Illegality defence reaffirmed by the Supreme Court
It has long been established – ever since Lord Mansfield declared in Holman v Johnson (1775) 1 Cowp 341 that “no court will lend its aid to a man who founds his cause of action upon an immoral or an illegal action” – that illegality can bar civil claims under English law.
That doctrine was reconsidered and reaffirmed this year by the Supreme Court in the exceptional (and very sad) case of Lewis‑Ranwell v G4S Health Services (UK) Ltd & Ors [2026] UKSC 2 in which the Supreme Court found that the claims Mr Lewis-Ranwell advanced in negligence and under the European Convention on Human Rights should be struck out owing to the illegality defence.
Background:
It is worth pausing to note that the facts giving rise to this Supreme Court judgment are deeply sad.
Mr Lewis-Ranwell had been diagnosed with schizophrenia in his mid-twenties and had previously received psychiatric intensive care. In early February 2019, he was twice arrested and detained by the police on suspicion of burglary and assault. Whilst in custody, he behaved violently, appeared mentally unwell, and was seen by mental health practitioners. He was, nevertheless, released into the community without undergoing a mental health assessment on the morning of 10 February 2019.
On the day of his release, and in the course of a serious psychotic episode, Mr Lewis-Ranwell violently murdered three elderly men.
He was tried with murder and, during the course of his criminal trial, the Jury passed a note to the Judge saying “We, the Jury, have been concerned about the state of the psychiatric health service provision in our county of Devon. Can we be reassured that the failings in care for ALR will be appropriately addressed following this trial”. Ultimately, Mr Lewis-Ranwell was found not guilty of murder by reason of insanity. A hospital and restriction order followed to protect the public at large.
Mr Lewis-Ranwell later commenced civil proceedings, which were the subject of the Supreme Court’s judgment, in which he sought significant financial compensation from various parties (including G4S Health Services and Devon and Cornwall Police).
In short, Mr Lewis-Ranwell contended that the Defendants had caused him significant loss by negligently (and/or in breach of his human rights) failing to provide him with adequate care and by releasing him into the community and that, but for that negligence, he would have been admitted to hospital and the killings would not have occurred.
The Defendants denied the claims and certain of them applied for strike out on the basis that the claims were barred by the doctrine of illegality.
The Supreme Court’s decision:
The Supreme Court, in contrast to the Court of Appeal, unanimously held that the illegality defence applied.
Although Mr Lewis-Ranwell had not been convicted of a crime (by reason of his insanity), the Supreme Court found that the threshold for the illegality defence to apply was met as he had killed the three men without lawful justification. His acts were not, on any view, trivial acts of unlawfulness capable of barring an otherwise legitimate claim.
Applying the policy-based considerations in Patel v Mirza [2016] UKSC 42; [2017] AC 467, the Supreme Court found that, even assuming the Defendants had acted negligently, the claim should not proceed.
In applying the guidance in Patel v Mirza to the doctrine of illegality in the context of Mr Lewis-Ranwell‘s claim, the Supreme Court found that:
- Allowing the claim to proceed could give rise to inconsistencies that would damage the integrity of the legal system; public confidence in the legal system would be undermined if a criminal court lawfully made a hospital and restriction order and the civil courts thereafter ordered payment of compensation for the consequences of that lawful detention;
- Alternative procedures and forums, such as inquests and public inquiries, were better suited for the purpose of examining concerns like those expressed by the Jury at the criminal trial; and
- Denying the claim was proportionate given the seriousness of Mr Lewis-Ranwell’s acts and their centrality to the heads of loss claimed.
Takeaways for businesses
Although the facts of Lewis-Ranwell are exceptional, the decision has wider significance. It serves as a clear reminder that the illegality defence remains a potent bar to civil recovery in appropriate cases. The Supreme Court emphasised that the defence is not limited to cases involving a criminal conviction, and that its application is not determined by formal classification alone. Rather, the court must ask whether allowing the claim would damage the coherence and integrity of the legal system by permitting compensation for loss arising out of serious unlawful conduct.
Homicide is thankfully not an issue most businesses face on a day-to-day basis. However, the principle that criminal conduct is not required for the illegality defence to apply is of wider application. The Supreme Court was clear that criminal responsibility is not required for the doctrine to be engaged. Rather, the question is whether the conduct at the core of the claim constitutes unlawful behaviour of sufficient seriousness.
For businesses or individuals considering bringing legal proceedings to enforce rights or seek redress for any wrongdoing, it is worth carrying out a thorough investigation as early as possible to establish exactly what wrongdoing has occurred, and by whom. If there are questions about the conduct of those acting on behalf of a business or individual (for example, any agents or employee), such conduct could engage the doctrine of illegality. It is particularly worth keeping an eye out for fraud and bribery, particularly for businesses operating internationally. Whether the activity in question is sufficiently serious to prevent recovery will be highly fact-specific.
For businesses, ensuring that you have robust policies and procedures in place to promote compliance with law and regulation, together with clear reporting mechanisms, is likely to be the best way of preventing wrongdoing from occurring in the first place. Moreover, irrespective of any legal liability, businesses should be alive to the negative reputational consequences that often ensue whenever potential illegality is identified.
Subcribe to news and views
