An assessment of decision-making capacity is the accepted procedure for determining when a person is not competent. An inferential gap exists between the criteria for capacity specific abilities and the legal requirements to understand relevant information and appreciate the consequences of a decision. This gap extends to causal influences on a person'scapacity to decide. Using a published case of depression, we illustrate that assessors' uses of diagnostic information is frequently not up to the task of bridging this inferential gap in (...) a justifiable way. We then describe cases of faulty judgement which challenge the understanding of diagnostic causal influences. These cases help to clarify the nature of the expertise required for capacity assessments. In practice, the requirements of decision-making capacity are often abandoned to other considerations due to a lack of requisite expertise. The legal policy supporting decision-making capacity as a means to protective intervention is justified only if the requisite expertise is developed. We propose the requisite expertise to be developed in the long term as a distinct multidisciplinary endeavour. (shrink)

The authors examine recent arguments purporting to show that mental incompetence (lack of decision-making capacity) is not a necessary condition for intervention in a person's best interests without consent. It is concluded that these arguments fail to show that competent wishes could justifiably be overturned. Nonetheless, it remains an open question whether accounts of decision-making capacity based solely on the notions of understanding and appreciation can adequately deal with various complexities. Different possible ways of resolving these complexities are outlined, all (...) of which need further exploration. (shrink)

Various complexities that arise in the application of legal and/or clinical criteria to the actual assessment of competence/capacity are discussed, and a particular way of understanding the nature of such criteria is recommended.