltd (then known by a different name) for 1½-2 years between about 1953 and 1955. In the course of this employment he worked at various different premises. Typical lagging work involved the removal of old lagging, the mixing of lagging paste, the cutting of lagging sections and the sweeping up of dust and debris. Asbestos materials were used on a daily basis. The activities of laggers generated high levels of dust containing asbestos. In these circumstances Mr Fox was exposed to large amounts of asbestos dust, often for many hours each day. He was described by a witness as being covered in dust from head to foot. No measures were taken to protect him from such exposure. From 1955-1989 he worked as a docker/holdsman in the Liverpool Docks. Until the late 1960s or early 1970s asbestos fibre was imported into Liverpool Docks in sacks. Mr Fox told his wife that he was regularly involved in moving asbestos cargo and that asbestos was regularly released into his breathing area. The work of handling asbestos cargoes would have exposed Mr Fox to substantial amounts of dust and it is unlikely that any measures would have been taken to protect him from such exposure. But there is no evidence of when and for how long and how frequently Mr Fox handled cargoes containing asbestos, nor of what cargoes he handled, nor of the identity of his employers when he was engaged in handling asbestos. Spousal do not dispute that they were in breach of duty in exposing Mr Fox to substantial amounts of asbestos dust in the course of his employment by them. In 1995 he developed symptoms of mesothelioma and he died on 24 April 1996 at the age of 63. It is accepted that his condition was caused by exposure to asbestos dust. After his death his widow brought these proceedings against Spousal. Her claim was dismissed by Judge Mackay, sitting as a judge of the Queen's Bench Division in Liverpool on 27 March 2001. Her appeal against that decision was dismissed by the Court of Appeal in the judgment already referred to. She challenges that decision on appeal to the House.
  6. Mr Matthews was employed by Associated Portland Cement Manufacturers (1978) Ltd from 1973-81 at their factory in Strood, Kent. He was exposed to asbestos during the last four years of this employment when working as a boilerman. Each day he spent some time (up to about an hour) in the boilerhouse where the boiler and ancillary pipework were lagged with asbestos material. On a number of occasions (adding up to about 2 days in all) he was in close proximity to men removing lagging from pipes, and such work created large amounts of asbestos dust. On a daily basis he was exposed to dust and debris from the lagging. He walked across pipework disturbing the lagging. He regularly swept the floor in the boilerhouse, stirring up asbestos dust and debris. No effective measures were taken to protect him from exposure to asbestos dust. For 5-6 weeks in January and February 1973 Mr Matthews was employed by British Uralite plc at their factory in Higham, Kent, where the company manufactured pipes from asbestos material, and Mr Matthews worked on this process. Large amounts of dust containing asbestos fibres were created by the manufacturing process and such dust permeated the atmosphere of the factory. During each working day Mr Matthews had prolonged and substantial exposure to asbestos dust. No measures were taken to protect him against such exposure. Between 1965 and 1967 Mr Matthews was employed by Maidstone Sack and Metal and was again exposed to significant quantities of asbestos dust. For 12 months of this period he operated a scrap metal press and some of the items fed into the press had asbestos linings. For about 2 weeks he worked in a boilerhouse in Chatham Dockyard dismantling a boiler and pipework, during which time he spent a day removing asbestos lagging from the boiler and pipes, which was dusty work. Maidstone Sack and Metal can no longer be sued. Mr Matthews consulted his doctor complaining of chest pain in March 1999. In February 2000 a diagnosis of mesothelioma was made. His condition has continued to deteriorate, and his life expectancy is now measured in months. Associated Portland Cement and British Uralite admit that Mr Matthews' mesothelioma was caused by exposure to asbestos dust, and that each of them exposed Mr Matthews to asbestos dust in breach of duty. Mr Matthews issued proceedings against both these companies in April 2001. On 11 July 2001 Mitting J gave judgment in his favour against both defendants and awarded damages. The defendants appealed against that decision, and the Court of Appeal allowed their appeal and set aside the award in Mr Matthews' favour. He has appealed against that decision. It should be recorded that, before the hearing of his appeal in the House, the defendants agreed to pay Mr Matthews the sum awarded by the judge with interest and costs, without prejudice to the issues in the appeal.
  7. It has been recognised for very many years, at any rate since the "Report on Effects of Asbestos Dust on the Lungs and Dust Suppression in the Asbestos Industry" by Merewether and Price in 1930 and the making of the Asbestos Industry Regulations 1931, that it is injurious to inhale significant quantities of asbestos dust. At first, attention was focused on the risk of contracting asbestosis and other pulmonary diseases. It is a characteristic of asbestosis that the disease, once initiated, will be influenced by the total amount of dust thereafter inhaled. Thus in the case of asbestosis the following situation may arise. C may contract asbestosis as a result of exposure to asbestos dust while employed by A, but without such exposure involving any breach of duty by A. C may then work for B, and again inhale quantities of asbestos dust which will have the effect of aggravating his asbestosis. If this later exposure does involve a breach of duty by B, C will have no claim against A but will have a claim against B. B will not escape liability by contending that his breach of duty is not shown to have had any causative effect.
  8. From about the 1960s, it became widely known that exposure to asbestos dust and fibres could give rise not only to asbestosis and other pulmonary diseases, but also to the risk of developing a mesothelioma. This is a malignant tumour, usually of the pleura, sometimes of the peritoneum. In the absence of occupational exposure to asbestos dust it is a very rare tumour indeed, afflicting no more than about one person in a million per year. But the incidence of the tumour among those occupationally exposed to asbestos dust is about 1,000 times greater than in the general population, and there are some 1,500 cases reported annually. It is a condition which may be latent for many years, usually for 30-40 years or more; development of the condition may take as short a period as 10 years, but it is thought that that is the period which elapses between the mutation of the first cell and the manifestation of symptoms of the condition. It is invariably fatal, and death usually occurs within 1-2 years of the condition being diagnosed. The mechanism by which a normal mesothelial cell is transformed into a mesothelioma cell is not known. It is believed by the best medical opinion to involve a multi-stage process, in which 6 or 7 genetic changes occur in a normal cell to render it malignant. Asbestos acts in at least one of those stages and may (but this is uncertain) act in more than one. It is not known what level of exposure to asbestos dust and fibre can be tolerated without significant risk of developing a mesothelioma, but it is known that those living in urban environments (although without occupational exposure) inhale large numbers of asbestos fibres without developing a mesothelioma. It is accepted that the risk of developing a mesothelioma increases in proportion to the quantity of asbestos dust and fibres inhaled: the greater the quantity of dust and fibre inhaled, the greater the risk. But the condition may be caused by a single fibre, or a few fibres, or many fibres: medical opinion holds none of these possibilities to be more probable than any other, and the condition once caused is not aggravated by further exposure. So if C is employed successively by A and B and is exposed to asbestos dust and fibres during each employment and develops a mesothelioma, the very strong probability is that this will have been caused by inhalation of asbestos dust containing fibres. But C could have inhaled a single fibre giving rise to his condition during employment by A, in which case his exposure by B will have had no effect on his condition; or he could have inhaled a single fibre giving rise to his condition during his employment by B, in which case his exposure by A will have had no effect on his condition; or he could have inhaled fibres during his employment by A and B which together gave rise to his condition; but medical science cannot support the suggestion that any of these possibilities is to be regarded as more probable than any other. There is no way of identifying, even on a balance of probabilities, the source of the fibre or fibres which initiated the genetic process which culminated in the malignant tumour. It is on this rock of uncertainty, reflecting the point to which medical science has so far advanced, that the three claims were rejected by the Court of Appeal and by two of the three trial judges.
  9. Principle
  10. In a personal injury action based on negligence or breach of statutory duty the claimant seeks to establish a breach by the defendant of a duty owed to the claimant, which has caused him damage. For the purposes of analysis, and for the purpose of pleading, proving and resolving the claim, lawyers find it convenient to break the claim into its constituent elements: the duty, the breach, the damage and the causal connection between the breach and the damage. In the generality of personal injury actions, it is of course true that the claimant is required to discharge the burden of showing that the breach of which he complains caused the damage for which he claims and to do so by showing that but for the breach he would not have suffered the damage.
  11. The issue in these appeals does not concern the general validity and applicability of that requirement, which is not in question, but is whether in special circumstances such as those in these cases there should be any variation or relaxation of it. The overall object of tort law is to define cases in which the law may justly hold one party liable to compensate another. Are these such cases? A and B owed C a duty to protect C against a risk of a particular and very serious kind. They failed to perform that duty. As a result the risk eventuated and C suffered the very harm against which it was the duty of A and B to protect him. Had there been only one tortfeasor, C would have been entitled to recover, but because the duty owed to him was broken by two tortfeasors and not only one, he is held to be entitled to recover against neither, because of his inability to prove what is scientifically unprovable. If the mechanical application of generally accepted rules leads to such a result, there must be room to question the appropriateness of such an approach in such a case.
  12. In March v E & MH Stramare Pty Ltd (1991) 171 CLR 506 at 508, Mason CJ, sitting in the High Court of Australia, did not "accept that the 'but for' (causa sine qua non) test ever was or now should become the exclusive test of causation in negligence cases" and (at p 516) he added:
  13. "The 'but for' test gives rise to a well-known difficulty in cases where there are two or more acts or events which would each be sufficient to bring about the plaintiff's injury. The application of the test 'gives the result, contrary to common sense, that neither is a cause': Winfield and Jolowicz on Tort, 13th ed (1989), p. 134. In truth, the application of the test proves to be either inadequate or troublesome in various situations in which there are multiple acts or events leading to the plaintiff's injury: see, e.g., Chapman v Hearse, Baker v Willoughby [1970] AC 467; McGhee v National Coal Board; M'Kew (to which I shall shortly refer in some detail). The cases demonstrate the lesson of experience, namely, that the test, applied as an exclusive criterion of causation, yields unacceptable results and that the results which it yields must be tempered by the making of value judgments and the infusion of policy considerations."
  14. In Snell v Farrell [1990] 2 SCR 311 at 320, Sopinka J, delivering the judgment of the Supreme Court of Canada, said:
  15. "The traditional approach to causation has come under attack in a number of cases in which there is concern that due to the complexities of proof, the probable victim of tortious conduct will be deprived of relief. This concern is strongest in circumstances in which, on the basis of some percentage of statistical probability, the plaintiff is the likely victim of the combined tortious conduct of a number of defendants, but cannot prove causation against a specific defendant or defendants on the basis of particularized evidence in accordance with traditional principles. The challenge to the traditional approach has manifested itself in cases dealing with non-traumatic injuries such as man-made diseases resulting from the widespread diffusion of chemical products, including product liability cases in which a product which can cause injury is widely manufactured and marketed by a large number of corporations."
    McLachlin J, extra-judicially ("Negligence Law - Proving the Connection", in Torts Tomorrow, A Tribute to John Fleming, ed Mullany and Linden, LBC Information Services 1998, at p 16), has voiced a similar concern:

    "Tort law is about compensating those who are wrongfully injured. But even more fundamentally, it is about recognising and righting wrongful conduct by one person or a group of persons that harms others. If tort law becomes incapable of recognising important wrongs, and hence incapable of righting them, victims will be left with a sense of grievance and the public will be left with a feeling that justice is not what it should be. Some perceive that this may be occurring due to our rules of causation.
    In recent years, a conflation of factors have caused lawyers, scholars and courts to question anew whether the way tort law has traditionally defined the necessary relationship between tortious acts and injuries is the right way to define it, or at least the only way. This questioning has happened in the United States and in England and has surfaced in Australia. And it is happening in Canada. Why is this happening? Why are courts now asking questions that for decades, indeed centuries, did not pose themselves, or if they did, were of no great urgency? I would suggest that it is because too often the traditional 'but-for', all-or-nothing, test denies recovery where our instinctive sense of justice - of what is the right result for the situation - tells us the victim should obtain some compensation."
  16. My noble and learned friend Lord Hoffmann has, on more than one occasion, discouraged a mechanical approach to the issue of causation. In Environment Agency (formerly National Rivers Authority) v Empress Car Co. (Abertillery) Ltd [1999] 2 AC 22 at 29, he said:
  17. "The first point to emphasise is that common sense answers to questions of causation will differ according to the purpose for which the question is asked. Questions of causation often arise for the purpose of attributing responsibility to someone, for example, so as to blame him for something which has happened or to make him guilty of an offence or liable in damages. In such cases, the answer will depend upon the rule by which responsibility is being attributed."
    More recently, in Kuwait Airways Corporation v Iraqi Airways Co (Nos 4 and 5) [2002] 2 WLR 1353, p 1388, para 128, he said:

    "There is therefore no uniform causal requirement for liability in tort. Instead, there are varying causal requirements, depending upon the basis and purpose of liability. One cannot separate questions of liability from questions of causation. They are inextricably connected. One is never simply liable; one is always liable for something and the rules which determine what one is liable for are as much part of the substantive law as the rules which determine which acts give rise to liability".
    Laws LJ was reflecting this approach when he said in Rahman v Arearose Ltd [2001] QB 351 at 367-368:

    "So in all these cases the real question is, what is the damage for which the defendant under consideration should be held responsible. The nature of his duty (here, the common law duty of care) is relevant; causation, certainly, will be relevant - but it will fall to be viewed, and in truth can only be understood, in light of the answer to the question: from what kind of harm was it the defendant's duty to guard the claimant? . . . Novus actus interveniens, the eggshell skull, and (in the case of multiple torts) the concept of concurrent tortfeasors are all no more and no less than tools or mechanisms which the law has developed to articulate in practice the extent of any liable defendant's responsibility for the loss and damage which the claimant has suffered."
  18. I do not therefore consider that the House is acting contrary to principle in reviewing the applicability of the conventional test of causation to cases such as the present. Indeed, it would seem to me contrary to principle to insist on application of a rule which appeared, if it did, to yield unfair results. And I think it salutary to bear in mind Lord Mansfield's aphorism in Blatch v Archer (1774) 1 Cowp 63 at 65, quoted with approval by the Supreme Court of Canada in Snell v Farrell (above):
  19. "It is certainly a maxim that all evidence is to be weighed according to the proof which it was in the power of one side to have produced, and in the power of the other to have contradicted."
    Authority
  20. In Bonnington Castings Ltd v Wardlaw [1956] AC 613, the pursuer contracted pneumoconiosis as a result of inhaling silica dust. The dust came from two sources, a pneumatic hammer and swing grinders, both in the dressing shop where he worked. The dust emanating from the pneumatic hammer involved no breach of duty by the employer, but that from the swing grinders did. In a claim against his employer he succeeded before the Lord Ordinary, Lord Wheatley, and by a majority in the First Division of the Court of Session, the Lord President (Lord Clyde) dissenting. The issue on appeal was whether the employer's admitted breach of duty in relation to the swing grinders had caused the pursuer's disease. In his leading opinion, Lord Reid made plain that "the employee must in all cases prove his case by the ordinary standard of proof in civil actions: he must make it appear at least that on a balance of probabilities the breach of duty caused or materially contributed to his injury" (p. 620). He pointed out that pneumoconiosis is caused by a gradual accumulation in the lungs of minute particles of silica inhaled over a period of years (p. 621), and he regarded the real question as "whether the dust from the swing grinders materially contributed to the disease" (p. 621). He considered that any contribution which was not de minimis must be material. The evidence showed that even if more dust came from the pneumatic hammer than from the swing grinders, there was enough dust from the grinders to make a substantial contribution towards the pursuer's disease (p. 622). The pursuer was accordingly entitled to succeed. With these conclusions, Viscount Simonds, Lord Tucker, Lord Keith of Avonholm and Lord Somervell of Harrow agreed, Lord Keith laying stress at p. 626 on the nature of pneumoconiosis as a disease of gradual incidence and on the cumulative effect of inhalation of dust from the grinders over a period, which might be small in proportion but substantial in total quantity. The case differs from the present in two obvious respects. First, the pursuer had only one relevant employer, who was not legally liable for producing some of the dust which the pursuer inhaled but was potentially liable for the balance. Secondly, pneumoconiosis is, like asbestosis, a condition which is aggravated by the inhalation of increased quantities of dust so that, even if the "innocent" dust had been the first and major cause of the condition, the "guilty" dust, if in significant quantities, could properly be said to have made it worse.
  21. Nicholson v Atlas Steel Foundry and Engineering Co Ltd [1957] 1 WLR 613 was factually a variant of Wardlaw's case. The claim was made by the widow and children of Mr Nicholson, who had worked in the dressing shop of the defenders' steel foundry, had inhaled dust containing minute siliceous particles while doing so, had contracted pneumoconiosis and had died. The complaints made in the action related not to the creation of dust in the dressing shop but to the defenders' failure to provide adequate ventilation to extract the dust. It was common ground that the deceased must inevitably have inhaled a quantity, even a large quantity, of noxious particles about which he could have no cause of complaint, and the only question was whether, in addition to those particles, he was, owing to the fault of the defenders in failing to provide adequate ventilation, bound to have inhaled a number of other particles which made a material contribution to his illness (p 616). The Lord Ordinary found for the family, but his decision was reversed by the First Division. In the House the argument centred on the statutory duty to provide proper ventilation imposed by section 4(1) of the Factories Act 1937, and Viscount Simonds said (at p 618):
    ". . . . if the statute prescribes a proper system of ventilation by the circulation of fresh air so as to render harmless, so far as practicable, all fumes, dust and other impurities that may be injurious to health, generated in the course of work carried on in the factory, and if it is proved that there is no system or only an inadequate system of ventilation, it requires little further to establish a causal link between that default and the illness, due to noxious dust, of a person employed in the shop. Something is required as was held in Wardlaw's case. I was a party to that decision and would not in any way resile from it. But it must not be pressed too far. In the present case there was, in my opinion, ample evidence to support the appellants' case."
    Since the family could not complain of the production of dust, and the deceased had been forced to inhale some noxious particles without having any legal complaint, it was doubly incumbent on the employer to safeguard him against any additional risk (p 616). Viscount Simonds' conclusion was clearly expressed (at pp 619-620):
    "For it appears to me that [the evidence] clearly established that dust containing dangerous particles of silica was emitted into the air by the operation of pneumatic hammers on the castings, that this dust hung about in concentrated form longer than it would have if there had been better ventilation, and that improved roof ventilators were practicable and would have effectively improved the conditions. It follows that owing to the default of the respondents the deceased was exposed to a greater degree of risk than he should have been, and, though it is impossible, even approximately, to quantify the particles which he must, in any event, have inhaled and those which he inhaled but need not have, I cannot regard the excess as something so negligible that the maxim 'de minimis' is applicable. Accordingly, following the decision in Wardlaw's case, I must hold the respondents liable."
    Lord Oaksey and Lord Morton of Henryton agreed. Lord Cohen agreed and said (at p 622):

    "Pneumoconiosis is a progressive disease. The longer a workman is exposed to an intense cloud the graver must be the risk of infection. In the present case it is clearly established by the evidence that at any rate down to 1949 the tool with which the deceased was working on dirty castings created a thick cloud of dust which must have necessarily included siliceous particles to an extent which cannot classed as 'de minimis'. The respondents are admittedly not to blame for the generation of this cloud, but any failure to provide proper ventilation must, I think, lengthen the period during which the cloud remains intense. It seems to me to follow that the respondents' failure to provide adequate ventilation must increase the risk to which the workmen are exposed. Reading the evidence as a whole, I think it establishes that (to use the language of Lord Reid in Wardlaw's case) 'on a balance of probabilities the breach of duty caused or materially contributed to' the injury."
    Lord Keith of Avonholm regarded it as common sense that better ventilation would have appreciably diminished the dust which was in the air for the deceased to inhale (p 627) and accordingly concluded that his death from pneumoconiosis should be ascribed at least partially to the fault of the defenders. Again the case involved a single employer: but the dust, although "innocent" when first produced became, in effect, "guilty" because of the employer's conduct in allowing it to remain in the air for an excessive period. It is noteworthy that two members of the House (Viscount Simonds and Lord Cohen) attached significance to the exposure of the deceased to an increased risk.

  22. Gardiner v Motherwell Machinery and Scrap Co Ltd [1961] 1 WLR 1424, another Scottish case, concerned a pursuer who had worked for the defenders for a period of some three months, demolishing buildings, and had contracted dermatitis. In an action against the defenders he claimed that they should have provided him with washing facilities but had failed to do so and that their failure had caused him to suffer from dermatitis. This contention was upheld by the Lord Ordinary (Lord Kilbrandon) who awarded him damages. The defenders did not on appeal challenge the finding of breach but contended that the pursuer had failed to prove any connection between his disease and the work which he had been doing. The First Division accepted this argument and found for the defenders, a decision against which the pursuer appealed. In his leading opinion in the House, Lord Reid considered at some length the conflict of medical evidence at the trial and its treatment by the First Division, and expressed his conclusion (at p 1429):
  23. "In my opinion, when a man who has not previously suffered from a disease contracts that disease after being subjected to conditions likely to cause it, and when he shows that it starts in a way typical of disease caused by such conditions, he establishes a prima facie presumption that his disease was caused by those conditions. I think that the facts proved in this case do establish such a presumption. That presumption could be displaced in many ways. The respondents sought to show, first, that it is negatived by the subsequent course of the disease and, secondly, by suggesting tinea pedis as an equally probable cause of its origin. I have found the case difficult, but on the evidence as it stands I have come to the opinion that they have failed on both points. If the appellant's disease and consequent loss should be attributed to the work which he was doing in the respondents' service, it was not argued that they are not liable."
    Lord Cohen and Lord Guest agreed, as did Lord Hodson although with some initial hesitation. Lord Guest described the question as a pure question of fact whether on the balance of probabilities the dermatitis had arisen from the pursuer's employment (p 1431). The House would seem to have regarded the pursuer as establishing a prime facie case which the defenders had failed to displace.

  24. In the course of the present appeals much argument was directed to the decision of the House in McGhee v National Coal Board [1973] 1 WLR 1. The earlier stages of that case are reported at 1973 SC(HL) 37 and are important in understanding what the House decided. Mr McGhee had been employed by the National Coal Board for about 15 years, almost always working in pipe kilns. For some 4½ days he then worked at a brick kiln, giving up because of a dermatitic condition which had by then developed. The work inside the kiln was very hot and very dusty. The heat made men sweat profusely and the operation of the fan caused them to be covered in dust and grit. The pursuer contended that his dermatitis had been caused by his period of working in the brick kiln, short though it had been. The employers contended that his work had not caused the dermatitis and that it was non-occupational in origin. There was at the trial a conflict of medical evidence but the Lord Ordinary (Lord Kissen) held that the pursuer had contracted the dermatitis in the course of his work at the brick kiln and as a result of his exposure to dust and ashes when working there (p 39). Counsel for the pursuer accepted at trial that he could not establish a breach of statutory duty nor a breach of common law duty based on a failure to ventilate, but relied on two alleged breaches by the employers: of a duty to take care that the kiln had cooled sufficiently before men went in to work in it and of a duty to take reasonable care to provide adequate showers to enable men to remove dust from their bodies. The Lord Ordinary rejected the first of these complaints on a number of grounds, including the lack of proof that the breach of duty, even if established, had caused or materially contributed to the dermatitis: it was not enough that a reduction of heat would have lessened the risk (p 41). The Lord Ordinary concluded that the employers were at fault in failing to provide showers (p 42) but found against the pursuer on the basis of evidence given by two expert dermatologists, Dr Hannay and Dr Ferguson, called by the pursuer and the employers respectively. He said (at pp 42-43):
  25. "As I have maintained earlier, the pursuer, in order to succeed, must also establish, on a balance of probabilities, that this fault on the part of the defenders 'caused or materially contributed to his injury', that is to his contracting dermatitis. Dr Hannay's evidence was that he could not say that the provision of showers would probably have prevented the disease. He said that it would have reduced the risk materially but he would not go further than that. Dr Ferguson said that washing reduces the risk. Pursuer's counsel maintained that a material increase in the risk of contracting a disease was the same as a material contribution to contracting the disease and that Dr Hannay established this by his evidence. I think that defenders' counsel was correct when he said that the distinction drawn by Dr Hannay was correct and that an increase in risk did not necessarily mean a material contribution to the contracting of the disease. The two concepts are entirely different. A material increase in risk may refer only to possibilities and may not make a possibility into a probability. It may strengthen the possibility but that cannot mean that in all such cases the possibility has become a probability. What the pursuer has to show is that, as he avers, he would not have contracted the disease but for the defenders' breach of duty. He has to show that this was probable and the degrees of risk have no relevance unless they make the contraction of the disease more probable than not contracting the disease. He cannot succeed if the only inference from the evidence is that lack of shower baths is a possibility as a cause of his having contracted the disease and the provision of shower baths would have increased the possibility but not made it a probability. That is the only inference which I can draw from Dr Hannay's evidence and that was the best evidence for the pursuer. Causal connection between fault and the contraction of the disease has not been established."
  26. The pursuer appealed to the First Division against the dismissal of his claim. The medical evidence given at the trial was reviewed in detail, and in particular an exchange between cross-examining counsel and Dr Hannay ( pp 43-44, 47, 50):
  27. "Q. Do I understand you to say you are not in a position to say that the provision of showers would probably have prevented his contracting this skin trouble?
    A. No one could say that that would prevent that man developing the condition. It would be likely to reduce the chances."
    In answer to further questions the doctor repeated his opinion that he could only say that the provision of showers would have reduced the chances of the pursuer contracting dermatitis and that that was as far as he was able to go. In the course of his judgment the Lord President, Lord Clyde, considered the pneumoconiosis cases and expressed his conclusion (at p 44):

    "But in contrast to the pneumoconiosis cases, the present case is essentially concerned with proof of the causal connection between the fault alleged (i.e. inadequate washing facilities) and the development of dermatitis. Even if the pursuer had established (as he did not) that the absence of washing facilities increased the risk of the pursuer getting dermatitis, that would clearly not prove that the absence of these facilities caused the disease, nor indeed would it go any distance towards proving it. For risk of dermatitis and causation of dermatitis are two quite separate matters."
    Lord Migdale was of the same opinion (at pp 47-48):

    "Counsel for the pursuer contended that as it was now accepted that the failure to provide a shower was a breach of the duty which the defenders owed to the pursuer to take reasonable steps for his well-being, the doctors' evidence that it would have materially reduced the risk of dermatitis is enough to link the failure with the injury. Counsel for the defenders, on the other hand, contended that the test of causal connection between the breach and the injury is whether the provision of a shower would, on a balance of probabilities, have prevented the dermatitis. The Lord Ordinary says an increase in risk does not mean a material contribution to the contracting of the disease. A material increase in risk may refer only to possibilities and it does not make a possibility into a probability. 'What the pursuer has to show is that, as he avers, he would not have contracted the disease but for the breach of duty'. He has to show this on a balance of probabilities.
    In my opinion this is correct. Unless the pursuer can point to evidence that shows that a shower would more probably have avoided the disease than not, he cannot succeed and I do not find that evidence in this case."
    Lord Johnston was more hesitant, but in view of the other opinions did not feel inclined to take the view that the evidence was sufficient to allow him to hold that the test of the balance of probability had been satisfied (p 50).

  28. On appeal to the House counsel for the pursuer faced the problem, as he had at trial and in the First Division, that his own evidence precluded a finding that the absence of a shower had probably caused the pursuer's dermatitis. Mr Davidson QC accordingly relied on the evidence that provision of a shower would have materially reduced the risk to contend that he had made out a prima facie case. The contrary argument for the employers was advanced by Mr James Mackay QC, as reported at p 51:
  29. "It was accepted that [the provision of washing facilities] would have been a reasonable precaution, but it did not follow that this would have eliminated the risk. The employee might have developed dermatitis in any event. If the precaution would not have prevented the disease, the appellant was not entitled to damages. In the case of pneumoconiosis the inhalation of dangerous dust inevitably created a basis for the disease by accumulation, whereas in the case of dermatitis a particle of grit would cause the disease only if there were an abrasion which opened up the layer below the horny outer layer of the skin. In the case of pneumoconiosis all the particles could be blamed. It was not so in the case of dermatitis. The mere fact that shower baths would have reduced the chances of the contraction of the disease did not mean that what was probable would thereby have been rendered improbable."
    Thus the issue, as presented to the House, was whether the pursuer could succeed despite his inability to show that he would probably not have suffered dermatitis but for the defenders' failure to provide the showers which they should have provided.
  30. In the House, opinions were given by all five members of the Appellate Committee which heard the appeal and the appeal was allowed: [1973] 1 WLR 1. Lord Reid, giving the first opinion, described the pursuer's complaint based on the failure to provide shower facilities as raising "a difficult question of law" (p 3). He pointed out that the breach of duty in relation to showers was admitted, and it was admitted that the disease was attributable to the work which the pursuer had performed in the brick kiln, but it was contended that the pursuer had not proved that the defenders' failure to carry out the admitted duty had caused the onset of the disease (p 3). Lord Reid's understanding of the evidence, and his view of the proper approach to it, appear from the following passage of his opinion (at pp 4-5):
  31. "In the present case the evidence does not show - perhaps no one knows - just how dermatitis of this type begins. It suggests to me that there are two possible ways. It may be that an accumulation of minor abrasions of the horny layer of the skin is a necessary precondition for the onset of the disease. Or it may be that the disease starts at one particular abrasion and then spreads, so that multiplication of abrasions merely increases the number of places where the disease can start and in that way increases the risk of its occurrence.
    I am inclined to think that the evidence points to the former view. But in a field where so little appears to be known with certainty I could not say that that is proved. If it were, then this case would be indistinguishable from Wardlaw's case. But I think that in cases like this we must take a broader view of causation. 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. It does not and could not explain just why that is so. But experience shows that it is so. Plainly that must be because what happens while the man remains unwashed can have a causative effect, though just how the cause operates is uncertain. I cannot accept the view expressed in the Inner House that once the man left the brick kiln he left behind the causes which made him liable to develop dermatitis. That seems to me quite inconsistent with a proper interpretation of the medical evidence. Nor can I accept the distinction drawn by the Lord Ordinary between materially increasing the risk that the disease will occur and making a material contribution to its occurrence.
    There may be some logical ground for such a distinction where our knowledge of all the material factors is complete. But it has often been said that the legal concept of causation is not based on logic or philosophy. It is based on the practical way in which the ordinary man's mind works in the everyday affairs of life. From a broad and practical viewpoint I can see no substantial difference between saying that what the defender did materially increased the risk of injury to the pursuer and saying that what the defender did made a material contribution to his injury."
    Lord Wilberforce acknowledged the need for the pursuer to establish both a breach of duty and a causal connection between the default and the disease complained of (p 5), and also the difficulties of proof which the pursuer faced (pp 5-6):

    "[The pursuer's medical expert] could not do more than say that the failure to provide showers materially increased the chance, or risk, that dermatitis might set in."
    Lord Wilberforce accepted that merely to show that a breach of duty led to an increase of risk was not enough to enable a pursuer to succeed, but continued (at page 6):

    "But the question remains whether a pursuer must necessarily fail if, after he has shown a breach of duty, involving an increase of risk of disease, he cannot positively prove that this increase of risk caused or materially contributed to the disease while his employers cannot positively prove the contrary. In this intermediate case there is an appearance of logic in the view that the pursuer, on whom the onus lies, should fail - a logic which dictated the judgments below. The question is whether we should be satisfied, in factual situations like the present, with this logical approach. In my opinion, there are further considerations of importance. First, it is a sound principle that where a person has, by breach of a duty of care, created a risk, and injury occurs within the area of that risk, the loss should be borne by him unless he shows that it had some other cause. Secondly, from the evidential point of view, one may ask, why should a man who is able to show that his employer should have taken certain precautions, because without them there is a risk, or an added risk, of injury or disease, and who in fact sustains exactly that injury or disease, have to assume the burden of proving more: namely, that it was the addition to the risk, caused by the breach of duty, which caused or materially contributed to the injury? In many cases, of which the present is typical, this is impossible to prove, just because honest medical opinion cannot segregate the causes of an illness between compound causes. And if one asks which of the parties, the workman or the employers, should suffer from this inherent evidential difficulty, the answer as a matter of policy or justice should be that it is the creator of the risk who, ex hypothesi must be taken to have foreseen the possibility of damage, who should bear its consequences."
    Having referred to Wardlaw's and Nicholson's cases Lord Wilberforce concluded (at page 7):

    "The present factual situation has its differences: the default here consisted not in adding a material quantity to the accumulation of injurious particles but by failure to take a step which materially increased the risk that the dust already present would cause injury. And I must say that, at least in the present case, to bridge the evidential gap by inference seems to me something of a fiction, since it was precisely this inference which the medical expert declined to make. But I find in the cases quoted an analogy which suggests the conclusion that, in the absence of proof that the culpable addition had, in the result, no effect, the employers should be liable for an injury, squarely within the risk which they created and that they, not the pursuer, should suffer the consequence of the impossibility, foreseeably inherent in the nature of his injury, of segregating the precise consequence of their default."
    Lord Simon of Glaisdale considered that Wardlaw's and Nicholson's cases established a rule (at page 8)
    "that where an injury is caused by two (or more) factors operating cumulatively, one (or more) of which factors is a breach of duty and one (or more) is not so, in such a way that it is impossible to ascertain the proportion in which the factors were effective in producing the injury or which factor was decisive, the law does not require a pursuer or plaintiff to prove the impossible, but holds that he is entitled to damages for the injury if he proves on a balance of probabilities that the breach or breaches of duty contributed substantially to causing the injury. If such factors so operate cumulatively, it is, in my judgment, immaterial whether they do so concurrently or successively."
    Lord Simon then continued (page 8):

    "The question, then, is whether on the evidence the appellant brought himself within this rule. In my view, the failure to take steps which would bring about a material reduction of the risk involves, in this type of case, a substantial contribution to the injury. In this type of case a stark distinction between breach of duty and causation is unreal. If the provision of shower baths was (as the evidence showed) a precaution which any reasonable employer in the respondents' position would take, it means that such employer should have foreseen that failure to take the precaution would, more probably than not, substantially contribute towards injury: this is sufficient prima facie evidence."
    Lord Simon regarded "material reduction of the risk" and "substantial contribution to the injury" as mirror concepts. Any other conclusion would mean that the defenders were under a legal duty which they could, on the present state of medical knowledge, ignore (page 9).

    Lord Kilbrandon appears to have adopted a more orthodox approach to tortious liability. He said (at page 10):

    "When you find it proved (a) that the defenders knew that to take the precaution reduces the risk, chance, possibility or probability of the contracting of a disease, (b) that the precaution has not been taken, and (c) that the disease has supervened, it is difficult to see how those defenders can demand more by way of proof of the probability that the failure caused or contributed to the physical breakdown ... In the present case, the pursuer's body was vulnerable, while he was bicycling home, to the dirt which had been deposited on it during his working hours. It would not have been if he had had a shower. If showers had been provided he would have used them. It is admittedly more probable that disease will be contracted if a shower is not taken. In these circumstances I cannot accept the argument that nevertheless it is not more probable than not that, if the duty to provide a shower had not been neglected, he would not have contracted the disease. The pursuer has after all, only to satisfy the court of a probability, not to demonstrate an irrefragable chain of causation, which in a case of dermatitis, in the present state of medical knowledge, he could probably never do."
    In Lord Salmon's opinion the question before the House was whether the pursuer's dermatitis was proved to have been caused or materially contributed to by the defenders' negligence (page 11). He rejected the view, expressed by the Lord President (see paragraph 18 above) that to increase the risk of injury was not, in the circumstances of this case, to cause the injury. In such a case he regarded it as unrealistic and contrary to ordinary common sense to hold that the negligence which materially increased the risk of injury did not materially contribute to causing it (pages 11-12). He observed (at page 12):

    "I think that the approach by the courts below confuses the balance of probability test with the nature of causation. Moreover, it would mean that in the present state of medical knowledge and in circumstances such as these (which are by no means uncommon) an employer would be permitted by the law to disregard with impunity his duty to take reasonable care for the safety of his employees."
    Lord Salmon's conclusion (pages 12-13) was expressed in these terms:

    "In the circumstances of the present case, the possibility of a distinction existing between (a) having materially increased the risk of contracting the disease, and (b) having materially contributed to causing the disease may no doubt be a fruitful source of interesting academic discussions between students of philosophy. Such a distinction is, however, far too unreal to be recognised by the common law."
  32. This detailed review of McGhee permits certain conclusions to be drawn. First, the House was deciding a question of law. Lord Reid expressly said so (page 3). The other opinions, save perhaps that of Lord Kilbrandon, cannot be read as decisions of fact or as orthodox applications of settled law. Secondly, the question of law was whether, on the facts of the case as found, a pursuer who could not show that the defender's breach had probably caused the damage of which he complained could nonetheless succeed. Thirdly, it was not open to the House to draw a factual inference that the breach probably had caused the damage: such an inference was expressly contradicted by the medical experts on both sides; and once that evidence had been given the crux of the argument before the Lord Ordinary and the First Division and the House was whether, since the pursuer could not prove that the breach had probably made a material contribution to his contracting dermatitis, it was enough to show that the breach had increased the risk of his contracting it. Fourthly, it was expressly held by three members of the House (Lord Reid at page 5, Lord Simon at page 8 and Lord Salmon at pages 12-13) that in the circumstances no distinction was to be drawn between making a material contribution to causing the disease and materially increasing the risk of the pursuer contracting it. Thus the proposition expressly rejected by the Lord Ordinary, the Lord President and Lord Migdale was expressly accepted by a majority of the House and must be taken to represent the ratio of the decision, closely tied though it was to the special facts on which it was based. Fifthly, recognising that the pursuer faced an insuperable problem of proof if the orthodox test of causation was applied, but regarding the case as one in which justice demanded a remedy for the pursuer, a majority of the House adapted the orthodox test to meet the particular case. The authority is of obvious importance in the present appeal since the medical evidence left open the possibility, as Lord Reid pointed out at page 4, that the pursuer's dermatitis could have begun with a single abrasion, which might have been caused when he was cycling home, but might equally have been caused when he was working in the brick kiln; in the latter event, the failure to provide showers would have made no difference. In McGhee, however, unlike the present appeals, the case was not complicated by the existence of additional or alternative wrongdoers.
  33. In Wilsher v Essex Area Health Authority a problem of causation arose in a different context. A prematurely-born baby was the subject of certain medical procedures, in the course of which a breach of duty occurred. The baby suffered a condition (abbreviated as RLF) of a kind which that breach of duty could have caused, and the breach of duty increased the risk of his suffering it. But there were a number of other factors which might have caused the injury. In the Court of Appeal ([1987] QB 730 at 771-772) Mustill LJ concluded a detailed review of McGhee by making this statement of principle:
  34. "If it is an established fact that conduct of a particular kind creates a risk that injury will be caused to another or increases an existing risk that injury will ensue; and if the two parties stand in such a relationship that the one party owes a duty not to conduct himself in that way; and if the first party does conduct himself in that way; and if the other party does suffer injury of the kind to which the risk related; then the first party is taken to have caused the injury by his breach of duty, even though the existence and extent of the contribution made by the breach cannot be ascertained."
    Omitted from this statement is any reference to condition (5) in the composite question formulated in paragraph 2 at the outset of this opinion. It was on this omission that Sir Nicolas Browne-Wilkinson V-C founded his dissenting opinion (at page 779):

    "To apply the principle in McGhee v National Coal Board [1973] 1 WLR 1 to the present case would constitute an extension of that principle. In the McGhee case there was no doubt that the pursuer's dermatitis was physically caused by brick dust: the only question was whether the continued presence of such brick dust on the pursuer's skin after the time when he should have been provided with a shower caused or materially contributed to the dermatitis which he contracted. There was only one possible agent which could have caused the dermatitis, viz, brick dust, and there was no doubt that the dermatitis from which he suffered was caused by that brick dust.
    In the present case the question is different. There are a number of different agents which could have caused the RLF. Excess oxygen was one of them. The defendants failed to take reasonable precautions to prevent one of the possible causative agents (e.g. excess oxygen) from causing RLF. But no one can tell in this case whether excess oxygen did or did not cause or contribute to the RLF suffered by the plaintiff. The plaintiff's RLF may have been caused by some completely different agent or agents, e.g. hypercarbia, intraventicular haemorrhage apnoea or patent ductus arteriosus. In addition to oxygen, each of those conditions has been implicated as a possible cause of RLF. This baby suffered from each of those conditions at various times in the first two months of his life. There is no satisfactory evidence that excess oxygen is more likely than any of those other four candidates to have caused RLF in this baby. To my mind, the occurrence of RLF following a failure to take a necessary precaution to prevent excess oxygen causing RLF provides no evidence and raises no presumption that it was excess oxygen rather than one or more of the four other possible agents which caused or contributed to RLF in this case.
    The position, to my mind, is wholly different from that in the McGhee case [1973] 1 WLR 1, where there was only one candidate (brick dust) which could have caused the dermatitis, and the failure to take a precaution against brick dust causing dermatitis was followed by dermatitis caused by brick dust. 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. A failure to take preventative measures against one out of five possible causes is no evidence as to which of those five caused the injury."
    On the defendants' appeal to the House, this passage in the Vice-Chancellor's judgment was expressly approved by Lord Bridge of Harwich, who gave the only opinion, with which Lord Fraser of Tullybelton, Lord Lowry, Lord Griffiths and Lord Ackner concurred, and the appeal was allowed: [1988] AC 1074,1090-1092. It is plain, in my respectful opinion, that the House was right to allow the defendants' appeal in Wilsher, for the reasons which the Vice-Chancellor had given and which the House approved. It is one thing to treat an increase of risk as equivalent to the making of a material contribution where a single noxious agent is involved, but quite another where any one of a number of noxious agents may equally probably have caused the damage. The decision of the Court of Appeal did indeed involve an extension of the McGhee principle, as Mustill LJ recognised: [1987] QB 730, 771-772. Lord Bridge was also, as I respectfully think, right to describe the observations of Lord Wilberforce on reversal of the burden of proof (see paragraph 20 above) as expressing a "minority opinion" (p 1087), if Lord Wilberforce was suggesting more than that the proof of an increased risk can found a prima facie case which casts an evidential burden on the defendant. But much difficulty is caused by the following passage in Lord Bridge's opinion in which, having cited the opinions of all members of the House in McGhee, he said (p 1090):

    "The conclusion I draw from these passages is that McGhee v National Coal Board [1973] 1 WLR 1 laid down no new principle of law whatever. On the contrary, it affirmed the principle that the onus of proving causation lies on the pursuer or plaintiff. Adopting a robust and pragmatic approach to the undisputed primary facts of the case, the majority concluded that it was a legitimate inference of fact that the defenders' negligence had materially contributed to the pursuer's injury. The decision, in my opinion, is of no greater significance than that and to attempt to extract from it some esoteric principle which in some way modifies, as a matter of law, the nature of the burden of proof of causation which a plaintiff or pursuer must discharge once he has established a relevant breach of duty is a fruitless one."
    This is a passage to which the Court of Appeal very properly gave weight ([2002] 1 WLR 1052, 1080, para 103), and in argument on these appeals counsel for the respondents strongly relied on it as authority for their major contention that a claimant can only succeed if he proves on the balance of probabilities that the default of the particular defendant had caused the damage of which he complains. As is apparent from the conclusions expressed in paragraph 21 above, I cannot for my part accept this passage in Lord Bridge's opinion as accurately reflecting the effect of what the House, or a majority of the House, decided in McGhee, which remains sound authority. I am bound to conclude that this passage should no longer be treated as authoritative.
    The wider jurisprudence
     23. The problem of attributing legal responsibility where a victim has suffered a legal wrong but cannot show which of several possible candidates (all in breach of duty) is the culprit who has caused him harm is one that has vexed jurists in many parts of the world for many years. As my noble and learned friend Lord Rodger of Earlsferry shows (see paras 157-160 below) it engaged the attention of classical Roman jurists. It is indeed a universal problem calling for some consideration by the House, however superficially, of the response to it in other jurisdictions.

  35. Professor Christian von Bar (The Common European Law of Torts, 2000, vol 2, pp 441-443) has written:
  36. "The phenomenon of double causation is thus an insufficient argument against the but - for test. It is merely peripheral. Of greater importance are the many cases in which, although one cannot speak of a scientifically ascertainable or explicable 'cause' and 'effect', courts have awarded compensation on the basis of fault and probability. German law on medical negligence provides the example of the reduced burden of proof of causation in cases of grave treatment errors. Recent environmental legislation has reacted to the problem of scientifically uncertain causal relationships in a similar manner. The reversal of the burden of proof regarding causation is no more than a reduction of the probability required for attribution. A further development has arisen in the Netherlands regarding liability for medicines in the context of DES liability. The Hoge Raad's solution, on the basis of Art 6.99BW, of holding jointly liable to cancer sufferers the manufacturers of all those carcinogenic medicines available at the time when the victims' mothers had taken those substances is clearly unjustifiable under the conditio sine qua non rule. If the issue is seen to be whether the victim or the person posing the risk is better positioned to bear that risk, the solution is more comprehensible."
    In similar vein, Professor Walter van Gerven (van Gerven, Lever and Larouche: Cases, Materials and Text on National, Supranational and International Tort Law, 2000, p 441), surveying the tort law of, in particular, Germany, France and Britain, wrote:

    "In many cases, it will be possible for the victim to show that he or she has suffered injury, that it has been caused by someone who must have been at fault, but the author of that fault will not be identifiable. The best that the victim will be able to achieve is to define a class of persons of which the actual tortfeasor must be a member. Strictly speaking, however, the basic conditio sine qua non test will not be met, since it cannot be said of any member of the class that the injury would not have happened 'but for' his or her conduct, given that in fact any other member could have caused the injury. Nonetheless, all the legal systems studied here have acknowledged that it would be patently unfair to deny recovery to the victim for that reason."
    At p 461, after reference to McGhee's case ([1973] 1 WLR 1) and Wilsher's case ([1988] AC 1074) van Gerven added:

    "McGhee had put English law on the same path as German law, albeit with a different and arguably stronger rationale (negligent creation of risk instead of impossibility for the plaintiff to prove causation). Furthermore, it must be noted that some French legal writers are advocating that French law moves away from perte d'une chance towards a reversal of the burden of proof on the basis of the negligent creation of risk. It is unfortunate that the House of Lords retreated from McGhee at a time when laws were converging. In the end, the sole relief for the plaintiff under English law is that it suffices for the purposes of causation to show that the conduct of the defendant made a material contribution to the injury, even if it was not its sole cause."
    He concluded (at p 465):

    "In certain cases, the plaintiff can show that he or she suffered injury, that it was caused by some person and that the other conditions of liability are otherwise fulfilled but for the fact that the actual tortfeasor cannot be identified among the members of a class of persons. In these cases, the strict application of the 'but for' test would result in the claim of the plaintiff being dismissed, but all systems under study here make an exception to the rules of causation to provide the plaintiff with compensation."
  37. In Germany cases of this kind have been held to be covered by the second sentence (to which emphasis has been added) of BGB §830.1 which provides:
  38. "If several persons have caused damage by an unlawful act committed in common each is responsible for the damage. The same rule applies if it cannot be discovered which of several participants has caused the damage by his act."
    Of this provision Markesinis and Unberath (The German Law of Torts, 4th ed, 2002, p 900) states:

    "§830.1, second sentence, applies the same rule to a different situation where several persons participate in a course of conduct which, though not unlawful in itself, is potentially dangerous to others. The difference between this and the previous situation lies in the fact that whereas in the former case of joint tortfeasors the loss is caused by several persons acting in consort, in the latter case only one person has caused the loss but it is difficult if not impossible to say which one has done so. (The classic illustration is that of the huntsmen who discharge their guns simultaneously and the pellets from one unidentifiable gun hit an innocent passer-by.) In this case, as well, §830 BGB adopts the same rule and makes all the participants liable to the victim for the full extent of damage."
    It is evident that this approach has been applied in Germany in a number of different situations: see Palandt, Bürgerliches Gesetzbuch, 61 ed 2002, para 830. Thus cases decided on this basis have included personal injury caused by several individuals throwing stones in a fight; personal injury of a pedestrian who passes a construction site operated by different companies; personal injury by a New Year's Eve rocket launched by a group of individuals who were all firing rockets; liability of several hunters for the personal injury of a passer-by; liability of a houseowner for the personal injury of a pedestrian who walks on a dangerous path and is hurt on the borderline between the houseowner's land and an unfinished street owned by the local authority; and personal injury of a patient after various interrelated operations conducted by different doctors. The extent to which this approach to causation may be subject to certain restrictive conditions appears to be a matter of some uncertainty; see van Gerven, op. cit, p 446.
  39. The BGB is not alone in expressly recognising the problem of the indeterminate defendant. Article 926 of the Greek Civil Code, entitled "Damage caused by several persons" provides:
  40. "If damage has occurred as a result of the joint action of several persons, or if several persons are concurrently responsible for the same damage, they are all jointly and severally implicated. The same applies if several persons have acted simultaneously or in succession and it is not possible to determine which person's act caused the damage."
    The second sentence of this provision would appear to cover the contingency under consideration, although the contrary has been asserted: Unification of Tort Law: Causation, ed J Spier, 2000, at p 77. A somewhat similar provision is to be found in the Austrian Civil Code:

    "1302 In such a case, if the injury is inadvertent, and it is possible to determine the portions thereof, each person is responsible only for the injuries caused by his mistake. If, however, the injury was intentional, or if the portions of the individuals in the injury cannot be determined, all are liable for one and one for all; however, the individual who has paid damages is granted the right to claim reimbursement from the others."
    A similar provision is also found in the Netherlands Civil Code (Article 6.99 BW: see paragraph 29 below).

  41. The problem of attribution has repeatedly arisen in the context of shooting incidents, described by Professor Markesinis as "The classic illustration" in the passage quoted in para 25 above. In Litzinger v Kintzler (Cass. civ. 2e, 5 June 1957, D 1957 Jur. 493), where a group of huntsmen fired a salvo to mark the end of a deer hunt and the plaintiff was shot, the French Cour de Cassation held the whole group liable since "the whole group created a risk through its negligent conduct, and the injury to the plaintiff constituted a realisation of that risk" (see van Gerven, op cit. at pp 442-444). It appears that this reasoning (depending on a broad view of acting in concert) has been reaffirmed in later cases (ibid). In Spain, a provision of the Hunting Act 1970 provides that "In the case of hunting with weapons, if the author of the personal injury is not known, all members of the hunting party shall be jointly and severally liable." This is not a problem which is confined to Europe. In Summers v Tice 199 P 2d 1 (1948) each of two defendants at or about the same time shot at a quail and in doing so fired towards the plaintiff who was struck by shot. The Supreme Court of California referred (at p 3) to earlier authority and said:
  42. "These cases speak of the action of defendants as being in concert as the ground of decision, yet it would seem they are straining that concept and the more reasonable basis appears in Oliver v Miles, supra. There two persons were hunting together. Both shot at some partridges and in so doing shot across the highway injuring plaintiff who was travelling on it. The court stated they were acting in concert and thus both were liable. The court then stated . .
    'We think that . . . each is liable for the resulting injury to the boy, although no one can say definitely who actually shot him. To hold otherwise would be to exonerate both from liability, although each was negligent, and the injury resulted from such negligence.' [Emphasis added]."
    The conclusion of the court was expressed on p 4, para 5, and p 5, para 7 of the judgment:

    "When we consider the relative position of the parties and the results that would flow if plaintiff was required to pin the injury on one of the defendants only, a requirement that the burden of proof on that subject be shifted to defendants becomes manifest. They are both wrongdoers - both negligent toward plaintiff. They brought about a situation where the negligence of one of them injured the plaintiff, hence it should rest with them each to absolve himself if he can . . . We have seen that for the reasons of policy discussed herein, the case is based upon the legal proposition that, under the circumstances here presented, each defendant is liable for the whole damage whether they are deemed to be acting in concert or independently."
    The Summers alternative liability theory was incorporated in the Restatement Second of Torts, section 433B, subdivision (3) pages 441-447, which provides:

    "Where the conduct of two or more actors is tortious, and it is proved that harm has been caused to the plaintiff by only one of them, but there is uncertainty as to which one has caused it, the burden is upon each such actor to prove that he has not caused the harm."
    The Supreme Court of Canada confronted this situation in Cook v Lewis [1951] SCR 830, in which Cartwright J, with whom a majority agreed, said at p 842:

    "I do not think it necessary to decide whether all that was said in Summers v Tice should be accepted as stating the law of British Columbia, but I am of opinion, for the reasons given in that case, that if under the circumstances of the case at bar the jury, having decided that the plaintiff was shot by either Cook or Akenhead, found themselves unable to decide which of the two shot him because in their opinion both shot negligently in his direction, both defendants should have been found liable."
  43. In a Norwegian case (see Nils Nygaard, Injury/Damage and Responsibility, 2000, pp 342-343) F was a passenger on a motor scooter and was injured in an accident caused either by a cable stretched across the street by a construction company or by the motor scooter falling onto him or as a result of collision with a truck, or by any combination of these factors. In giving judgment (RG 1969 p 285 at 293) the Norwegian court said:
  44. "As stated in the beforementioned conclusions made by experts, they could not conclude whether the situation that resulted in crushed bones in F's left hip region, was a result of falling on the cobble stones in the street or from the truck's front tyre, that ended up on top of F's left hip region. It is possible that the injuries were partially a result of the fall and being hit by the truck. We cannot say anything definite about this. The court finds that it cannot conclude whether it is the fall or being hit by the truck or a combination of both these factors that caused the injury. After a collective evaluation of the whole event the court finds that A (construction company), the scooter and the truck each have a part in F getting injured and each of them must naturally be seen as adequate cause of injury."
    This decisions bears a strong resemblance to that reached by the English Court of Appeal in Fitzgerald v Lane [1987] QB 781, decided after the decision of the Court of Appeal in Wilsher [1987] QB 730 but before the decision of the House of Lords ([1988] AC 1074).

  45. Increasingly in recent years, the problem of attribution has arisen in more complicated factual situations. Sindell v Abbott Laboratories 26 Cal. 3d 588 (1980) was a class action for personal injuries said to have resulted from pre-natal exposure to the anti-miscarriage drug diethylstilbestrol (DES) which had been manufactured by one of a potentially large number of defendants. The plaintiff could not identify which particular defendant had manufactured the drug responsible for her injuries. However, her complaint alleged that the defendants were jointly and individually negligent in that they had manufactured, marketed and promoted DES as a safe drug to prevent miscarriage without adequate testing or warning of its dangerous side effects; that they had collaborated in their marketing methods, promotion and testing of the drug; that they had relied on each others' test results; that they had adhered to an industry-wide safety standard; and that they had produced the drug from a common and mutually agreed generic formula. The court distinguished Summers on the basis that in that case all the parties who were or could have been responsible for the harm to the plaintiff were joined as defendants, whereas in Sindell there were approximately 200 drug companies which had made DES, any of which might have manufactured the injury-producing drug. The court held that it would be unfair, in such circumstances, to require each defendant to exonerate itself. Further, it said that there might be a substantial likelihood that none of the five defendants joined in the action had made the DES which caused the injury, and that the offending producer, not named, would escape liability. The court surmounted this problem by adapting the Summers rule so as to apportion liability on the basis of the defendant's market share. See pp 593-595, 602-603, 604-605 and 612-613. A very similar case concerning the same drug arose in the Netherlands in B v Bayer Nederland BV (Hoge Raad, 9 October 1992, NJ 1994, 535) which turned on Article 6.99 BW. That provision is in these terms:
  46. "Where the damage may have resulted from two or more events for each of which a different person is liable, and where it has been determined that the damage has arisen from at least one of these events, the obligation to repair the damage rests upon each of these persons, unless he proves that the damage is not the result of the event for which he himself is liable".
    In para 3.7.1 of its judgment the Hoge Raad held:

    "The facts of the present case fall under that provision, on the assumption that it can be proved that [i] each of the firms which put DES in circulation in the relevant period was at fault in so doing and could thus be held liable, [ii] the total injury of each victim could have been caused by any of these 'events' - i.e. putting DES in circulation - and [iii] the injury occurred because of at least one of these 'events' . . .
    "[Article 6.99BW] aims to remove the unfairness arising from the fact that the victim must bear his or her own damage because he or she cannot prove whose action caused his or her harm. The victims in the present case are faced with such an evidentiary difficulty . . .".
    In para 3.7.5 of its judgment the court said:

    "It is sufficient for each DES daughter to establish . . . in relation to each of the pharmaceutical companies:
    (i)
    that the pharmaceutical company in question put DES in circulation during the relevant period and can therefore be found liable because it committed a fault;
    (ii)
    that another or several other producers - regardless of whether they are parties to the proceedings or not - also put DES in circulation during the relevant period and can therefore also be found liable because it (they) committed a fault; and
    (iii)
    that she suffered injury that resulted from the use of DES, but that it is no longer possible to determine from which producer the DES originated."
    In principle the burden of proof on these issues rests on the DES daughter concerned."
    See van Gerven, op cit, at pages 447-448.

  47. Cases decided in the High Court of Australia do not disclose a clear ratio on which the appellants were able to rely before the House, although they drew attention to dicta which were helpful to them. For example, in Chappel v Hart (1998) 195 CLR 232 at 244, para 27, McHugh J said, in a passage reminiscent of McGhee, although without referring to that case:
  48. "Before the defendant will be held responsible for the plaintiff's injury, the plaintiff must prove that the defendant's conduct materially contributed to the plaintiff suffering that injury. In the absence of a statute or undertaking to the contrary, therefore, it would seem logical to hold a person causally liable for a wrongful act or omission only when it increases the risk of injury to another person. If a wrongful act or omission results in an increased risk of injury to the plaintiff and that risk eventuates, the defendant's conduct has materially contributed to the injury that the plaintiff suffers whether or not other factors also contributed to that injury occurring. If, however, the defendant's conduct does not increase the risk of injury to the plaintiff, the defendant cannot be said to have materially contributed to the injury suffered by the plaintiff. That being so, whether the claim is in contract or tort, the fact that the risk eventuated at a particular time or place by reason of the conduct of the defendant does not itself materially contribute to the plaintiff's injury unless the fact of that particular time or place increased the risk of the injury occurring."
    In that case McHugh J dissented on the facts but in Naxakis v Western General Hospital (1999) 197 CLR 269 both Gaudron J (at p 279, para 31) and Callinan J (at p 312, para 127) quoted what he had said with approval. In Canada, Sopinka J, speaking for the Supreme Court in Snell v Farrell [1990] 2 SCR 311 said, at pp 326-327:

    "I have examined the alternatives arising out of the McGhee case. They were that the plaintiff simply prove that the defendant created a risk that the injury which occurred would occur. Or, what amounts to the same thing, that the defendant has the burden of disproving causation. If I were convinced that defendants who have a substantial connection to the injury were escaping liability because plaintiffs cannot prove causation under currently applied principles, I would not hesitate to adopt one of these alternatives. In my opinion, however, properly applied, the principles relating to causation are adequate to the task. Adoption of either of the proposed alternatives would have the effect of compensating plaintiffs where a substantial connection between the injury and the defendant's conduct is absent. Reversing the burden of proof may be justified where two defendants negligently fire in the direction of the plaintiff and then by their tortious conduct destroy the means of proof at his disposal. In such a case it is clear that the injury was not caused by neutral conduct. It is quite a different matter to compensate a plaintiff by reversing the burden of proof for an injury that may very well be due to factors unconnected to the defendant and not the fault of anyone."
    Sopinka J suggested, at p 328, that dissatisfaction with the traditional approach to causation stemmed to a large extent from its too rigid application by the courts in many cases, and that causation need not be determined by scientific precision. Despite this judgment the Manitoba Court of Appeal, in Webster v Chapman (1997) 155 DLR (4th) 82 held, relying on McGhee, that no distinction should be made in that case between materially increasing the risk of damage and materially contributing to the damage.

  49. There is a small but important body of authority on the problem of attribution in mesothelioma cases where the plaintiff has been exposed to asbestos during employment by more than one employer. Bendix Mintex Pty Ltd v Barnes (1997) 42 NSWLR 307 was such a case. A majority of the Court of Appeal of New South Wales held against the plaintiff on the causation issue, relying on Wilsher [1988] AC 1074 among much other authority. Stein JA dissented, citing with approval the following passage from the judgment of King CJ in Birkholtz v R J Gilbertson Pty Ltd (1985) 38 SASR 121 at 130:
  50. ". . . the law's view of causation is less concerned with logical and philosophical considerations than with the need to produce a just result to the parties involved. Where a defendant is under a legal duty to take precautions to protect the plaintiff from the risk of contracting disease, and, by omitting those precautions he substantially increases the risk of the plaintiff contracting that disease, the law treats that increase in risk as a sufficient basis, in the absence of evidence showing how the infection occurred, for an inference that the omission of the precautions materially contributed to the contracting of the disease. Justice requires such an approach to the problem of causation and it is the approach which was taken by the House of Lords in McGhee v National Coal Board [1973] 1 WLR 1."
    The majority decision in Bendix was followed in Wallaby Grip (BAE) Pty Ltd v Macleay Area Health Service (1998) 17 NSWCCR 355. A different result was reached in E M Baldwin & Son Pty Ltd v Plane (1999) Aust Torts Reports 81-499, but on different medical evidence. A different view of the law was also expressed in Rutherford v Owens-Illinois Inc 67 Cal. Rptr. 2d 16 (1997). In a judgment with which the Chief Justice and all save one member of the Supreme Court of California concurred, Baxter J observed (at p 19):

    "Proof of causation in such cases will always present inherent practical difficulties, given the long latency period of asbestos-related disease, and the occupational settings that commonly exposed the worker to multiple forms and brands of asbestos products with varying degrees of toxicity. In general, however, no insuperable barriers prevent an asbestos-related cancer plaintiff from demonstrating that exposure to the defendant's asbestos products was, in reasonable medical probability, a substantial factor in causing or contributing to his risk of developing cancer. We conclude that plaintiffs are required to prove no more than this. In particular, they need not prove with medical exactitude that fibers from a particular defendant's asbestos-containing products were those, or among those, that actually began the cellular process of malignancy."
    Baxter J reviewed earlier cases such as Summers 119 P 2d 1 (1948) and Sindell 26 Cal. 3d 588 (1980) and specifically addressed the factual possibility that a mesothelioma may be caused by inhalation of a single fibre, acknowledging (at pp 30-31) that the single fibre theory raised an apparently unanswerable question: "which particular fibre or fibres actually caused the cancer to begin forming[?]". He observed (at p 31) that plaintiffs could not be expected to prove the scientifically unknown details of carcinogenesis or trace the unknowable path of a given asbestos fibre. For reasons given very clearly but at some length Baxter J rejected a burden-shifting approach to cases of this kind. At p 36 the judgment concluded:

    "In the context of a cause of action for asbestos-related latent injuries, the plaintiff must first establish some threshold exposure to the defendant's defective asbestos-containing products, and must further establish in reasonable medical probability that a particular exposure or series of exposures was a 'legal cause' of his injury, ie, a substantial factor in bringing about the injury. In an asbestos-related cancer case, the plaintiff need not prove that fibers from the defendant's product were the ones, or among the ones, that actually began the process of malignant cellular growth. Instead, the plaintiff may meet the burden of proving that exposure to defendant's product was a substantial factor causing the illness by showing that in reasonable medical probability it was a substantial factor contributing to the plaintiff's or decedent's risk of developing cancer."
    The dissent of Mosk J related solely to the court's decision on shifting of the burden: he considered (p 38) that the decision of the majority would deprive numerous plaintiffs suffering from latent diseases caused by exposure to asbestos in the workplace from recovering full compensation.

  51. This survey shows, as would be expected, that though the problem underlying cases such as the present is universal the response to it is not. Hence the plethora of decisions given in different factual contexts. Hence also the intensity of academic discussion, exemplified by the articles of the late Professor Fleming ("Probabilistic Causation in Tort Law" 68 Canadian Bar Review, No 4, December 1989, 661) and Professor Robertson ("The Common Sense of Cause in Fact", 75 Tex L Rev (1996-1997), 1765). In some jurisdictions, it appears, the plaintiff would fail altogether on causation grounds, as the Court of Appeal held that the present appellants did. Italy, South Africa and Switzerland may be examples (see Unification of Tort Law: Causation, ed J Spier, 2000 at pp 90, 102 and 120). But it appears that in most of the jurisdictions considered the problem of attribution would not, on facts such as those of the present cases, be a fatal objection to a plaintiff's claim. Whether by treating an increase in risk as equivalent to a material contribution, or by putting a burden on the defendant, or by enlarging the ordinary approach to acting in concert, or on more general grounds influenced by policy considerations, most jurisdictions would, it seems, afford a remedy to the plaintiff. Development of the law in this country cannot of course depend on a head-count of decisions and codes adopted in other countries around the world, often against a background of different rules and traditions. The law must be developed coherently, in accordance with principle, so as to serve, even-handedly, the ends of justice. If, however, a decision is given in this country which offends one's basic sense of justice, and if consideration of international sources suggests that a different and more acceptable decision would be given in most other jurisdictions, whatever their legal tradition, this must prompt anxious review of the decision in question. In a shrinking world (in which the employees of asbestos companies may work for those companies in any one or more of several countries) there must be some virtue in uniformity of outcome whatever the diversity of approach in reaching that outcome.
  52. Policy
  53. The present appeals raise an obvious and inescapable clash of policy considerations. On the one hand are the considerations powerfully put by the Court of Appeal ([2002] 1 WLR 1052 at 1080, para 103) which considered the claimants' argument to be not only illogical but
  54. "also susceptible of unjust results. It may impose liability for the whole of an insidious disease on an employer with whom the claimant was employed for quite a short time in a long working life, when the claimant is wholly unable to prove on the balance of probabilities that that period of employment had any causative relationship with the inception of the disease. This is far too weighty an edifice to build on the slender foundations of McGhee v National Coal Board [1973] 1WLR 1, and Lord Bridge has told us in Wilsher v Essex Area Health Authority [1988] AC 1074 that McGhee established no new principle of law at all. If we were to accede to the claimants' arguments, we would be distorting the law to accommodate the exigencies of a very hard case. We would be yielding to a contention that all those who have suffered injury after being exposed to a risk of that injury from which someone else should have protected them should be able to recover compensation even when they are quite unable to prove who was the culprit. In a quite different context Lord Steyn has recently said in Frost v Chief Constable of Yorkshire [1999] 2 AC 455, 491 that our tort system sometimes results in imperfect justice, but it is the best the common law can do."
    The Court of Appeal had in mind that in each of the cases discussed in paras 14-21 above (Wardlaw, Nicholson, Gardiner, McGhee) there was only one employer involved. Thus there was a risk that the defendant might be held liable for acts for which he should not be held legally liable but no risk that he would be held liable for damage which (whether legally liable or not) he had not caused. The crux of cases such as the present, if the appellants' argument is upheld, is that an employer may be held liable for damage he has not caused. The risk is the greater where all the employers potentially liable are not before the court. This is so on the facts of each of the three appeals before the House, and is always likely to be so given the long latency of this condition and the likelihood that some employers potentially liable will have gone out of business or disappeared during that period. It can properly be said to be unjust to impose liability on a party who has not been shown, even on a balance of probabilities, to have caused the damage complained of. On the other hand, there is a strong policy argument in favour of compensating those who have suffered grave harm, at the expense of their employers who owed them a duty to protect them against that very harm and failed to do so, when the harm can only have been caused by breach of that duty and when science does not permit the victim accurately to attribute, as between several employers, the precise responsibility for the harm he has suffered. I am of opinion that such injustice as may be involved in imposing liability on a duty-breaking employer in these circumstances is heavily outweighed by the injustice of denying redress to a victim. Were the law otherwise, an employer exposing his employee to asbestos dust could obtain complete immunity against mesothelioma (but not asbestosis) claims by employing only those who had previously been exposed to excessive quantities of asbestos dust. Such a result would reflect no credit on the law. It seems to me, as it did to Lord Wilberforce in McGhee [1973] 1 WLR 1 at 7, that
    "the employers should be liable for an injury, squarely within the risk which they created and that they, not the pursuer, should suffer the consequence of the impossibility, foreseeably inherent in the nature of his injury, of segregating the precise consequence of their default."
    Conclusion
  55. To the question posed in paragraph 2 of this opinion I would answer that where conditions (1)-(6) are satisfied C is entitled to recover against both A and B. That conclusion is in my opinion consistent with principle, and also with authority (properly understood). Where those conditions are satisfied, it seems to me just and in accordance with common sense to treat the conduct of A and B in exposing C to a risk to which he should not have been exposed as making a material contribution to the contracting by C of a condition against which it was the duty of A and B to protect him. I consider that this conclusion is fortified by the wider jurisprudence reviewed above. Policy considerations weigh in favour of such a conclusion. It is a conclusion which follows even if either A or B is not before the court. It was not suggested in argument that C's entitlement against either A or B should be for any sum less than the full compensation to which C is entitled, although A and B could of course seek contribution against each other or any other employer liable in respect of the same damage in the ordinary way. No argument on apportionment was addressed to the House. I would in conclusion emphasise that my opinion is directed to cases in which each of the conditions specified in (1) - (6) of paragraph 2 above is satisfied and to no other case. It would be unrealistic to suppose that the principle here affirmed will not over time be the subject of incremental and analogical development. Cases seeking to develop the principle must be decided when and as they arise. For the present, I think it unwise to decide more than is necessary to resolve these three appeals which, for all the foregoing reasons, I concluded should be allowed.
  56. For reasons given above, I cannot accept the view (considered in the opinion of my noble and learned friend Lord Hutton) that the decision in McGhee was based on the drawing of a factual inference. Nor, in my opinion, was the decision based on the drawing of a legal inference. Whether, in certain limited and specific circumstances, a legal inference is drawn or a different legal approach is taken to the proof of causation, may not make very much practical difference. But Lord Wilberforce, in one of the passages of his opinion in McGhee quoted in paragraph 20 above, wisely deprecated resort to fictions and it seems to me preferable, in the interests of transparency, that the courts' response to the special problem presented by cases such as these should be stated explicitly. I prefer to recognise that the ordinary approach to proof of causation is varied than to resort to the drawing of legal inferences inconsistent with the proven facts.
  57. LORD NICHOLLS OF BIRKENHEAD
    My Lords,
  58. I have no hesitation in agreeing with all your Lordships that these appeals should be allowed. Any other outcome would be deeply offensive to instinctive notions of what justice requires and fairness demands. The real difficulty lies is elucidating in sufficiently specific terms the principle being applied in reaching this conclusion. To be acceptable the law must be coherent. It must be principled. The basis on which one case, or one type of case, is distinguished from another should be transparent and capable of identification. When a decision departs from principles normally applied, the basis for doing so must be rational and justifiable if the decision is to avoid the reproach that hard cases make bad law. I turn therefore to consider the departure from the normal, and the basis of that departure, in the present appeals.
  59. In the normal way, in order to recover damages for negligence, a plaintiff must prove that but for the defendant's wrongful conduct he would not have sustained the harm or loss in question. He must establish at least this degree of causal connection between his damage and the defendant's conduct before the defendant will be held responsible for the damage.
  60. Exceptionally this is not so. In some circumstances a lesser degree of causal connection may suffice. This sometimes occurs where the damage flowed from one or other of two alternative causes. Take the well-known example where two hunters, acting independently of each other, fire their guns carelessly in a wood, and a pellet from one of the guns injures an innocent passer-by. No one knows, and the plaintiff is unable to prove, from which gun the pellet came. Should the law of negligence leave the plaintiff remediless, and allow both hunters to go away scot-free, even though one of them must have fired the injurious pellet?
  61. Not surprisingly, the courts have declined to reach such an unjust decision: see Summers v Tice (1948) 199 P 2d 1, a decision of the Supreme Court of California, and Cook v Lewis [1951] SCR 830, a decision of the Supreme Court of Canada. As between the plaintiff and the two hunters, the evidential difficulty arising from the impossibility of identifying the gun which fired the crucial pellet should redound upon the negligent hunters, not the blameless plaintiff. The unattractive consequence, that one of the hunters will be held liable for an injury he did not in fact inflict, is outweighed by the even less attractive alternative, that the innocent plaintiff should receive no recompense even though one of the negligent hunters injured him. It is this balance ('.. outweighed by ..') which justifies a relaxation in the standard of causation required. Insistence on the normal standard of causation would work an injustice. Hunting in a careless manner and thereby creating a risk of injury to others, followed by injury to another person, is regarded by the law as sufficient causal connection in the circumstances to found responsibility.
  62. This balancing exercise involves a value judgment. This is not at variance with basic principles in this area of the law. The extent to which the law requires a defendant to assume responsibility for loss following upon his wrongful conduct always involves a value judgment. The law habitually limits the extent of the damage for which a defendant is held responsible, even when the damage passes the threshold 'but for' test. The converse is also true. On occasions the threshold 'but for' test of causal connection may be over-exclusionary. Where justice so requires, the threshold itself may be lowered. In this way the scope of a defendant's liability may be extended. The circumstances where this is appropriate will be exceptional, because of the adverse consequences which the lowering of the threshold will have for a defendant. He will be held responsible for a loss the plaintiff might have suffered even if the defendant had not been involved at all. To impose liability on a defendant in such circumstances normally runs counter to ordinary perceptions of responsibility. Normally this is unacceptable. But there are circumstances, of which the two hunters' case is an example, where this unattractiveness is outweighed by leaving the plaintiff without a remedy.
  63. The present appeals are another example of such circumstances, where good policy reasons exist for departing from the usual threshold 'but for' test of causal connection. Inhalation of asbestos dust carries a risk of mesothelioma. That is one of the very risks from which an employer's duty of care is intended to protect employees. Tragically, each claimant acquired this fatal disease from wrongful exposure to asbestos dust in the course of his employment. A former employee's inability to identify which particular period of wrongful exposure brought about the onset of his disease ought not, in all justice, to preclude recovery of compensation.
  64. So long as it was not insignificant, each employer's wrongful exposure of its employee to asbestos dust and, hence, to the risk of contracting mesothelioma, should be regarded by the law as a sufficient degree of causal connection. This is sufficient to justify requiring the employer to assume responsibility for causing or materially contributing to the onset of the mesothelioma when, in the present state of medical knowledge, no more exact causal connection is ever capable of being established. Given the present state of medical science, this outcome may cast responsibility on a defendant whose exposure of a claimant to the risk of contracting the disease had in fact no causative effect. But the unattractiveness of casting the net of responsibility as widely as this is far outweighed by the unattractiveness of the alternative outcome.
  65. I need hardly add that considerable restraint is called for in any relaxation of the threshold 'but for' test of causal connection. The principle applied on these appeals is emphatically not intended to lead to such a relaxation whenever a plaintiff has difficulty, perhaps understandable difficulty, in discharging the burden of proof resting on him. Unless closely confined in its application this principle could become a source of injustice to defendants. There must be good reason for departing from the normal threshold 'but for' test. The reason must be sufficiently weighty to justify depriving the defendant of the protection this test normally and rightly affords him, and it must be plain and obvious that this is so. Policy questions will loom large when a court has to decide whether the difficulties of proof confronting the plaintiff justify taking this exceptional course. It is impossible to be more specific.
  66. I should comment briefly on the much discussed case of McGhee v National Coal Board [1973] 1 WLR 1. As I understand it, the decision of your Lordships' House is an example of the application of the approach discussed above. In the circumstances of that case the House departed from the usual threshold 'but for' test of causal connection and treated a lesser degree of causal connection as sufficient. The novelty in the decision lay in the adoption of this approach in this country and, further, in the type of claim to which this approach was applied: there, as with the present appeals, the field of industrial disease. Given the medical evidence in McGhee, it was not open to the House, however robustly inclined, to draw an inference that the employer's negligence had in fact caused or materially contributed to the onset of the dermatitis in the sense that, but for that negligence, the dermatitis would not have occurred. Instead, a less stringent causal connection was regarded as sufficient. It was enough that the employer had materially increased the risk of harm to the employee: see Lord Reid, at page 5, Lord Wilberforce, at page 7, Lord Simon of Glaisdale, at page 8 ('failure to take steps which would bring about a material reduction of the risk'), and Lord Salmon, at pages 12-13.
  67. In an area of the law already afflicted with linguistic ambiguity I myself would not describe this process of legal reasoning as a 'legal inference' or an 'inference of causation'. This phraseology tends to obscure the fact that when applying the principle described above the court is not, by a process of inference, concluding that the ordinary 'but for' standard of causation is satisfied. Instead, the court is applying a different and less stringent test. It were best if this were recognised openly.
  68. LORD HOFFMANN
    My Lords,
  69. In one of the three appeals before your Lordships, the appellant Mr Matthews is suffering from a cancer (mesothelioma) caused by exposure to asbestos. Between 1973 and 1981 he was exposed to substantial quantities of asbestos dust in the course of successive employments by the two respondents, Associated Portland Cement and British Uralite. It is accepted that both employers were in breach of duty - the link between asbestos and cancer was well known by the mid 1960s - and that both exposures contributed substantially to the risk that he would contract the disease. But the precise mechanism by which asbestos causes cancer is unknown. It may be caused by the mutation of a single cell caused by a single asbestos fibre. At any rate, it is impossible to say that it was more likely to have been caused by the exposure to asbestos during employment with the one respondent rather than the other. And on that ground the Court of Appeal has held that Mr Matthews' claim must fail. It was said to be a rule of law that in order to succeed against either respondent, he must prove that, but for its breach of duty, he would not have contracted the disease. It applied the same rule to the other two appeals before your Lordships, which raise a similar point.
  70. My Lords, in my opinion the rule applied by the Court of Appeal is not a correct statement of the causal connection between breach of duty and damage which the law requires in a case such as this. I think it is sufficient, both on principle and authority, that the breach of duty contributed substantially to the risk that the claimant would contract the disease.
  71. I shall first consider the question in principle. It is axiomatic that the law will not impose liability to pay compensation for damage unless there is a relevant causal connection between the damage and the defendant's tort, breach of contract or statutory duty. But what amounts to a relevant causal connection?
  72. Everyone agrees that there is no scientific or philosophical touchstone for determining the relevant causal connection in any particular case. The relevance of a causal connection depends upon the purpose of the inquiry. In the present case, the House is required to say what should be the relevant causal connection for breach of a duty to protect an employee against the risk of contracting (among other things) mesothelioma by exposure to asbestos.
  73. It is frequently said that causation is a question of fact or a matter of common sense. Both of these propositions are true but they need to be analysed with some care in order to avoid confusion.
  74. First, in what sense is causation a question of fact? In order to describe something as a question of fact, it is necessary to be able to identify the question. For example, whether someone was negligent or not is a question of fact. What is the question? It is whether he failed to take reasonable care to avoid such damage as a reasonable man would have foreseen might result from his conduct. That question is formulated by the law. It is the law which says that failure to take reasonable care gives rise to liability. And the question is then answered by applying the standard of conduct prescribed by the law to the facts.
  75. The same is true of causation. The question of fact is whether the causal requirements which the law lays down for that particular liability have been satisfied. But those requirements exist by virtue of rules of law. Before one can answer the question of fact, one must first formulate the question. This involves deciding what, in the circumstances of the particular case, the law's requirements are. Unless one pays attention to the need to determine this preliminary question, the proposition that causation is a question of fact may be misleading. It may suggest that one somehow knows instinctively what the question is or that the question is always the same. As we shall see, this is not the case. The causal requirements for liability often vary, sometimes quite subtly, from case to case. And since the causal requirements for liability are always a matter of law, these variations represent legal differences, driven by the recognition that the just solution to different kinds of case may require different causal requirement rules.
  76. Then there is the role of common sense. Of course the causal requirements for liability are normally framed in accordance with common sense. But there is sometimes a tendency to appeal to common sense in order to avoid having to explain one's reasons. It suggests that causal requirements are a matter of incommunicable judicial instinct. I do not think that this is right. It should be possible to give reasons why one form of causal relationship will do in one situation but not in another.
  77. In my opinion, the essential point is that the causal requirements are just as much part of the legal conditions for liability as the rules which prescribe the kind of conduct which attracts liability or the rules which limit the scope of that liability. If I may repeat what I have said on another occasion, one is never simply liable, one is always liable for something - to make compensation for damage, the nature and extent of which is delimited by the law. The rules which delimit what one is liable for may consist of causal requirements or may be rules unrelated to causation, such as the foreseebility requirements in the rule in Hadley v Baxendale (1854) 9 Exch 341. But in either case they are rules of law, part and parcel of the conditions of liability. Once it is appreciated that the rules laying down causal requirements are not autonomous expressions of some form of logic or judicial instinct but creatures of the law, part of the conditions of liability, it is possible to explain their content on the grounds of fairness and justice in exactly the same way as the other conditions of liability.
  78. In the law of negligence, for example, it has long been recognised that the imposition of a duty of care in respect of particular conduct depends upon whether it is just and reasonable to impose it. Over vast areas of conduct one can generalise about the circumstances in which it will be considered just and reasonable to impose a duty of care: that is a consequence of Donaghue v Stevenson [1932] AC 562. But there are still situations in which Lord Atkin's generalisation cannot fairly be applied and in which it is necessary to return to the underlying principle and inquire whether it would be just and reasonable to impose liability and what its nature and extent should be: see Caparo Industries plc v Dickman [1990] 2 AC 605.
  79. The same is true of causation. The concepts of fairness, justice and reason underlie the rules which state the causal requirements of liability for a particular form of conduct (or non-causal limits on that liability) just as much as they underlie the rules which determine that conduct to be tortious. And the two are inextricably linked together: the purpose of the causal requirement rules is to produce a just result by delimiting the scope of liability in a way which relates to the reasons why liability for the conduct in question exists in the first place.
  80. Across most grounds of liability, whether in tort, contract or by statute, it is possible to generalise about causal requirements. These generalisations are explored in detail by Hart and Honoré (Causation in the Law, 2nd ed 1985). They represent what in ordinary life would normally be regarded as the reasonable limits for attributing blame or responsibility for harm: for example, that the de