Key takeaways
Illegality functions as a public policy rule
This prevents courts from awarding compensation for consequences of a claimant’s unlawful conduct.
Greater consideration of early strike out applications
There is now a clear platform for defendants to argue that proceedings should not continue.
There remains a clear duty of care to identify and manage risk
Specifically, in the context of mental health assessments.
The Supreme Court has unanimously held that a man who killed three people (though found not guilty by reason of insanity) cannot recover civil damages in negligence for his own losses linked to the killings.
Ranwell -v- G4S Health Services (UK) Ltd and others [2026] UKSC 2
The judgment underscores that illegality functions as a public policy rule preventing courts from awarding compensation for the consequences of a claimant’s own grave unlawful conduct, even when that conduct occurred during an episode of psychosis.
Background
In February 2019, the Claimant (Alexander Lewis Ranwell), was assessed by various mental health professionals whilst under arrest. However on the day of his release he killed three elderly men during an episode of psychosis.
The Claimant was found not guilty of murder by reason of insanity and detained under a hospital order. He subsequently issued wide ranging civil claims against four defendants, arguing that, but for alleged negligent failures in his mental health assessment, the killings would have been avoided.
He sought compensation for detention related losses, psychiatric injury, reputational harm, future care costs, and an indemnity against civil claims by the victims’ families.
Three defendants applied to strike out the negligence claim based on the doctrine of illegality, and the matter eventually came before the Supreme Court.
Supreme Court’s decision
The Court held that the doctrine of illegality was a complete bar to the negligence claim.
The judgment proceeds in two stages:
Threshold: engagement of the illegality doctrine
The Court confirmed criminal responsibility is not required. What matters is whether the conduct at the core of the claim constitutes unlawful behaviour of sufficient seriousness. Unlawful killing (regardless of an insanity acquittal) crosses that threshold.
Application of Patel -v- Mirza [2016] UKSC 42
The Court then applied the structured public policy analysis from Patel v Mirza, focusing on:
Whether denying the claim furthers the purpose of the legal prohibition
It was agreed that allowing a killer (even one not criminally responsible) to claim compensation for the consequences of those killings, would undermine that purpose.
Impact on other relevant public policies
The Court emphasised that public accountability for systemic failings should largely occur through inquests, inquiries, and safeguarding reviews, rather than private civil damages claims.
Proportionality
Given the gravity of the unlawful conduct and its centrality to every head of damage, denying the claim was proportionate.
Implications for healthcare providers
Fewer claims
Future claimants will be clearer as to the significant difficulties they will face attempting to recover losses arising from their own violent or criminal acts, and so we would expect fewer claims to be brought.
Greater consideration of early strike out applications
Where the claimant’s losses flow directly from serious unlawful acts, there is now a clear platform for defendants to argue that proceedings should not continue and so this should be carefully considered at an early stage, to minimise costs.
Accountability may take other forms
Whilst a welcome decision for healthcare providers, there remains a clear duty of care to identify and manage risk in the context of mental health assessments. Alleged failures may well be explored via alternative routes, including inquests, public inquiries etc, and so it will be important to have robust policies and processes in place and to document all decision-making carefully.
