Eva Westley, Marna Miller, Rebecca Goodvin, Casey Hicks - December 2019

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 reducing marijuana use. The 2018 Washington State Legislature directed WSIPP to update this inventory. This is the fourth update in the series.

Adam Darnell, Kristofer Bitney - September 2017

Initiative 502, passed by Washington voters in November 2012, legalized the limited adult possession and private consumption of cannabis, as well as its licensed production and sale. The initiative directs WSIPP to evaluate the impact of the law in a series of reports between 2015 and 2032.

In this second required report we address preliminary findings from analyses of effects of I-502 on non-monetary outcomes. We used two main analysis strategies. We examined the effect of I-502 enactment on cannabis abuse treatment admissions, comparing Washington to similar non-legalizing states before and after I-502 enactment. We also examined how local differences in the amount of legal cannabis sales affected cannabis abuse treatment admissions, youth and adult substance use, and drug-related criminal convictions.

These analyses represent an intermediate step towards the ultimate benefit-cost evaluation of I-502 that is required by the law.

Bailey Ingraham, 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, using national survey data between 2004 to 2019, we compared changes in the rates of reported cannabis, alcohol, and other substance use in Washington relative to comparable states after the enactment of I-502 and the advent of a licensed retail market. We do not find evidence that the enactment of I-502 or the advent of cannabis retail sales in Washington significantly changed reported adult or youth cannabis use, alcohol use, or other substance use compared to non-legalizing states.

Sean Hanley - November 2013

The Washington State Institute for Public Policy is directed to conduct a benefit-cost analysis of the implementation of I-502, which legalizes recreational cannabis use for adults within the state. As a preliminary step, we analyzed population-level data to begin monitoring four key indicators of cannabis use prior to implementation.

We used data from the 2002 to 2011 administrations of the National Survey on Drug Use and Health to examine trends in the prevalence of current cannabis use, lifetime cannabis use, age of initiation, and cannabis abuse or dependency. We examined these trends separately for youth and adults in Washington, and also provide estimates for Colorado (the other state that has legalized recreational cannabis use) and the rest of the United States (US).

Examining trends in this manner will allow us to monitor whether the implementation of I-502 appears to affect these key indicators of marijuana use over time. Although more sophisticated analyses will be required for us to evaluate the policy, these initial trends provide a baseline to compare future data against. The prevalence of cannabis use in the past 30 days—a key indicator of the proportion of people who are current cannabis users—appears to be on the rise in recent years among both youth and adults in Washington, Colorado, and the US. The other indicators of use appear to be relatively stable or increasing slightly over time. In general, the estimates from Washington are slightly higher than the US and slightly lower than Colorado.

We will continue to monitor these trends over time within the context of our larger benefit-cost analysis to examine whether the new policy appears to affect marijuana use rates within the state.

Adam Darnell - September 2015

Initiative 502, passed by Washington voters in November 2012, legalized the limited adult possession and private consumption of cannabis, as well as its licensed production and sale. The initiative directs WSIPP to evaluate the impact of the law in a series of reports between 2015 and 2032.

It is too early in the history of I-502 to evaluate outcomes. This first required report describes the research plan for the overall study and presents preliminary data on the status of implementation of the law as of June 30, 2015. Ultimately, WSIPP’s evaluation will include a full descriptive study of implementation; an outcome study to identify causal effects of the law on a range of outcomes (e.g., substance use and abuse, health, criminal justice, traffic safety); and a benefit-cost analysis of the net economic impact of the law.

Matt Lemon, Annie Pennucci, Sean Hanley, Steve Aos - October 2014

Initiative 502, passed by Washington voters in November 2012, legalized recreational cannabis use for adults in the state. The initiative directs WSIPP to evaluate the policy in a series of reports between 2015 and 2032.

As part of this assignment, we reviewed the evaluation literature on 23 youth marijuana prevention and treatment programs. This review updates an earlier report that focused on a subset of the programs; to view the initial report click here.

Marna Miller, Katelyn Kelley - December 2022

The 2021 Washington State Legislature directed WSIPP to review the research for any relationships between adolescent substance use and adolescent nutrition on subsequent mental illness in early adulthood.

For substance use, we found that adolescent alcohol use was associated with an increased risk of later depression. Adolescent cannabis use was associated with an increased risk for depression and psychosis, but we found no evidence that adolescent misuse of opioids or cocaine is associated with mental illness in young adults.

For nutrition, we found that higher quality diet in adolescence was associated with a lower risk for later depression. Obesity during adolescence was associated with an increased risk for depression in young adults, especially in females. Finally, we found no evidence of a link between adolescent intake of omega-3 fatty acids and any mental illness in young adulthood.

Chasya Hoagland, Bethanne Barnes, Adam Darnell - June 2017

The Washington State Institute for Public Policy is directed to conduct an evaluation and benefit-cost analysis of the implementation of I-502, which legalizes recreational marijuana use for adults within the state. As a supplemental step, WSIPP's Board of Director's authorized WSIPP to analyze employment and wage data for employees in marijuana businesses.

We used data from The Washington State Liquor and Cannabis Board (LCB) combined with Unemployment Insurance (UI) wage data from the Washington State Employment Security Department (ESD) to analyze employment in Washington State businesses that have been issued marijuana licenses.

Roxanne Lieb - October 1996

In 1990, Washington State enacted a civil commitment law for persons found to be sexually violent predators. As of September 1996, 38 persons are housed at the Special Commitment Center in Monroe, Washington; 21 have been committed under the Act, and the others are awaiting trial. This paper summarizes records from the Special Commitment Center regarding the residents' criminal history, offense pattern, treatment history, and mental health diagnosis.

Sean Hanley, Steve Aos - September 2014

Initiative 502, passed by Washington voters in November 2012, legalized recreational marijuana use for adults in the state. The initiative directed WSIPP to evaluate the policy by considering benefits and costs across a number of key areas including public health, public safety, and criminal justice.

As part of this assignment, we reviewed the evaluation literature on 13 youth prevention programs. These programs are on the state Department of Behavioral Health and Recovery’s preliminary list of evidence-based programs with marijuana prevention outcomes.

To view an update to this report, please click here.