#2347 - Proof Of Causation - Tort Law

Material Contribution to harm

The Rule

• If we know something has made a material contribution to a disease, recovery is available even if the proportions are not known so long as the tortious one is material

  • Bonnington Castings v Wardlaw – C was exposed to silica dust from two sources – one which was tortious and one which was not. He developed a respiratory disease, but it was clear that the contribution of the tortious disease, while not small, was vastly lesser than the first.

    • Held

      • Recovery permitted - the swing grinders contributed a quota of silica dust which was not negligible to C’s lungs

        • and helped to produce the disease from which he suffered

  • MOD v AB and Others [2010]:

    • Smith LJ

      • In Bonnington, the claim succeeded because the tortious exposure to silica dust had materially aggravated (to an unknown degree)

        • the pneumoconiosis which the claimant might well have developed in any event as the result of non-tortious exposure to the same type of dust.

          • The tort did not increase the risk of harm; it increased the actual harm

• But the principle cannot be used for indivisible conditions

  • MOD v AB and others [2010]:

    • Smith LJ

      • As far as cancer is concerned, C 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.

        • In those cases, the pneumoconiosis and the weakness were divisible conditions.

          • [although the proportions themselves could not be determined]

• It does not matter if one of the causes is natural causes and one is tortious

  • Both McGhee, Bonnginton had cases where the source of the dust was the employer, albeit that some was tortious and some not

    • In Wilsher, the multiple different causal agents – some natural and some not – defeated the claim both for material contribution and increase of risk

  • Bailey v MOD [2008]: C received negligent treatment, but also contracted pancreatitis, which contributed to the fact that C was so weak she was in a state where she aspirated vomit, causing brain damage.

    • Waller LJ

      • Judge decided at first instance that this was a case where MOD had made a material contribution to the risk of C aspirating vomit

        • As their lack of care had meant C was in such a weak state

          • This meant MOD had either increased the risk of C aspirating vomit

          • OR materially contributed to the deterioration which allowed C to aspirate vomit and cause brain damage.

      • If the evidence demonstrates on a balance of probabilities that the injury would have occurred as a result of the non-tortious cause or causes in any event,

        • C will have failed to establish that the tortious cause contributed.

      • If the evidence demonstrates that ‘but for’ the contribution of the tortious cause the injury would probably not have occurred,

        • C will (obviously) have discharged the burden.

      • 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 C will succeed.

• Swinging further towards claimants

  • Canning-Kishver v Sandwell and West Birmingham Hospitals

    • Sir Christopher Holland

      • The evidence does not establish on balance of probabilities that A's brain injury arose simply from her immaturity.

        • That cannot be excluded as a possibility but there is nothing to say that that non tortious cause was probable and the evidence of the experts militated against this.

          • However, the fact of residual possibilities militates against success for A by reference to a ‘but for’ test.

      • However I find on balance of probabilities the contribution of the collapse occasioned by the breach of duty

        • constituted a contribution to the harm than was more than negligible so that the claim succeeds.

Was Bailey dealing with material contribution or increase in risk?

• Reference to material increase in risk, but seems to be different

  • While there was reference to Fairchild and material increase in risk,

    • Waller LJ seems to base his decision on material contribution, which is not the same as the material increase in risk doctrine and not subject to Wilsher.

  • Bailey: It is unclear whether the case was decided on the basis of the two factors combining to make a sufficient weak condition

    • If it is this, then it fits within the narrow Bonnington

• Subsequent cases have interpreted it as material contribution

  • MOD v AB and Others [2010]:

    • Smith LJ (who agreed with Waller LJ in Bailey v MOD)

      • As far as cancer is concerned, C cannot rely on proving that the radiation exposure has made a material contribution to the disease, as in Bailey and Bonnington

        • Cancer is an indivisible condition; one either gets it or one does not.

          • The condition is not worse because one has been exposed to a greater or smaller amount of the causative agent.

      • In Bailey, the tort (a failure of medical care) increased C’s physical weakness. She would have been quite weak in any event as the result of a condition she had developed naturally.

        • No one could say how great a contribution each had made to the overall weakness save that each was material.

          • It was the overall weakness which led to the inhalation of vomit and resulting brain damage.

          • In those cases, the pneumoconiosis and the weakness were divisible conditions.

Material increase in Risk

The rule

• Fairchild v Glenhaven Funeral Services

  • Lord Bingham

    • McGhee did lead to new principle of law

      • Essentially that those who made a material increase to the risk of harm

        • Should be treated, in the absence of any other evidence, as having materially contributed to the harm.

    • On policy grounds, would also be unjust to deny C recourse as clearly wrong has been done by set of Ds

      • But medical evidence hasn’t kept pace and does not allow C to pick out the individual D.

        • Therefore all Ds are joint and severally liable to C –

          • they can sort out the proportions they owe amongst themselves, but C does not need to prove who it is.

• Ministry of Defence v AB and others [2010]:

  • Smith LJ

    • Under the Fairchild exception, it will be sufficient for C to show that the tort has materially increased the risk that he will develop the condition complained of.

      • That exception is of very narrow application based upon the particular facts of the case which involved the disease of mesothelioma.

Is there a difference between material contribution and material increase in risk?

• McGhee was a new principle of law – they denied there was a difference between risk and contribution

  • McGhee v NCB:

    • Lord Reid

      • I cannot accept the distinction drawn between materially increasing the risk that the disease will occur

        • and making a material contribution to its occurrence

      • From a broad and practical viewpoint I can see no substantial difference

        • between saying that what D did materially increased the risk of injury to C

          • and saying that what D did made a material contribution to his injury

    • Lord Simon:

      • The argument about increase of risk and material contribution are best suited to philosophy, not law.

• The confusion came b/c the court was not sure how the dermatitis occurred

  • Either through contribution....

    • Lord Reid

      • It may be that an accumulation of minor abrasions of the horny layer of the skin

        • is a necessary precondition for the onset of the disease.

      • I am inclined to think that the evidence points to the former view.

        • But in a field where so little appears to be known with certainty I could not say that that is proved.

          • If it were this, then this case would be indistinguishable from Bonnington

  • Or from a single exposure

    • Lord Reid

      • Or it may be that the disease starts at one particular abrasion and then spreads,

        • so that multiplication of abrasions merely increases the number of places where the disease can start

  • In the absence of this, a broader test was adopted

    • Lord Reid

      • But I think that in cases like this we must take a broader view of causation.

        • I can see no substantial difference between saying that what D did materially increased the risk of injury to C

          • and saying that what D did made a material contribution to his injury.

    • Lord Wilberforce sought to draw a distinction with Bonnington where D gave C an additional amount of tortious dust

      • whereas in McGhee it was all the same dust, it’s just that the lack of washing facilities “increased the risk” of dermatitis arising.

    • Me: the key is that McGhee extended to time periods – one when exposed to tortious damage the other not.

      • It was to this extent an extension of Bonnington

      • But the only reason for the material increase in risk approach was b/c of the unknown trigger

        • Was the condition divisible or indivisible? – had we been able to tell, the broader rule may or may not have been needed.

• Why the difference is key to Fairchild

  • The court in Fairchild adopted the extension of McGhee to time periods of harm so was in that way the same

  • But an expanded rule was required b/c unlike McGhee, in Fairchild there was no uncertainty about how the mechanism worked –

    • it had happened at one period in time and one alone, not over time, but there was no way to tell which period it had occurred

    • Ministry of Defence v AB and others [2010]:

      • Smith LJ

        • C’s difficulty was that they could not show which D’s asbestos had...