Unreasonable reasons: normative judgements in the assessment of mental capacity

The recent Mental Capacity Act (2005) sets out a test for assessing a person's capacity to make treatment choices. In some cases, particularly in psychiatry, it is unclear how the criteria ought to be interpreted and applied by clinicians. In this paper, I argue that this uncertainty arises because the concept of capacity employed in the Act, and the diagnostic tools developed to assist its assessment, overlook the inherent normativity of judgements made about whether a person is using or weighing information in the decision-making process. Patients may fail on this criterion to the extent that they do not appear to be handling the information given in an appropriate way, on account of a mental impairment disrupting the way the decision process ought to proceed. Using case law and clinical examples, I describe some of the normative dimensions along which judgements of incapacity can be made, namely epistemic, evaluative and affective dimensions. Such judgements are complex and the normative standards by which a clinician may determine capacity cannot be reduced to a set of criteria. Rather, in recognizing this normativity, clinicians may better understand how clinical judgements are structured and what kinds of assumption may inform their assessment.