Mental Illness Does Not Bar Illegality Defence

In Henderson -v- Dorset Healthcare University NHS Foundation Trust (2020) UKSC 43, the Supreme Court dismissed a claim for damages in negligence brought by a schizophrenia patient who stabbed her mother to death during a serious psychotic episode on the basis of the illegality defence.


The claimant, Ecila Henderson, has suffered from paranoid schizophrenia since 1995 and has had numerous admissions to hospital under the Mental Health Act. On 25 August 2010, whilst living in supported accommodation and experiencing a serious psychotic episode, she stabbed her mother to death. She was convicted of manslaughter by reason of diminished responsibility and was sentenced to hospital detention.

Following the criminal trial, the claimant brought a negligence claim against Dorset Healthcare University NHS Foundation Trust. She sought damages for a depressive order and post-traumatic stress disorder caused by her killing of her mother, loss of liberty caused by her compulsory detention in hospital, loss of amenity arising from the consequences to her of having killed her mother, £61,944 being the share in her mother’s estate which she is unable to recover as a result of the operation of the Forfeiture Act 1982 and the future costs of psychotherapy and a care manager/support worker.

The Trust admitted liability/negligence for failing to return the claimant to hospital because of her psychotic state and admitted that the killing of her mother would not have occurred had they done so. However, the Trust argued that, due to claimant’s criminal act of manslaughter, the negligence claim was barred for illegality. This argument was accepted by the trial judge and in the Court of Appeal. The claimant appealed to the Supreme Court.

Illegality/Ex Turpi Causa Non Oritur Actio

This legal doctrine (which literally means ’from an illegal act an action does not arise’) offers a complete defence to negligence claims. For public policy reasons the law does not allow the recovery of damages from criminal conduct in order to preserve the integrity of the legal system.

Gray v Thames Trains Ltd involved a claimant who had been convicted of manslaughter on the grounds of diminished responsibility. The House of Lords held that his claim was barred by the defence of illegality because the damages sought resulted from the sentence imposed by the criminal court and/or the claimant’s own criminal act of manslaughter.

In the Supreme Court, Ecila Henderson argued that the reasoning in Gray did not apply or could be distinguished from her claim because Gray concerned a claimant with significant personal responsibility for his crime. In contrast, in Ecila Henderson’s criminal trial, the judge had said that the claimant had no significant degree of responsibility for what she had done as she was in the midst of a psychotic episode.

The Decision Of The Supreme Court

The Supreme Court unanimously dismissed the claimant’s appeal and found that her claim against the Trust was barred by the illegality defence. The crucial consideration in Gray was that the claimant had been found to be criminally responsible for his conduct and not the degree of personal responsibility. The fact that Ecila Henderson had been convicted of manslaughter on the grounds of diminished responsibility meant that responsibility for her criminal act was diminished but it was not removed.

The claimant was therefore unable to recover damages for personal injury and loss of amenity and for the costs of psychotherapy and a care manager/support worker because they resulted from the claimant’s unlawful killing of her mother. The damages for her loss of liberty during her detention in hospital could not be recovered because that loss resulted from the sentence imposed on her by the criminal court. In relation to the claim in respect of the mother’s estate, the Supreme Court held it would be entirely inappropriate for the court to subvert the operation of the Forfeiture Act 1982 by allowing the claimant to recover from the Trust that which she was not permitted to recover under the Act.

If you have any questions about the above case study or would like to speak with a medical negligence solicitor, call us for a free consultation on 02920 391773 or contact Linda Williams by email.

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