The Court of Appeal took a holistic approach in calculating contributory negligence in lung cancer claims; assessing 'blameworthiness' rather than a purely epidemiological approach of the relative risk of developing lung cancer.

The Facts

The deceased had smoked for a long period before commencing employment with the Defendant as a general decorator. Approximately 20% of his working time was spent in conditions where there was asbestos dust.

It was agreed by the parties the Claimant's death was caused by the combined effects of smoking (from the age of 14 until his death aged 74) and exposure to asbestos dust whilst working for the Defendant during the period 1966 and 1986. Post mortem lung analysis showed an asbestos fibre count above the level at which the risk of contracting lung cancer doubles.

First instance

The court held contributory negligence should not be assessed by reference to a mathematical calculation based on the relative risks from smoking and asbestos exposure alone, as argued by the Defendant.

The contributory negligence appraisal was largely influenced by policy considerations and the general practice in employers’ liability cases that where there is a breach of statutory duty the contributory negligence figure cannot exceed 50%.

Lung cancer is an indivisible disease and there are possibly other factors which could be taken into account and contributed to the condition, such as genetics. Accordingly, although the risk from smoking was between double and treble the risk from asbestos exposure, having considered all the relevant factors, the court assessed contributory negligence at 30%.

The Defendant was granted permission to appeal. It contended that from a mathematical perspective considering relative risks, the discount for contributory negligence should be between 85% and 90%, as the far greater share of the risk was caused by smoking.


The court held the concept of responsibility under section 1 of the Law Reform (Contributory Negligence) Act 1945 ('the 1945 Act') is not limited to causation, but also encompasses blameworthiness.

The Defendant was under a statutory duty to protect the Claimant and failed to do so. The legislative intention of the 1945 Act was to create a general rule capable of flexible application to all types of cases. Furthermore it would be incorrect to draw a general distinction between a claimant who contributes to his injury by conduct related to work and one who contributes to his injury by conduct not related to work.

The first instance judge was therefore correct not to undertake a purely mathematical assessment of the relative risk of contracting lung cancer. In undertaking the apportionment, appropriate weight had been given to competing considerations and underlying policies.

It was noted that had the assessment only considered relative risks, it would not have differentiated between the Defendant's blameworthiness in exposing employees to asbestos and that of the deceased in smoking, which would have been wrong in principle.

The judge was right to attach substantial weight to the Defendant's blameworthiness in exposing the deceased to asbestos in breach of a strict statutory duty when the dangers were well known. By contrast, less blame attached to the deceased's conduct in continuing to smoke after the dangers to health became known. It was also necessary to consider the period of 'innocent' smoking (when the risks weren't known) and the medical uncertainty of that earlier period. Accordingly the judge's apportionment of contributory negligence at 30% was well within the range of options open to him.

What can we learn?

  • The Court of Appeal restricted themselves to a narrow consideration of Judge Cotter's first instance decision. The finding is very fact specific and there may be instances where greater degree of contributory negligence is attached to the claimant. However, it is likely public policy will the driving force in cases of this nature. A breach of statutory duty by the defendant will always be likely to be considered to be the principal cause.
  • This was a case in which ordinary causation principles apply; i.e. the asbestos exposure was at a level sufficient to 'double the risk' of contracting lung cancer. The decision leaves open the issue of what would happen if causation could not be established on this basis, but the material contribution to risk test (i.e. Fairchild) needed to be utilised.
  • The Court of Appeal in Heneghan adopted a two stage test with the Claimant establishing medical causation (as between the competing causes) on the basis of a material contribution to risk but then having to apportion damages in line with the contribution to increasing risk. This opens up the possibility in certain factual scenarios of a defendant, fixed with a liability under the Fairchild test, still being able to argue that damages should be apportioned to very low percentages or, in extreme cases, to a level within the de minimis threshold. It is likely an appropriate test case will be heard before the Court of Appeal on this point.
  • It should perhaps be applauded that the Court of Appeal was prepared to allow the 30% contributory negligence finding. In October 2016, a US court gave judgment in a lung cancer case which noted the claimant bore no responsibility for his smoking habit because he was addicted and therefore was not held to be responsible.The causation element attributable to smoking was therefore disregarded. This is a worrying development, which will result in significantly larger pay-outs for insurers.