The best interests of mentally incapacitated patients without a living will.

I have previously suggested that doctors’ moral duty to respect mentally incapacitated patients’ autonomy during decision-making can be fulfilled by helping them prepare a written living will before they become incapacitated.1 Mentally incapacitated patients fall into two categories: ‘formerly-competent’ and ‘never-competent’ and only the former are capable of preparing living wills. For those with living wills, the ethical standard of informed consent applies and in those without, two other ethical standards are available: the substituted judgement standard and the best interests standard. Both standards are potentially applicable to ‘formerly-competent’ patients, but in ‘never-competent’ patients, medical decisions can only be guided by the best interests standard, one that should be narrowly and medically defined. In this paper, I will evaluate the best interests standard as it is used in Part IVC of the Hong Kong Mental Health Ordinance (MHO) and also discuss the substituted judgement standard and the Mental Capacity Act (2005) for England and Wales (MCA).