To describe similarities and differences in mental health legislation between five jurisdictions: the Republic of Ireland, England and Wales, Scotland, Ontario (Canada), and Victoria (Australia).

An in-depth examination was undertaken focussing on the process of involuntary admission, review of Admission Orders and the legal processes in relation to treatment in the absence of patient consent in each of the five jurisdictions of interest.

All jurisdictions permit the detention of a patient if they have a mental disorder although the definition of mental disorder varies between jurisdictions. Several additional differences exist between the five jurisdictions, including the duration of admission prior to independent review of involuntary detention and the role of supported decision making.

Across the five jurisdictions examined, largely similar procedures for admission, detention and treatment of involuntary patients are employed, reflecting adherence with international standards and incorporation of human rights-based principles. Differences exist in relation to the criteria to define mental disorder, the occurrence of automatic review hearings in a timely fashion after a patient is involuntarily admitted and the role for supported decision making under mental health legislation.