The aim of this paper is to clarify what is involved in the notion of capacity as used in the Mental Capacity Act of 2005. This act (hereafter MCA) sets out the conditions for ascertaining whether an individual lacks the mental capacity to make a decision. Where there is evidence for an individual lacking capacity, and further inquiry confirms this to be the case, then another individual is assigned to decide in the individual’s best interests. Because judgements about whether someone has or lacks capacity can have significant consequences, in particular in the context of healthcare, it is crucial to come to a full and accurate understanding of what it is to have—or lack—capacity. Considered in the context of mental healthcare, we will see that ascertaining whether an individual has capacity is not only an ethical matter concerning the avoidance of harms, but also has political implications concerning what choices or conceptions of value the state should, via the health service, permit.

I will be asking whether meeting the conditions set out in the MCA requires certain evaluative commitments. This question is particularly testing in the context of issues that arise concerning mental health, where what is believed relevant or given weight in making a decision appears to be bound up with the mental health problems about which decisions are being made. In this paper I will first clarify and elaborate on the claim that the conditions for capacity as set out in the MCA are value-laden (cf. Owens et al. 2009; Sections 7.2–7.4). Then I will show that whilst the conditions are indeed value-laden, and presuppose that