Mr Lewis-Ranwell, suffering from severe paranoid schizophrenia, killed three men during a psychotic episode. Found not guilty of murder by reason of insanity, he sued healthcare providers for negligence, seeking compensation for detention and other losses. The Supreme Court held the illegality defence barred his civil claims.
Facts
Mr Lewis-Ranwell had schizophrenia and was detained twice in police custody in February 2019. On his pleaded account, mental health professionals saw or spoke to him, and a Mental Health Act assessment was discussed but not arranged before his release. He later killed three men during a psychotic episode. He was found not guilty of murder by reason of insanity and made subject to a hospital order with restrictions under sections 37 and 41 of the Mental Health Act 1983.
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The Civil Claim
The claimant brought proceedings against the defendants alleging negligence in failing to provide adequate mental health care and assessment, claiming this caused his release in a psychotic state and the subsequent killings. He sought damages for loss of liberty during detention, loss of reputation, past and future loss of earnings, psychiatric injury, and an indemnity against claims by victims’ families.
Issues
The central issues were:
- Whether the defence of illegality was engaged by the claimant’s civil claim in negligence, given he was found not guilty by reason of insanity rather than convicted of a criminal offence.
- If the illegality defence was engaged, whether it barred the claimant’s claim in whole or in part.
Judgment
The Court considered the strike-out applications on the assumed facts pleaded by the claimant. It did not decide whether the defendants had been negligent.
The Threshold Question
The Supreme Court held that the claimant’s conduct was unlawful so as to engage the illegality defence, notwithstanding the verdict of not guilty by reason of insanity. The Court emphasised that the distinction between diminished responsibility and insanity in criminal law should not fetter civil law analysis. Lord Hodge and Lord Lloyd-Jones stated:
“Killing another human being without lawful justification breaches a fundamental moral rule in our society – you shall not kill. This is so even when the person who has killed bears no criminal responsibility for his actions.”
The Court rejected the argument that the absence of criminal responsibility should preclude the illegality defence, holding that the claimant’s actions engaged the public interest and warranted the Patel assessment.
The Patel Assessment
Applying the trio of considerations from Patel v Mirza [2016] UKSC 42:
Stage (a): Underlying Purpose of the Prohibition
The prohibition against killing serves to preserve life and promote respect for its sanctity. The Court identified multiple inconsistencies that would arise if the claim were allowed:
“To allow the claimant to recover compensation for his detention would be wholly inconsistent with the rule requiring his detention. It would be inconsistent for a civil court to order the payment of compensation to the claimant for the consequences of his lawful detention ordered by a criminal court.”
The Court reasoned that insanity did not prevent liability in tort for battery. Allowing an indemnity against liability to the victims’ estates would undermine that position. Public confidence in the legal system would be undermined.
Stage (b): Other Relevant Public Policies
While denying the claim prevents ventilation of complaints, alternative procedures such as inquests exist for examining standards of care. The Court concluded the policy considerations at stage (a) greatly outweighed those at stage (b).
Stage (c): Proportionality
The Court held denial of the claim was proportionate given:
“The brutal killing of three innocent men is of the utmost seriousness. The conduct was central to all heads of loss claimed and the effective cause of such loss.”
Consistency with Previous Authority
The Court confirmed its approach was consistent with Clunis v Camden and Islington Health Authority [1998] QB 978, Gray v Thames Trains Ltd [2009] AC 1339, and Henderson v Dorset Healthcare University NHS Foundation Trust [2021] AC 563, whilst clarifying that the presence of criminal responsibility was not determinative. Lord Hamblen’s reasoning in Henderson was explained as not depending on criminal liability but on consistency principles:
“For one branch of the law to enable a person to profit from behaviour which another branch of the law treats as being criminal or otherwise unlawful would tend to produce inconsistency and disharmony in the law, and so cause damage to the integrity of the legal system.”
Implications
This judgment significantly clarifies that the illegality defence applies to civil claims arising from unlawful killings even where the claimant was found not guilty by reason of insanity. The decision confirms that:
- The threshold for engaging the illegality defence does not require criminal responsibility but depends on whether conduct engages the public interest.
- The M’Naghten rules distinction between insanity and diminished responsibility does not govern the scope of the illegality defence in civil proceedings.
- Consistency and coherence of the legal system remain the paramount considerations under the Patel framework.
- A claimant cannot recover compensation for losses flowing from lawful detention ordered as a consequence of their unlawful acts, nor obtain an indemnity against tort liability to their victims.
The judgment has significant implications for claims by mentally disordered persons against healthcare providers, establishing that the absence of moral culpability does not immunise claims from the illegality defence where allowing them would produce inconsistency damaging to the integrity of the legal system.
Verdict: Appeal allowed. The Supreme Court held that the illegality defence barred the claimant’s civil claim in negligence against the appellant defendants (G4S Health Services (UK) Ltd, Devon Partnership NHS Trust, and Devon County Council) in its entirety. The negligence claims against the three appellants were struck out. The Human Rights Act claims and the claims against the Chief Constable were outside the ruling.
Reported citations: [2026] AC 1085; [2026] 2 WLR 187; [2026] WLR(D) 46.
Source: Lewis-Ranwell v G4S Health Services (UK) Ltd and others [2026] UKSC 2
