For claims in the tort of negligence, the claimant must show that the defendant caused them a loss. The Courts have defined the test for causation, which is split into factual and legal causation. They have also needed to determine the meaning of ‘loss’.
The first case summaries involve questions of factual causation, which usually requires an application of the ‘but-for’ test. Where there has been issues of evidence and proof, the Courts have applied a different test looking at the contribution to the risk of damage or harm.
The next set of summaries concern the test for legal causation: proving the defendant in law caused the loss. The Courts have to decide whether an intervening event has broken the chain of causation. This is to decide whether the defendant is responsible for the claimant’s loss.
The final cases concern the meaning of ‘loss’.
1 – Factual Causation
The Courts usually apply the ‘but-for’ test to determine whether the act of the defendant factually ‘caused’ the claimant’s loss. If the loss would not have occurred ‘but-for’ the defendant’s actions, the Courts will say as a matter of fact that the defendant caused the loss.
Barnett v Chelsea and Kensington Hospital Management Committee 
Barnett demonstrates that the defendant must cause the loss, and it is for the claimant to show this. In Barnett, the claim was dismissed because, even though the doctor was negligent, on the balance of probability the doctor’s failure to take reasonable care had not caused the defendant’s death.
For successive tortious events, the second defendant is only liable for any extra damage they cause.
Performance Cars Ltd v Abraham 
Performance Cars Ltd v Abraham raised a novel point concerning successive events. Where two events cause the same harm which requires the same cost of repair, the second defendant can not be said to have caused this loss. The second defendant is only liable for any extra damage caused.
The House of Lords approved the decision in Performance Cars Ltd v Abraham. Where two persons do successive, separate acts causing the same loss, the second person is not liable for that loss. The second defendant will only be liable for any extra damage caused. Jobling v Associated Dairies 
In Jobling v Associated Dairies, the House of Lords reaffirmed the ‘vicissitudes’ principle to reduced the damages award where a second, natural event which would have occurred anyway overtook the claimant’s initial injury.
Exception to the but-for test: material contribution to harm or the risk of harm
Wardlaw v Bonnington Castings Ltd 
In Bonnington Castings, the House of Lords held the defendant was liable to the full extent for the claimant’s harm where their negligence was one of a number of sources of the damage but materially contributed to the injury.
In Holtby, the Court of Appeal concluded, following Bonnington Castings, that the defendant did factually cause the damage because they materially contributed to it, but only held them liable to the extent of their contribution. McGhee v National Coal Board 
In McGhee v ‘NCB’, the House of Lords concluded that materially contributing to the risk of injury was equivalent to materially contributing to the harm. Fairchild v Glenhaven Funeral Services 
In Fairchild v Glenhaven Funeral Services, the HL held that where a claimant is unable to prove the but-for cause of their injuries due to insufficient medical knowledge, it is sufficient to show the defendant materially contributed to the risk of harm for the purposes of causation in the tort of negligence. Barker v Corus UK Ltd 
In Barker v Corus, the House of Lords extended the principle from Fairchild v Glenhaven Funeral Services to cases where the claimant was exposed to dust by tortious and non-tortious sources. Compensation Act 2006
The Compensation Act 2006 reversed the House of Lords’ decision in Barker v Corus on apportionment in cases where the claimant has suffered mesothelioma. Sienkiewicz v Greif (UK) Ltd 
In Sienkiewicz v Greif (UK) Ltd, the Supreme Court held the defendant liable for the full loss of negligently exposing the claimant to asbestos, even though the defendant only increased the risk of harm by a small amount.
Exception to the but-for test: loss of a chance
Hotson v East Berkshire Area Health Authority 
In Hotson v East Berkshire AHA, because there remained a 75% chance the claimant would anyway have suffered his injuries but-for the defendant’s negligence, the House of Lords held ‘on the balance of probability’ that the defendant had not caused the claimant’s loss.
In Allied Maples Group, the Court of Appeal clarified that where subsequent events are uncertain a claimant must show there was a “substantial” chance they would not have suffered a loss but-for the defendant’s negligence.
2 – Legal Causation
Intervening acts, or novus actus interveniens, can break the chain of causation between the defendant and the victim. Whilst factually they might be a cause for the loss, legally they are not said to have caused the loss.
Intervening natural events
Carslogie Steamship Co v Royal Norwegian Government 
In Carslogie, the House of Lords concluded claimants owe no damages in the tort of negligence where a subsequent natural event means the claimant suffered no further loss.
The Oropesa 
The Oropesa is an example where the subsequent act of another person did not break the chain of causation. It highlights that a person is still the legal cause for loss even when it occurs due to a person’s response to a negligent act.
Knightley v Johns clarified the law on ‘novus actus interveniens’ in the tort of negligence. It’s an example where subsequent acts by a third party broke the chain of causation between an act and injury. Topp v London Country Bus 
Topp v London Country Bus is an example of a case where the act of a third party likely broke the chain of causation between the defendant and the victim. Stansbie v Troman 
In Stansbie v Troman, due to the specific duty of care owed by the defendant the intervening act of a third party did not break the chain of causation. The breach of their duty made them directly responsible for the loss.
Haynes v Harwood 
Haynes v Harwood is an example of a case where the claimant’s own act did not constitute a novus actus interveniens.
McKew v Holland makes clear that the act of the claimant themselves can constitute a novus actus interveniens. This will be the case where the claimant acts unreasonably. Wieland v Cyril Lord Carpets Ltd 
Wieland v Cyril Lord Carpets Ltd is an example where the claimant’s own acts did not constitute a novus actus interveniens. Reeves v Commissioner of Police of the Metropolis 
In Reeves v Commissioner of Police of the Metropolis, the HL held that a person’s decision to commit suicide did not break the chain of causation between the police’s negligent act and the claimant’s loss. Corr v IBC Vehicles Ltc 
Corr v IBC Vehicles Ltd is an example where the victim’s own act was not a novus actus interveniens. Spencer v Wincanton Holdings Ltd 
The CA in Spencer v Wincanton Holdings Ltd discussed and clarified the correct test for deciding whether the chain of causation has been broken.
3 – Meaning of Loss
Rothwell v Chemical & Insulating Co Ltd 
In Rothwell v Chemical & Insulating Co Ltd, the House of Lords held that the claimants had not suffered actionable damage, and therefore could not recover in the tort of negligence.
In Dryden v Johnson Matthey Plc, the Supreme Court held that platinum sensitisation (an asymptomatic condition) did constitute actionable physical damage.