Mental capacity as a safeguard

The 2005 Mental Capacity Act ² is the centrepiece of the safeguards included in the Assisted Dying Bill that was recently voted through the House of Commons in Westminster, before running out of time in the House of Lords – with near-identical legislation reintroduced to Parliament once again (the Terminally Ill Adults (End of Life) Bill), with its first reading on 17 June 2026 and a second reading scheduled for 11 September 2026. ¹ However, the Mental Capacity Act was simply not designed for providing safeguards in this way – either for the population to which this legislation would apply, or regarding the decision to die with assistance. It was designed to ensure as much autonomy as possible for the psychiatrically and neurologically unwell, and it applies only to the psychiatrically and neurologically unwell. It was created to replace more paternalistic ‘status-based’ legislation, to minimise paternalistic intervention and to raise thresholds for involuntary intervention in a way that protects individual liberty and creates an ‘empowering ethos’. ^{Reference Bartlett3,4} Its core agenda was to guard against paternalism, not to provide safeguards against potential abuse in assisted dying. Its scope was limited to the psychiatrically and neurologically unwell, and does not cover the broader class of vulnerable individuals. It is not fit for purpose because it was designed for a radically different purpose and has a radically different scope.

Worries about assisted dying

Several disability rights organisations have expressed similar concerns about Westminster’s proposals for assisted dying legislation. Reasons offered for this concern include the lack of ‘access to good quality support and services’, ⁵ meaning that ‘choosing to die may seem like the only viable option’; ⁶ that ‘for some people the idea of becoming disabled … may seem like a frightening or intolerable prospect’ and that ‘many in our society think our lives are not worth living’. ⁶

They thus worry that assisted dying may not be a ‘real choice’, ⁵ for reasons including interpersonal pressure (real or perceived), diffuse social pressure via widespread ableist values, insufficient support and overwhelming negative emotion in the face of a terminal diagnosis. The Mental Capacity Act is not entirely without tools for specifying how their decision-making might be undermined. These factors might render those making a decision about assisted dying unable to understand relevant information, retain that information over the course of making their decision or use and weigh that information in the process of making their decision.

They might be unable to use and weigh the potential value in a period of life with disability in light of ableist views; the strength of these ingrained views might even mean that they cannot understand that there can be such value. They might be unable to unable to use and weigh this prospective value in light of their fear and despair, given the strong cognitive biases associated with negative affect, even when that affect is of much weaker forms – biases in attention and memory might even mean that they are unable to retain the information. They might also be unable to use and weigh it in light of perceived interpersonal pressure, or because they cannot understand or retain it. ^{Reference Gough7,Reference Ariyo, Kane, Owen and Ruck Keene8,Reference Gough9}

Inclusion London’s statement on assisted dying asserts that:

It is hard to persuade those without experience of disability to understand, use and weigh the kind of independence, dignity and autonomy that people with a disability can enjoy with the right support – to overcome the pervasive, ableist views of disability and exclusionary views of independence, dignity and autonomy. It is more than merely hard when those people have just been told that they are imminently going to die, and to experience a period of severe pain and disability on the way to death.

Problems with the impairment requirement

The Mental Capacity Act was designed for limiting paternalism around the psychiatrically and neurologically unwell. It was not designed for providing safeguards for the broader population regarding decisions to die. The Act is explicit that failure to meet the above conditions – failure on the ‘functional test’ of decisional capacity – must be caused entirely by mental or neurological disorder. Interpersonal pressure, non-pathological overwhelming emotion and diffuse social pressure are all explicitly ruled out as potentially undermining decisional capacity.

This interpretation of the Mental Capacity Act was enshrined in 2013 in PC v NC v City of York Council [2013] EWCA Civ 478. In that case, a woman with intellectual disabilities, PC, expressed a preference to live with her husband, NC. NC was a convicted sex offender. Safeguarding concerns were raised: NC presented a danger to PC. In the initial ruling, PC was deemed to lack the capacity to decide whether to live with NC. She was unable to acknowledge or understand that he was a convicted sex offender, and hence unable to understand the risks of living with him, as relevant to criterion 1. However, she was only unable to understand this, the Court of Protection initially ruled, because of the interaction of her intellectual disability and the interpersonal pressure NC applied to her. The Court of Appeal overturned this: the law was clear, it was ruled, that a lack of capacity under the Mental Capacity Act must be caused entirely by the relevant ‘impairment’. This was authoritatively endorsed in 2021 by the Supreme Court in A Local Authority v JB [2021] UKSC 35, and is the starting point for assessments of capacity.

Although the jurisdiction of the High Court can be invoked to cover cases of interpersonal pressure, the invocation of the paternalistic powers of the High Court presupposes the full capacity of the person undergoing such pressure. As such, those whose inability to decide turns on the interaction of interpersonal pressure and impairment, such as PC, fall between the cracks, protected neither by the Mental Capacity Act nor by the jurisdiction of the High Court. ^{Reference Ariyo, Kane, Owen and Ruck Keene8}

The Terminally Ill Adults (End of Life) Bill risks reproducing the same problems. The current draft of the bill includes an explicit clause guarding against ‘dishonesty, coercion, or pressure’. This is a good idea. However, as in the current legislative ecosystem, this is seen as a separate issue from questions of capacity. As is a problem for the current legislative ecosystem, these two issues are not so easily disentangled. A slightly biased presentation of the case for assisted dying might not cross the relevant threshold for counting as dishonest, coercive or applying pressure, if such a threshold is based on what would mislead, coerce or pressure a person with no cognitive or neurological impairment. A slight impairment might not qualify an individual for protection under the part of the Bill that calls on capacity legislation. A person with only a slight impairment, faced with an only slightly biased presentation of the case for assisted dying, might therefore not qualify for protections under the Bill. In reality, however, the interaction of the slight impairment and slightly biased presentation might suffice to mean that the person does not, in fact, pass the functional test of capacity, for reasons not wholly explained by their impairment.

Problems with affect and motivation

Even setting aside the Mental Capacity Act’s impairment requirement, there are many who worry that the Mental Capacity Act’s current functional criteria are ill-equipped to deal with issues of affect, motivation and value; this is the consensus in at least the philosophical literature on the topic. ^{Reference Hawkins, Charland and Zalta10} It is unclear whether, for example, they are able to deal with the possibility of affect circumventing otherwise intact decision-making capacities, at least as the law is currently interpreted and applied. ^{Reference Craigie and Davies11}

For example, people with major depressive disorder often appear to be ‘cognitively intact’ and perform well on the criteria for decision-making included in the Mental Capacity Act. Their affect and motivation, however, appear to be disordered in ways that affect their decision-making, without necessarily affecting the criteria included in the Act: they may be driven by overwhelming affect or urges to self-harm, suicide or treatment-refusal even if they can understand, retain and use and weigh all the relevant information and even if these actions are not in their own subjective best interest. The associated 2007 Code of Practice for the Act has some tools for dealing with these kinds of case, ¹² and in clinical practice, clinical judgement and the 1983 Mental Health Act mean that such individuals rarely go without treatment. ¹³ Even so, it is far from clear that they are neatly covered by the strict criteria included in the Mental Capacity Act.

These two issues – the lack of a criterion for dealing with affect and the overzealous impairment requirement – overlap in relation to assisted dying. If an individual is overwhelmed by affect that is not pathological – perhaps in that it is not disproportionate to or unwarranted by their situation ^{Reference Horwitz and Wakefield14} – it is far from clear that its effects on decision-making are neatly covered by the criteria included in the functional test of the Mental Capacity Act. None of the associated complements to this functional test can be invoked, and the impairment requirement would entail that there is no warrant for ruling incapacity under the Mental Capacity Act. As such, many of the core kinds of worrying case for assisted dying – people making an incapacitated decision out of overwhelming pain and despair – are not safeguarded against by the Mental Capacity Act.

An opportunity for reform

If the Mental Capacity Act is to be used as the arbiter of free choice in assisted dying, it requires substantial reforms. This is not necessarily a bad thing. There are those already calling for reforms to the Act from a number of different angles and perspectives. My own view is that the impairment requirement should be either removed entirely or reformulated to require that the failure on the functional test be explicable by relevant experts (where this would include the kinds of sociocultural and interpersonal factors attested to by psychiatrists and social workers), and that an explicit criterion on the functional test should be added to deal with overwhelming affect (a proposal I have developed elsewhere). ^{Reference Gough7} These are, in my view, the biggest problems with using the Act both in the current legislative ecosystem and in its proposed use for assisted dying decisions.

I am aware that my own view is likely partial. There should be a review of the Mental Capacity Act, as there has recently been for the Mental Health Act, which might be beneficial both for providing safeguards for assisted dying and for the use of the Act in clinical practice more broadly. Merely tailoring, or tinkering with, capacity law for use in assisted dying risks ignoring systemic problems with the Act in its extant roles, thereby both failing to remedy these already-extant issues and also importing them into assisted dying legislation – as I believe is the case in the Assisted Dying (Jersey) Law 2026’s capacity provisions. ¹⁵

If these problems are not ignored, it may be possible to tap into the political hunger for well-regulated assisted dying, to improve and reform the Mental Capacity Act more broadly. If these problems are ignored, however, we may end up with assisted dying legislation that provides inadequate protections against vulnerable people being pressured into an earlier death than necessary – and one that relies almost entirely on extremely difficult judgement calls and discretionary decisions on the part of already overworked and underresourced medical professionals to prevent extreme abuses.