Correlation does not imply causation

R (Wandsworth) v HM Senior Coroner for Inner West London [2021] EWHC 801 (Admin)

Most coroners won’t see any need to take extra care round a swimming pool when a Nicholas Cage film is about to be released, even given the clear relationship between one of Hollywood’s most prolific star’s film appearances and the number of people who die by drowning (see here). Nevertheless, in this recent Judicial Review case, the High Court have felt the need to remind coroners of the important principle in coronial law (sadly without any reference to Mr Cage) that correlation is not proof of causation.

The fact someone lived in a place where asbestos was present was not sufficient to establish that their fatal mesothelioma was caused by inhaling fibres from that asbestos. More is needed before a Coroner can be satisfied on the balance of probabilities, that a potential exposure to asbestos has more than minimally, negligibly or trivially contributed to a death. That the deceased was possibly exposed to asbestos at a particular address, and that asbestos is very often the cause of the mesothelioma that killed them cannot justify an inquest conclusion that asbestos exposure caused the death.


At Mrs Johns’ inquest two essential facts were not disputed: (1) that she died from bronchopneumonia resulting from malignant mesothelioma; and (2) that asbestos had been present at her council flat (owned by the applicant, Wandsworth Borough Council (‘WBC’).

The relevant history was that in 2003 WBC instructed contractors to remove some asbestos boards that had been present in Mrs Johns’ flat ever since she moved there in 1996. During this 4 day process, she had vacated the flat. Fourteen years later, Mrs Johns was diagnosed with mesothelioma and she died shortly afterwards. Having been told by the family that she had lived in a property containing asbestos, the hospital reported her death to the Coroner. As Mrs Johns had never worked, there was no suggestion that her exposure to asbestos had any industrial origin.

Following a short inquest, the Senior Coroner concluded that Mrs Johns had died from “exposure to asbestos whilst resident at [her flat], causing malignant mesothelioma.” WBC were unhappy with this conclusion and brought judicial review proceedings arguing that the conclusion should not have made any reference to asbestos causing her illness.

The inquest

At a pre-inquest review hearing (‘PIRH’) the Coroner had, with all the interested persons’ agreement, heard evidence from a pathologist. As noted by the High Court, this was (despite the agreement), an irregular way of proceeding. Oral evidence should not be taken at a PIRH (see the Chief Coroner’s Guidance No. 22, here). It is not clear why the simple solution of commencing the inquest, hearing that evidence and then formally adjourning to a later date, had not been adopted.

Nonetheless, at that PIRH the pathologist gave causation evidence regarding the “extremely strong association” between asbestos dust exposure and malignant mesothelioma. He also told the court that there was “often and usually” a long delay between the exposure and the onset of mesothelioma. He went on to say that “it was entirely reasonable to assume” that exposure to asbestos while living at the flat had led to the malignant mesothelioma and so he was “entirely satisfied on the balance of probabilities that living in accommodation where asbestos exposure has occurred has led to and caused this death.” As the High Court later pointed out, this was a comment that strayed far beyond the sphere of the medical expertise of a pathologist.[1]

Three months later, at the inquest itself, the Senior Coroner summarised her note of that earlier pathology evidence, and then indicated to the parties that she was likely to find that Mrs Johns died as a result of mesothelioma due to exposure to asbestos in her flat. The counsel present (including a representative for WBC) all declined the opportunity offered to address her on the law.

The Coroner then went on to find that she was “entirely satisfied that the cause of death was …. 1a bronchopneumonia and 1b malignant mesothelioma” and that she was also “entirely satisfied that the only reasonable place that Linda can have exposed to asbestos was while resident at [her flat].

Failure to raise the point at the inquest is not determinative

The High Court, using notable understatement, said that it was “regrettable” that counsel for WBC had not addressed the Coroner on the law or sufficiency of the evidence, but that did not preclude the judicial review challenge now being brought. Due to the inquisitorial nature of the proceedings and the fact that submissions from IPs at inquests are not determinative of any position, it was for the Coroner herself to decide whether there was sufficient evidence to make such a finding. Accordingly, WBC’s failure to challenge the Coroner’s provisional indication at the inquest was not fatal to the application.

Nevertheless, one can have some sympathy with a coroner being challenged in the High Court over something that was not raised with her at the relevant time. Barristers have a duty to assist the court and coroners are entitled to rely to some extent on the counsel appearing before them to help them on the law and sufficiency of evidence, rather than allowing a coroner to go astray and then complaining about it later.


The court was very clear in setting out the well-worn case law on causation in inquests. For causation of death to be established, the threshold is whether on the balance of probabilities, the event or conduct more than minimally, negligibly or trivially contributed to the death.[2]

As the Coroner adopted a neutral stance, the Court heard submissions only from WBC who did not dispute the very strong and well-established link between asbestos and mesothelioma. WBC’s case rather was that:

  • There was no positive evidence Mrs Johns had ever been exposed to freely circulating asbestos dust at her flat;
  • Mesothelioma does have other causes beyond asbestos which the evidence had not adequately addressed or excluded at the inquest;
  • Even if asbestos had caused Mrs Johns’ mesothelioma, exposure could have been at a place other than her flat; and
  • The Coroner was wrong to rely on the pathologist’s opinion on what had caused Mrs Johns’ mesothelioma as this was outside his expertise;
  • The Coroner failed to apply the ‘Galbraith plus test’ by asking herself whether there was sufficient evidence upon which to conclude that mesothelioma was caused as a result of asbestos exposure at the flat and whether such a finding was safe.

The court agreed with WBC, analysing the issue in two stages:

  • First, it had to consider whether the coroner could properly find on the balance of probabilities that Mrs John’s mesothelioma was caused by asbestos exposure.
  • Second, it had to consider whether the coroner could be satisfied on the balance of probabilities that such exposure took place at the flat.

On the first question, it could not be safely assumed that mesothelioma was invariably caused by exposure to asbestos fibres. Although the statistical association between the two was ‘extremely strong’, it was by no means absolute. By itself, that someone has mesothelioma is incapable of establishing a causal link in any particular case. A causal link requires some evidence specific to the particular case.

Coroners must take care not to confuse statistical probability with the balance of probabilities

Living in close proximity to products or materials that happen to contain asbestos does not necessarily entail exposure to asbestos fibres. On the evidence before the Coroner, there was no more than a possibility that the illness was the result of exposure to asbestos fibres at the flat. Crucially, a mere possibility does not meet the required test of causation.

It was impossible to say from the evidence that, on the balance of probabilities, an exposure to asbestos at the flat had made an actual and material contribution to the death. Therefore, such a finding could not safely be left on the Record of Inquest. The High Court quashed the inquest conclusion and substituted the Coroner’s findings with its own Box 3  finding that the deceased “was diagnosed with malignant mesothelioma in July 2018 and despite treatment this led to and caused her death on 27 August 2018 at St George’s Hospital.”  Box 4 was to read simply “Malignant mesothelioma.”


Alongside the decision in R (Chidlow) v Senior Coroner for Blackpool and Flyde [2019] EWHC 581 (Admin) (see our earlier blog here), this case is a further reminder to Coroners of the proper use of statistics.

In Chidlow, the court held that even when the established survival rate is over 50%, it cannot simply be assumed that the deceased would be a survivor without some evidence supporting the proposition that their individual case would fall into the surviving group. Something more than being a potential figure in a statistic will be needed to safely find that the deceased would probably have survived.

The judgment, makes no mention of the pathologist having undertaken a fibre count at the post mortem. As Dr Robert Forrest (who is both an Assistant Coroner and a forensic toxicologist) has helpfully reminded your blogger, mesothelioma without asbestos exposure is very rare indeed. Had the post mortem identified asbestos fibres in the lung tissue, then the link between asbestos exposure and mesothelioma would presumably have been stronger.

The difficulty, of course, is that whilst coroners could request a fibre count to demonstrate or exclude asbestos exposure on lung tissue in all cases of mesothelioma, such tests are expensive and are still an imperfect marker of asbestos exposure. The vast majority of mesothelioma cases referred to coroners come with an in-life histological diagnosis on a lung biopsy sample. This avoids the distress to the bereaved of an autopsy being conducted for diagnosis, but doesn’t sample sufficient tissue to do a formal fibre count. And, of course, even if the presence of asbestos is established at post mortem, the hurdle of establishing where that particular asbestos came from might still prove insurmountable.

It is abundantly clear that Coroners must only record matters as causative based on positive evidence about the individual in question, and not just on general statistics. Even an extremely strong positive correlation between two things will not establish causation.

Importantly, as the High Court noted, the Fairchild[3] principles arising from cases concerning civil liability in mesothelioma cases are not to be imported into coronial proceedings. Personal injury lawyers will be aware that in Fairchild the House of Lords approved the principle that liability might fall on any defendant who had materially increased the risk of harm, in circumstances where causation could not be shown adopting the ordinary “but for” and “balance of probabilities” tests.

In Fairchild, the court created an exception in tort law on the basis of public policy so as not to deny any remedy to a claimant who could not show causation against one of many possible tortfeasors. But, that principle has no application in coronial investigations where issues of civil liability should have no relevance to an inquest’s conclusion.

The final conclusion substituted by the court made no reference at all to asbestos in Mrs John’s ROI, although following Lewis and Tainton it is arguable that the Coroner could lawfully have recorded possible causes of death or a neutral exposition of the facts in Box 3, saying something along the lines of:

“Mrs Johns was diagnosed with malignant mesothelioma in 2018. Despite treatment, the malignant mesothelioma led to and caused her death by bronchopneumonia. She had lived in a flat where asbestos was present. However, it cannot be said that exposure to that asbestos probably caused her mesothelioma, although it is possible that it did so.”

Narrative conclusions in Mesothelioma cases are now likely to be the way forward.



[1] In Fairchild v Glenhaven Funeral Services Ltd [2003] 1 AC 32, the House of Lords summarised the relationship of asbestos to mesothelioma as follows: “From about the 1960s, it became widely known that exposure to asbestos dust and fibres could give rise not only to asbestosis and other pulmonary diseases, but also to the risk of developing a mesothelioma. In the absence of occupational exposure to asbestos dust it is a very rare tumour indeed, afflicting no more than about one person in a million per year. But the incidence of the tumour among those occupationally exposed to asbestos dust is about 1,000 times greater than in the general population. It is a condition which may be latent for many years…It is invariably fatal, and death usually occurs within 1-2 years of the condition being diagnosed. …It is not known what level of exposure to asbestos dust and fibre can be tolerated without significant risk of developing a mesothelioma, but it is known that those living in urban environments (although without occupational exposure) inhale large numbers of asbestos fibres without developing a mesothelioma. It is accepted that the risk of developing a mesothelioma increases in proportion to the quantity of asbestos dust and fibres inhaled: the greater the quantity of dust and fibre inhaled, the greater the risk. But the condition may be caused by a single fibre, or a few fibres, or many fibres.”

[2] making reference to R (Tainton) v HM Coroner for Preston and West Lancashire [2016] EWHC 1396 (Admin)