Proving causation: Material contribution

Proving causation: Material contribution

Where an injury could have had more than one cause, what must be proved to establish causation? This issue has engaged the courts, and two differing answers have been forthcoming. The differing and inconsistent tests are categorised as the ‘material contribution’ test and the ‘but for’ or direct cause test.

For material contribution to be proved, the breach need not be the sole, or even principal, cause of the damage, although it must have materially contributed to it. The criteria of material contribution can be particularly difficult to assess where the court is faced with the task of evaluating multiple causes.

The Bonnington test

In Bonnington Castings v Wardlaw [1956] 1 All ER 615 the claimant worked in a factory where he was exposed to silica dust. He suffered pneumoconiosis and subsequently sued his employers. They defended on the basis that it was inevitable he would be exposed to some dust at work from the processes. That was 'non-tortious dust'. He was also exposed to more dust due to the employers' negligence, which was referred to as 'tortious dust'. The claimant could not prove which dust caused the disease. Put another way, he could not prove that, but for the exposure to non-negligence dust, he would have been disease-free. The claimant won on the ground that the tortious dust made a material contribution to the disease.

Material increase in the risk of developing injury

The material contribution test was fully explored in Fairchild v Glenhaven Funeral Services [2002] UKHL 22, [2002] 3 All ER 305. The claimant had suffered mesothelioma and it was caused by exposure to asbestos dust with several different employers long ago in his youth. Mesothelioma is a cancer that starts by an unknown process in the pleura around the lung. Just one asbestos fibre can cause it. Some fibres lie on the pleura and merely cause irritation and scarring (plaques) and others, for reasons unknown, irritate the cells enough to trigger cancerous growth and death. The claimant could not prove which employer exposed him to the fibre that caused the triggering of cancer, so on the 'but for' test he failed. He could, however, prove every employer who exposed him to asbestos increased the risk that he would suffer the disease. The House of Lords applied the 'material increase in the risk' test and gave judgment for the claimant. Subsequent analysis of Fairchild in Sienkiewicz v Greif (UK) 2011] UKSC 10 2011] All ER (D) 107 (Mar) has raised the possibility that it introduced a new tort of negligently increasing the risk of personal injury.

Recent decisions of the High Court

More recently, the High Court have applied the test for material contribution in two cases to find in favour of the claimants.

In Leigh v London Ambulance Service NHS Trust [2014] EWHC 286 (QB) [2014] All ER (D) 201 (Feb), the claimant suffered a dislocated kneecap on a bus. Despite numerous calls for an ambulance, help did not arrive until 50 minutes after the injury, which was accepted by the Trust to be a delay of 17 minutes, about one-third of the total period between the dislocation and the arrival of the paramedics. The claimant suffered pain and suffering from the dislocation and consequent psychiatric and psychological damage arising from the incident. She claimed damages for the psychiatric and psychological damage. It was agreed that arising from the accident she had suffered Post Traumatic Stress Disorder (PTSD). It was also agreed that, from a date that was in issue, the claimant had suffered dissociative seizures.

The focus of the argument in Reaney v University Hospital of North Staffordshire NHS Trust and another [2014] EWHC 3016 (QB) [2014] All ER (D) 153 (Sep) was how the court should approach the award of damages when there is an underlying injury, that was non-negligently caused, and the subsequent negligent injury dramatically increases the claimant’s needs. The defendants admitted the negligent exacerbation of the claimant’s T7 paraplegia by deep (grade 4) pressure sores with the consequent infection of the bone marrow, abnormal shortening of the muscle tissue of her legs and a hip dislocation. The Queen’s Bench Division considered the extent to which the claimant’s condition had been made worse and what damages should be paid. Applying the principle that a tortfeasor had to take his victim as he found him and make full compensation for their worsened condition, the court found the defendants’ negligence had made the claimant’s position materially and significantly worse than it would have been but for that negligence.

The judgment in Reaney goes some way towards providing significant guidance on dealing with cases where there is an injury on top of an existing injury, and the judge’s obiter comments regarding material contribution demonstrate this to be a well-established principle that both parties should take into account when assessing causation of damage.

Click here to download our Practice Note detailing further guidance on how the Mesothelioma compensation scheme operates.

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