KEY CASEMultiple causes

known that the risk of developing dermatitis could be reduced if workers could shower before leaving work, as this would lessen the amount of time the dust was in contact with their skin. The defendants had not installed any showers, and the claimant argued that they had been negligent in not doing so. To succeed in his claim, he had to prove that this negligence had caused his dermatitis – but because showers would only have less- ened the risk, not removed it, the ‘but for’ test did not work. It was impossible to say that the damage would not have happened ‘but for’ the defendant’s negligence, but equally impossible to say that it would definitely still have happened without the negligence.

As a result, in cases where there is more than one possible cause of damage, the courts have modified the ‘but for’ test, in an attempt to find a fair way to decide whether liabil- ity should be imposed. Unfortunately, they have come up with not one test, but several. In many cases, the result will differ according to which test is applied, yet it remains dif- ficult to predict which approach a court will take in a particular case. This is bad for liti- gants, but not quite as bad as it sounds for law students tackling problem questions; as long as you can say what the possible tests are, and what result each one is likely to lead to, you are not expected to be able to predict which a court would actually opt for.

The simplest approach is that which was actually taken by the House of Lords in

McGhee. They said that in cases where there was more than one possible cause, causa-

tion could be proved if the claimant could show that the defendant’s negligence had materially increased the risk of the injury occurring; it was not necessary to show that it was the sole cause. In that case, the lack of showers was held to substantially increase the risk to Mr McGhee, and he won his case.

A similar test was used in Page v Smith (No 2) (1996), which arose from the action dis- cussed earlier, in the section on psychiatric injury (p. 43), involving an accident victim who claimed that the shock reactivated a previous physical illness, ME. The defendant claimed that the claimant had not proved that the accident had caused the recurrence of his illness. The Court of Appeal held that the question to be answered was, as in McGhee: ‘did the accident, on the balance of probabilities, cause or materially contribute to or materially increase the risk of’ the claimant developing the symptoms he complained of? As we can see, the McGhee test has been used in cases over the past 30 years (and continues to be good law). During the same period, however, the courts have also used a completely different test, which in many cases would give the opposite result to the

McGhee rule.

This test was used in Wilsher v Essex Health Authority (1988), a tragic case concerning a claimant who was born three months early, with a number of health problems associated with premature birth. He was put on an oxygen supply and, as a result of a doctor’s admitted negligence, was twice given too much oxygen. He eventually suffered permanent blindness, and the hospital was sued. However,

medical evidence suggested that although the overdoses of oxygen could have caused the claimant’s blindness, it could also have been caused by any one of five separate

A claimant must prove, on a balance of probabilities, that the defendant’s negligence was a material cause of their injury; it is not enough merely to increase the risk of damage.

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medical conditions which he suffered from. The House of Lords held that the claimant had to prove, on a balance of probabilities, that the defendant’s breach of duty was a material cause of the injury; it was not enough to prove that the defendant had increased the risk that the damage might occur, or had added another possible cause of it. On the facts of the case, the defendant’s negligence was only one of the possible causes of the damage, and this was not sufficient to prove causation.

●‘Loss of a chance’ cases

A third approach is taken to causation in cases which involve what is called ‘loss of a chance’. Often these are medical negligence cases, and a typical example might involve a claimant being diagnosed with cancer, who has a certain percentage chance of being cured, but has that chance reduced by their doctor’s delay in diagnosing or treating the illness. In such cases the court then has to decide whether the delay can be said to have caused the patient not to have been cured, or whether that would have been the situation even if the doctor had not acted negligently. Loss of a chance can also involve financial losses, where a claimant misses out on the chance of a lucrative deal, or a well-paid job, because of the defendant’s negligence.

The key case on loss of chance with respect to injury or ill- ness is Hotson v East Berkshire Health Authority (1987). Here the claimant, a young boy, had gone to hospital after falling from a rope and injuring his knee. An X-ray showed no apparent injury, so he was sent home. Five days later, the boy was still in pain, and when he was taken back to the hospital, a hip injury was diagnosed and treated. He went

on to develop a condition known as avascular necrosis, which is caused when the blood supply to the site of an injury is restricted, and eventually results in pain and deformity. This condition could have arisen as a result of the injury anyway, but medical evidence showed that there was a 25 per cent chance that if he had been diagnosed and treated properly on his first visit to the hospital, the injury would have healed and the avascular necrosis would not have developed. The Court of Appeal treated this evidence as relev- ant to the issue of damages, holding that it meant his action could succeed but he should receive only 25 per cent of the damages he would have got if the condition was wholly due to the defendant’s negligence.

The House of Lords, however, ruled that this was the wrong approach; what was really in issue was whether the claimant had proved that the defendant’s negligence caused his condition. The court held that he had not: the law required that he should prove causa- tion on a balance of probabilities, which means proving that it was more likely that they had caused his condition than that they had not. What the medical evidence showed was that there was a 75 per cent chance of him developing the condition even if the negli- gence had not occurred; proving causation on a balance of probabilities required at least a 51 per cent chance that the negligence caused the damage.

In ‘loss of a chance’ cases, claimants must prove causation on a balance of probabilities, which means proving it was more likely than not that the negligence caused the injury.

Multiple causes

This approach was challenged in Gregg v Scott (2005). The claimant had visited his GP, complaining of a lump under his left arm, but the doctor said it was nothing to worry about. Nine months later, the lump was still there, so the claimant consulted another GP, who referred him to a surgeon. The lump was diagnosed as cancer, and it was shown to have grown during the time between visiting the first and second GP. The claimant was treated, and the cancer went into remission, but it was not known whether he was actu- ally cured.

The claimant sued the doctor on the basis that the delay had made it less likely that he would be cured, but it was not possible to prove this was the case. Statistics showed that out of every 100 people who developed the same kind of tumour, 17 would be cured if they had prompt treatment, but not if their treatment was delayed by a year; 25 would be cured even if their treatment was delayed by a year; and 58 would be incur- able regardless of how much treatment they had and when. The claimant therefore argued that he had originally had a 42 per cent chance of being cured (adding together the figures for those who would be cured even if treatment was delayed, and those who would only be cured if they received prompt treatment). By delaying his treatment, the doctor had reduced his chances to 25 per cent.

The House of Lords rejected this argument, and said that the claimant could succeed only if he could prove that the defendant’s negligence made it more likely than not that he would not be cured. Since the statistics showed that it was more likely than not that his cancer would not have been curable (a 58 per cent chance against a 42 per cent one), this had not been proved. The claimant also argued that even if it could not be proved that the doctor’s negligence caused the spread of his cancer, he should be able to claim for ‘loss of a chance’, meaning a reduction in his chances of survival. The House of Lords said this could not form the basis of a claim in medical negligence.

Damages for loss of a chance have been allowed in cases where the loss is purely finan- cial. In Stovold v Barlows (1995), the claimant claimed that the defendant’s negligence had caused him to lose the sale of his house. The Court of Appeal decided that there was a 50 per cent chance that the sale would have gone ahead had the defendant not been negligent, and on this basis they upheld the claimant’s claim, but awarded him 50 per cent of the damages that he would normally have won (thus following the approach it had taken in Hotson, and not that taken by the House of Lords in that case).

In Allied Maples Group v Simmons & Simmons (1995), the claimants hoped to make a particular business deal, but were prevented from doing so by the defendant’s negli- gence; it was possible that the deal might not have gone ahead for other reasons even if the negligence had not happened. The Court of Appeal held that where the damage alleged depends on the possible action of a third party (in this case the other party to the deal), the claimant must prove that the chance was a substantial one, as opposed to pure speculation on what might have happened. If so, the action can succeed on causation, and the evaluation of the chance will be taken into account when calculating damages.

●Multiple tortfeasors

In the cases discussed above, the question has been whether damage was caused by the defendant, or by one or more non-negligent acts or situations, such as accident or illness.

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What happens when the damage was definitely caused by negligence, but there is more than one party which could have been responsible? This often arises in cases concerning work-related illnesses which take many years to develop, so that it is not always clear at which point during the claimant’s working life the damage was done. In Holtby v

Brigham & Cowan (2000), the claimant suffered asbestosis as a result of breathing

asbestos dust at work over a long period. He had been employed by the defendants for approximately half that time, and by other firms doing similar work for the rest; for rea- sons which are not important here, he was only suing the defendants. The Court of Appeal stated that the defendants were liable if it was proved that their negligence had made a material contribution to the claimant’s disability; their negligence did not have to be the sole cause of it. However, if the injury had also been partially caused by the negligence of others, the defendants would only be liable for the proportion they had caused. In deciding how big this proportion was, the judge followed the practice of insur- ance companies and related it to the amount of time the claimant had been exposed to the defendants’ negligence and, erring on the side of the claimant, set the proportion of liability at 75 per cent.

This approach can, however, work harshly against claimants, and this was revealed – and eventually to some extent corrected – in Fairchild v Glenhaven Funeral Services (2002). This case also concerned employees who had worked with asbestos, but here the disease caused was mesothelioma, an invariably fatal cancer that is almost always caused by asbestos. It is not entirely clear how mesothelioma is caused, but it is believed to be triggered by a single fibre of asbestos penetrating a cell in the lining of the lung, which then becomes malignant and eventually grows into a tumour. This makes it different from asbestosis, which generally gets worse the more asbestos the person is exposed to; with mesothelioma, the single event of the fibre entering the lung causes the disease. It may take up to 30 years to do so, but essentially the person’s fate is sealed when the fibre enters the lung, and the amount of previous or subsequent exposure is irrelevant. This was what caused problems for the claimants in Fairchild.

The claimants (some of the men had already died, so their cases were brought by their widows) had been exposed to asbestos over long periods during their working lives, as a result of negligence by a series of different employers. By the time they sued, many of the companies were no longer in existence, so the claimants sued only those who were. Previously, in mesothelioma cases, the courts had taken the approach that all significant exposure to asbestos up to around 10 years before the symptoms developed could be said to have contributed to the causation of the disease. But in Fairchild, the High Court held that it was necessary for the claimant to prove which fibre had caused the disease, and only the employer at that time would be liable. Since it was impossible to know, let alone prove, which fibre had caused the disease, this ruling had the potential to mean that mesothelioma sufferers would never be able to sue those who had caused their dis- ease unless they had only been exposed to asbestos by one employer.

As there are over 1,300 cases of the disease each year, and the figure is expected to more than double over the next 20 years, the decision caused considerable anxiety. But to many people’s surprise, the Court of Appeal upheld the High Court’s approach, and confirmed that where a claimant with mesothelioma has been exposed to asbestos by different employers at different times, and it cannot be proved, on a balance of

Multiple causes

probabilities, which period of exposure caused the illness, he or she cannot recover dam- ages from any of the employers.

On a strict definition of causation, this at first sight looks plausible, if callous, but a closer look shows a number of problems. First, although the disease is caused by one inhalation of fibres and not cumulative exposure, you do not have to be a mathematical genius to work out that the more times you are exposed to asbestos, the higher the chance that on one of those occasions you will breathe some in. On this basis, it would not seem difficult to argue that each of the employers had increased the claimants’ risk of getting the disease, just as the employer in McGhee did.

Secondly, the focus on the one ‘guilty fibre’ somehow suggests that only the employer who the claimant was working for at the time the fibre was inhaled did any- thing wrong – whereas in fact all of them had negligently exposed their employees to a substance which had the potential to kill them, prematurely and painfully. Ignoring this fact does not sit well with tort’s claim to act as a deterrent to careless and dangerous behaviour.

Thirdly, the parties who would actually be paying any damages would be insurance companies, who had been taking premiums for decades during which the risks of asbestos were well known, and now wanted to escape liability. In fact, while the case was awaiting its House of Lords hearing, the insurance companies concerned offered the claimants a full settlement, which, if accepted, would have meant the cases would not be heard. As a result, although the Fairchild claimants would have been compen- sated, thousands of other victims would have remained at the mercy of the Court of Appeal judgment. The president of the Association of Personal Injury Lawyers, Frances McCarthy, called the offer ‘a cynical and underhanded attempt to prevent the cases being heard’.

In the event, the House of Lords did hear the case, and came to a different view. They said that where an employee had been negligently exposed by different defendants, dur- ing different periods of employment, to inhalation of asbestos, a modified approach to proof of causation was justified. In such a case, proof that each defendant’s wrongdoing had materially increased the risk of contracting the disease was sufficient to satisfy the causal requirements for liability. Applying that approach, the claimants could prove cau- sation on a balance of probabilities, and the defendants were liable.

However, the benefits for claimants of the Fairchild decision were then restricted by the House of Lords decision in Barker v Corus (2006). In this case, a group of defendant employers sought to argue that, where an employee was negligently exposed to asbestos by more than one different employer, each employer’s liability should be calculated according to the length of time the employer spent with them and, where relevant, to the type of asbestos involved (some kinds being more hazardous than others). In addi- tion, one of the employees in the case had been self-employed for part of his career, and the companies which had employed him for the rest of the time argued that exposure to asbestos during his period of self-employment was his own responsibility, so they should not be liable for it.

The House of Lords rejected the argument about self-employment, basing their find- ing on the principle explained in McGhee (see p. 101). They pointed out that in McGhee,

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