This book has been written to reflect modern ideas about what constitutes good mental health nursing care, and you will see that values such as partnership working within the framework of a therapeutic relationship have been deliberately stressed. However, the role of the mental health nurse has always required some involvement in what is essentially custodial care. It is necessary for us as mental health nurses to try to balance the demands of these two seemingly paradoxical elements of the role of a mental health nurse. This chapter is intended to introduce you to some aspects of mental health law. We have partly based this upon the law as it currently applies in England and Wales but you will notice that we have also tried to include some material from an international perspective. The history of the profession of mental health nursing is inextricably bound up with the story of the rise and fall of the asylum and with institutionalized models of care. It was only following the Macmillan commission, which was set up to investigate allegations of abuse at Prestwich Hospital in 1924, that the term ‘psychiatric nurse’ (which later evolved to mental health nurse, Department of Health 1994) became a commonly used description (Coppock and Hopton 2000). Prior to this time, people working in institutions for the mentally disordered were more oft en referred to as ‘attendants’ or ‘keepers’ (Nolan 1998), and as these names imply, their roles were mostly custodial or supervisory in nature. Mental health nursing has moved away from this limited model of providing ‘care’ but is still unusual amongst other health care professions in that its members continue to be involved in compulsory detention (even though the main responsibility for this rests with the medical profession; Rogers and Pilgrim 2001). In England and Wales the 1983 Mental Health Act and its 2007 update is currently the legislation directing compulsory treatment of people with mental disorder. In common with legislation in most countries, this Mental Health Act aims to achieve a balance between the rights of the individual mental health patient to be treated and protected and the perceived need to protect others.