Associate Health Minister Casey Costello was warned that scrapping the smokefree law would be viewed as a breach of the Treaty of Waitangi.
RNZ has obtained Ministry of Health documents sent to Costello, in which health officials say the law she is repealing would have generated health gains for Maori which were five times that of the general population.
Health officials also warned the Minister that overturning the smokefree law could inflict serious reputational damage on New Zealand.
Guyon Espiner speaks to Lisa Owen.
