Brief on Mental Capacity Assessment


paper cut outs of people


The brief

Project PERFECT researchers Sophie Stammers and Lisa Bortolotti have prepared a brief for policy makers and mental health and social care professionals, entitled "Mitigating the risk of assumptions and biases in assessments of mental capacity". 

Mental health and social care professionals routinely assess the capacity of people to make decisions about their lives, in accordance with the Mental Capacity Act 2005 (MCA). The briefing note outlines how the functional approach to testing capacity in the MCA underdetermines decisions, describing the risks for stereotypes and assumptions to affect outcomes. It advocates for the need for specific training for professionals using the MCA to enable them to recognise the role of value judgements in capacity decisions, to mitigate the effects of stereotyping and assumptions, and to improve decision making.


Do you want to know more?

Download the full brief (accessible PDF file)


Do you want to join the conversation?

Watch the Webinar which was streamed live on 26 March at noon.

Join the conversation using the #MentalCapacity2020 hashtag on Twitter.

Add your comments to a post on the Mental Elf blog, written by Alex Ruck Keene. 



  • Antonis Kousoulis, Mental Health Foundation
  • David Crepaz-Keay, Mental Health Foundation
  • Jillian Craigie, King’s College London
  • Alex Ruck Keene, 39 Essex Chambers
  • Victoria Butler Cole, 39 Essex Chambers
  • Baroness Sheila Hollins, Cross Bench Peer; St George's, University of London
  • Anneliese Dodds, Labour (Co-op) MP for Oxford East
  • Akiko Hart, National Survivor and User Network
  • Adrian Dunsterville, Care Quality Commission          
  • Lucy Series, Cardiff University
  • Natalie Banner, Wellcome Trust
  • Camillia Kong, Birkbeck
  • Alex Miller Tate, King’s College London
  • Eve Mundy, RE:CREATE Psychiatry 
  • Stephen Jeffreys, Suresearch
  • Barbara Norden, SureSearch
  • George Szmukler, Royal College of Psychiatrists
  • Clementine Maddock, Royal College of Psychiatrists
  • Vanessa Garrity, Sociable Angels, The Association for Child and Adolescent Mental Health (ACAMH)
  • Jeff Barlow, Independent Consultant (nursing, social work, best interest assessment) 
  • Maddie Jennings, British Association of Social Workers 
  • Jane Shears, British Association of Social Workers
  • Two anonymous consultants from the Youth Advisory Group, Institute for Mental Health, University of Birmingham
  • Helen Spandler, University of Central Lancashire
  • Anne Cooke, British Psychological Society; Canterbury Christchurch University



“There is now quite widespread recognition of the biases which affect decision-making, such as negativity bias in our retention of information from the media. Yet our awareness of these biases does not seem to feed in to our understanding of mental health, which often categorises people as ‘irrational’ in an unspecified way. This can be a political issue; I’ve been urged previously not to engage with people with mental ill-health on the grounds that they ‘would not be interested’, yet people suffering from mental ill-health are often not only interested in politics but have a great deal of importance to say and are not less ‘rational’, depending on the type of illness they are suffering from. These issues surely need more consideration, which is why I was pleased to see the progress of the PERFECT research project.” Anneliese Dodds – Labour (Co-op) MP for Oxford East


“I write as a member of Suresearch and a Survivor Researcher bringing first-hand experience of mental distress and mental health services into doing mental health research and training. I welcome this briefing’s focus on how assumptions and values can impact on capacity assessments, and its use of the research on the presence and operation of ‘irrationality’ in both those with and without psychiatric diagnoses.  I’m also aware that different conceptions of rationality, humanity and knowledge can operate in different cultures. The training suggested involves exploring and acknowledging the role of assumptions and values in assessments and is enriched by involving both practitioners and the perspectives of people with lived experience.”  Stephen Jeffreys – independent mental health survivor researcher


“This work responds at so many different levels to issues that I am encountering in lots of different contexts, from practice to policy development. It is really important, useful, and grounded, and provides extremely fruitful avenues for further work and further research.”  Alex Ruck Keene – barrister, writer and educator


“The most important things behind evaluating someone’s decision making capacity are social norms and values.  But these can clash, or have a rather difficult relationship.  Preserving one’s life, regardless of how one felt, was part of our Christian culture, and we are still devoted to suicide prevention.  But today, people’s right to make their own decision is greatly valued, and this can create an ambiguity when evaluating someone’s ability to make a decision. 

Those evaluating may have difficulty accepting a person’s right to refuse life saving treatment.  It can be easier to convince oneself that the person does not have capacity, and does not understand the risk.  Not wanting to take part in something life-saving could also be seen as a symptom of mental illness, and mental illness itself as a lack of capacity. This genuinely clashes with the idea that if someone has the ability to understand the procedure and its outcome, they have the capacity to decide.  There is probably no way of making it easier for people to decide whether the priority is saving someone’s life, or respecting their right to decide.

A person may also understand a procedure but be genuinely delusional, and believe something untrue about themselves or about the medical professionals that causes them to refuse.  This person does not have capacity, because they do not realise they are putting themselves at risk.  But if someone with anorexia refuses a procedure that would give them nourishment, it would have to be ascertained that they knew their life was at risk.” Barbara Norden – survivor researcher