Mental health law is a very challenging aspect of law practice, as it lies at the intersection of the protection of the right of vulnerable person – specifically mentally impaired persons – to take decisions concerning their medical treatment, and the assumption of such right by the state following its determination that a person no longer has the capacity to make such decision. A mental impairment could arise from several causes such as dementia, brain injuries, developmental or intellectual disabilities. In Ontario, there are basically three legislations that govern consent and capacity and mental health law: the Health Care Consent Act, the Mental Health Act and the Substitute Decisions Act. A determination by the state that a person lacks the mental capacity to take decision concerning his or her medical treatment often results in legal challenge by the person affect, and this is litigated before the Consent and Capacity Board (CCB). We offer our representation before this Board.