Henderson v Dorset Healthcare University NHS Foundation Trust  UKSC 43 (30 October 2020)
A suffers from paranoid schizophrenia or schizoaffective disorder. On 25 August 2010 she stabbed her mother to death whilst experiencing a serious psychotic episode. She was charged with her mother’s murder but, in view of the psychiatric evidence, the prosecution agreed to a plea of manslaughter by reason of diminished responsibility. That plea was accepted by the court... A has remained subject to detention... 
R has admitted liability in negligence in failing to return the appellant to hospital on the basis of her manifest psychotic state. The tragic killing of her mother would not have occurred had this been done. 
A advances various heads of damages against the respondent as a result of its admitted negligence. Liability for these heads of damages is denied on the grounds that the damages claimed by A are the consequence of: (i) the sentence imposed on her by the criminal court; and/or (ii) her criminal act of manslaughter, and are therefore irrecoverable by reason of the doctrine of ex turpi causa non oritur actio/illegality. 
Similar claims for damages to those made by the appellant were held to be irrecoverable by the House of Lords in Gray v Thames Trains Ltd  UKHL 33;  AC 1339, also a case of manslaughter on the grounds of diminished responsibility. The appeal raises the question of whether Gray can be distinguished and, if not, whether it should be departed from, in particular in the light of the Supreme Court decision concerning illegality in Patel v Mirza  UKSC 42;  AC 467 . 
[The psychiatric evidence did not support the defence of insanity but supported the defence of diminished responsibility...] [13 and 14]
the appeal should be dismissed...