The Royal College of Physicians of the UK, together with the Colleges of Edinburgh and Glasgow, have produced guidance on the diagnosis and management of people in the vegetative state (report of a working party of the Royal College of Physicians, 2003). Such guidance is important when the single criterion for awareness in an individual is the perception of that awareness by a potentially fallible observer. The current guidance is reviewed and comparisons made with existing arrangements in other countries. Consideration is given to the possibility of future improvements in diagnosis with the advent of imaging and metabolic assessments of brain function and the need to define the required qualifications and training for those "experts" who are currently involved in the diagnosis of the vegetative state.