SummaryIn a landmark decision, the Supreme Court of the UK ruled that the state has a special operational duty to protect the right to life in informal psychiatric in-patients (‘Rabone case'), in sharp distinction to general medical or surgical patients. We will argue that the significance of this case is general, not just local, and that it exposes four important unresolved problems in mental health law: the place of decision-making capacity; the meaning of ‘informal’ admission; parity between mental and physical health; and the accuracy of risk assessment.