For the last while, I (along with many others working in this area) have been struggling with the question of how to reconcile the Mental Capacity Act 2005 (MCA), with Article 12 of the UN Convention on the Rights of Persons with Disability (CRPD). As many readers of this blog will know, section 1(5) of the MCA requires that any decision made for or on behalf of a person who lacks capacity needs to be made in their ‘best interests’. In contrast, Article 12 CRPD requires that disabled people’s rights to equal treatment under the law are respected. This right includes the right to “enjoy legal capacity on an equal basis with others in all aspects of life” (Article 12(2)). In their clarificatory General Comment No 1 on the scope and interpretation of Article 12, the Committee on the Rights of Persons with Disabilities made clear that “The ‘best interests’ principle is not a safeguard which complies with article 12 in relation to adults” (paragraph 21).
Given the centrality of best interests decision making in contemporary English mental capacity law, we need to give serious consideration to how these two, seemingly opposing, positions can be reconciled. In order to get to that point, it will be helpful to think through the critiques of best interests. Five substantive critiques of best interests have been put forward in the academic literature on this topic. Firstly, best interests decision making can be “vague, uncertain and unpredictable.” Because of this, it is very difficult to predict what the outcome of a best interests determination will be. There is usually no single, logical, best outcome in the difficult cases where best interests are to be addressed. Courts, healthcare professionals, social workers and carers instead select from any number of possible outcomes.
Best interests decision making is often paternalistic, and imbued with the beliefs and values of the decision-maker, rather than those of the person who is at the centre of the decision. A third critique of best interests, originally put forward in the context of family law, is that it may be incompatible with Article 8 rights to respect for private life, family life and home. This may become especially troublesome when considering things like residential placements, whether or not these amount to a Deprivation of Liberty under the legislation (another big issue in contemporary mental capacity law).
The CommitteeRPD raise two further issues with best interests decision making. They argue that ‘best interests’ denies legal capacity on the basis of disability. This can take three forms, where legal capacity is denied because of: the status of the individual as having a particular diagnosis or impairment; the outcome of a particular decision is perceived to have negative consequences; or on functional grounds the person is not considered capable of making a decision. This functional approach is very close to the MCA understanding of capacity. Under the MCA, whenever a person is determined to lack capacity under the functional test set out in section 3, another person makes the decision instead, taking into consideration the views of that person, their family carers and the professionals involved in their care. The CommitteeRPD’s criticism of the functional approach is enlightening:
“This approach is flawed for two key reasons: (a) it is discriminatorily applied to people with disabilities; and (b) it presumes to be able to accurately assess the inner-workings of the human mind and, when the person does not pass the assessment, it then denies him or her a core human right — the right to equal recognition before the law. In all of those approaches, a person’s disability and/or decision making skills are taken as legitimate grounds for denying his or her legal capacity and lowering his or her status as a person before the law.” (Committee RPD, General Comment no 1, para 15)
A final critique of best interests is that it substitutes someone else’s decision (whether a health care professional, a judge, a social worker, a carer, or a family member) for that of the person with a cognitive impairment. Article 12 of the Convention on the Rights of Persons with Disabilities, by contrast, requires that people are supported to make their own decisions. Only when all practicable means to support the person to make their own decision have been exhausted would a decision be made on their behalf, in accordance with the best interpretation of their will and preferences, following Article 12(4).
Could this mean the end of best interests in our mental capacity law? Perhaps. If we take these criticisms of best interests seriously, it may well be that we need to re-think best interests under the MCA to ensure our compliance with the rights of persons with disabilities under the CRPD. There appears to be little appetite for a change to the language of best interests under the MCA. Instead, the focus of the House of Lords Select Committee was on better implementation of the empowering ethos of the legislation. But a key problem, as I see it, with the implementation of the MCA is the way that MCA best interests are routinely conflated with clinical understandings of ‘best interests’ despite the different normative content of the two approaches. As a result, it seems clear that we do need to find a new lexicon for decision making by, with and for people with intellectual disabilities, one that doesn’t rely on the words ‘best interests’, to ensure that supported decision making is the reality in all but the most difficult of cases. And when a person truly can’t make a decision for themselves, it must be their own preferences and values that guide the decisions made on their behalf. The task ahead is to find that lexicon, and to use it to build a new approach to empowering individuals with intellectual disabilities to shape their lives according to their own values, wishes and preferences.
 Flynn E & Arstein-Kerslake A ‘Legislating personhood: realising the right to support in exercising legal capacity’ (2014) 10 International Journal of Law in Context 81; Richardson, G ‘Mental Disabilities and the Law: From substituted to supported decision-making?’ (2012) 65 Current Legal Problems 333; House of Lords Select Committee on the Mental Capacity Act (2014) Mental Capacity Act 2005: Post-Legislative Scrutiny (London: TSO).
 Donnelly, M (2009) ‘Best Interests, Patient Participation and the Mental Capacity Act 2005’ Medical law Review 17: 1-19.
 Choudhury, S (2008) ‘Best Interest in the MCA 2005 – What can Healthcare Law Learn from Family Law?’ Health Care Analysis 16: 240-251.
 Fennell, P (2008) ‘Best Interests and Treatment for Mental Disorder’ Health Care Analysis 16: 255-267.
 Eekelaar, J (2002) ‘Beyond the welfare principle’ Child and Family Law Quarterly 11: 387.
 Harding, R (2012) ‘Legal Constructions of Dementia: Discourses of autonomy at the margins of capacity’ Journal of Social Welfare and Family Law 34(4): 425-442.