The role of nearest relative (NR) is intended as a safeguard in the Mental Health Act 1983 (as amended in 2007) to curb the excesses of professional discretion and protect patients from unwarranted compulsory hospitalisation. It is unique to the mental health compulsory detention process in England and Wales. There are, however, evident tensions in the role and a lack of clarity surrounding the precise functions of the NR. There is also some uncertainty and confusion among practitioners about the scope of the NR involvement, and government plans announced recentlyto review mental health legislation will include a focus on the role of family and carers in the care of detained patients. Despite long-standing concerns about the role, there is remarkably little published research available to date on its use and effectiveness, in so far as evaluating the extent to which it provides an adequate safeguard for patients, as intended by the legislation. This article will briefly explore the background to the role, highlight some of the difficulties and tensions within it and conclude with some observations about where further research and reform may be needed to provide greater protection and clarity for patients, relatives and health and social care practitioners.