In this paper, the authors (two clinicians with specialized practices in child and adolescent eating disorders and a lawyer who practices health law in Ontario, Canada) review pertinent aspects of clinical capacity assessment, with elaboration of the specific unique and complex issues which shape that assessment in children and adolescents with eating disorders. The relevant Ontario legislation and institutional framework governing consent and capacity in children and adolescents are reviewed. The literature on involuntary treatment and consent and capacity in patients with eating disorders is reviewed. Specific cases involving child and adolescent patients with eating disorders that have been heard by the Ontario Consent and Capacity Board (OCCB) in the past decade are discussed in order to elucidate the Board's views of consent and capacity in this vulnerable and challenging patient population. Strategies to support clinicians' therapeutic alliances with their patients while both are going through what can be a lengthy and potentially adversarial-seeming legal process are also discussed.