Causation

What does causation establish in a negligence claim?

Causation establishes the link between the defendant’s breach of duty and the damage suffered by the claimant.

What are the two main stages of causation in negligence?

The claimant must establish factual causation, after which the defendant may argue that legal causation has been broken by a novus actus interveniens.

Who bears the burden of proving factual causation in negligence?

The claimant bears the burden of proving factual causation.

Who bears the burden of establishing a novus actus interveniens in negligence?

The defendant bears the burden of showing that an intervening act broke the chain of legal causation.

What is the first test applied to establish factual causation in negligence?

The first test is the “but for” test.

What question is asked under the “but for” test in negligence?

On the balance of probabilities, but for the defendant’s breach, would the claimant have suffered the loss at that time and in that way?

When is factual causation satisfied under the “but for” test?

Factual causation is satisfied where the claimant would not have suffered the loss at that time and in that way but for the defendant’s breach.

When does the “but for” test fail in negligence?

The test fails where the claimant would have suffered the same loss at the same time and in the same way even without the defendant’s breach.

What standard of proof applies to factual causation in negligence?

Factual causation must be proved on the balance of probabilities, meaning that the breach was more likely than not to have caused the loss.

What level of probability must a claimant establish under the ordinary “but for” test?

The claimant must establish a probability of more than 50% that the defendant’s breach caused the loss.

What did Barnett v Chelsea and Kensington Hospital establish about factual causation?

Barnett v Chelsea and Kensington Hospital held that factual causation was not established because the patient would have died from poisoning even if the hospital had examined and treated him properly.

Why did the “but for” test fail in Barnett v Chelsea and Kensington Hospital?

The defendant’s breach made no difference to the outcome because the claimant would have died from the poisoning regardless.

What did Wilsher v Essex establish about multiple possible causes of an injury?

Wilsher v Essex held that factual causation was not established where the defendant’s breach was only one of five distinct possible causes of the claimant’s blindness.

Why did the ordinary “but for” test fail in Wilsher v Essex?

The claimant could prove only a 20% chance that the tortious factor caused the blindness, which was below the balance-of-probabilities threshold.

Why was the material-contribution test unavailable in Wilsher v Essex?

The five possible causes of blindness were distinct factors and were not operating together to produce the injury.

How is factual causation established where the breach consists of failing to advise a claimant about a risk?

The claimant must prove on the balance of probabilities that, if properly warned, they would not have undergone the procedure or would have deferred it.

What did Chester v Afshar establish about factual causation for failure to warn of medical risks?

Chester v Afshar indicates that the “but for” test is satisfied where the claimant proves that proper warning would have caused them to refuse or postpone the operation.

What must a claimant prove about their decision in a medical failure-to-warn claim?

The claimant must prove that proper advice would probably have changed the timing of, or decision to undergo, the treatment.

When may the material-contribution test be used in negligence?

The material-contribution test may be used where multiple causes operated together to produce the claimant’s injury and ordinary “but for” causation cannot be proved.

What must a claimant prove under the material-contribution test?

The claimant must prove that the defendant’s breach made a contribution to the injury that was more than negligible.

Do tortious and non-tortious factors both qualify under the material-contribution test?

Yes. The test may apply where tortious and non-tortious factors operated together to produce the claimant’s injury.

What did Bonnington Castings v Wardlaw establish about material contribution?

Bonnington Castings v Wardlaw held that causation was established where tortious and non-tortious dust operated together and the tortious dust made a more than negligible contribution to the claimant’s disease.

Why was the material-contribution test applied in Bonnington Castings v Wardlaw?

Medical evidence could not establish ordinary “but for” causation, but it showed that dust resulting from the breach contributed materially to the disease.

What did Bailey v Ministry of Defence establish about material contribution?

Bailey v Ministry of Defence held that causation was established where weakness caused by illness combined with weakness caused by negligent treatment to produce brain damage.

Why was material contribution available in Bailey v Ministry of Defence?

The claimant’s disease and the defendant’s negligent treatment operated together, and the negligent treatment made a material contribution to the resulting injury.

Can the material-contribution test apply where multiple causes operate sequentially?

Yes. It may apply where causes operate one after another, such as negligent treatment aggravating damage caused by an earlier head injury.

Can the material-contribution test apply where multiple causes operate simultaneously?

Yes. It may apply where tortious and non-tortious factors act at the same time to produce the injury.

What did Holmes v Poeton Holdings Ltd establish about material contribution?

Holmes v Poeton Holdings Ltd held that claimants may rely on material contribution whether the injury is divisible or indivisible.

What is a divisible injury for material-contribution purposes?

A divisible injury is one whose severity increases according to the claimant’s level of exposure to the causative factors.

What is an indivisible injury for material-contribution purposes?

An indivisible injury is one which, once contracted, does not become more severe according to the total amount of exposure that caused it.

How is liability apportioned where material contribution causes a divisible injury?

The defendant may be liable only for the extent to which their breach materially contributed to the divisible injury.

Does the material-contribution test apply where several distinct possible causes did not act together?

No. The test does not apply where the possible causes were independent alternatives rather than factors operating together: Wilsher v Essex.

When may the material-increase-in-risk test be used in negligence?

The test is confined to single-agent industrial-disease cases where scientific uncertainty prevents proof of which exposure caused the disease.

What is meant by a “single agent” in material-increase-in-risk cases?

A single agent is one harmful substance or factor, such as dust or asbestos, to which the claimant was exposed in both tortious and non-tortious circumstances.

What must a claimant prove under the material-increase-in-risk test?

The claimant must prove that the defendant’s breach materially increased the risk of contracting the relevant disease.

What did McGhee v National Coal Board establish about material increase in risk?

McGhee v National Coal Board held that causation could be established where the employer’s breach materially increased the claimant’s risk of developing dermatitis.

What uncertainty existed in McGhee v National Coal Board?

Experts could not determine whether the dermatitis resulted from lawful exposure during work or from the additional exposure caused by the absence of washing facilities.

Why could material contribution not be proved in McGhee v National Coal Board?

Experts could not show that tortious and non-tortious dust operated together to produce the dermatitis.

What evidence was sufficient to establish causation in McGhee v National Coal Board?

Evidence that leaving dust on the claimant’s skin for longer materially increased the risk of developing dermatitis was sufficient.

What did Fairchild v Glenhaven Funeral Services Ltd establish about multiple defendants?

Fairchild v Glenhaven Funeral Services Ltd held that each employer who exposed the claimant to asbestos could be liable because each exposure materially increased the risk of mesothelioma.

Why could ordinary factual causation not be proved in Fairchild v Glenhaven Funeral Services Ltd?

Scientific evidence could not determine which employer’s asbestos exposure caused the mesothelioma or whether the disease resulted from cumulative or single exposure.

What was sufficient to establish causation in Fairchild v Glenhaven Funeral Services Ltd?

The fact that each defendant exposed the claimant to asbestos was sufficient because each exposure materially increased the risk of mesothelioma.

What is the difference between material contribution and material increase in risk?

Material contribution requires the breach to contribute to the injury itself, while material increase in risk applies where scientific uncertainty allows proof only that the breach increased the risk of the disease.

When should loss of chance be considered in a causation analysis?

Loss of chance should be considered where the claimant cannot prove that the defendant’s breach caused the final outcome but argues that the breach deprived them of a valuable opportunity.

What did Hotson v East Berkshire Health Authority establish about loss of a medical chance?

Hotson v East Berkshire Health Authority rejected a claim for loss of a 25% chance of recovery because the claimant was most likely already destined to suffer paralysis from the original fall.

Why did the claimant fail in Hotson v East Berkshire Health Authority?

The evidence showed that there was a 75% likelihood that the original injury had already caused the paralysis, so causation could not be proved on the balance of probabilities.

What did Allied Maples Group v Simmons & Simmons establish about commercial loss of chance?

Allied Maples Group v Simmons & Simmons allowed recovery where negligent legal advice caused the claimant to lose a real and substantial chance of negotiating a protective contractual clause.

What must be shown for a recoverable commercial loss of chance under Allied Maples?

The claimant must show that the lost opportunity was real and substantial rather than merely speculative.

Why did the loss-of-chance claim succeed in Allied Maples Group v Simmons & Simmons?

There was a real and substantial chance that the seller would have agreed to the contractual clause if the solicitor had advised the claimant properly.

What is legal causation in negligence?

Legal causation asks whether an intervening event broke the chain between the defendant’s breach and the claimant’s eventual loss.

What is a novus actus interveniens?

A novus actus interveniens is a new intervening act that breaks the chain of causation between the defendant’s breach and later damage.

What is the effect of a novus actus interveniens on negligence liability?

The original defendant remains liable for loss occurring before the intervening act but is not liable for additional loss caused after the chain is broken.

What types of events may constitute a novus actus interveniens?

An exceptional natural event, an unforeseeable act of a third party, grossly unforeseeable medical treatment, or highly unreasonable conduct by the claimant may break the chain.

What is an “act of God” for the purposes of legal causation?

An act of God is an exceptional natural event, such as a lightning strike or extraordinary storm, that may break the chain of causation.

What did Carslogie Steamship Co Ltd v Royal Norwegian Government establish about intervening natural events?

Carslogie Steamship Co Ltd v Royal Norwegian Government held that the defendant was liable only for damage caused by the initial collision, not later damage caused by an exceptional storm.

Why did the storm break the chain of causation in Carslogie Steamship?

The repairs caused by the original collision were not immediately necessary, and the later heavy storm caused separate additional damage.

When will a third party’s act break the chain of causation in negligence?

A third party’s act may break the chain where it is highly unforeseeable and very unlikely to occur as a consequence of the original breach.

What did Knightley v Johns establish about third-party intervention?

Knightley v Johns held that a police officer’s negligent traffic-control instruction was a highly unforeseeable intervention that broke the chain from the original road accident.

What happened in Knightley v Johns?

The first defendant caused a road accident, after which a police officer negligently instructed the claimant to travel through a tunnel against the flow of traffic.

Why did the second defendant’s conduct break the chain in Knightley v Johns?

The negligent traffic-control instruction was sufficiently independent and highly unforeseeable in relation to the original defendant’s breach.

Will ordinary negligent medical treatment usually break the chain of causation?

No. Medical treatment will not usually break the chain unless it is so gross and egregious that it is unforeseeable.

What threshold must medical negligence meet to become a novus actus interveniens?

The medical treatment must be so gross and egregious that it falls outside what could reasonably have been foreseen.

What did Wright v Cambridge Medical Group establish about intervening medical treatment?

Wright v Cambridge Medical Group confirmed that the threshold is very high and that a negligent failure to refer the claimant was insufficient to break the chain.

Why did the medical negligence in Wright v Cambridge Medical Group not break the chain?

The failure to refer was negligent but was not so gross and egregious as to be unforeseeable.

When will a claimant’s own conduct break the chain of causation?

The claimant’s conduct may break the chain where it is highly unreasonable and independently causes further harm.

What did McKew v Holland establish about unreasonable claimant conduct?

McKew v Holland held that the claimant broke the chain by attempting to descend a steep staircase without a handrail despite an existing leg injury.

Why did the claimant’s conduct break the chain in McKew v Holland?

Descending the steep staircase without support while suffering from an unstable leg was highly unreasonable and caused the further injury.

What did Wieland v Cyril establish about reasonable claimant conduct?

Wieland v Cyril held that a claimant wearing a neck brace did not break the chain by accepting help while descending stairs because she acted with sufficient care.

Why was the chain of causation not broken in Wieland v Cyril?

The claimant’s conduct in accepting assistance on the stairs was a reasonable response to the limitations caused by her injury.

What did Spencer v Wincanton establish about claimant conduct and a second accident?

Spencer v Wincanton held that a claimant’s highly unreasonable conduct as an amputee could break the chain where it caused a later accident.

What is the key distinction between McKew v Holland and Wieland v Cyril?

In McKew, the claimant acted highly unreasonably and broke the chain; in Wieland, the claimant acted carefully and the chain remained intact.