Supreme Court ruling: Illegality defence applies despite insanity acquittal

The Supreme Court has unanimously ruled that a man found not guilty of murder by reason of insanity cannot pursue civil claims in negligence to recover compensation for the consequences of his killings, applying the doctrine of illegality to bar his claim.

The case

Mr Lewis-Ranwell, who had been diagnosed with schizophrenia, attacked and killed three elderly men in their homes on 10 February 2019. At the time, he was experiencing a serious psychotic episode and held the delusional belief that his victims were paedophiles.

Following his arrest, Mr Lewis-Ranwell was tried for murder but found not guilty by reason of insanity, meaning the jury accepted he carried out the killings but was not criminally responsible. He was detained at Broadmoor Hospital under a hospital order with restrictions, where he remains.

The negligence 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 were all negligent in failing to provide him with adequate mental health care or assessment in the days before the killings. He had been arrested twice shortly before the murders for suspected burglary and assault, and during both detentions, he behaved erratically and appeared severely mentally unwell. He was seen by mental health practitioners and the need for a mental health assessment was discussed but not arranged before he was released on bail. 

Mr Lewis-Ranwell alleged that, but for the alleged negligence, he would have been admitted to hospital, preventing the killings of the three men. He sought damages for the consequences of the killings, including his compulsory detention, and an indemnity against potential claims from the victims' families.

The legal issue

The central question was whether the doctrine of illegality – which prevents individuals from profiting from their own wrongdoing – barred Mr Lewis-Ranwell's civil claim in negligence, despite his lack of criminal responsibility.

The Supreme Court's decision

The Supreme Court held that the illegality defence applies even where there is no criminal conviction. The Court rejected the argument that the distinction between diminished responsibility (a partial defence reducing murder to manslaughter) and insanity (a complete defence) should determine the availability of the illegality defence in civil law.  

Key principles

The threshold question

The Court first considered whether the act in question – the killing of three men – constituted unlawful conduct serious enough to engage the illegality defence. A threshold is needed because it would be unjust if trivial acts of unlawfulness barred otherwise valid legal claims. The acts must engage the public interest, but the claimant’s actions do not have to carry criminal responsibility to cross the threshold. 

Was the defence of illegality engaged in this case? The Supreme Court held that, even though there was no finding of criminal responsibility, the jury's verdict established that Mr Lewis-Ranwell did kill the three men, breaching "the most fundamental moral rule in our society: you shall not kill". The claimant’s actions demonstrated the danger he posed to the public and accordingly the public interest. The killing of the men is unlawful conduct which engages the illegality defence.

Did the defence apply in the case?

The next issue to consider is whether the defence should apply to the present case, applying the framework set out in Patel v Mirza [2016] UKSC 42. The Court considered:

1. The purpose of the prohibition: The fundamental rule against killing exists to preserve life, protect the public, deter unlawful killing, and acknowledge wrongs done to victims. Allowing the claim would create inconsistencies damaging to the legal system's integrity – for example, compensating someone for lawful detention ordered to protect the public. 
2. Other public policies: Whilst courts generally should adjudicate civil wrongs, alternative procedures such as inquests and public inquiries are better suited to examining what went wrong. The policy of maintaining legal system integrity outweighed arguments for permitting the claim.
3. Proportionality: Given the utmost seriousness of killing three men and the centrality of these acts to all claimed losses, denying the claim was a proportionate response.

Significance

The judgment establishes that the illegality defence can bar civil claims even where the claimant has been acquitted by reason of insanity. The Court emphasised that criminal law distinctions between conduct that results in criminal responsibility and conduct that does not should not automatically govern civil law, and that the coherence and integrity of the legal system as a whole must be maintained.

Lord Hodge and Lord Lloyd-Jones delivered the judgment, with which Lord Reed, Lady Rose and Lady Simler agreed.