Abstract
This is a summary report on the first phase of four of seven sub-studies of a larger project funded to evaluate the impact of changes to cannabis law in Western Australia on cannabis use, the drug market, law enforcement, knowledge and attitudes, and cannabis-related harms. The evaluation investigates: police implementation of the changes; drug market effects; impact on regular cannabis users, population prevalence, knowledge and attitudes regarding cannabis and the law; effect on school children; effect on apprehended cannabis users; and population impact on health problems associated with cannabis use.