All drugs, including illicit drugs, licit drugs (e.g. alcohol and tobacco), and emerging synthetic drugs (e.g. carfentanil) can cause harm. Drug policy needs to take into account the harmfulness of a drug, considering both harms to individuals and to others including families, communities, and society. Drug harm ranking studies are a robust method for systematically quantifying drug harms, however, these need to be done locally to reflect cultural and social context, and improvements to the multi-criteria decision-making (MCDA) approach have been proposed. This study will complete a drug harms ranking study for New Zealand, considering the total population, plus analysis specific to both Māori and youth. A participatory and inclusive process will be utilised to extend the MCDA methodology, to build a nuanced picture of drug harm in New Zealand. This study will contribute to drug policy reform, inform resource allocation, and guide health promotion efforts to reduce drug harms.