Supreme Court’s decision on the illegality defence: Lewis-Ranwell v G4S Health Services (UK) Ltd and others (2026)

The Supreme Court has handed down its unanimous judgment barring the claimant from bringing civil claims in negligence arising from his unlawful killing of three men.

In the case of Lewis-Ranwell (Respondent) v G4S Health Services (UK) Ltd and others (Appellants) [2026] UKSC 2, on appeal from [2024] EWCA Civ 138, the Supreme Court delivered its judgment on the defence of illegality (or ex turpi causa) in respect of negligence claims on 21 January 2026.

Background

The claimant, Alexander Lewis-Ranwell, was charged with the murder of three men but found not guilty by reason of insanity. He brought civil proceedings against the defendants to recover compensation for the consequences of these killings.

On 10 February 2019, the claimant attacked and killed three elderly men, Mr Anthony Payne, Mr Richard Carter and Mr Roger Carter in the course of a serious psychotic episode. At his criminal trial, the claimant was found to have carried out the killings but not guilty of murder by reason of insanity, so he found not to be criminally responsible. The claimant remains detained at secure a hospital.

In the days before the killings, the claimant was arrested and detained twice on for a suspected burglary and an assault on an elderly man. During each detention, he behaved violently and appeared mentally very unwell. He was reviewed by mental health practitioners and the need for a mental health assessment was discussed but this was not arranged before the claimant was released on bail. 

The civil claim

Mr Lewis-Ranwell brought civil proceedings against four defendants – G4S Health Services (UK) Limited, the Chief Constable of Devon and Cornwall Police, Devon Partnership NHS Trust and Devon County Council. He alleged that they all negligently failed to provide him with adequate mental health care before the attacks. The claimant argued that but for the alleged negligence he would have been admitted to hospital and so the killings would have been prevented.

The claimant sought damages for his compulsory detention and an indemnity against potential claims by from the victims' families (presumably for wrongful death, including PSLAs suffered by the deceased men, statutory bereavement award, loss of financial and services dependency and funeral expenses).

Supreme Court’s decision

The Supreme Court concluded that the claimant’s claims in negligence were barred due to the illegality defence for the following reasons, applying the framework set out in Patel v Mirza [2016] UKSC 42:

1. Although there was no finding of criminal responsibility, Mr Lewis-Ranwell was found to have killed the three men and so his conduct was unlawful and engaged the illegality defence.
2. The law seeks to protect the public and deter unlawful killing. Allowing the claimant to recover damages for his lawful detention in a secure hospital and in negligence for the consequences of the killings would undermine public confidence in the legal system.
3. The public policy considerations in favour of maintaining the integrity of the legal system greatly outweigh those in favour of permitting the claim.
4. The killing of the three men was an act of the utmost seriousness and central (rather than incidental) to all heads of loss in the civil claim, so denying the claim is a proportionate response to the illegality.

The judgment has established that the illegality defence can bar civil claims even where the claimant has been acquitted of criminal conduct by reason of insanity. It is clear the Supreme Court’s principal concern in this type of case is to protect the coherence and integrity of the law and thereby, ultimately, preserve public confidence in the criminal and civil justice systems.