Persistent coercion dominance in New Zealand mental health legislation: an 18-year content analysis (2007-2025)

Background New Zealand ratified the UN Convention on the Rights of Persons with Disabilities in 2008, but whether this rights-based commitment altered the language of its primary mental health statute remains untested. Aims To quantify the balance of rights-affirming and coercive language in the Mental Health (Compulsory Assessment and Treatment) Act 1992 across all available registered versions, and to test whether the 2020 Amendment changed that balance. Method We performed a content analysis of 20 registered versions of the Act spanning 2007-2025. Rights-affirming and coercive terms were counted per 1,000 words, generating a rights ratio. Mann-Whitney U compared ratios before and after the 2020 Amendment, and Mann-Kendall tested monotonic change across the full series. Results The rights ratio remained persistently low across all versions (mean 0.122, range 0.098-0.158), with coercive terms outnumbering rights language by about 7:1. The 2020 Amendment produced no detectable change (pre-2020 mean 0.121; post-2020 mean 0.124; U=60, p=0.44), and no monotonic trend was detected across 2007-2025 (τ=-0.055, p=0.88). Cross-act comparison showed that this coercion dominance was specific to the Mental Health Act. Conclusions Across 18 years of documented versions, New Zealand’s primary mental health statute remained persistently coercion-dominant, with no detectable shift after the 2020 Amendment. These findings provide a quantitative baseline for judging whether future reform brings statutory language into closer alignment with rights-based psychiatric care.