Starson's paradox: Treatment capacity in the presence of delusional thinking.

The assessment of the capacity to consent to treatment for mental disorders remains a complex and contentious area of medico-legal practice in psychiatry around the world. In Canada, the definitive jurisprudential authority on the topic is the Supreme Court of Canada's landmark 6-3 ruling in Starson v. Swayze (Starson). Starson involved the case of an individual with psychosis, and the Court's interpretation of the 'appreciation' branch of the treatment capacity standard set out in the province of Ontario's Health Care Consent Act. While the majority opinion and its dissent shared a view on the relevance of lack of insight in dislodging the treatment capacity assumed under law, their application of this standard to the facts laid out in Starson differed significantly. Here, we revisit Starson as a case study to highlight the relevance of phenomenology to the treatment capacity test. Specifically, we posit that delusions introduce a logical tension in the law, considering the functional test for capacity as outlined in the HCCA and interpreted in Starson. Delusions may be seen to render capacity for their treatment under the current law logically incoherent. This work is thought to be of interest to those practicing in the fields of mental health and law, and to policymakers and other stakeholders involved in crafting capacity threshold tests in Canada and abroad.