Learning Outcomes
This article examines the principles of causation in negligence, covering both factual and legal causation. It explains the 'but for' test and its exceptions, including the material contribution test relevant to multiple causes and cumulative injuries. The article also outlines the concept of remoteness of damage and the impact of intervening acts (novus actus interveniens) on breaking the chain of causation. Understanding these principles is essential for applying the law of negligence correctly in SQE1 assessments involving scenarios with multiple potential causes or injuries.
SQE1 Syllabus
For SQE1, you need a practical understanding of how causation links a defendant's breach of duty to the claimant's loss in negligence claims. This includes applying rules for both factual and legal causation, especially in complex situations involving multiple potential causes or successive injuries. Key areas for revision include:
- The 'but for' test for factual causation and its application.
- Exceptions to the 'but for' test, such as the material contribution test (Bonnington Castings) and the material increase in risk approach (Fairchild).
- The distinction between divisible and indivisible injuries in the context of multiple causes.
- The concept of legal causation, including remoteness of damage (The Wagon Mound) and the 'egg-shell skull' rule.
- Identifying intervening acts (novus actus interveniens) and determining if they break the chain of causation.
Test Your Knowledge
Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.
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What is the primary test for establishing factual causation in negligence?
- The material contribution test.
- The 'but for' test.
- The foreseeability test.
- The proximity test.
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In which case was the principle established that a defendant could be liable if their breach materially contributed to the claimant's harm, even if it wasn't the sole cause?
- Barnett v Chelsea and Kensington Hospital Management Committee
- The Wagon Mound (No 1)
- Bonnington Castings Ltd v Wardlaw
- Baker v Willoughby
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True or False: The 'egg-shell skull' rule means a defendant is only liable for harm that was reasonably foreseeable, regardless of the claimant's pre-existing vulnerabilities.
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What legal principle determines whether harm suffered by a claimant is too far removed from the defendant's breach to be recoverable?
- Factual causation.
- Novus actus interveniens.
- Remoteness of damage (legal causation).
- Contributory negligence.
Introduction
Establishing that a defendant owed a duty of care and subsequently breached that duty is only part of a successful negligence claim. The claimant must also demonstrate that the defendant's breach caused the damage suffered. Causation acts as the essential link connecting the defendant's wrongful act to the claimant's harm. This involves satisfying tests for both factual causation (cause in fact) and legal causation (remoteness). This article explores these elements, particularly focusing on complexities arising from multiple causes and multiple injuries.
Factual Causation: The 'But For' Test
The starting point for determining factual causation is the 'but for' test. The court asks: 'But for the defendant's negligence, would the claimant have suffered the harm?' If the answer is 'no' (the harm would not have occurred without the defendant's breach), then factual causation is typically established.
Key Term: Factual Causation
The principle that the defendant's breach of duty was, as a matter of fact, a necessary condition for the claimant's harm occurring.
Worked Example 1.1
Ahmed attends hospital complaining of severe chest pains. Dr. Singh, the attending doctor, negligently fails to examine him properly and sends him home, advising rest. Ahmed suffers a fatal heart attack hours later. Medical evidence shows that even with prompt and correct treatment, Ahmed's condition was so advanced that he would have died regardless. Has Dr. Singh's negligence caused Ahmed's death?
Answer: No. Applying the 'but for' test, Ahmed would have died even if Dr. Singh had not been negligent. Therefore, Dr. Singh's breach did not cause the death. (Based on Barnett v Chelsea and Kensington Hospital Management Committee [1969]).
Problems with the 'But For' Test
The 'but for' test can be difficult to apply where there are multiple potential causes of the claimant's harm. If there are several factors, any one of which could have caused the harm independently, the 'but for' test might absolve all parties of responsibility, as it may be impossible to prove on the balance of probabilities that any single breach was the decisive cause.
Multiple Potential Causes
Where multiple factors contribute to the claimant's harm, especially in cases involving cumulative exposure or scientific uncertainty, the courts have developed alternative approaches to the 'but for' test.
Material Contribution to Harm
If the defendant's breach can be shown to have made a 'material contribution' to the claimant's harm, this may be sufficient to establish factual causation, even if the breach was not the sole cause. This test often applies where the harm results from the accumulation of a harmful substance from both negligent and non-negligent sources.
Key Term: Material Contribution to Harm
Where the defendant's breach made a more than negligible contribution to the claimant's injury, causation may be established even if the 'but for' test is not satisfied.
In Bonnington Castings Ltd v Wardlaw [1956], a factory worker developed pneumoconiosis from inhaling silica dust. Some dust exposure was non-tortious ('innocent dust'), while some resulted from the employer's breach of duty ('guilty dust'). The House of Lords held that because the 'guilty dust' had materially contributed to the disease, the employer was liable.
Material Increase in Risk
In exceptional cases involving scientific uncertainty (particularly mesothelioma caused by asbestos exposure), the courts have held that factual causation can be established if the defendant's breach materially increased the risk of the claimant suffering the harm.
In Fairchild v Glenhaven Funeral Services Ltd [2002], the claimants developed mesothelioma after being exposed to asbestos by several different employers over different periods. It was impossible to determine which exposure caused the fatal illness. The House of Lords held that each employer who had negligently exposed the claimant to asbestos, thereby materially increasing the risk of mesothelioma, could be held liable. This approach ensures claimants are not left without remedy due to evidential gaps caused by scientific uncertainty.
Key Term: Material Increase in Risk
In specific circumstances (e.g., mesothelioma), proof that the defendant's breach materially increased the risk of the claimant contracting the disease can establish factual causation.
Exam Warning
The Fairchild principle, imposing joint and several liability for materially increasing the risk of mesothelioma, was specifically restored for mesothelioma claims by s. 3 Compensation Act 2006, overriding the apportionment approach suggested in Barker v Corus UK Ltd [2006]. For other conditions, the common law principles around material contribution apply. Be precise about the type of harm alleged in the question.
Divisible vs. Indivisible Injuries
When multiple causes are involved, the nature of the injury is important:
- Divisible Injury: An injury that can be attributed incrementally to different exposures or causes (e.g., industrial deafness, where the severity relates to the cumulative exposure). Liability may be apportioned between defendants based on their contribution.
- Indivisible Injury: An injury that cannot be broken down into parts attributable to specific causes (e.g., mesothelioma, which can be triggered by a single fibre, or a broken leg from a multi-car pile-up). Where multiple defendants contribute to an indivisible injury, they are typically held jointly and severally liable, meaning the claimant can recover the full amount from any one defendant.
Legal Causation: Remoteness and Intervening Acts
Even if factual causation is established, the claimant must also demonstrate legal causation. This involves two key aspects: remoteness of damage and the absence of any intervening act breaking the chain of causation.
Remoteness of Damage
The defendant is only liable for damage that is of a reasonably foreseeable type as a consequence of their breach. This principle, established in Overseas Tankship (UK) Ltd v Morts Dock and Engineering Co Ltd (The Wagon Mound (No 1)) [1961], prevents liability extending to harms that are too remote.
Key Term: Remoteness of Damage
A legal principle limiting liability to types of harm that were reasonably foreseeable consequences of the defendant's breach of duty.
Worked Example 1.2
Workers negligently allow oil to spill from a ship into a harbour. The oil spreads to a nearby wharf where welding is taking place. Sparks ignite debris floating on the oil, causing a large fire that damages the wharf. Evidence showed it was not foreseeable that furnace oil floating on water could ignite in this way. Is the damage to the wharf too remote?
Answer: Yes. Applying the test from The Wagon Mound (No 1), the fire damage was not a reasonably foreseeable type of consequence of the oil spill. Although some damage from fouling was foreseeable, fire damage was considered too remote.
The 'Egg-Shell Skull' Rule
An exception to the foreseeability test for remoteness is the 'egg-shell skull' (or 'thin skull') rule. This rule states that the defendant must take their victim as they find them. If the claimant has a particular vulnerability that makes their injury more severe than would have been reasonably foreseeable, the defendant is liable for the full extent of the harm suffered.
Key Term: Egg-Shell Skull Rule
The principle that a defendant is liable for the full extent of the harm suffered by a claimant, even if the severity is due to the claimant's pre-existing vulnerability and was unforeseeable.
Worked Example 1.3
A worker suffers a minor burn on his lip due to his employer's negligence. The burn triggers a pre-existing cancerous condition, leading to the worker's death. Is the employer liable for the death, even if cancer developing from such a burn was unforeseeable?
Answer: Yes. As long as the initial type of injury (the burn) was foreseeable, the defendant is liable for the full consequences, including the unforeseeably severe outcome due to the claimant's pre-existing vulnerability. (Based on Smith v Leech Brain & Co Ltd [1962]).
Intervening Acts (Novus Actus Interveniens)
An intervening act or event occurring after the defendant's breach but before the claimant suffers the damage may break the chain of causation, relieving the defendant of liability for the subsequent harm.
Key Term: Novus Actus Interveniens
A new intervening act (by the claimant, a third party, or a natural event) that breaks the chain of causation between the defendant's breach and the claimant's ultimate harm.
- Act of the Claimant: If the claimant acts unreasonably following the defendant's breach, their actions may break the chain of causation (McKew v Holland & Hannen & Cubitts (Scotland) Ltd [1969]). The claimant's conduct must be highly unreasonable; mere carelessness might lead to contributory negligence instead.
- Act of a Third Party: An act by a third party will generally break the chain if it was unforeseeable and independent of the defendant's breach. Negligent medical treatment following an injury caused by the defendant is unlikely to break the chain unless it is grossly negligent.
- Natural Event: An unforeseeable natural event occurring after the breach may break the chain.
Multiple Sufficient Causes
Where two separate tortious acts occur consecutively, both contributing to the claimant's loss, complex questions arise.
- In Baker v Willoughby [1970], the claimant suffered a leg injury due to the defendant's negligence. Before the trial, he was shot in the same leg during a robbery, requiring amputation. The House of Lords held the original defendant remained liable for the ongoing effects of the initial injury, arguing the second tort did not erase the loss caused by the first.
- In Jobling v Associated Dairies Ltd [1982], the claimant suffered a back injury at work due to the employer's negligence. Later, he developed an unrelated spinal disease rendering him unfit for work. The House of Lords held the employer's liability ceased when the unrelated disease took effect, treating the disease as a vicissitude of life that obliterated the effects of the original tort.
Revision Tip
Distinguishing Baker and Jobling is fundamental. Baker involved two consecutive tortious acts, while Jobling involved a tort followed by a supervening non-tortious illness. The courts approach these scenarios differently, focusing on whether the second event removes the damage caused by the first tortious act.
Key Point Checklist
This article has covered the following key knowledge points:
- Causation in negligence requires proof of both factual causation and legal causation (remoteness).
- The primary test for factual causation is the 'but for' test: 'But for' the defendant's breach, would the harm have occurred?
- Where the 'but for' test is difficult to apply due to multiple potential causes, the 'material contribution to harm' test (Bonnington Castings) may establish factual causation if the breach made a more than negligible contribution.
- In exceptional cases of scientific uncertainty (like mesothelioma), demonstrating a 'material increase in risk' (Fairchild) can establish factual causation.
- Liability may be apportioned for divisible injuries but is typically joint and several for indivisible injuries caused by multiple tortfeasors.
- Legal causation (remoteness) limits liability to damage of a reasonably foreseeable type (The Wagon Mound (No 1)).
- The 'egg-shell skull' rule makes defendants liable for the full extent of harm, even if unforeseeably severe due to the claimant's vulnerability.
- A novus actus interveniens (new intervening act) by the claimant, a third party, or nature can break the chain of causation if it is sufficiently independent and unforeseeable.
- Cases involving consecutive causes (Baker, Jobling) require careful analysis of whether the second event affects the liability stemming from the first tortious act.
Key Terms and Concepts
- Factual Causation
- Material Contribution to Harm
- Material Increase in Risk
- Remoteness of Damage
- Egg-Shell Skull Rule
- Novus Actus Interveniens
