The recent Privy Council decision in Williams v The Bermuda Hospitals Board  has confirmed the role of ‘material contribution’ in establishing causation in clinical negligence claims and has already been followed in the subsequent High Court decision of John v Central Manchester and Manchester Children’s University Hospitals NHS Foundation Trust .
In brief, Williams involved a delay in performance of surgery to treat acute appendicitis. The claimant was admitted to a hospital emergency department complaining of abdominal pain at 11.17am. A CT scan was ordered but was not performed until 17.27 and was not reported to the treating doctor until 19.30. Surgery was performed at 21.30.
During the operation it was noted that the appendix had ruptured and there was wide spread sepsis in the pelvic region. This led to the claimant suffering heart and lung complications, for which he required life support in the intensive care unit. Fortunately, the claimant eventually made a full recovery.
The judge at first instance found that the CT scan should have been reported earlier, and that this had caused a delay in performing surgery of between 2 hours 20 minutes and 4 hours 15 minutes.
However, the judge applied the ‘but for’ test of causation and concluded that had the CT scan been obtained and interpreted promptly [the heart and lung] complications might have been avoided, but I am not satisfied that they probably would have been avoided.
On that basis, the judge awarded damages of $2,000 in respect of the claimant’s pain and suffering during the delay period but did not award any damages for the heart and lung complications.
This decision was reversed by the Court of Appeal in Bermuda. It was held that the trial judge had set the bar for proof of causation ‘unattainably high’ and that the test should have been whether the negligent delay in surgery had materially contributed to the claimant’s injury. On the basis of the medical evidence indicating that sepsis (the cause of the heart and lung complications) had been developing both prior to and during the delay period, the Court of Appeal found that the claimant had met the test for material contribution. The case was remitted for reassessment of damages, which were increased to $60,000, to reflect the heart and lung injury.
In giving the Court of Appeal’s judgment, Ward JA noted that the ‘but for’ test is sometimes relaxed, where the claimant would otherwise be unjustly required to prove the impossible, and he referred to the earlier case Bailey v Ministry of Defence  as an example of this principle.
The defendant appealed to the Privy Council on the basis that the Court of Appeal had been ‘led into error by a misinterpretation of “material contribution” as sufficient for the purposes of causation’.
The purpose of the appeal was to clarify this issue, as a matter of principle. The defendant agreed that, if the appeal was successful, they would not seek repayment of the claimant’s damages (which the claimant had donated to charity). Although not a party to the litigation in Williams, the NHS Litigation Authority made written submissions as an intervener, in the appeal.
A successful appeal in this case would have increased the hurdles faced by claimants, in establishing causation, in situations where it cannot be established, on the basis of medical science, the extent to which an act of negligence led to the claimant’s poor outcome.
Early cases involving material contribution to injury were generally related to industrial disease. However, in more recent years, this test has been considered by the courts in a medical context. Most notably in the 2008 Court of Appeal decision of Bailey in which it was held that, if it is not possible to prove, through medical science, what the claimant’s outcome would have been but for the negligence, it is sufficient for the claimant to prove that the negligence materially contributed to their injury.
The appeal in Williams was an attempt to roll back the position arguing that material contribution was now being interpreted too widely and should not apply in cases where the contributing factors occurred successively, rather than concurrently. Alternatively the defendant argued that any award of damages should be reduced to take into account the non-negligent contributory factors to the claimant’s injury.
The Privy Council reviewed the basis and interpretation of the material contribution test, as first established in Bonnington Castings Ltd v Wardlaw , and found for the claimant.
On considering whether a claimant can succeed in situations where negligent and non-negligent contributing factors do not occur at the same time, the Privy Counsel referred to the earlier House of Lords decision in McGhee v National Coal Board  (an industrial disease case), in which it had been decided that, if an injury is caused by two or more factors operating cumulatively then it is immaterial whether or not those factors also occur concurrently.
In Williams the Privy Council noted that the sequence of events in a case may provide important evidence as to whether, as a matter of fact, a negligent event has materially contributed to a claimant’s injury or has been so overtaken by subsequent events that it could not be said to have contributed to the injury. However ‘as a matter of principle, successive events are capable of each making a material contribution to the subsequent outcome’.
The Privy Council confirmed that claimants must prove that the defendant’s negligence made a material (ie more than negligible) contribution to the development of their injury. Following the earlier House of Lords authority in Wilsher v Essex Area Health Authority , the Privy Council noted that… a claim will fail if the most that can be said is that the claimant’s injury is likely to have been caused by one or more of a number of disparate factors, one of which was attributable to a wrongful act or omission of the defendant.
In considering whether the award of damages should be discounted to reflect the non-negligent contributory factors, the Privy Council referred to obiter from the earlier House of Lords decision in Hotson v East Berkshire Health Authority  (a clinical negligence claim) in which Lord Bridge stated that … if the plaintiff had proved on balance of probabilities that the authority’s negligent failure to diagnose and treat his injury promptly had materially contributed to the development of avascular necrosis [the condition which was the subject of the claim], I know of no principle of English law which would have entitled the authority to a discount from the full measure of damage to reflect the chance that, even given prompt treatment, avascular necrosis might well still have developed.
On this basis, the Privy Counsel dismissed the defendant’s appeal in Williams.
Although not directly relevant to their decision, the Privy Council also took the opportunity to provide an alternative interpretation of the decision in Bailey, describing this, not as a case in which material contribution applied, but instead as a case capable of being decided on the conventional ‘but for’ principle.
In Bailey a complex series of events led to the claimant being in an extremely weakened state and hospitalised in an intensive care unit. This was partly due to the defendant’s negligent mismanagement of her medical condition and partly due to the non-negligent development of a complication (pancreatitis). While in this weakened state, the claimant aspirated vomit, causing her to suffer cardiac arrest and brain damage. It was held by the Court of Appeal that the defendant’s negligence materially contributed to this outcome because it was one of several factors leading to the claimant being in a weakened state in which she was unable to prevent herself from aspirating vomit. It was not possible to ascertain the extent to which negligence had caused the claimant’s weakened state, as compared with the non-negligent pancreatitis. The Court of Appeal had therefore held the negligence had materially contributed to the claimant’s injury.
In Williams the Privy Council considered that the defendant had properly been found liable for the claimant’s injury in Bailey but that, in fact, the conventional ‘but for’ test had been met in that case the fact that [the claimant’s] vulnerability was heightened by her pancreatitis no more assisted the hospital’s case than if she had an egg shell skull.
This is a useful reminder to practitioners to carefully review the way in which causation is framed in every case and to consider whether, for claimants made vulnerable by their underlying medical condition or other non-negligent factors, the egg shell skull rule is applicable.
The more recent High Court decision of John followed the reasoning in Williams.
In this case, the claimant was a doctor who had suffered a head injury following a fall and had been admitted to hospital in the early morning. A CT scan was performed late in the afternoon, which identified a sub-dural haematoma in the brain, requiring urgent surgical treatment. The claimant was transferred by ambulance to a specialist centre where he underwent a neurosurgical procedure which relieved intra-cranial pressure caused by the haematoma. He subsequently developed a post-operative infection, which took a month to resolve. Unfortunately, the claimant was subsequently found to have sustained neurological deficits and was unable to return to work as a doctor.
It was found that there were negligent delays in performing the CT scan and arranging ambulance transfer on the day the claimant was admitted to hospital, which led to a delay in performance of the urgent neurosurgical procedure.
The claimant argued that the raised intracranial pressure which occurred during the delay period had materially contributed to his poor neurological outcome. The defendant argued, inter alia, that the poor outcome could be related instead to the effects of the post-operative infection and that the claimant could not prove that the outcome would have been avoided if the neurosurgical procedure had been performed promptly.
In the alternative, the defendant argued that it should only be liable for a proportion of the claimant’s injury, in accordance with the negligent contribution to the injury.
Picken J found for the claimant and confirmed that, for the purposes of material contribution, it is not necessary for negligent and non-negligent factors to be concurrent. The correct test was whether the negligent factor made a material contribution to the claimant’s injury. Where that is the case, the claimant is entitled to recover damages for the whole of the injury without reduction. In reaching this conclusion the judge noted that, in cases of this type, it is impossible to determine what the claimant’s condition would have been but for the negligence and, therefore, there is no proper basis upon which to apportion and reduce the damages.
Going forwards these judgments will assist in considering when and how the test of material contribution should be applied in clinical negligence claims.
Bailey v Ministry of Defence and anor  EWCA Civ 883
Bonnington Castings Ltd v Wardlaw  UKHL 1
Hotson v East Berkshire Health Authority  UKHL 1
John v Central Manchester and Manchester Children’s University Hospitals NHS Foundation Trust  EWHC 407 (QB)
McGhee v National Coal Board  UKHL 7
Williams v The Bermuda Hospitals Board  UKPC 4
Wilsher v Essex Area Health Authority  UKHL 11
This blog first appeared as an article in the May 2016 edition of Personal Injury Law Journal www.lawjournals.co.uk