This chapter delves deeper into the law’s understanding of capacity by looking into the Mental Capacity Act 2005 (MCA). The notion of capacity serves a critical role in the law’s response to vulnerable adults. It is also important as a pre-requisite to the rights to bodily integrity and autonomy, which are foundational human rights. The chapter draws distinction between those who have capacity and whose decisions require complete respect, and those who lack capacity and for whom decisions can be made by others based on an assessment of what is in their best interests. It suggests six ways in which a person might have capacity under the current law, and argues that autonomy should be understood as scalar, as everyone possesses autonomy to a greater or lesser extent.