On Capacity Assessment Practice
: Difficult and Contested Capacity Cases

Student thesis: Doctoral ThesisDoctor of Medicine by Research


Background: The functional model of mental capacity requires assessment of the ability of a person to make a specific decision at a specific time. In England and Wales, the model is codified by the Mental Capacity Act, 2005 (MCA), and overseen by the Court of Protection (CoP). There had been little research on how contested and difficult capacity cases are resolved in the CoP and in medical settings.

Aims: The aim of my thesis is to explore how the concept of mental capacity is applied in court and clinical practice by experienced judges and psychiatrists. I focus specifically on contested and difficult capacity cases. My objectives are: 1) To describe characteristics of capacity disputes before the CoP and to assess how judges comply with statutory criteria of the MCA in making capacity determinations, 2) To produce a typology that describes how judges and expert witnesses in the CoP justify their capacity determinations, and 3) To explore how experienced liaison psychiatrists identify and resolve difficult capacity cases in practice in a general hospital setting.

Methods: To address my first objective, I conducted a quantitative and case-based study of 40 capacity disputes before the CoP, using descriptive statistics to describe case characteristics and an audit approach to assess how judges comply with statutory criteria. To address my second objective, I undertook a qualitative content analysis of 131 capacity judgments in which rationales for impaired or intact capacity were given, to develop a typology of capacity rationales. To address my third objective, I interviewed 26 liaison psychiatrists and used thematic analysis to examine types of difficulty and how these were resolved in practice. Overall, I used a predominantly qualitative approach, with a view to achieving rich description of complex processes and exploring the meaning of mental capacity to those who apply it.

Results: The Capacity Disputes Study found that judges ruled on a wide range of decisional issues, with 70% cases involving a subject (P) with an intellectual disability or dementia. Disputes included disagreement between experts or professionals in 15 cases, and judges overruled expert consensus in 4 cases. Judges considered the support principle in only 57.5% cases; however, useful examples of support were cited. Judges upheld decision-specificity in their rulings: in 13 cases, P was found to have capacity, and in 5 cases, P was
judged to have capacity in relation to certain issues but to lack capacity in relation to others. The most common inability cited was ‘use or weigh’, cited in 21 of 23 cases where P lacked capacity for one or more issues.

The Typology of Capacity Rationales Study resulted in a typology of 9 categories of rationales given by judges or experts for their capacity findings (reliability: kappa = 0.63): P’s impaired or intact ability 1) to grasp information or concepts, 2) to imagine/ abstract, 3) to remember, 4) to appreciate, 5) to value/ care, 6) to think through the decision non-impulsively, 7) to reason, 8) to give coherent reasons, and 9) to express a stable preference. Rationales most frequently linked to MCA criterion ‘understand’ were ability to grasp information or concepts (43%) or to appreciate (42%), and to MCA criterion ‘use or weigh’ were abilities to appreciate (45%) or to reason (32%). Appreciation was the most frequently cited rationale across all diagnoses. Judges often used rationales without linking them explicitly to any MCA criteria (42%).

The Interview Study interviewed 26 liaison psychiatrists, identifying four types of difficulty in capacity assessment in the general hospital setting, with difficulties spanning clinical and ethical domains: 1) Difficulty determining whether the decision is the patient’s own or driven by illness, 2) Difficulty in applying ethical principles, 3) Difficulty in avoiding personal bias, and 4) Procedural difficulties. The liaison psychiatrists presented as self-reflective and described multiple creative strategies used to resolve difficult cases.

Conclusions: In combination, the above studies suggest that experienced judges and psychiatrists approach contested and difficult capacity assessments in a thoughtful and nuanced way. Through analysing court practice, I have developed a structured capacity rationale typology which could increase transparency and reliability of capacity judgments. I have also identified useful examples of supported decision-making and practical strategies for resolution of hard cases. This should contribute to education and training of practitioners approaching hard cases. Future research may further develop and test these tools and strategies across different settings.

Date of Award1 Aug 2022
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorAlexander Ruck Keene (Supervisor), Gareth Owen (Supervisor) & Scott Kim (Supervisor)

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