Evaluating the impacts of cannabis legalization: The International Cannabis Policy Study.

An increasing number of jurisdictions have legalized non-medical cannabis use, including Canada in October 2018 and several US states starting in 2012. The policy measures implemented within these regulated markets differ with respect to product standards, labelling and warnings, public education, retail policies, marketing, and price/taxation. The International Cannabis Policy Study (ICPS) seeks to evaluate the impacts of these policy measures as well as the broader population-level impact of cannabis legalization using a quasi-experimental research design. The objective of this paper is to describe the ICPS conceptual framework, methods, and baseline estimates of cannabis use. The ICPS is a prospective cohort survey conducted with national samples of 16-65-year-olds in Canada and the US. Data are collected via an online survey using the Nielsen Consumer Insights Global Panel. Primary survey domains include: prevalence and patterns of cannabis use; purchasing and price; consumption and product types; commercial retail environment; problematic use and risk behaviours; cannabis knowledge and risk perceptions; and policy-relevant outcomes including exposure to health warnings, public educational campaigns, and advertising and promotion. The first annual wave was conducted in Aug-Oct 2018 with 27,169 respondents in three geographic 'conditions': Canada (n = 10,057), US states that had legalized non-medical cannabis (n = 7,398) and US states in which non-medical cannabis was prohibited (n = 9,714). The ICPS indicates substantial differences in cannabis use in jurisdictions with different regulatory frameworks for cannabis. Future waves of the study will examine changes over time in cannabis use and its effects associated with legalization in Canada and additional US states.