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Washington State Institute for Public Policy

Cannabis Legalization Evaluation

In November 2012, Washington State voters passed Initiative 502 to regulate and tax the use and sale of cannabis for persons twenty-one years of age and older. As part of I-502, WSIPP was directed to “conduct cost-benefit evaluations of the implementation” of the law. The evaluations must include measures of impacts on public health, public safety, cannabis use, the economy, the criminal justice system, and state and local costs and revenues.

A preliminary report was released in September 2015. The second required report was released in September 2017, and the third required report was released in September 2023. The last mandated report is due in 2032.

Previous Findings
Supplemental to the ongoing benefit-cost evaluation of cannabis legalization authorized by Initiative 502 in 2012, the 2018 Washington State Legislature directed WSIPP to conduct additional cannabis research. WSIPP was directed to update its inventory of programs for the prevention and treatment of youth cannabis use; examine current data collection methods measuring the use of cannabis by youth and potential ways to improve on these methods; and identify effective methods used to reduce or eliminate the unlicensed cultivation or distribution of marijuana in jurisdictions with existing legal marijuana markets.

Related reports:
Monitoring Trends in Use Prior to Implementation of I-502 and Employment and Wage Earnings in Licensed Marijuana Businesses.

Recent Findings
Initiative 502 and Cannabis-Related Public Health and Safety Outcomes: Third Required Report
We describe findings from analyses of the relationship between non-medical cannabis legalization or licensed retail operations and various outcomes. First, we examined how cannabis possession misdemeanor conviction rates changed in Washington after the passage of I-502. Second, we examined how reported cannabis use has changed in Washington after the passage of I-502 compared to non-legalizing states. Last, we specifically focused on the impact of local access to licensed non-medical retailers. For these analyses, we examined how retail access relates to substance abuse and traffic safety outcomes within the state over time.

Reported Substance Use: Using national survey data, we compared changes in the rates of reported cannabis, alcohol, and other substance use in Washington after the enactment of I-502 and the start of a licensed retail market, relative to changes in comparable states that did not legalize non-medical cannabis.

Cannabis-Related Convictions: We examined how rates of cannabis possession misdemeanor convictions have changed since the enactment of I-502. We examined conviction rates separately for different ages, sex, and racial groups.

Traffic Fatalities: We examined the relationship between greater access to licensed non-medical cannabis retailers and the prevalence of fatal traffic collisions. We also examined the relationship between retail accessibility and the prevalence of drivers involved in a fatal crash who test positive for THC both alone and in combination with alcohol.

Substance Use Disorder Diagnoses: We examined the relationship between greater access to licensed non-medical cannabis retailers and the probability of cannabis use disorder, alcohol use disorder, or opioid use disorder diagnoses.

High School Outcomes: We examined the relationship between school proximity to an operational non-medical cannabis retailer and high school outcomes, including attendance, disciplinary outcomes, and high school graduation.
Amani Rashid, (360) 664-9804 View Legislation