Rehman & Others v Secretary of State for Health and Social Care & Others: Covid 19 care home claims failed on causation

In Rehman and others^[1], the High Court struck out 23 Covid‑19 fatal claims arising from the  contraction of the disease in care and nursing homes.

Master Davison held that the claimants’ pleaded cases on causation—whether framed as material contribution to harm under Bonnington Castings^[2] or material increase in risk under the Fairchild^[3] exception—had no real prospect of success.

The judgment is a clear signal that Covid‑19 employer and public liability claims must be proved on the ordinary “but for” causation basis unless they genuinely meet the narrow Fairchild criteria, which these claims did not.

Background and pleaded theories of causation

The cohort comprised fatal claims by relatives of elderly residents who died in the first wave of the pandemic. The Secretary of State (SoS) was sued alongside care homes and their insurers. 

The policy focus was the March Discharge Requirements and April Admissions Guidance in 2020, which did not mandate 14‑day isolation for asymptomatic admissions. Against care homes, the allegations included failures to implement adequate infection control. Conventional care shortcomings were pleaded but were not the subject of this decision.

On causation, the claimants advanced two routes. First, they asserted material contribution to injury, contending Covid‑19 infection is dose‑related and that “guilty” exposures attributable to negligence materially contributed to the infection and eventual manifestation of the disease. Secondly, they invoked the Fairchild material increase in risk approach, arguing that attribution to a particular source was scientifically impossible in early 2020 and that tortious exposures materially increased the risk of infection and death.

Material contribution to harm: why Bonnington could not carry the day

The court assumed for argument’s sake that Covid‑19 disease is or may be dose‑related. In other words, that Covid-19, an indivisible disease, was caused by the cumulative effect of infective particles acting on the body "and it requires a threshold dose of viral particles to be inhaled or ingested before infection is likely to occur..."

The claim nevertheless failed on material contribution because the claimants expressly accepted they could not prove that the infectious particles which caused any individual resident’s infection were the “guilty” particles generated by the alleged breaches. They could show, at most, that tortious exposures increased ambient viral load and hence the risk of infection. That is not the Bonnington test.

Master Davison noted that material contribution requires proof that the defendant’s breach made a real, non‑trivial contribution to the injury itself, not merely to the risk of that injury. In Bonnington, the claimant inhaled both innocent and guilty dust, all of which, acting cumulatively, caused the pneumoconiosis. By contrast, the Rehman claimants disavowed the ability to show that the causal infection event involved any “guilty” particles. Recasting a risk argument as “contribution to the mechanism of injury” did not cure the defect; the mechanism here was the infection itself, and the claimants could not link that event to tortious particles.

The judge was clear about the policy implications. Allowing a risk‑only case to prove material contribution would collapse the boundary between contribution to harm and contribution to risk, effectively importing Fairchild without its controls into the general run of disease claims and opening the floodgates.

Material increase in risk: why Fairchild did not apply

Turning to the Fairchild exception, the court applied the requirements identified by Lord Rodger in Fairchild, as subsequently refined: the principle is designed for cases where it is inherently impossible, as a matter of current science, to prove causation on the balance of probabilities; the defendant must have created a material risk of the kind of injury suffered; and the injury must have resulted from the eventuation of that risk. Fairchild is exceptional and attempts to extend it beyond mesothelioma have largely failed.

The claims failed at the threshold. Master Davison concluded that it was not inherently impossible, as opposed to very difficult, to prove Covid‑19 infection causation by ordinary means. He was persuaded that, in that respect, Covid-19 was entirely different to mesothelioma. The difficulty in these cases was evidential—no testing at the time, incomplete records, competing exposures—rather than a scientific impossibility of attribution of the kind encountered in mesothelioma. Indeed, the court noted that infectious disease claims, including Covid‑19, can sometimes be proved on conventional “but for” grounds, for example by drawing on spatiotemporal outbreaks, likely transmission routes and exclusion of alternatives.

The claimants’ reliance on a Fairchild fallback was driven by gaps in their evidence in these particular cases, not by a scientific bar applying to the whole class of Covid‑19 claims. "Their difficulty is not, in truth, scientific impossibility; it is lack of evidence."

Proportionality concerns reinforced the conclusion. If Fairchild applied, a minor tortious lapse increasing circulating virus might trigger liability for all downstream infections in a home, and policy‑level failures could expose the SoS to sweeping liability without claimant‑specific causation. That would be unjust and outside Fairchild’s narrow remit.

What the court did—and did not—decide

The court ordered that the Covid-19 element of the claims be struck out and/or summary judgment be given in favour of the defendants. The judgment does not preclude Covid‑19 claims proved on the ordinary "but for" causation basis with robust evidence, nor does it pronounce on breach or standard of care. It confines itself to the pleaded causation theories and the concessions made.

Practical implications for insurers, care providers and public authorities

The judgment builds on a series of cases examining exceptions to the "but for" causation test, including the Court of Appeal judgment in Sanderson v Hull^[4], a case which also concerned infectious disease. Parties should expect courts to demand proof that negligent exposures actually contributed to the development of the disease on the balance of probabilities; risk alone will not suffice. Fairchild will not be available unless claimants can show that, as a class, Covid‑19 infection cases present an inherent scientific impossibility of attribution comparable to mesothelioma, which Master Davison was satisfied they could not.

For defendants, early challenges to Fairchild‑based pleadings and to attempts to relabel risk as contribution are likely to succeed. For claimants, the path lies through careful, claimant‑specific evidence of transmission dynamics, timing and plausible source, coupled with the exclusion or minimisation of alternative exposures. Reliance on disclosure to “fill the gaps”, as was the claimants' strategy in this case, will be risky where the pleaded case concedes the core attribution problem.

Conclusion

Rehman is a decisive reaffirmation that Covid‑19 claims must meet orthodox causation standards unless they genuinely can be shown to fall within the tightly controlled Fairchild enclave. The court rejected material contribution because the claimants could not show that tortious particles contributed to the eventuation of the disease, and it rejected Fairchild because the difficulty was evidential rather than inherently scientific. For the market, the case provides a principled framework to assess and, where appropriate, to contest Covid‑19 disease claims on causation at an early stage.

That, at least, is how matters stand currently. It remains to be seen whether the claimants appeal. The causation challenge posed by conditions arising from the cumulative effect of multiple factors continues to challenge attempts to apply consistent principles and do justice to both claimant and defendant.

^[1] [2026] EWHC 6 (KB) 

^[2] Bonnington Castings Ltd v Wardlaw [1956] A.C. 613

^[3] Fairchild v Glenhaven Funeral Services Ltd (t/a GH Dovener & Son) [2002] UKHL 22

^[4] [2008] EWCA Civ 1211