Causation is a concept in law which seeks to connect people’s actions with particular results. Our common-sense understanding of causation is that one thing causes another. The question that often arises in tort cases is whether it is possible to say that the breach of duty on behalf of a particular claimant caused the damages that a claimant is seeking. Normally questions of causation can be broken down into three. Firstly, as a matter of fact, was the defendant’s negligence a cause of the claimant’s harm? Secondly, even if the defendant’s negligence was a cause of the claimant’s harm, was there any intervening act which broke the chain of causation? Thirdly, if the defendant’s act was the cause of the claimant’s harm, was the damage caused or claimed too remote?

The first question that the court will need to establish is whether in fact the defendant’s negligence was the cause of the harm suffered by the claimant. In dealing with this question, the court will ask a simple question:-

“As a matter of fact, was the defendant’s negligence a cause of the claimant’s damage?”

This was explored in the case of Barnett v Chelsea and Kensington Hospital Management Committee [1969]. In this case a nightwatchman finished his duty early and felt unwell. A doctor in the casualty department of his local hospital told him to leave and see his own doctor. Later on the same day the nightwatchman died of arsenic poisoning. The court held that why the hospital had breached its duty of care, the breach was not the case of death.

When factual causation is considered of this kind it is necessary to ascertain whether the defendant’s breach of duty actually caused the loss about which the claimant is claiming.

A simple way of expressing this is but for the defendant’s breach of duty would the harm to the claimant have occurred. If the answer is yes then the harm would still have occurred in any event and the claimant has failed to establish causation and the claim against the defendant must fail.

In a civil case a person alleging a particular fact must prove it on the balance of probabilities. This means that causation must be able show on the balance of probabilities that the harm suffered was caused by the defendant. If the claimant fails to prove that then the claimant’s claim will fail.

In the case of Bonnington Castings Ltd v Wardlow [1956] AC 613 the House of Lords held that the claimant had succeeded in establishing causation because he could show that the defendant’s breach of duty created “guilty dust” which materially contributed to a disease from which he suffered. The claimant need not show that the defendant’s breach of duty was the only cause of the damage to the claimant or even the main cause. The claimant simply has to show that it materially contributed to the damage. This is known as the material contribution approach.

In the case of McGhee v National Coal Board [1973] the House of Lords extended the material contribution approach to cover creation of a material increase in the risk of injury rather than a material injury to the risk itself. The principle of material increase in risk is best viewed as an exception to the usual rules of causation.

One issue that arises is what if a claimant is injured more than once? A claimant may have completely separate accidental injuries. Difficulties of causation arise when one injury follows another and the two injuries impact on each other. An example of this can be seen in Performance Cars v Abraham in which a defendant negligently collided with a Rolls Royce owned by the claimant. As a result the car would have need a partial respray. However, the same part of the car had already been damaged in an earlier accident and therefore it would have needed a respray in any event. The Court of Appeal held that the claimant could not claim the cost of the respray from the defendant in the second incident because the defendant’s breach had not caused the need for the respray as such a need already existed.

Divisible injury proportionate damages

Where the court has evidence which will enable it to divide up the injuries suffered by the client, it will apportion the damages accordingly. In Holtby v Brigham & Cowan [2000] 3 All ER 41 injury could be divided because cumulative exposure to asbestos had caused a disease which got progressively worse the longer that the exposure continued. The court apportioned the damages to be paid according to the length of time the claimant had worked for each employer and had been exposed to asbestos in different scenarios. It is obviously important to note that most injuries cannot be divided up in this way.

Sometimes injury is invisible. Under section 1 and 2 of the Civil Liability Contribution Act 1978 where two or more people are responsible for the same damage, the court has the power to apportion the damage between them. Where two or more defendants are liable to the claimant in respect of the same damage, each defendant is liable to the claimant in full. The claimant would be able to recover full damage from one defendant even if the other is insolvent or untraceable. Where two or more persons are liable to the claimant in respect of the same damage the claimant is entitled to sue any or all of them and is entitled to recover the full amount of their loss from any or all of them. Under the Civil Liability Contribution Act a person liable for damage suffered by another person may recover a contribution from any other person liable for the same damage. Although the court may apportion blame between the defendants the apportionment does not affect the claimant as far as the enforcement of any judgment is concerned.

Breaking the chain of causation

Often the chain of causation between a breach of duty and harm can be broken by the intervening act of a third party. There are a number of rules established by case law which dictate whether intervening acts will break the chain of causation or not.

The instinctive interventions of a third party will not break the chain of causation. In the case of Scott v Shepherd [1773] 2 WMBI 892 the defendant threw a lit firework into a crowd. The claimant instinctively picked it up and threw it away from himself. Then another person did the same. It landed at the foot of the claimant and exploded. The court decided that the defendant was still liable to the claimant. The acts of the person throwing the firework after it had been initially thrown into the crowd constituted an instinctive reaction in a moment of alarm and did not break the chain of causation.

The chain of causation is also unlikely to be broken by the negligent action of a third party which the defendant ought to have foreseen as a likely result of his negligence. In the case of Knightley v Johns [1982] the defendant’s negligent driving caused his car to block the exit of a busy tunnel. A police inspector took charge and ordered the claimant to drive back against the traffic to close the tunnel. The claimant was struck by a vehicle in the tunnel and was injured. The Court of Appeal held that the defendant was not liable. The defendant could not have foreseen the act of the police inspector and the intervening act broke the chain of causation between the claimant and the defendant.

It is more likely that the conduct of a third party that is reckless or intentional rather than just negligent will be treated as an intervening act. This can be seen in the case of Lamb v Camden Borough Council in which squatters entered a house while it was left unoccupied and being repaired. The squatters caused damage. The court held that the defendants were not liable for the squatters’ actions once they had entered the building. Whether or not the chain of causation has been broken is often a question of fact which depends on the judgment the court makes about the circumstances of a particular case. As a broad rule it can be said that the chain of causation is unlikely to be broken by an action which the defendant ought to have foreseen as a likely consequence of his negligence.

The situation might arise where the claimant does something which may break the chain of causation. In the case of McKew v Holland & Hannen & Cubitts (Scotland) Limited [1969] 3 All ER 1621 the defendant’s negligence weakened the claimant’s leg leaving it with a tendency to give way. When the claimant descended a steep staircase, his leg gave way, and he suffered further injuries. The House of Lords held that the claimant had acted unreasonably and had broken the chain of causation.

In most cases if the claimant acts in a careless manner, rather than say the claimant’s act amounts to a intervening act the defendant will raise the defence of contributory negligence which we will consider later.


The court will also have to consider whether the damage suffered by the claimant is remote from the breach that gave rise to the damage. The issue of remoteness was considered extensively in the case called Wagon Mound No. 1 [1961] All ER 1404. This case is normally referred to as Wagon Mound No. 1. In this case the defendant was operating a ship called the Wagon Mound. Employees allowed oil to spill onto the water of Sydney Harbour. The claimant built ships and owned a wharf in the harbour where employees were using welding equipment. The oil collected around the wharf. The manager of the claimant ordered work to stop while he made enquiries about it. He concluded that the oil was not likely to ignite, and welding work continued. The oil did ignite hot metal from the claimant’s welding and set fire to the debris in the water which then ignited the oil. The claimant’s wharf and a ship were damaged. The issue arose as to whether the claimant could recover the cost of the damage from the defendant. The case held that the test for remoteness of damage is one of reasonable foreseeability. The court has to ask whether the damage was of such kind that a reasonable person would have foreseen it.

Put simply, “if a reasonable person would not have foreseen the damage it cannot be recovered”. However there are two provisos to this rule which are known as the similar in type rule and the eggshell skull rule.

The similar in type rule is considered in Hughes v Lord Advocate [1963] All ER 705. Here the court confirmed the rule that an injury must be reasonably foreseeable. On the facts of this case it was not accepted by the court that the damage suffered by the claimant was foreseeable. However, the claimant did suffer an injury of the type which was foreseeable and it did not matter that the precise way in which the injury was caused was not foreseeable. The court therefore held that the defendant was liable to the claimant for the injuries. This was applied in the case of Tremain v Pike [1969] All ER 1303. Here the claimant worked on the defendant’s farm. The defendant negligently allowed rats to proliferate on the farm. The claimant came into contact with the rats. He contracted a rare condition, Weil’s disease, which is caught by contact with rats’ urine. The court said that this kind of injury was not foreseeable. The type of injury which was foreseeable in those circumstances was injury from bites. The injury suffered by the claimant was so unusual that it was not foreseeable even under the similar in type proviso. Damages were therefore not recoverable. This rule can be summarised by saying that if the injury was of a type that was foreseeable it does not necessarily matter that the precise way in which the accident occurred was not foreseeable.

The second proviso is the eggshell skull rule. This is described as a rule that you must take your victim as you find him. In the case of Robinson v Post Office [1974] the claimant suffered slight injuries to his leg as a result of the defendant’s negligence. The claimant saw a doctor who gave him an anti-tetanus injection. Unfortunately the claimant suffered a severe allergic reaction. The claimant sued the defendant for both the original injury and the further injury arising out of the allergic reaction. In this case the claimant succeeded. The defendant ought reasonably to have foreseen that as a result of the negligence the claimant would require medical treatment so the necessity for anti-tetanus injections were reasonably foreseeable.  The defendant was liable for the consequence of the medical treatment even though he could not reasonably foresee the precise extent of the consequences and could not have foreseen that they would have been so severe.