The Elusiveness of the Illegality Defence
Date: 27 April 2026 (Monday)
Venue: Academic Conference Room, 11/F, Cheng Yu Tung Tower Centennial Campus, The University of Hong Kong
Time: 12:00 noon-1:15 pm
This is an in-person event.
Prior registration is required.
Abstract
When a patient kills friends and strangers, and is thereafter detained by court order (whether for murder, or for manslaughter by reason of diminished responsibility, or for detention on the grounds of insanity), then that same patient may seek to sue their treating doctors and/or health authority for negligence. The allegation, typically, is that the defendants failed to provide the patient with adequate care and mental health assessment, thereby allowing the killings to occur. In response, the defence of illegality will typically be pleaded by the defendants against the patient. The principles governing the application of the illegality defence have long been mired in controversy, uncertainty, and schisms amongst leading jurists. The recent decision of the UK Supreme Court in Lewis-Ranwell v G4S Health Services (UK) Ltd [2026] UKSC 2 is the latest judicial examination of the topic, and its implications for both UK and Hong Kong jurisprudence are wide-reaching.
Speaker
Rachael Mulheron KC (Hon) FBA is Professor of Tort Law and Civil Justice at Queen Mary University of London. Since 2023, Rachael has served as a member of the Competition Appeal Tribunal. She specialises in Torts, Medical Negligence, Collective (Class) Actions, and Civil Justice more generally. She is author of the leading text, Principles of Tort Law (2nd edn, Cambridge University Press, 2020), and her work on Tort Law has been judicially cited by the UK Supreme Court and in several overseas jurisdictions. Prior to her academic career, Rachael practised as a solicitor in Construction Law in Brisbane, Australia. In 2021, Rachael was appointed as Honorary Queen’s Counsel for services to law reform, and in 2024, was elected as a Fellow of the British Academy.
Chair
Prof Craig Purshouse, Deputy Director of the Centre for Medical Ethics and Law & Deputy Director of the Centre for Private Law, The University of Hong Kong
Organiser
Centre for Medical Ethics and Law
Supporting Organisations
Medical Ethics and Humanities Unit, The University of Hong Kong
Centre for Private Law, The University of Hong Kong
