Material contribution historically has been plagued by overenthusiastic lawyers and judges who have, over the last 70 years, turned it into a minefield of case law and full of traps for the clinical negligence lawyer trying to find a way through for their client on causation.
Fortunately, for those of us who find ourselves currently toiling in that particular field, we are now able to enjoy a window of relative clarity and simplicity of which our predecessors would be very envious.

The case law now supports the following propositions –
a) It is an alternative to the “But For” test;
b) It applies where the “But For” test does not provide the answer on causation – it is not possible to prove that the injury would probably have been avoided or probably have been the same, but for the negligence;
c) It is satisfied if there were a number of causes of the injury, one of which is the negligence and its contribution or effect was more than negligible;
d) It matters not whether –
– The causes are consecutive or simultaneous;
– The causes are cumulative;
– The injury is “divisible” – meaning dose related.

Do we need to know the history ?
– Well, the answer to that is “probably no”, and the recent 2023 Court of Appeal decision in Holmes v Poeton Holdings is probably sufficient
– but because the history of the test is so mired in complication, it is probably useful to be aware of the history of it if you are going to argue for or against it applying to a particular case.

Bonnington Castings v Wardlaw 1956 AC 613
• Employee claimed silica dust from grinders caused pneumoconiosis
• Non negligent and negligent silica dust exposure
• House of Lords held sufficient for C to prove on balance of probabilities that the negligent silica exposure caused or materially contributed to his pneumoconiosis
• Material means more than de minimis or more than negligible
• Majority of exposure was non negligent
• But some was negligent
• More than de minimis or neglible and did help to produce the disease
• Causation established.

Material contribution didn’t really feature in clinical negligence
Until …

Bailey v MoD 2008 EWCA Civ 883
• ERCP followed by pancreatitis
• Negligent resuscitation
• Aspiration of vomit
• Cardiac arrest
• Hypoxic brain injury
• The Court asked –
• Is it sufficient to prove negligence made a material contribution – something more than negligible to the weakness ?
• In cumulative cause cases
• But for negligence, injury avoided – claim succeeds
• But for negligence, injury the same – claim fails
• “In a case where medical science cannot establish the probability that ‘but for’ an act of negligence the injury would not have happened but can establish that the contribution of the negligent cause was more than negligible, the ‘but for’ test is modified, and the claimant will succeed.”
• “The instant case involved cumulative causes acting so as to create a weakness and thus the judge in my view applied the right test, and was entitled to reach the conclusion he did”.

MOD v AB and Others 2010 EWCA Civ 1317
• Much relied on by Defendants to argue Material Contribution only applies to “divisible” / dose related injuries
• Atomic tests military veterans’ case
• Claimed radiation materially contributed to injury
• “This method of proving causation (by showing that the tort made a material contribution to the condition or disease) is only available where the severity of the disease is related to the amount of exposure; further exposure to the noxious substance in question is capable of making the condition worse.”
• “We accept that, at least so far as cancers are concerned, the claimants cannot rely on proving that the radiation exposure has made a material contribution to the disease, as in Bailey and Bonnington Castings. This principle applies only where the disease or condition is ‘divisible’ so that an increased dose of the harmful agent worsens the disease”.

Williams v Bermuda 2016 UKPC 4
• C claimed in delay in CT scan for appendicitis led to delay in appendicectomy
• C suffered burst appendix, sepsis, a myocardial ischaemic event and lung complications requiring ventilation on ITU
• “sepsis from the ruptured appendix caused injury to his heart and lungs”
• “It is immaterial whether the cumulative factors operate concurrently or successively”
• Claimant won on material contribution.

Holmes v Poeton Holdings [2023] EWCA Civ 1377
• Personal injury case
• C claimed employer’s negligent exposure to trichloroethylene caused Parkinson’s disease;
• Trial judge – “whereas a divisible injury will necessarily be the result of cumulative causes, by contrast an indivisible injury can result from a single non-cumulative cause or cumulative causes”.
Divisible/indivisible – different type of injury from asbestos exposure provides classic illustration of both
• Asbestos can have 2 effects –
• Divisible – does related – asbestosis
• Indivisible – on/off – mesothelioma.
Court of Appeal in Holmes v Poeton held MC applies to indivisible as well as divisible injury
• Citing examples –
• The cardiac arrest and brain damage in Bailey v MoD
• The heart and lung injuries in Williams v Bermuda
• were both examples of indivisible injuries to which material contribution had been applied
(divisible = dose related)
• But C failed to prove material contribution on the evidence.

Can you give me some examples of it being applied ?

Bailey v MoD 2008 EWCA Civ 883
• Aspiration of vomit leading to cardiac arrest and hypoxic brain injury
Popple v Bimingham Women’s NHSFT 2012 EWCA Civ 1628 –
• hypoxic birth injury
Sido John v Central Manchester NHSFT 2016 EWHC 407 QB
• traumatic brain injury
Williams v Bermuda 2016 UKPC 4
• sepsis from a ruptured appendix causing injury to heart and lungs
Andrews v Greater Glasgow Health Board 2019 CSOH 31
• bowel ischaemia
Leach v North East Ambulance NHSFT 2020 EWHC 2914 QB
• PTSD
CNZ v Royal Bath Hospitals NHS FT and SoS for Health and Social Care 2023 EWHC 19 KB
• Acute profound hypoxia causing cerebral palsy.

Are there situations where it won’t help a Claimant ?
Whenever you are considering the test for causation, it is worth remembering other ways in which causation can fail …..

– a claimant fails to prove measurable damage from the negligence (Tahir v Haringey HA 1998 Lloyd’s Rep Med 104);
– all a claimant can prove is that the negligence increased the risk of injury (also Tahir v Haringey HA 1998 Lloyd’s Rep Med 104);
– in a case with a number of potential causes for an injury a claimant fails to prove the operative one was probably the negligent one (Wilsher v Essex AHA 1988 AC 1074).

Also remember –
• The case where it is possible to apportion that element or proportion of the Claimant’s injury probably attributable to the Defendant’s negligence

So – to recap …

The case law now supports the following propositions for Material Contribution –
a) It is an alternative to the “But For” test; Bailey
b) It applies where the “But For” test does not provide the answer on causation – it is not possible to prove that the injury would probably have been avoided or probably have been the same, but for the negligence; Bailey / Williams
c) It is satisfied if there were a number of causes of the injury, one of which is the negligence and its contribution or effect was more than negligible; Bailey / Williams
d) It matters not whether –
– The causes are consecutive or simultaneous; Williams
– The causes are cumulative;
– The injury is “divisible” – meaning dose related. Holmes

Take home points ?

Material contribution …
• The Claimant’s friend
• The Defendant’s enemy
• Over complicated in the case law
• Historically underused
• Easier than you think
• Just got easier.

Dr Simon Fox KC
28.4.24