Capacity and incapacity: An appropriate border for non-consensual interventions?

Those who support decision-making capacity as a criterion for non-consensual interventions for persons with mental disabilities (mental illness, learning disability, neurodivergence, acquired brain injury and dementia) argue that it creates parity between physical and mental health approaches to care, support and treatment. It is also argued that such an approach aligns with European Court of Human Rights direction relating to restrictions of a person with a mental disability's rights under Articles 5 and 8 of the European Convention on Human Rights. Indeed, the presence or absence of decision-making capacity has been adopted as a criterion for non-consensual intervention under mental capacity legislation across all UK jurisdictions. Decision-making capacity has also been adopted as a criterion for psychiatric treatment interventions under the Mental Capacity Act (Northern Ireland) 2016 and the Mental Health (Care and Treatment) (Scotland) Act 2003. More recently, however, the use of decision-making capacity as a determining factor for intervention has been challenged on human rights, particularly following the adoption of the Convention on the Rights of Persons with Disabilities, and on practical support grounds. This was considered by the Scottish Mental Health Law Review (2019-2022) which recommended an alternative, arguably more human rights compliant and support effective, Autonomous Decision-Making test. This article will consider the use of mental capacity as an appropriate border for non-consensual interventions under mental health and capacity law. In doing so, it will consider the wider arguments for and against such use, how this was addressed by the Scottish Mental Health Law Review and what lessons may be learned from this exercise.