Querying the Call to Introduce Mental Capacity Testing to Mental Health Law: Does the Doctrine of Necessity Provide an Alternative?

Trends in international human rights law have challenged States globally to rethink involuntary mental health interventions from a non-discrimination perspective. The United Nations Convention on the Rights of Persons with Disabilities (CRPD) in particular prohibits laws that discriminate on the basis of disability. However, a key criterion for compulsory mental health treatment under typical mental health legislation is a psychiatric diagnosis (in conjunction with risk of harm and other criteria). Hence, for people with mental health disabilities, rights to liberty and consent in healthcare are held to a different standard compared to other citizens. A prominent law reform option being explored by some governments and commentators for achieving non-discrimination is to replace the diagnostic criterion for triggering involuntary intervention with an assessment of mental capacity. After all, every citizen is subject to restrictions on autonomy where they are deemed to lack mental capacity, such as where concussion necessitates emergency service. However, the use of mental capacity “testing” is seen by diverse commentators as wanting in key respects. A prominent criticism comes from the United Nations Committee on the Rights of Persons with Disabilities, which considers mental capacity assessments a form of disability-based discrimination. This article queries the call to replace the diagnostic criterion in mental health law with an assessment of mental capacity in the light of jurisprudence on equality and non-discrimination in international human rights law. Instead, we examine the doctrine of necessity as an area of law, which might help identify specific thresholds for overriding autonomy in emergency circumstances that can be codified in a non-discriminatory way. We also consider the need for deliberative law reform processes to identify such measures, and we suggest interim, short-term measures for creating a “supported decision-making regime” in the mental health context. The article focuses in particular on the Australian context of mental health law reform, though the analysis can be generalised to international trends in mental health law.