"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 o n 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."
"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."
"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."
"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."
"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"
"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."
"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."
". . . . 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."
"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."
"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."
"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."
"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."
"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."
"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."
"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 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."
"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."
"§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."
"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."
"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."
"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]."
"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."
"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."
"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"
"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."
". . . 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 ."
"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."
"If one asks which of the parties, the workman or the employers, should suffer from this inherent evidential difficulty [i.e. the absence of knowledge of the mechanism by which dust caused the disease], 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."
"To hold otherwise would mean that the respondents were under a legal duty which they could, in the present state of medical knowledge, with impunity ignore."
"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."
"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."
"5. The risk of mesothelioma increases in proportion to the dose of asbestos received and each successive period of exposure augments the risk that mesothelioma will occur. There is no evidence of a threshold dose below which there is no risk but at low levels of exposure the risk is very small, whereas a lagger with his high level of exposure has a 10% chance of dying from mesothelioma. Mesothelioma usually occurs in persons who have inhaled millions of asbestos fibres in the course of their work. ….. 7. The mechanism by which asbestos causes mesothelioma being unknown, the transformation of a normal mesothelial to a cancerous cell could be due to the action of a single fibre, a few fibres or multiple fibres. It is believed that carcinogenesis of mesothelioma is a multi-stage process involving a sequence of 6 or 7 genetic changes which together result in a normal mesothelial cell being transformed into a malignant mesothelioma cell. Asbestos is probably involved at one or more stages of this process."
"Reliance was placed on Wardlaw v Bonnington Castings and Nicholson v Atlas Steel Foundry and Engineering Co . The dicta in these cases were followed in Gardiner v Motherwell Machinery and Scrap Co which applied the principles of the two earlier cases. Where there were a number of contributory factors to an injury, it was enough to bring the case within the dicta if the employers were guilty in relation to one."
"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."
"My Lords, I agree with the judge below to the extent that merely to show that a breach of duty increases the risk of harm is not, in abstracto, enough to enable the pursuer to succeed. He might, on this basis, still be met by successful defences. Thus, it was open to the respondents, while admitting, or being unable to contest, that their failure had increased the risk, to prove, if they could, as they tried to do, that the appellant's dermatitis was 'non-occupational'. 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."
"But Bonnington Castings Ltd v Wardlaw[1956] AC 613 and Nicholson v Atlas Steel Foundry and Engineering Co Ltd[1957] 1 WLR 613 establish, in my view, 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. The question, then, is whether on the evidence the appellant brought himself within this rule. In my view, a 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."
"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 the circumstances of the present case it seems to me 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 the injury."
"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."
"Reading all the speeches together, the principle applied by the House seems to me to amount to this. 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. If this is the right analysis, it seems to me that the shape taken by the enhancement of the risk ought not to be of crucial significance. In the McGhee case[1973] 1 WLR 1 , the conduct of the employers made it more likely that the pursuer would contract dermatitis, and he did contract dermatitis. Here, the conduct of those for whom the defendants are liable made it more likely that Martin would contract RLF, and he did contract RLF. If considerations of justice demanded that the pursuer succeed in the one case, I can see no reason why the plaintiff should not succeed in the other."
"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."
"My Lords, it seems to me that both these paragraphs, particularly in the words I have emphasised, amount to saying that, in the circumstances, the burden of proof of causation is reversed and thereby to run counter to the unanimous and emphatic opinions expressed in Bonnington Castings Ltd v Wardlaw[1956] AC 613 to the contrary effect. I find no support in any of the other speeches for the view that the burden of proof is reversed and, in this respect, I think Lord Wilberforce's reasoning must be regarded as expressing a minority opinion."
"A distinction is, of course, apparent between the facts of Bonnington Castings Ltd v Wardlaw , where the "innocent" and "guilty" silica dust particles which together caused the pursuer's lung disease were inhaled concurrently and the facts of McGhee v National Coal Board[1973] 1 WLR 1 where the "innocent" and "guilty" brick dust was present on the pursuer's body for consecutive periods. In the one case the concurrent inhalation of "innocent" and "guilty" dust must both have contributed to the cause of the disease. In the other case the consecutive periods when "innocent" and "guilty" brick dust was present on the pursuer's body may both have contributed to the cause of the disease or, theoretically at least, one or other may have been the sole cause. But where the layman is told by the doctors that the longer the brick dust remains on the body, the greater the risk of dermatitis, although the doctors cannot identify the process of causation scientifically, there seems to be nothing irrational in drawing the inference, as a matter of common sense, that the consecutive periods when brick dust remained on the body probably contributed cumulatively to the causation of the dermatitis. I believe that a process of inferential reasoning on these general lines underlies the decision of the majority in McGhee's case."
"The conclusion I draw from these 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."
"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. …. The question, then, is whether on the evidence the appellant brought himself within this rule. In my view, a 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."
"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 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 the circumstances of the present case it seems to me 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 the injury."
"the decision of this House may be taken as holding that in the circumstances of that case it was reasonable to infer that there was a relationship between contraction of dermatitis in these conditions and the absence of washing facilities and therefore it was reasonable to hold that absence of washing facilities was likely to have made a material contribution to the causation of 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."
"But where the layman is told by the doctors that the longer the brick dust remains on the body, the greater the risk of dermatitis, although the doctors cannot identify the process of causation scientifically, there seems to be nothing irrational in drawing the inference, as a matter of common sense, that the consecutive periods when brick dust remained on the body probably contributed cumulatively to the causation of the dermatitis."
"The jury's power to draw the inference that the aggravation of petitioner's tubercular condition, evident so shortly after the accident, was in fact caused by that accident, was not impaired by the failure of any medical witness to testify that it was in fact the cause. Neither can it be impaired by the lack of medical unanimity as to the respective likelihood of the potential causes of the aggravation, or by the fact that other potential causes of the aggravation existed and were not conclusively negated by the proofs. The matter does not turn on the use of a particular form of words by the physicians in giving their testimony. The members of the jury, not the medical witnesses, were sworn to make a legal determination of the question of causation."
"Adopting that robust approach, my firm conclusion in this case is that the claimant's exposure to asbestos fibres in the employment of the two defendants, did materially contribute to, and so cause his mesothelioma. I reach that conclusion by a simple, direct process of reasoning, readily understandable to a layman. The claimant was exposed by each defendant and by both defendants, to asbestos fibres, in quantities sufficient greatly to increase his risk of contracting mesothelioma, on the evidence of Dr. Rudd, by up to a thousand times the general population risk. They owed him statutory and common law duties to take steps to minimise that risk. They failed to do so. He contracted the very disease against which it was their duty to take those steps. In those circumstances, like Lord Reid in McGhee , I can see no substantial difference between saying that what the defendant did materially increased the risk of injury to the claimant and saying that what the defendants did made a material contribution to his injury. It seems to me wholly artificial to require a claimant to prove which fibre, or fibres, inhaled in whose employment in precisely what circumstances, caused or set off or contributed to the process by which one or more mesothelial cells became malignant. In principle, it is just as artificial as requiring proof in a case in which a pool of liquid, collected from separate sources, has caused injury, of precisely which molecule was the mechanical cause of injury. Even though the precise mechanism by which the claimant's mesothelioma was caused or set off cannot be established, those conclusions point, inexorably, to the finding that the defendants' breaches of duty materially contributed to his contracting the disease. In other words, the evidence which I have heard proves, on the balance of probabilities, that their breach of duty caused his injury."
"Two theories of causation emerge from an analysis of the speeches of the Lords in this case. The first, firmly espoused by Lord Wilberforce, is that the plaintiff need only prove that the defendant created a risk of harm and that the injury occurred within the area of the risk. The second is that in these circumstances, an inference of causation was warranted in that there is no practical difference between materially contributing to the risk of harm and materially contributing to the harm itself."
" McGhee v National Coal Board was considered by the House of Lords in Kay v Ayrshire and Arran Health Board[1987] 2 All ER 417 ; Hotson v East Berkshire Area Health Authority[1987] 2 All ER 909 , and Wilsher v Essex Area Health Authority[1988] 1 All ER 871 . It is clear from those decisions that McGhee is not now, and never was, authority for the legally adventurous proposition that if a breach of duty is shown, and damage is proven within the area of risk that brought about the duty, and if the breach of duty materially increases the risk of damage of that type, then the onus of proof shifts from the plaintiff to the defendant to disprove the causal connection. That proposition could be derived only from the speech of Lord Wilberforce and it is now clear that it was never a binding principle emerging from the McGhee case. But McGhee remains a worthwhile study. And there is a somewhat more cautious principle underlying the decision in that case. However, it is not an "onus" principle but an "inference" principle. …. The "inference" principle derived from McGhee , and from the Canadian cases to which I have referred, is this: Where a breach of duty has occurred, and damage is shown to have arisen within the area of risk which brought the duty into being, and where the breach of duty materially increased the risk that damage of that type would occur, and where it is impossible, in a practical sense, for either party to lead evidence which would establish either that the breach of duty caused the loss or that it did not, then it is permissible to infer, as a matter of legal, though not necessarily logical, inference, that the material increase in risk arising from the breach of duty constituted a material contributing cause of the loss and as such a foundation for a finding of liability. …. Whether the inference of causation should in fact be made in any particular case depends on whether it is in accordance with common sense and justice in that case to say that the breach of duty which materially increased the risk ought reasonably to be considered as having materially contributed to the loss."
"Has the failure to take those precautions been shown to have caused or materially contributed to the contracting of the disease by the appellant? It might be argued as a matter of strict logic, that the fact that given precautions would substantially diminish the risk, does not prove that failure to take those precautions materially contributed to the appellant's infection unless it can be established how that infection occurred. But 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 ."
"In refining the concept of legal cause we must also ensure that the triers of fact in asbestos-related cancer cases know the precise contours of the plaintiff's burden. The generally applicable standard instructions on causation are insufficient for this purpose. Those instructions tell the jury that every "substantial factor in bringing about an injury" is a legal cause (BAJI No. 3.76), even when more than one such factor "contributes concurrently as a cause of the injury" (BAJI No. 3.77). They say nothing, however, to inform the jury that, in asbestos-related cancer cases, a particular asbestos-containing product is deemed to be a substantial factor in bringing about the injury if its contribution to the plaintiff or decedent's risk or probability of developing cancer was substantial. Without such guidance, a juror might well conclude that the plaintiff needed to prove that fibers from the defendant's product were a substantial factor actually contributing to the development of the plaintiff's or decedent's cancer. In many cases, such a burden will be medically impossible to sustain, even with the greatest possible effort by the plaintiff, because of irreducible uncertainty regarding the cellular formation of an asbestos-related cancer. We therefore hold that, in the trial of an asbestos-related cancer case, although no instruction "shifting the burden of proof as to causation" to defendant is warranted, the jury should be told that the plaintiff's or decedent's exposure to a particular product was a substantial factor in causing or bringing about the disease if in reasonable medical probability it was a substantial factor contributing to plaintiff's or decedent's risk of developing cancer."
"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."
"as between an innocent plaintiff and a defendant who has committed a breach of duty to the plaintiff and by so doing materially increased the risk of loss to the plaintiff, in a situation where it is impossible, as a practical matter, to prove whether the breach of duty caused the loss, it is more in keeping with a common sense approach to causation as a tool of justice, to let the liability fall on the defendant."
"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] 1 WLR 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 our judgment, what Lord Reid said in McGhee[1973] 1 WLR 1 , at pp 4G to 5B, in the passage of his speech which forms the basis of Mr Langstaff's argument, must be read in the context of that case. There was only one causative agent, brick dust, and only one possible tortfeasor, Mr McGhee's employer. In that situation Lord Reid was prepared to find causation established in the absence of scientific proof. Lord Bridge in Wilsher has made it clear that the same technique cannot be used where there is more than one causative agent. It seems to us that for the same reasons the same technique cannot be used where there is more than one tortfeasor, unless of course the evidence establishes, on the balance of probabilities, that the disease was caused by cumulative exposure."
"In my judgment, 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."
"the source of his disease was the dust from both sources, and the real question is whether the dust from the swing grinders materially contributed to the disease. What is a material contribution must be a question of degree. A contribution which comes within the exception de minimis non curat lex is not material, but I think that any contribution which does not fall within that exception must be material. I do not see how there can be something too large to come within the de minimis principle but yet too small to be material."
"It is a common and familiar principle that in an action seeking such relief it is incumbent upon the pursuer to prove both that the defenders were guilty of negligence, and that such negligence caused, or materially contributed to, the injuries received."
"My Lords, I do not think that it can be wrong to approach this question from the angle that, 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. The appellants rightly or wrongly by their pleadings assumed the burden not only of proving that there was a causal link between default and disease but also of proving that it was practicable for the respondents to have reduced the risk by the provision of additional roof ventilators and openings in the walls for the admission of fresh air."
"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."
"that the washing facilities which were provided were inadequate and primitive, and that, if they had been up to standard, the risk of dermatitis would have been very much reduced."
"In my opinion, the defenders neglected to supply reasonable washing facilities in the circumstances, and thereby exposed the pursuer to an enhanced risk of contracting industrial dermatitis. They are accordingly liable to him in damages."
"It was their duty to take reasonable care to provide adequate washing facilities including showers, soap and towels to enable men to remove dust from their bodies. In each and all of said duties the defenders failed and so caused said disease. Had the defenders fulfilled said duties incumbent on them the pursuer would not have contracted said disease."
"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 that 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"
"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 it 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."
"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."
"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."
"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."
"idque est consequens auctoritati veterum qui, cum a pluribus idem servus ita vulneratus esset ut non appareret cuius ictu perisset, omnes lege Aquilia teneri iudicaverunt."
"This is in keeping with the view handed down from the old lawyers, who, where the same slave was wounded by several persons under such circumstances that it did not appear by whose hand it was that he died, came to the conclusion that they were all liable [under the lex Aquilia]."
"sed si plures servum percusserint, utrum omnes quasi occiderint teneantur, videamus. et si quidem apparet, cuius ictu perierit, ille quasi occiderit tenetur: quod si non apparet, omnes quasi occiderint teneri Iulianus ait, et si cum uno agatur, ceteri non liberantur: nam ex lege Aquilia quod alius praestitit, alium non relevat, cum sit poena."
"But if a number of persons struck him, it is a point to consider whether all are not liable, as having [all] killed him. As to this, if it is known who struck the fatal blow, that one is liable, as having killed him; but, if it is not known, then, according to Julianus, all are liable, as having slain, and if an action is brought against one, this does not release the others, because, under the lex Aquilia , payment by one man is no discharge to another, as it is a case of penal damages."
"Plaintiffs cannot be expected to prove the scientifically unknown details of carcinogenesis, or trace the unknowable path of a given asbestos fiber. But the impossibility of such proof does not dictate use of a burden shift. Instead, we can bridge this gap in the humanly knowable by holding that plaintiffs may prove causation in asbestos-related cancer cases by demonstrating that the plaintiff's exposure to defendant's asbestos-containing product in reasonable medical probability was a substantial factor in contributing to the aggregate dose of asbestos the plaintiff or decedent inhaled or ingested, and hence to the risk of developing asbestos-related cancer, without the need to demonstrate that fibers from the defendant's particular product were the ones, or among the ones, that actually produced the malignant growth."
"They say nothing, however, to inform the jury that, in asbestos-related cancer cases, a particular asbestos-containing product is deemed to be a substantial factor in bringing about the injury if its contribution to the plaintiff or decedent's risk or probability of developing cancer was substantial. Without such guidance, a juror might well conclude that the plaintiff needed to prove that fibers from the defendant's product were a substantial factor actually contributing to the development of the plaintiff's or decedent's cancer. In many cases, such a burden will be medically impossible to sustain, even with the greatest possible effort by the plaintiff, because of irreducible uncertainty regarding the cellular formation of an asbestos-related cancer. We therefore hold that, in the trial of an asbestos-related cancer case, although no instruction 'shifting the burden of proof as to causation' to defendant is warranted, the jury should be told that the plaintiff's or decedent's exposure to a particular product was a substantial factor in causing or bringing about the disease if in reasonable medical probability it was a substantial factor contributing to plaintiff's or decedent's risk of developing cancer."
"Haben mehrere durch eine gemeinschaftlich begangene unerlaubte Handlung einen Schaden verursacht, so ist jeder für den Schaden verantwortlich. Das Gleiche gilt, wenn sich nicht ermitteln lässt, wer von mehreren Beteiligten den Schaden durch seine Handlung verursacht hat."
"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."
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