Court of Appeal rules that defence of illegality in civil claim is not available if not guilty of criminal offence by reason of insanity

United Kingdom

In Lewis-Ranwell v G4S Health Services (UK) Ltd and others [2024] EWCA Civ 138, the Court of Appeal recently held, by a majority of 2 to 1, that where a person has committed a crime, but has been found not guilty by reason of insanity, the defence of illegality will not prohibit them from claiming damages from those who were responsible for assessing their mental wellbeing at the relevant time.

Whilst these circumstances are unusual, they are not novel. This Judgment is particularly important for providers of mental health services and their insurers.

Background – Criminal Proceedings

On 10 February 2019, Mr Lewis-Ranwell (the Respondent), whilst suffering from a serious psychotic episode, killed three men. He was diagnosed with schizophrenia in his mid-twenties and had spells in psychiatric intensive care in 2016 and 2017. Within the 48 hours prior to the killings, he had been held in police custody. Despite the Respondent exhibiting concerning behaviour during this time, he was released on bail and went on to kill.

The Respondent’s case was that, on 8 February 2019, he was arrested for burglary. The Respondent informed police officers that he had previously been sectioned and been given medication for his mental health but that he was not, at that time, medicated. The Respondent’s mother spoke with police officers by telephone and warned them that her son was having a psychotic episode which often led to him becoming violent. She commented that she would have “grave concerns” if her son was to be released whilst suffering from a psychotic episode. Despite this, the Respondent was considered fit for release and was released from on bail at around 3am on 9 February 2019.

During the early hours of 9 February 2019, the Respondent attacked an elderly gentleman. Consequently, he was arrested and detained for a second time. During this period of detention, G4S Health Services (UK) Limited, the police and Devon County Council spoke about the arrangements necessary for a Mental Health Act (MHA) assessment to be conducted. The Respondent’s condition appeared to be deteriorating; he was seen by health care professionals, the Force Medical Examiner (an employee of G4S Health Services (UK) Limited), and a mental health practitioner but was deemed not to be psychotic. On 10 February 2019, the Respondent was granted bail and was released. Shortly thereafter, he was involved in a series of incidents which cumulated in him killing three elderly men in their homes.

At the end of 2019, the trial was held and three psychiatrists gave evidence that the Respondent knew what he was doing, but not that it was immoral or unlawful. The jury found the Respondent not guilty by reason of insanity and he was acquitted of murder and manslaughter. The Court, acting in accordance with section 5 (1) and 5 (3) of the Criminal Procedure (Insanity) Act 1964, made a hospital order with restrictions and the Respondent was detained in hospital.

Civil Proceedings – Strike Out Application

In February 2020, the Respondent commenced civil proceedings against G4S Health Services (UK) Limited, the Chief Constable of Devon and Cornwall Police, Devon Partnership NHS Trust and Devon County Council (together the Appellants). The Respondent alleged that the Appellants were all negligent in their treatment of him in the period between 8 and 10 February 2019. The Appellant claimed damages for personal injury, loss of liberty, loss of reputation and loss of dignity, along with an indemnity in respect of any claim brought against him as a consequence of his violence towards others in the period between 9 and 11 February 2019.

The Appellants, save for the Police, made an application to the Court for a striking out order on the grounds of illegality; described as a rule of public policy that "no court will lend its aid to a man who founds his cause of action upon an immoral or an illegal act"[1]. In order to strike out the claim pursuant to the defence of illegality, the Appellants were required to demonstrate that the Respondent knew that his actions were wrong[2]. The Appellants, therefore, needed to show that the Respondent was guilty of a criminal act or a quasi-criminal act[3].

First Instance Decision

At first instance, the application for a strike out order was dismissed.

The Court held that “a verdict of not guilty by reason of insanity is unequivocally a verdict that a defendant is not guilty of the offence charged; and … bears no criminal responsibility for the killing”[4]. As such, the Appellants failed to demonstrate that the Respondent was guilty of a criminal act.

The Appellants also failed to demonstrate that the Respondent had carried out a quasi-criminal act. A quasi-criminal act is an act that engages the public interest in the same way as a criminal act would.[5]  The Court found, inter alia, that:

  1. Permitting the claim to continue would not enable the Respondent to profit from his own wrongdoing, the Respondent had no knowledge of wrongfulness given the finding of insanity.
  2. Whilst a claimant cannot claim for damages stemming from a lawfully imposed sentence because of their breach of a criminal law, in this case, restrictions were imposed on the Respondent as a result of his mental illness, not as a result of any criminal act.
  3. There was nothing incoherent in allowing the claim, which was based on a third-party's negligence; it would not harm the integrity of the legal system. 
  4. Potential compensation for the Respondent would not necessarily offend the public notion of the fair distribution of resources, as the Respondent had not been found guilty of a criminal act.

The strike out application was, therefore, dismissed. The judgment was appealed by the Appellants to the Court of Appeal.

Court of Appeal Decision

The Court of Appeal held, by a majority of 2 to 1, that where a person has committed a crime but has been found not guilty by reason of insanity, the defence of illegality will not prohibit them from claiming damages from those who owed them a duty of care at the time.

Underhill LJ provided the leading judgment, which was approved by Sharp LJ. They found that, in cases such as this one, the illegality defence will not apply where a claimant had no moral culpability for their actions (e.g. where they are found not guilty by reason of insanity). They found that this approach corresponded with the principles of legal coherence and public confidence in the law.

When considering the principles of legal coherence, the majority held that this decision did not cause inconsistency with the notion that a claimant should not be able to claim damages for the consequences of their own illegal actions. The Respondent in this case, however, was not guilty of any illegal acts.

The Appellants asserted that, given the victims’ families could have sued the Respondent in tort for damages, despite the finding of insanity, the verdict caused inconsistency between the criminal and tortious approaches. Underhill LJ referenced Stable J's observation that the law of tort’s intention is to compensate a person who has suffered loss, as opposed to punishing the wrongdoer. Furthermore, the majority held that the case law did not support this assertion. The case law referred to claimants who had been found guilty but with diminished responsibility, unlike this case where the Respondent bore no “responsibility” at all.

In terms of public confidence in the law, the Appellants asserted that allowing the claim would risk bringing the law into disrepute; public opinion would not condone the claim continuing. Underhill LJ found that the Respondent had “suffered a serious injury (in the technical sense) from the failures of others who owed him a duty to protect him from harm of the kind that he in fact suffered”[6] and that we must “consider what justice truly requires in a situation which most humane and fair-minded people would recognise as far from straightforward... 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”[7].

Whilst Andrews LJ gave a dissenting judgment, disagreeing that the lack of personal responsibility should allow the Respondent to make a claim, the majority ruled that the Appeal was dismissed.


The requirements for the defence of insanity were set out in the M'Naghten Rules: in order to plead insanity the defendant must demonstrate that they were, at the time of the committing of the act, “labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong”[8]. This must be demonstrated by the defendant on the balance of probabilities, a lower burden than beyond reasonable doubt which is the burden of proof for the crime itself.

Where an individual is or, arguably, should have been receiving mental health services and there were alleged failures by those who owed them a duty of care, it is possible that if they are charged with a criminal offence, they could plead insanity. If they are acquitted on the grounds of insanity and if they go on to bring a civil claim, those owing the duty of care are unlikely to be able to rely on the illegality defence.

Whilst these circumstances are unusual, they are not novel. After a couple of particularly high profile cases recently, involving individuals with a history of mental health illness killing others, there is currently a real spotlight on the processes followed and decisions made by mental health providers and others with respect to detention. It is always possible for lessons to be learned in these types of cases and for those providing care and treatment to consider if there are steps which could be taken to mitigate risks in the future.

If you are interested in discussing this Judgment further, please contact the Key Contacts listed above.

[1] Holman et Al' v Johnson, alias Newland (1775) 98 E.R. 1120, Lord Mansfield at p. 1121  

[2] Traylor v Kent and Medway NHS Social Care Partnership Trust [2022] EWHC 260 (QB), [2022] 4 W.L.R. 35, [2022] 2 WLUK 122

[3] Les Laboratoires Servier v Apotex Inc [2014] UKSC 55, [2015] A.C. 430, [2014] 10 WLUK 876

[4] Lewis-Ranwell v G4S Health Services (UK) Limited and others [2022] EWHC 1213 (QB), para. 131

[5] Les Laboratoires Servier v Apotex Inc [2014] UKSC 55, [2015] A.C. 430, [2014] 10 WLUK 876

[6] Lewis-Ranwell v G4S Health Services (UK) Limited and others [2024] EWCA Civ 138, para. 90

[7] Lewis-Ranwell v G4S Health Services (UK) Limited and others [2024] EWCA Civ 138, para. 104

[8] R. v M'Naghten (1843) 8 E.R. 718