How to apply the MCA capacity criteria more transparently and reliably

By Scott Kim, Nuala Kane, Alex Ruck Keene, Gareth Owen.

A lot is at stake in a mental capacity evaluation. An error can lead to a capacitous adult’s decision being ignored or even overruled, or to a vulnerable, incapacitous person being abandoned to their ‘rights.’ Unfortunately, there is no simple formula that generates the right answer, only a set of broad—and vague—criteria like ‘ability to use or weigh’ or ‘to understand’ (Mental Capacity Act 2005).

How can we minimize error when we apply such broad concepts? ‘To use or weigh’ seems particularly fuzzy—what are its boundaries and what is in it? ‘Understanding’ on the other hand is beguilingly familiar yet used in so many different senses.

Indeed, when we studied how the courts explained their capacity determinations, we found 9 different categories of ‘rationales’ used to justify the judgments. Of course, these rationales have face validity as well as prima facie authority of the courts. But in many (42%!) cases they are used without explicit connection to the capacity criteria; and when they are tied to capacity criteria, the courts’ practice is not uniform, with overlapping boundaries between the capacity criteria that result in a conceptual thicket.

It is not hard to see that such a situation could hinder communication between assessors, make evaluations less transparent and reliable, and make scientific study of mental capacity difficult.

Our paper is an attempt to clarify this situation. It turns out that nearly all of the overlapping, fuzzy boundaries and ambiguous meanings of MCA capacity criteria can be addressed by three simple recommendations. Readers will have to read our paper to judge whether they agree with how we arrived at these conclusions but those familiar with capacity evaluations using the MCA criteria will, we think, recognize their potential value.

First, capacity assessors should always tie the rationales they give to a specific MCA criterion. Indeed, the very need for an assessment arises from the fact that the criteria are not self-implementing; one needs to connect the criteria to the specific phenomena and explain the connection to the law.

Our second recommendation begins with the recognition that there is a wide range of phenomena that can be called ‘understanding,’ from the prosaic sense of mere comprehension/absorption of information to other uses that can easily overlap with the other MCA criteria (especially ‘use or weigh’ criterion). Indeed, the term is so flexible that it could even be used as a substitute for ‘capacity’ (as when we ask, ‘Does he understand what he is doing?’—even when we know the person has absorbed the information). We thus recommend that in the setting of a capacity evaluation, the ability to understand be used in a technical, narrow sense of mere comprehension/absorption of relevant information.

Third, because the ability to use or weigh criterion is a compound concept, we cannot avoid the fact that it will cover multiple types of rationales. In fact, the very general and broad nature of this criterion has been a perennial concern in the field. To be fair to the legislators, we need to remind ourselves that the space between absorption of relevant information (successful input) and the expression of a choice (output) is particularly difficult to describe. They chose to cover this large space with ‘the ability to use or weigh’ criterion. Our study shows that in that space, there are 6 types of rationales that are used by the courts. Our third recommendation therefore is when using the use or weigh criterion, one should focus on these 6 rationales. We recognize that 6 is a lot to think about, but at least they provide a clear boundary as well as specific content to what has long been recognized as a complex and broad criterion.

No doubt many objections can be raised. Some might argue that if the Mental Capacity Act needs such guidance, then perhaps the law itself should be improved. Others might instead think that we are attempting to rewrite the law with our suggestions. But our goal is more modest, concerned with the immediate needs of capacity assessors who must apply the MCA criteria to persons with a variety of impairments in a multitude of contexts.

Others, after reading our paper, may object to our typology of rationales, as to its completeness, redundancy, or definitions. Others might object to our limiting the scope of the understanding criterion. We welcome such critiques, as it is consistent with our goal: to promote a more transparent and granular dialogue among scholars, and assessors, of capacity.


Paper title: Broad Concepts and Messy Realities: Optimizing the Application of Mental Capacity Criteria

Authors: Scott Y H Kim, Nuala B Kane, Alex Ruck Keene, Gareth S. Owen

Affiliations: Department of Bioethics, Clinical Center, National Institutes of Health, Bethesda, USA; Mental Health, Ethics and Law Research Group, Department of Psychological Medicine, King’s College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK; Dickson Poon School of Law, King’s College London, UK; 39 Essex Chambers, London, UK

Competing interests: The authors declare no competing interests.

Social media accounts of post authors: @NIHbioethics; @scottbioethics; @MHealthJustice



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