Selena Plowden KC successful in landmark Court of Appeal decision


Court of Appeal rules that the illegality defence does not bar insanity cases

On Tuesday 20th February 2024, the judgment of the Court of Appeal in Lewis-Ranwell v G4S Health Services (UK) Ltd and Others [2024] EWCA Civ 138 was handed down.

The Claimant, Alexander Lewis-Ranwell, had killed three men whilst experiencing a psychotic episode. He was charged with three counts of murder and was found not guilty by reason of insanity.

In the days before the killings, the Claimant had been twice arrested and released by the police, including shortly before the killings, for assaulting an elderly man with a saw. Whilst under arrest, the Claimant behaved erratically and violently and was apparently very mentally unwell. The Claimant claims damages against the police and three further Defendants responsible for providing mental health services to him whilst in police custody on the basis that it was negligent to release him, rather than to take appropriate steps to safeguard his (and others’) wellbeing.  

During the criminal trial, the jury sent a note to the Judge in the following terms:

“ We the Jury have been concerned at the state of psychiatric health service provision in our county of Devon. Can we be reassured that the failings in care for [the Claimant] will be appropriately addressed following this trial.”

Three of the Defendants sought to strike out the claim, relying on the illegality or ex turpi causa defence,  which had succeeded in previous cases where psychotic claimants had been convicted of diminished responsibility manslaughter  (Clunis v Camden & Islington HA [1998] QB 978; Gray v Thames Trains Ltd [2009] UKHL 33; Henderson v Dorset University NHS Foundation Trust [2020] UKSC 43).

The Defendants’ application had failed before Garnham J in the High Court ([2022] EWHC 1213 (QB)). Their appeal to the Court of Appeal has now been dismissed (Underhill LJ and Dame Victoria Sharp in the majority, Andrews LJ dissenting).

After a comprehensive review of domestic and foreign authorities, Underhill LJ, in the leading judgment, applies the now orthodox analysis described by the Supreme Court in Patel v Mirza [2016] UKSC 42. 

He accords full weight to public policy considerations including ensuring (i) consistency in the law and (ii) public confidence and concludes that these do not require dismissal of the claim.

Consistency: he accepts the Claimant’s “straightforward case” that the verdict of not guilty by reason of insanity is an acquittal. The Defendants had argued that although the Claimant was not criminally liable, the fact he had committed a criminal/ unlawful act was sufficient to engage the ex turpi causa defence.  Underhill LJ considers that whilst the argument is superficially appealing, it does not accord with the fundamental justice of the matter nor reflect the basic perception in the previous authorities that there is a requirement for moral culpability.

Dame Victoria Sharp agrees, focusing on the principled difference in criminal law between the defences of diminished responsibility manslaughter and insanity and the bright line between the two which was recognised in Clunis, Gray and Henderson

As to the wider public confidence principle, Underhill LJ states, at [104]:

“…the values of our society are not reflected by debarring a claimant from seeking compensation in this kind of case. It is necessary… to go beyond “instinctive recoil” and to consider what justice truly requires in a situation which most humane and fair-minded people would recognise as far from straightforward. Taking that approach, although of course those who are killed or injured must always be treated as the primary victims, it is fair to recognise that the killer also may be a victim if they were suffering from serious mental illness and were let down by those responsible for their care…”

The Defendants sought permission to appeal to the Supreme Court. That application was rejected by the Court of Appeal.

Selena Plowden KC represented the successful Claimant. Her junior was Christopher Johnson and they were instructed by James Edmondson of Clarke Wilmott Solicitors. Invaluable analysis and critique was provided by Dr Matthew Dyson and by Rachel Woodward, and they were assisted at the hearing by Louise Hayes.

You can read the judgment here:

For more information, please contact Senior Practice Manager, Caroline Evans.



Selena Plowden KC

Call: 1991 Silk: 2020

Louise Hayes

Call: 2022

Related Practice Areas

Clinical Negligence

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