Social Role Valorisation theory, advanced to enhance the lives of disadvantaged groups of people, has addressed community care and lay advocacy for patients and users but has ignored the roles of relatives and carers. [In this article, the term ‘patient’ is used to describe a person who is detained under the Mental Health Act, liable to be detained, or in hospital on an informal basis. The term ‘service user’ describes someone receiving psychiatric services but who is neither hospitalised nor subject to compulsion.] The nearest relative was introduced as a legal category under the Mental Health Act 1959 without a theoretical base, although it was perceived as a safeguard and a way of supporting advocacy for patients. If recent proposals to reform legislation come into force, the role of patient advocacy will be enhanced whilst the nearest relative will be replaced by the new roles of nominated person and carer. This paper reinforces the importance of using governing principles to guide legislation, as supported by the most comprehensive in‐depth research recently conducted into the nearest relative role.