To recap, factual causation is the principle that a negligent act or omission has resulted in an adverse outcome/injury to an individual.
Legal Causation is the principle that damage must not be ‘too remote’, it has to be within the scope of one’s duty of care owed to another, though this is for another day.
Last week I talked about the ‘but for test’ – which is perhaps the broadest and least scientific test for establishing causation. This week I am going to talk about other aspects on the subject of causation.
The Material Contribution Test
In certain cases, the Court may decide to use this test instead of the ‘but for test’, usually when there is more than one cause of injury/damage. To prove causation using this test, a claimant does not have to prove that the Defendant’s negligent act/omission was the sole or even main cause of injury – provided they can prove that the negligence made a material contribution to the injury.
This was portrayed in the somewhat complicated case of Bailey –v- MoD & Portsmouth Hospitals Trust (2007). In this case the claimant underwent unsuccessful surgery to remove a gallstone at a Hospital under the control of the First Defendant. Post-operatively the Claimant was transferred to the Second Defendant’s Hospital. Two weeks after the operation, the claimant fell asleep and subsequently choked on her own vomit, leading to cardiac arrest and hypoxic brain damage. It was found that the claimant’s inability to respond naturally and effectively to the emergence of vomit from the gut was partly due to her weakened condition arising from the First Defendant’s breach of duty (the earlier failure to remove the gallstone was found to be negligent), though also due to her suffering from acute and severe pancreatitis at the same time – which was not the fault of the Defendant.
The question here was whether there was a causal connection between the claimant’s overall weakness when the injury occurred, and the negligent surgery 2 weeks previously. The Trial Judge decided that causation was established as although the breach of duty contributed partly to the outcome, and it could not be said to be the greater part (note that this differs to the ‘but for test’ threshold of 51%) – it could be inferred that it materially contributed to the injury.
The Material Increase to Risk Test
In some situations, a material increase to the risk of injury may amount to a material contribution, or even suffice in it’s own right to establish causation.
This can be seen in the asbestosis case of Fairchild –v- Glenhaven Funeral Services Ltd, (2002). In this case the House of Lords ruled that even though the claimant was unable to prove that his employment with the Defendant led to him contracting mesothelioma as a result of breathing in asbestos dust, the increased risk of the exposure was enough to find that the Defendants were liable.
The Egg Shell Skull
It is a well-established legal principle that a Defendant must take the claimant as he finds him. Therefore if a claimant is susceptible to a particular type of injury, this will not absolve the Defendant of liability.
This doctrine can be seen in the case of Smith v Leech Brain  in which a widow brought a claim against the defendant under the Fatal Accidents Act for the death of her husband. The defendant employed the husband. As a result of their negligence he incurred a burn to his lip. The lip contained pre-cancerous cells which were triggered by the injury sustained. He died three years later from cancer. The Trial Judge held that the burn was a foreseeable consequence of the defendant's negligence and this resulted in the death. The defendant was liable for his death. It was not necessary to show that death by cancer was foreseeable, nor that an ordinary person would not have died from the injury. The egg shell skull rule applies and the defendant must take his victim as he finds him.
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