— The claimant killed three men (delusionally believing that he was killing them for being paedophiles), was found not guilty of murder by reason of insanity, then sought compensation for the consequences of those unlawful killings. (1) The Supreme Court first considered the "threshold question": asking in what circumstances the illegality defence is engaged. All the previous caselaw involved diminished responsibility, but the difference between that and insanity (whether on the basis of not knowing the nature and quality of the act, or of not knowing it was wrong) was just a matter of degree and so the same principles applied. The killings were unlawful conduct for the purpose of engaging the illegality defence. (2) On the facts of the case, the negligence claims were barred by the illegality defence: (a) the underlying purpose of the prohibition transgressed (you shall not kill) would be enhanced by denial of the claim; (b) policy considerations were in favour of denial; (c) denial would not be disproportionate response to the illegality.
Full details available at: https://www.mentalhealthlaw.co.uk/Lewis-Ranwell_v_G4S_Health_Services_(UK)_Ltd_(2026)_UKSC_2?id=210126-2142