Carl Heneghan (son & administrator of the estate of James Leo Heneghan, deceased) v Manchester dry docks Ltd & 5 ORS (2014)

The court had to assess the damages payable to the claimant (H), who had brought claims under the Law Reform (Miscellaneous Provisions) Act 1934 and the Fatal Accidents Act 1976 arising from the death of his father (F).

F had died of lung cancer. During the course of his working life, he had been exposed to asbestos fibres and dust. He had been employed by the six defendants (D) on a sequential basis between 1961 and 1974. There were earlier employers who had not been sued. The parties had agreed that F's exposure to asbestos over the course of his working life could be quantified and that the total exposed "share" of the defendants sued was 35.2 per cent. The parties' medical experts had agreed that F's risk of contracting lung cancer had been increased both by asbestos exposure and by his having smoked and that, on the balance of probabilities, he would not have developed lung cancer had he not been exposed to asbestos. The sole issue was whether each defendant was liable for damages in full (£175,000) or for only £61,600, being 35.2% of that sum.

HELD: In cases of this kind, there were two categories to consider. The first embodied the conventional common law approach: in a case where medical causation was in issue, strict adherence to logic and principle demanded proof on the balance of probabilities either of the whole of the damage suffered or of a material part of it, Bonnington Castings Ltd v Wardlaw [1956] A.C. 613 applied.

The second category comprised cases which were covered by the principle in Fairchild, in which it was held that the test of causation was whether the employer had materially increased the risk of harm to the claimant. H had argued that the common law had recognised a category of case which fell between the conventional approach and the Fairchild "extension". It was said that if a case fell within that intermediate category, it would be sufficient to prove on the balance of probabilities that the risk of injury or damage was materially increased. Such a principle, H asserted, could only apply when medical causation was proved under the conventional test and the issue was whether the defendant under scrutiny had caused the claimant's loss. H's intermediate category did not exist: it was in fact the same as the second category.

Although causation was a unitary concept, it was often convenient and helpful in a multi-party case to state that there were two stages to the inquiry. At the first stage, the court considered whether medical causation had been made out. Here medical causation involved considering whether H had proved that F's lung cancer had been caused by asbestos fibres and dust rather than by smoking. At the second stage, the court considered whether causation was proved against each of the defendants. Given the opinion of the medical experts, H succeeded at the first stage. However, he failed at the second stage. It was simply a question of doing the basic arithmetic and concluding that the contributions of each of the defendants, whether viewed individually or collectively, amounted to less than 51 per cent.

Further, it made no sense to say that each defendant's exposures materially contributed to the disease process. The evidence did not establish that every asbestos fibre, or exposure, was or must have been implicated in that process. The aetiology of lung cancer was different from silicosis or pneumoconiosis. In those cases, which depended on the gradual accumulation of lung dust, the disease process was continuous and the concept of material contribution had an intelligible role. In lung cancer cases, there was no analogue to the gradual accumulation in the lungs of asbestos or cigarette smoke. The risk of the disease eventuating was proportionate to the quantum of exposure, but that was a statistical judgment, not an assessment which could be linked to the physical presence of deposits of dust in the lung. H's case was instead covered by the Fairchild principle. That principle had been held to apply in mesothelioma cases; however, lung cancer and mesothelioma were legally indistinguishable; the preconditions set out in the authorities for the application of the principle were met in lung cancer cases, Fairchild applied and Sienkiewicz v Greif (UK) Ltd considered. H had conceded for the purposes of this action (but not any appeal) that should it be found that the Fairchild principle applied, he could not avoid apportionment given the decision in Barker v Corus UK Ltd. Damages would therefore be limited to the sum of £61,600 being 32.5% of the total sum.