The recent case of David Bradley, who shot and killed four members of his family after telling his doctor he 'wanted to kill someone', has raised the question of whether a healthcare professional could ever be held liable for failing to take steps to constrain a potentially dangerous patient. Until recently, it was considered that the United Kingdom courts would be reluctant to impose a duty to protect third parties. However, the European Court of Human Rights' decision in Osman v UK — while not directly concerning healthcare professionals — has opened the door for just such a duty. When this duty will arise, and how it can be discharged, remain challenging questions. Furthermore, healthcare professionals face the unenviable task of balancing competing duties, in which the rights — and safety — of their patients must also be borne in mind.