When undertaking any intervention for an individual, you must be mindful of the legal authority or justification for the act. By intervention, we mean the full gamut of medical treatments or any act that relates to the care or welfare of that person. In this chapter, we will first consider the general legal principles that apply in almost any setting, but we have then divided the subsequent sections based on the location where care is predominantly provided (i.e. a domestic/home situation, care home or hospital). Although this is somewhat arbitrary, it broadly correlates with the progressive deterioration of the clinical state and in the transitions from living at home, to hospital or care home and through to the end of life. It therefore allows us to consider some situation-specific questions and how the law applies in negotiating the moves between locations or care settings.