Learning Outcomes
This article examines the principles of legal causation in negligence, focusing on how certain events occurring after the defendant's breach can affect liability. You will learn to identify and analyse intervening acts (novus actus interveniens), including acts of God, acts of third parties, and acts of the claimant. You will also understand the concept of remoteness of damage and the 'eggshell skull' rule. This knowledge is essential for applying causation principles to SQE1 assessment scenarios and determining the extent of a defendant's liability.
SQE1 Syllabus
For SQE1, you need to understand how the chain of causation can be broken in negligence claims. This involves applying the rules relating to legal causation and remoteness of damage.
Pay particular attention in your revision to:
- The concept of novus actus interveniens (a new intervening act).
- How acts of God can break the chain of causation.
- When the actions of a third party will break the chain of causation.
- The circumstances in which the claimant's own actions might break the chain.
- The test for remoteness of damage (The Wagon Mound test).
- The application of the 'eggshell skull' rule.
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.
- What is the legal term for an intervening act that breaks the chain of causation?
- True or False: If damage caused by a defendant's negligence is made worse by an unforeseeable natural event, the defendant is always liable for the full extent of the damage.
- In what circumstances might the negligent act of a third party not break the chain of causation following the defendant's initial negligence?
- What is the general principle known as the 'eggshell skull' rule?
Introduction
Establishing factual causation using the 'but for' test (covered elsewhere) is only the first step in proving causation in negligence. Even if the defendant's breach was a factual cause of the claimant's harm, the defendant may not be legally responsible if the chain of causation is broken by a subsequent event, or if the damage is considered too remote. This article focuses on legal causation, exploring the rules that determine whether the defendant's breach remains the legally relevant cause of the claimant's loss. We will examine intervening acts and the principles of remoteness.
Breaking the Chain of Causation: Novus Actus Interveniens
Sometimes, an event occurs after the defendant's breach of duty but before the claimant suffers damage, or further damage. If this subsequent event is sufficient to break the chain of causation linking the breach to the damage, it is known as a novus actus interveniens (a new intervening act). The effect is that the defendant will not be liable for the damage occurring after the intervening act, as the legal responsibility shifts.
Key Term: Novus Actus Interveniens A new intervening act by a third party, the claimant, or an act of God, which is significant enough to break the chain of causation between the defendant's negligent act and the claimant's loss or damage.
Whether an act breaks the chain depends on its nature and foreseeability. The main categories are acts of God, acts of third parties, and acts of the claimant.
Intervening Acts: Acts of God
An act of God refers to a natural event that is so extraordinary and unforeseeable that it is considered outside human control or foresight.
Key Term: Act of God A natural event of exceptional and unforeseeable force (eg, earthquake, unprecedented storm) that occurs independently of human action.
If such an event occurs after the defendant's breach and contributes to the claimant's damage, it may break the chain of causation, absolving the defendant from liability for the additional damage caused by the natural event. The key factor is whether the natural event was foreseeable.
Worked Example 1.1
A defendant negligently damages the claimant’s roof, leaving it exposed. Before repairs can be made, an exceptionally severe hurricane, unprecedented in the region, completely destroys the claimant's house. Is the defendant liable for the destruction of the house?
Answer: Probably not. While the defendant is liable for the initial roof damage, the hurricane might be considered an unforeseeable Act of God. If its severity was truly unprecedented and unforeseeable, it would likely break the chain of causation, meaning the defendant is not liable for the house's destruction, only the initial roof damage.
Intervening Acts: Acts of Third Parties
The actions of a third party occurring after the defendant's breach can also break the chain of causation. However, this depends heavily on the foreseeability and nature of the third party's actions.
If the third party's actions were a foreseeable consequence of the defendant's negligence, the chain is unlikely to be broken.
Worked Example 1.2
Defendant A negligently leaves an excavation site unsecured. Children trespass onto the site and one falls into a trench, suffering injury. Is Defendant A liable?
Answer: Likely yes. It is generally foreseeable that children might trespass onto unsecured sites and injure themselves. The children's actions, while technically those of a third party, are a foreseeable consequence of the defendant's initial negligence in failing to secure the site. The chain of causation is unlikely to be broken.
However, if the third party's actions are unforeseeable, deliberate, reckless, or highly negligent, they are more likely to be considered a novus actus interveniens.
Worked Example 1.3
Defendant B negligently causes a minor road traffic accident, slightly damaging Claimant C's car. While they are waiting for assistance, Third Party D, driving recklessly at high speed, crashes into C's stationary car, causing significant further damage and injuring C. Is B liable for the injuries and further damage caused by D?
Answer: Likely no. While B is liable for the initial minor damage, D's reckless driving is likely seen as a new, independent act breaking the chain of causation. B could not reasonably foresee such reckless behaviour. B would not be liable for the harm caused solely by D's intervention.
Medical negligence following an injury caused by the defendant is generally treated as foreseeable and usually does not break the chain unless it is palpably wrong or grossly negligent.
Intervening Acts: Acts of the Claimant
A claimant's own actions after the defendant's breach can also break the chain of causation, but only if the claimant's conduct was entirely unreasonable in the circumstances. The law expects claimants to take reasonable care for their own safety.
Worked Example 1.4
Due to Defendant E's negligence, Claimant F suffers a leg injury that occasionally makes the leg give way. F is aware of this weakness. Later, F decides to descend a steep, narrow staircase without a handrail and without assistance. The leg gives way, F falls, and suffers further injury. Is E liable for the second injury?
Answer: Unlikely. F's action in attempting to use the difficult stairs despite knowing the leg's weakness might be considered entirely unreasonable. This unreasonable conduct would constitute a novus actus interveniens, breaking the chain of causation. E would be liable for the initial leg injury but not the injury from the fall.
It is important to distinguish between the claimant's conduct breaking the chain of causation (which absolves the defendant of liability for subsequent damage) and contributory negligence (which reduces the damages awarded but does not eliminate liability entirely). For the claimant's act to break the chain, it must be more than merely careless; it must be unreasonable in the circumstances.
Remoteness of Damage
Even if factual causation is established and the chain of causation is unbroken, a defendant will not be liable if the damage suffered by the claimant is considered too ‘remote’ a consequence of the breach. Remoteness acts as a legal limit on the extent of a defendant’s liability.
Key Term: Remoteness of Damage A legal principle limiting liability in negligence to types of damage that were reasonably foreseeable consequences of the defendant's breach.
The leading test for remoteness comes from Overseas Tankship (UK) Ltd v Morts Dock & Engineering Co Ltd (The Wagon Mound (No 1)) [1961] AC 388. The test is whether the type or kind of damage suffered by the claimant was reasonably foreseeable at the time of the defendant's breach.
- It is the type of harm, not the extent or manner of its occurrence, that must be foreseeable.
- If the type of harm was foreseeable, the defendant is liable even if the extent of the harm was far greater than expected.
- If the type of harm was foreseeable, the defendant is liable even if the precise way it happened was unforeseeable.
Worked Example 1.5
Defendant G negligently starts a small fire which blocks an access road. Claimant H, driving a tanker carrying flammable liquid, has to take a long detour. Due to the delay and H's unrelated heart condition, H suffers a heart attack. Is G liable for H's heart attack?
Answer: Unlikely. While some delay or inconvenience (economic loss) might be foreseeable from blocking a road, personal injury in the form of a heart attack is likely not the type of harm reasonably foreseeable from G's negligence in starting a small fire. The damage is probably too remote.
The 'Eggshell Skull' Rule
An important exception or clarification to the remoteness rule is the 'eggshell skull' (or thin skull) rule. This principle states that the defendant must take their victim as they find them.
Key Term: Eggshell 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 or weakness, provided the initial type of harm was reasonably foreseeable.
If the type of initial injury was foreseeable, the defendant is liable for all the consequent harm, even if its extent was unforeseeable because the claimant had a particular vulnerability (eg, a brittle bone condition, a particular allergy, or even a pre-existing psychological vulnerability).
Worked Example 1.6
Defendant J negligently causes a minor burn to Claimant K's hand. Due to an unknown and rare pre-existing condition, K develops severe complications resulting in permanent disability. Is J liable for the full extent of the disability?
Answer: Yes. Injury by burning was a foreseeable type of harm. Applying the eggshell skull rule, J must take K as they find them, including the rare condition. J is liable for the full extent of the disability, even though the severity of the outcome was not foreseeable.
Summary
Legal causation filters the consequences of a defendant's breach, limiting liability to those harms that are not too remote and where the chain of causation remains intact.
- Novus Actus Interveniens: A new act can break the chain if it is unforeseeable and independent.
- Acts of God: Must be exceptional and unforeseeable natural events.
- Acts of Third Parties: Break the chain if unforeseeable, deliberate, or reckless; do not break the chain if a foreseeable consequence of the defendant's breach.
- Acts of the Claimant: Break the chain only if entirely unreasonable.
- Remoteness (The Wagon Mound Test): Liability is limited to damage of a type that was reasonably foreseeable at the time of the breach.
- Type vs. Extent/Manner: Foreseeability applies to the type of harm, not its exact extent or the precise way it occurred.
- Eggshell Skull Rule: Defendant takes the claimant as they find them; liable for the full extent of harm if the initial type of harm was foreseeable, even if the extent was unforeseeable due to claimant's vulnerability.
Understanding these principles is essential for correctly analysing liability in SQE1 negligence scenarios where events occur after the initial breach.
Key Point Checklist
This article has covered the following key knowledge points:
- Legal causation assesses whether the defendant's breach remains the operative cause of the damage despite subsequent events.
- A novus actus interveniens (new intervening act) can break the chain of causation.
- Acts of God (exceptional, unforeseeable natural events) can break the chain.
- Acts of third parties break the chain if unforeseeable and independent, but not if they are a foreseeable consequence of the defendant's negligence.
- Acts of the claimant break the chain only if entirely unreasonable.
- Remoteness of damage limits liability to types of harm that were reasonably foreseeable (The Wagon Mound test).
- The foreseeability test applies to the type of harm, not the extent or manner of occurrence.
- The 'eggshell skull' rule means the defendant is liable for the full extent of foreseeable types of harm, even if exacerbated by the claimant's vulnerability.
Key Terms and Concepts
- Novus Actus Interveniens
- Act of God
- Remoteness of Damage
- Eggshell Skull Rule
