Understanding Mental Capacity:

A Guide to Decision-Making

Given everything happening in the legislative field as regards assisted suicide, I have been contacted by many people asking me to explain a bit more about mental capacity and how it is assessed. This is because under the Assisted Dying bill, which recently passed third reading in the Commons and now heads to the Lords, a person requesting assisted dying must have the mental capacity to make a clear, settled, and voluntary decision to end their life, free from coercion or undue influence. This decision must be made at the time of the request, meaning contemporaneous capacity is essential. The bill does not (yet) allow advance requests (e.g., via advance directives) or proxy decisions (e.g., by an LPA attorney) for assisted dying. The bill adopts the definition of mental capacity from the Mental Capacity Act 2005 (MCA 05).

Before I explain mental capacity and how it is assessed under the MCA 05, I want to make clear that the Royal College of Psychiatrists has raised concerns that the MCA 05, designed for decisions about treatment and best interests, is not well-suited for assessing capacity to choose to end one’s life. This is because the latter is a novel and complex decision, and the MCA lacks specific provisions for it. Capacity assessments for assisted dying are distinct from treatment decisions, as they involve evaluating a person’s wish to die, potentially influenced by mental disorders like depression. The MCA’s assumption of capacity and duty to support decision-making does not therefore adequately address these nuances. However, we are where we are, and I therefore feel that the information below may be invaluable to some, not only as regards the Assisted Dying bill, but also regarding other matters which regularly come up in people’s lives. I have therefore written this article as a general overview of mental capacity and how it is assessed, rather than focusing on this area just with respect to the Assisted Dying bill.