Supreme Court revisits civil illegality in death by killing case - Michael Brooks Reid, Temple Garden Chambers

18/02/26. Michael Brooks Reid discusses the recent Supreme Court case G4S Health Services (UK) Ltd v Lewis-Ranwell [2026] UKSC 2, in which the panel was asked to decide, in the absence of any direct authority, whether the doctrine of illegality prevented a claimant from recovering losses in respect of his killing of three elderly men, in circumstances where he had been found not guilty of murder by reason of insanity.
Facts
The Claimant was diagnosed with schizophrenia and had previously been in psychiatric intensive care. On 8 and 9 February 2019, he was twice held in police custody, for suspected burglary and then for causing grievous bodily harm. He exhibited severe mental illness during these detentions, and the need for a mental health assessment was discussed but not actioned. On 10 February 2019, he killed three elderly men, delusionally believing them to be paedophiles. He was charged with murder but found not guilty by reason of insanity and detained under hospital and restriction orders.
The Claimant brought negligence claims against four parties, including G4S Health Services, a provider of forensic medical care to persons in custody, alleging their negligence led to his release into the community in a psychotic state and the subsequent killings. He argued that, with proper intervention, he would have been hospitalised rather than killing these men. The Claimant sought to recover damages in respect of, inter alia,loss of liberty during past and future detention, loss of earnings, psychiatric injury, loss of reputation, and an indemnity against any claims brought against him by the victim’s families.
The Issue
The defendants applied to strike out the claims based on the doctrine of illegality. Until this case, there was no direct domestic authority on the application of the doctrine where a claimant had been absolved of criminal culpability.
Lower Courts
The first instance judge held that the illegality defence applied only where the claimant knew they were acting unlawfully, dismissing the strike out application on the basis of the finding of insanity. The decision was upheld by the Court of Appeal (Andrews LJ dissenting).
Supreme Court
Lord Hodge and Lloyd-Jones (delivering a unanimous judgment of the Court) reviewed the authorities, both from domestic courts and Commonwealth jurisdictions.
The panel noted the...
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