Material Contribution and Covid-19
Rehman v Secretary of State for Health and Social Care & Ors [2026] EWHC 6 (KB)
Introduction
In Rehman, Master Davison considered applications by the Defendants to strike out twenty-three claims arising from deaths in care homes from Covid-19 during the pandemic. The claims were brought under the Law Reform (Miscellaneous Provisions) Act 1934 and the Fatal Accidents Act 1976. All but one of the Claimants alleged that the Secretary of State’s policy not to mandate 14-day isolation of asymptomatic patients upon discharge from hospital to care homes was negligent. The Claimants also alleged that there was a failure by care homes to ensure sufficient Covid-19 protection measures. On the Claimants’ case, these breaches of duty caused care home residents to contract Covid-19, which led to their deaths [1]. The Defendants sought to strike out the claims under CPR 3.4(2)(a) on the basis that the Claimants had no realistic prospect of success because they could not prove causation [6].
Claimants’ Case
The Claimants argued that they had reasonable prospects of success in establishing either that the Defendants’ negligence made a material contribution to the disease or, alternatively, that it materially contributed to the risk of suffering Covid-19 [7]-[9].
Material Contribution to Harm
Master Davison held that the doctrine of material contribution to harm did not apply to the facts of Rehman. Applying Bonnington Castings v Wardlaw [1956] AC 613, the Claimants were required to prove that the “guilty” covid-19 particles circulating as a result of the alleged breach of duty caused or partly caused their disease. Master Davison’s decision proceeded on the basis that the Claimants had conceded that they could not prove that the “guilty” particles at least partly caused their disease and accepted it may have been caused entirely by “innocent” particles. There was no evidence to prove that the “guilty” particles contributed to their disease [25].
The Claimants sought to argue that a material contribution to harm argument was available because there was evidence of a culpable increase in the environment prevalence of the Covid-19. However, as Master Davison noted, “to show a culpable increase in the environment of a circulating virus (or any other agent of disease) and a corresponding increase in the risk of disease is not the same as showing that the agent caused or partly caused or (to adopt Lord Reid’s expression [in Bonnington]) “helped to produce” the disease.” What the Claimants were in fact arguing was material contribution to risk [27].
Master Davison also held that Rehman was different to other material contribution cases. For example, in Bonnington, there was no doubt that the Claimant had inhaled some “guilty” silica dust. In Williams v Bermuda Hospitals Board [2016] UKPC 4, similarly, the Defendant accepted that the negligent period of delay materially contributed to the sepsis. In Rehman, however, the Claimants conceded that they could not prove that the “guilty” Covid-19 particles made a material contribution to their disease [26].
Material Contribution to Risk
The Claimants also sought to prove causation on a material contribution to risk basis. They submitted that Fairchild v Glenhaven Funeral Services [2002] UKHL 22 applied. However, Master Davison rejected this. After rehearsing Lord Rodger’s conditions for establishing causation in Fairchild, Master Davison held that the Claimants in Rehman could not the satisfy the first of Lord Rodger’s conditions. It was not “inherently impossible” to prove how their disease was caused [33]-[34]. Rehman was not like a mesothelioma case, where it is inherently impossible to prove which exact asbestos fibre caused the cancer. As Master Davison explained, even if a claimant in a mesothelioma claim was followed by a CCTV camera for their entire employment, they still could not prove which asbestos fibre caused their mesothelioma [34].
This difference between mesothelioma cases and Covid-19 in terms of scientific impossibility was demonstrated by Edwards v 2 Sisters Food Group Ltd [2025] EWHC 1312 (KB). In Edwards, employees in a chicken factory brought claims against their employer for failing to prevent their exposure to Covid-19 at the factory. On appeal, Sir Peter Lane agreed with the Claimants that it was arguable that causation could be established on a conventional “but for” basis and refused the Defendant’s strike out application. For example, in Edwards, some Claimants lived alone, travelled to work in their own vehicles, and alleged that they had no other environmental Covid-19 exposure. They therefore argued that the Defendant’s alleged negligence must have caused their infection: “but for” the failures to safeguard them from exposure, they would not have suffered Covid-19. This analysis would not be possible in a mesothelioma case or other diseases where the “material contribution to risk” test has been applied [34]-[35].
Master Davison therefore struck out the claims but has subsequently granted permission to appeal on the following grounds:
- Whether the judge was wrong to hold that the Bonnington Castings principle does not apply to cases of infectious disease and specifically Covid-19.
- Whether the judge was wrong to hold that the Fairchild principle does not apply to cases of infectious disease and specifically Covid-19.
A date for the appeal is yet to be fixed.
Comment
There are four points arising from Rehman.
First, Master Davison’s careful analysis of causation principles is important reading. It illustrates the exacting requirements of establishing causation and further emphasises the iterative approach that has been consistently endorsed by the courts in recent years. The following three stage approach applies:
- Can the Claimant prove on the balance of probabilities that causation is established on a “but for” basis? If not, can medical science resolve “but for” causation in favour of the Defendant?
- If medical science cannot resolve the question of “but for” causation, can the Claimant establish that the Defendant’s negligence materially contributed to the harm?
- If the Claimant cannot establish a material contribution to the harm itself, can the Claimant establish that the Defendant’s negligence made a material contribution to the risk of harm applying Lord Rodger’s six factors in Fairchild, with the relevant modification in Barker v Corus [2006] UKHL 20?
Secondly, the Claimants failed in Rehman because of a lack of evidence, not because the legal approach to material contribution in Covid-19 cases is uncertain. As Master Davison succinctly put it, “their difficulty is not, in truth, scientific impossibility; it is lack of evidence.” Indeed, Master Davison noted that the recasting of Bonnington in the manner sought by the Claimants would bring it into the realms of Fairchild [34]-[35]. Rehman is therefore an important reminder that good evidence is as important as tight legal argument in material contribution cases.
Thirdly, Rehman does not resolve the interesting question of whether Covid-19 is a cumulative or non-cumulative disease. The Claimants had alleged that Covid-19 is a cumulative disease. On their case, for Covid-19 to become symptomatic it requires an individual to inhale or ingest enough Covid-19 particles to cross a certain threshold. A small number of particles would be insufficient. Therefore, even where an individual is exposed to both “innocent” particles in the air as well as “guilty” particles caused by negligence, the inhalation of those “guilty” particles would satisfy the material contribution to harm test [15]. Nevertheless, Master Davison did not need to resolve the point on the facts of Rehman. Even on the Claimants’ case that it was a cumulative disease, they could not make out causation [24]. This difficult but important question in Covid-19 cases therefore remains up for debate.
Finally, whilst Master Davison’s analysis in relation to material contribution to risk of harm is orthodox, it might in hindsight be said that the policy reasoning in Fairchild should in fact apply in the Covid-19 context. Simply retorting that Covid-19 is outside the scope of Fairchild enclave because it is not “inherently impossible” to prove how the disease is caused is perhaps unjust. Whilst Covid-19 is obviously not the same as mesothelioma for the reasons advanced in Rehman, it remains to be seen whether the arguments deployed by the Claimants in Edwards will be sufficient to make out causation. If the trial judge in Edwards accepts that the Claimants inevitably had a baseline exposure to Covid-19 during the pandemic, for example walking from their front door to their car, or from their car to the factory door, which is not negligently caused, the policy arguments for allowing recovery in Fairchild become apt in Covid-19 cases. Indeed, it may be so difficult to find a suitable case with no environmental exposure that it is de facto impossible to establish how the disease was caused. In those circumstances, there may be a good argument that Covid-19 cases in fact do fall within the scope of the first condition (or that material contribution to risk should apply to Covid-19 cases because of the policy reasons in Fairchild if that is wrong). Of course, if the trial judge in Edwards were to accept, on the balance of probabilities, that the Claimants had no other environmental exposure and the exposure in the factory caused their disease, then the analysis in respect of Covid-19 cases falling outside of the Fairchild enclave is lucid. At present, there can be no objection to Master Davison’s approach in Rehman given Sir Peter Lane’s analysis at the interlocutory stage in Edwards, but the point remains to be determined by a tribunal of fact.
The Claimants were represented by Jeremy Hyam KC and Isabel McArdle of 1 Crown Office Row.
