Death is the end point of a process of irreversible and progressive loss of vital organ function leading to certain and irreversible cessation of the characteristics that define life. Perhaps surprisingly, there is no globally accepted definition of what constitutes death, and in the UK, there is no statutory definition. However, successive working parties of the medical Royal Colleges have produced guidance for the diagnosis and confirmation of neurological death and these have been revised more recently to include death after cardiorespiratory arrest.1 The irreversible loss of consciousness with the irreversible loss of the capacity to breathe produced by brain stem death (BSD) is accepted in the UK as the death of the individual and can be diagnosed using clinical tests of brain stem function. Diagnosis of BSD allows the discontinuation of treatment, which is no longer in the patient’s best interest and thereby reduces distress to relatives, carers and positively impacts on the costs of health care. Diagnosing BSD on these ethical, humanitarian and utilitarian grounds also facilitates organ donation when patients and families choose to donate.