...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. ...

Adam Darnell - May 2019

The 2018 Washington State Legislature directed WSIPP to conduct additional cannabis research, supplemental to the ongoing benefit-cost evaluation of cannabis legalization authorized by Initiative 502 in 2012. As part of this supplemental work, WSIPP was directed to examine current data collection methods measuring the use of marijuana by youth and potential ways to improve on these methods. In this report, we focused on the Washington Healthy Youth Survey, the primary source of data on cannabis use among Washington youth. We reviewed the evidence for harmful consequences of cannabis use focusing on how cannabis use was measured, and we examined recently developed surveys that reflect the state-of-the-art in survey measurement of marijuana use. With this information, we identified a set of potential improvements to the HYS while considering the practical limitations of revisions to an existing survey.

Amani Rashid, Paige Wanner - September 2023

In November 2012, Washington State voters passed Initiative 502 (I-502), which legalized limited possession, private use, and commercial sales of cannabis for adults. Specifically, I-502 legalized the possession of up to one ounce of cannabis (about 28 grams) for personal use for individuals ages 21 and older.

In this report, we examined how rates of cannabis possession misdemeanor convictions have changed since the enactment of I-502. We found that cannabis possession conviction rates dropped to almost zero among adults of legal age immediately after I-502 went into effect. Rates also substantively dropped for underaged individuals after NMC legalization, but not as dramatically as for adults ages 21 and over. Across all age groups, we find no significant changes in conviction rates after the advent of NMC retail operations.

Adam Darnell, Michael Hirsch, Paige Wanner - August 2019

The 2018 Washington State Legislature directed WSIPP to conduct additional cannabis research, supplemental to the ongoing benefit-cost evaluation of cannabis legalization authorized by Initiative 502 in 2012. As part of the new assignments, WSIPP was directed to examine effective methods for suppressing unlicensed cultivation and distribution of marijuana in jurisdictions with legal markets. We found very little evidence on that topic. Instead, we identified numerous factors that could contribute to the survival of the illicit marijuana market in the context of legalization, such as continuing prohibitions in other states and regulations that reduce the competitive advantage of the legal market. We examined key regulatory features in the nine states with licensed non-medical cannabis supply systems and found that states varied widely in the level of restriction imposed on legal supply systems. We conclude by outlining a practical strategy for monitoring illicit market reductions as the state’s approach to legalization develops.

Bailey Ingraham, Amani Rashid - June 2023

In November 2012, Washington State voters passed Initiative 502 (I-502), which legalized limited possession, private use, and commercial sales of cannabis for adults. In this report, we describe the evolution of cannabis-related policy, revenues, and expenditures over the past decade.

We first describe the implementation of I-502 and summarize major cannabis-related policy milestones through the fiscal year 2022. In addition, we detail aspects of the Washington cannabis market structure and regulatory rules and compare components of non-medical cannabis (NMC) legalization nationwide. Second, we describe cannabis-related sales, excise tax revenues, and spending of those revenues over the last decade. In fiscal year 2022, cannabis retailers sold nearly $1.4 billion in cannabis products, and just over half a billion dollars were generated in excise tax revenues. Most of these revenues are transferred to the general fund and state basic health plan trust, and less than 20% goes to state agencies for prevention, healthcare, research, and cannabis industry oversight. Since fiscal year 2016, this distribution of expenditures has not significantly changed, although the total dollar amount of cannabis-related revenue and expenditure has nearly tripled.

Amani Rashid, Nathan Adams - September 2023

In November 2012, Washington State voters passed Initiative 502 (I-502), which legalized limited possession, private use, and commercial sales of cannabis for adults. In this report, we examined if greater access to licensed non-medical cannabis (NMC) retailers relates to disordered substance use diagnoses among Medicaid beneficiaries in Washington State. We found that a lower average travel time to an NMC retailer predicts a small increase in the probability that a claim includes a diagnosis of cannabis use disorder (CUD), alcohol use disorder (AUD), or opioid use disorder (OUD) among Medicaid beneficiaries ages 21 and older and beneficiaries ages 12-17. We also found that in neighborhoods with multiple retailers located in proximity (within 5 or 10 minutes), an increase in the number of retailers predicts a higher likelihood of CUD.

Amani Rashid - September 2023

In November 2012, Washington State voters passed Initiative 502 (I-502), which legalized limited possession, private use, and commercial sales of cannabis for adults. In this report, we examined the relationship between greater access to licensed non-medical cannabis (NMC) retailers and the prevalence of fatal traffic collisions. We found that a lower average travel time to an NMC retailer is related to both a modest increase in the prevalence of total drivers involved in a fatal traffic collision and drivers who test positive for THC. These findings suggest that in areas with more cannabis use (as measured by easier access to legal cannabis retail), there are more drivers involved in fatal traffic collisions. We found no evidence that retail access relates to the prevalence of drivers who test positive for alcohol alone (BAC at least 0.08), or any amount of alcohol in combination with THC.

Adam Darnell, Rebecca Goodvin, Matt Lemon, Marna Miller - December 2016

Initiative 502 (I-502) legalized recreational cannabis for adults in Washington State. The law directs the Washington State Institute for Public Policy (WSIPP) to conduct a benefit-cost evaluation of the implementation of I-502.

In this report we summarize the research evidence for 51 programs for the prevention or treatment of youth cannabis use. The programs reviewed include those nominated by DBHR as well as programs from WSIPP’s current set of inventories that have evidence for cannabis outcomes.

Amani Rashid - September 2023

In November 2012, Washington State voters passed Initiative 502 (I-502), which legalized limited possession, private use, and commercial sales of cannabis for adults. The law also directed the Washington State Institute for Public Policy (WSIPP) to evaluate various public health, public safety, and economic impacts of the implementation of I-502 in a series of reports.

In this 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.

These analyses represent an intermediate step towards the ultimate legislatively mandated benefit-cost evaluation of I-502.

Adam Darnell, Rebecca Goodvin, Sara del Moral, Casey Hicks, Paige Wanner, Eva Westley - December 2018

Initiative 502 (I-502) legalized recreational cannabis for adults in Washington State. The law directs a portion of cannabis revenues to be spent on substance abuse prevention and treatment services that have been demonstrated to be effective. Specifically, state law requires at least 85% of programs funded by cannabis revenues to be evidence-based or research-based and up to 15% to be promising practices. In this inventory, we rate the research evidence for programs intended for the prevention or treatment of youth substance use, and we identify those specifically effective for marijuana. The 2018 Washington State Legislature directed WSIPP to update this inventory. This is the third update in the series.