Read about other areas of negligence:
It is obvious that in order to blame an individual for their actions, there must be some link between the action and the damage caused: we cannot blame someone completely unconnected with the damage. This link is what causation seeks to establish. Direct causation can be established by using the 'but-for' test. But for, or put otherwise, except for the action of the defendant, could the harm have occurred? Factual (i.e. direct) causation is proved when the answer is, yes, the damage could only have because of the Defendant.
However, while the basic test is a simple one, the situation becomes more complex when there are multiple causes of an injury, or where an action intervenes between the Defendant's action and the ultimate damage. Thus a second type of causation exists in these more complex situations, known as legal causation or remoteness. In those cases, the Defendant may have been the direct (factual) cause of the accident but they will not be held liable since the court considers that the injury was too remote. Cases involving legal causation remain difficult to decipher in some situations though the general principles are clear.
The but-for test is the basic causation test in negligence claims. The object of the test is to evaluate whether the Claimant's injury would have occurred without the defendant's actions. The question is: can we suggest that the injury would not have occurred to the Claimant except for the action of the Defendant. An important preliminary point to note is that the cause of the injury is to be judged on a balance of probabilities i.e. what is more likely. Thus, as long as it is more likely than not (even if only 51% vs. 49%) that but-for the Defendant's action the injury would not have occurred, it will be held that the but-for test is satisfied. The idea of how much an action caused an injury is usually best explained in percentages, thus the cases will often speak in these terms.
An example of the but-for test is Barnett v Chelsea & Kensington Hospital [1969] 1 QB 428. A nightwatchman had gone to the Defendant's hospital after drinking some tea and becoming ill. One of the doctors told the nightwatchman to go home and consult his own doctor. A few hours later the man died from arsenic poisoning. The judge said that it was negligent to send him away but questioned whether the negligence caused the death: but-for the Defendant sending the man away, would he have lived? The medical evidence was that the nightwatchman was at the hospital by 8.10am, he could have been admitted by 11am and it was possible that a diagnosis could have been made by 12.30pm. However, if the nightwatchman was not treated before 12pm, the chances of his survival were not good. The court refused to impose liability on the basis that, by the time a diagnosis and treatment could be administered, it would have been too late to save the man's life. Thus it could not be said that only because of the negligence (but-for the negligence) the man would have survived as even if there had been no negligence he would have died anyway.
So, the basic principles are:
• There must but-for causation, or in other words, only because of the negligence the Claimant suffered injury,
• The court will make decisions of fact on a balance of probabilities.
• Thus, the court in Barnett found that the watchman probably wouldn't have survived even if there was no negligence; it did not find that he definitely wouldn't have survived, simply that the chance of him not surviving was higher than 50%.
The but-for test is simple and therefore very useful. However, it becomes more problematic in cases where there is a lot of uncertainty as to how much the defendant contributed. Thus, what happens in situations where the court cannot say that the Defendant caused the injury on a balance of probabilities?
In Hotson v East Berkshire Area Health Authority [1987] AC 750, the 13 yr old Claimant fell from a tree and broke his hip. He was taken to hospital where they failed to diagnose the broken hip and sent him home. He returned several days later complaining of pain and the correct diagnosis was made. However, some time later his injury turned into a condition called avascular necrosis. The court found that there was a 75% chance that the avascular necrosis would have developed even if there had been no negligence. The judge at first instance awarded the Claimant 25% of the damages he would have received had it been proved that the avascular necrosis was entirely the Defendant's fault (the Court of Appeal upheld this). The House of Lords, however, found for the Defendant on the grounds that the Claimant could not prove that it was more likely than not that the Defendant's negligence resulted in the avascular necrosis. The House held that the practice of discounting damages to reflect the percentages was simply incorrect. If the likelihood that the Defendant caused the injury was 51% or above, then the law treats it the same as if it were 100% certain.
The House of Lords rejected the loss of chance rationalisation for the case. This rationalisation states that when the Claimant arrived at the hospital he had a 25% chance of not contracting the disease. However, because of the Defendant's negligence he lost the chance of falling within that 25%, thus he should be compensated for the loss of that chance. However, this situation needs to be contrasted with damages for future injury. In cases where there may be a future injury (i.e. damage to foot may cause reduced mobility in the future) the court will adopt a partial compensation approach. Thus if the chance of developing a future problem is 30%, the court will award the Claimant 30% of the compensation they would have received for that injury.
The House of Lords has been more willing to innovate than in Hotson in cases involving toxic substances in the workplaces. In these cases, there are two causes which are not alternative causes (i.e. it was either the doctor's fault or it occurred naturally, as in Hotson ) but rather cumulative causes, meaning that they worked together to cause the injury.
Bonnington Castings v Wardlaw [1956] AC 613. The facts of the case were that Claimant contracted a lung disease after working in the Defendant's shop for 8 years. The disease is caused by the inhalation of silicone dust which was partly caused by the use of a pneumatic hammer. However, there was no known way of preventing inhalation of this type of dust and so the Defendants could not be liable for not providing a face mask. The other source of the dust was from a certain machine which was not properly maintained and thus the extraction fan did not extract the dust properly. The Defendant was negligent as to this. The question was whether the negligent source of dust caused the lung disease. The House of Lords held in favour of the Claimant.
Firstly, the House of Lords did not use the but-for test as the causes were cumulative, not alternative. Secondly, the Houes of Lords applied a 'material contribution' test and asked whether the negligent dust had been a 'material cause' of the injury. It was a material cause because it was not a negligible amount. Even though the court said that most of the dust was probably from the hammer, a material amount was from the broken machine and this was sufficient for finding that causation existed. So in situation where two cumulative causes, the material cause test, not the but-for test, must be applied. The Claimant does not need to prove that the injury occurred only because of the Defendant's negligence (the but-for test), but simply that their negligence was a material cause.
As to the question of how much compensation the Claimant received, in Bonnington he received full compensation. However, since then, the courts have said that the compensation must be proportionate to the amount of contribution: Holtby v Brigham & Cowan [2003] 3 ALL ER 421. However, it is important to note that it is only possible to make an award for proportionate compensation when the injury is divisible . For example, where one Defendant injures the Claimant's arm and the other the Claimant's leg the injuries are divisible. Whereas if Defendant one exposes the Claimant to a poisonous substance and then later on Defendant two exposes them to the same substance, the injury suffered in the same. It is difficult to quantify how much each has contributed to the disease because, for example, the exposure from Defendant one may only have weakened the Claimant, making him susceptible to Defendant two's exposure, rather than actually giving him the injury.
In McGhee v National Coal Board [1973] 1 WLR 1, the Claimant cleaned bricks inside of kilns. The bricks were dusty and he developed a skin condition. The court held that it was negligent for the Defendant employer to not provide a showering facility, as this meant that the Claimant had to cycle home in order to wash the dust off of himself. The medical evidence said that the skin condition was caused by (1) the brick dust and (2) the exertion of having to cycle home. The Defendant could not be liable for (1), but could be for (2). The court held that the fact that the man had to cycle home covered in the dust, materially increased the risk of his disease. It is important to note that the reasoning here is different from Bonnington Castings v Wardlaw where it was certain that there had been a material contribution to the injury. In McGhee, all that could be said was that there was a material contribution to the risk of the injury. Fairchild illustrates this point.
In Fairchild v Glenhaven Funeral Services [2002] 3 WLR 89, the House of Lords dealt with the situation where a man was exposed to asbestos by several negligent employers. It was unknown whether the mesothelioma (cancer) was caused by a single strand of asbestos being lodged in the lungs or by cumulative exposure. It may have been the case that the strand lodged itself in the Claimant's lungs during the employment of Defendant three, meaning that there is no causation with Defendant one and Defendant two. However, it simply was not possible to state this with evidential certainty. Instead the court used the material contribution to risk test, and said that the Defendants had all contributed to the risk of the Claimant getting mesothelioma. The House of Lords applied the material risk test and found all employers liable. Fairchild is an important case because it confirms the material contribution to risk test in McGhee and because the House of Lords gives a discussion of principle and policy behind the law. In 2006, the House of Lords had to deal with the question of apportionment between defendants when one is insolvent: Barker v Corus [2006] UKHL 20. The question was whether the solvent Defendant pays the insolvent Defendant's share; the House of Lords said no.
What is the solution to a situation where the Defendant injures the Claimant but before the matter gets to the court, a supervening event causes the same injury to the Claimant. Is it fair to hold the defendant to account for an injury which would have been suffered anyway?
Baker v Willoughby [1970] AC 467. The Claimant was injured in a car accident which resulted in injury to his leg and ankle. Before the trial, however, the Claimant was shot by two robbers which resulted in his leg being amputated. There were two lines of argument: First, that the second event completely removed the leg and thus there was no longer a leg in which to feel discomfort and pain, so the Defendant should not be liable for compensation after the supervening event. The opposite argument was that the Defendant's actions meant that the Claimant suffered injury which would last for the rest of his life. The supervening event simply made that worse and the Defendant should be liable for his share of the compensation. The court adopted the second line of reasoning and held that the defendant must pay his share. They held that the first tort continued beyond the supervening event and was simply made worse by it; the supervening event did not end the Defendant's liability for the first tort. If the robbers were caught and brought to court they would have to pay their share, which would be the additional loss of having a stiff leg to have no leg at all.
A good illustration is Performance Cars v Abraham [1962] 1 QB 33, where the Defendant crashed his car into the Claimant's car causing minor damage. Two weeks earlier the Claimant had had another accident which required the side of the car to be repainted. The Defendant was only liable for putting the car back into the condition it was in before his accident, namely, a damaged car needing repainting.
In Jobling v Associated Dairies [1982] AC 794, the Claimant injured his back because of the Defendant's negligence and could only do light work. However, before the trial the Claimant contracted a spinal disease (completely unrelated to the injury) which made him unable to work at all. The House of Lords distinguished the case from Baker primarily on the factual grounds that the supervening event was a disease, rather than a tort. Illness is an ordinary part of life, it is a 'vicissitude' of life. Thus the House of Lords held that the disease obliterated the pre-existing injury, and the Defendant was not liable for ongoing compensation. This is line of reasoning 1, which was rejected in Baker. Is the distinction between tort/disease that convincing? The House of Lords were a little cautious themselves. Arguably, it is not fair to make the Defendant pay for injuries which would have occurred anyway by disease. But then again, why make a Defendant pay for injuries which would have occurred anyway because of another tortfeasor?
In these cases, as opposed to the cases just considered, the Defendant's negligence is not sufficient by itself to cause the injury. Rather the injury is caused by a supervening event. The negligence, however, creates the opportunity for the injury to occur. The latin phrase novus actus interveniens is used to describe the intervening act. An example from Lord Hoffman in Empress Car v National rivers [1992] 2 AC 22, will assist:
• A factory owner leaves an oil drum in a dangerous place and a worker comes by, lights a cigarette and throws it towards the barrels causing a fire. It would be the owner's fault for leaving the barrels in a dangerous place where an accident was likely to happen.
• If, however, the workman knew that the barrels were flammable and still threw a match, it would be difficult to say that the factory owner caused the fire. Similarly, if the drum had been struck by lightning it would be hard to say that the owner caused it.
It should be clear from the examples that the question of whether a novus actus breaks the chain of causation will depend on the duty of care of the Defendant. If the factory owner had a duty of care to protect the barrels from lightning then there would be causation if lightning caused the fire. It is only because lightning striking the barrel is such a rare occurrence that we can say it broke the chain of causation between the owner's negligence (leaving the barrels in an unsafe place) and the damage by fire.
In Knightley v Johns [1982] 1 WLR 349, the 1st Defendant caused an accident in a tunnel. The police were called but the officer in charge forgot to close the entrance of the tunnel so cars couldn't continue to enter. This was in breach of police codes. The officer in charge then sent two police constables down the tunnel against the flow of traffic in order to close the tunnel. They did so though it was in breach of codes for them to do so. One of the constables was injured by an oncoming car (through no fault of the driver's) and he sued. The trial judge found that 1st Defendant, the driver of the car which originally cause the need for the police to be called out, was liable and the failures by the officer in charge and Claimant himself did not break the chain of causation. The Court of Appeal held that the chain was broken by the officer in charge. They said that the question of when a novus actus break the chain of causation is a matter of common sense but it did enunciate some principles of wider application. The Court asked whether the injury was a probable and foreseeable result of the actions of officer in charge. The answer was yes and thus the chain was broken. In addition, negligent conduct is more likely to break the chain of causation than non-negligent conduct.
It is important to note that when we talk about a novus actus by the Claimant himself, the court will usually deal with this by contributory negligence, rather than saying that the Claimant's action broke the chain of causation. This is, however, something which is considered in the Defences section below. This won't be the case when a duty of care is owed. In Reeves v Commissioner of Police for the Metropolis [2000] 1 AC 360, the House of Lords held that the suicide of a prisoner in a police cell did not break the chain of causation as the police had a duty to watch the prisoner. The police knew that the prisoner had suicidal tendencies and the police owed him a duty of care to stop him committing suicide.
Remoteness is often called legal causation, and does not concern itself with deciding whether there is causation as a matter of fact, but rather is concerned with whether it is fair to impose liability. It has already been established in these cases that factual causation exists, the issue is whether it is fair to impose liability. The issues in remoteness are therefore largely to do with policy. The idea is similar to the concepts encountered in duty of care topic, where the court will only impose liability if it is just and reasonable. The general question is: was it foreseeable that that type of harm would occur?
Overseas Tankship v Morts Dock (The Wagon Mound (No 1)) [1961] AC 388. The respondents were ship-builders, they owned a wharf with tools on it. A ship was docked along the wharf and was being worked on by the respondents. The Appellants had control of a ship called the Wagon Mound which was docked about 600 yards away. The Wagon Mound was unloading gasoline which negligently allowed to get into the water and spread over to the respondent's wharf. The Respondent's manager became aware of the spill and told his workmen not to do any welding. He asked the owner of the dock where the Wagon Mound was docked whether it was safe to weld, and after receiving an affirmative answer he told his workmen that they could weld but to be cautious. Some sparks from the welding fell into the water and caused a fire. The trial judge found that some cotton was floating on a piece of debris under the wharf and that sparks from the welding fell onto this. The judge said that the appellants could not have known that it was possible for the gasoline to burn when floating on water. The court held that the Appellants were not liable as the damage by fire was not a reasonably foreseeable consequence. The court overruled an earlier case called Re Polemis in which it was held that the Defendant is liable for all damage as long as it is a direct result of their actions, regardless of whether it was foreseeable.
Though note that this goes beyond undergraduate negligence law and touches on quanitifcation of damages, which is a topic explored on the LPC. There is also the possibility in cases where future injury is possible, for the court to leave the case open and give the claimant the right to apply, if and when the injury occurs, for further compensation.
A negligible or trivial amount falls within the de minimis non curat lex principle, which means 'the law doesn't care about trivialities'. This is a principle which applies in some areas of law. The idea is simply that the actions of the defendant must have had an effect which is not so small that it can be ignored.
