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Kiannah Sepeda-Miller
By Kiannah Sepeda-Miller May 12, 2019

Cassidy puffs up what stats say about teen marijuana use

Among the issues taking center stage in Springfield as lawmakers enter the final stretch of the legislative session is whether Illinois should join a growing number of states in lifting a prohibition on recreational marijuana.

While the legislation under consideration would bar legal sales to those under 21, critics have raised concerns that the easier access could still lead to greater use among teens.

One Democratic lawmaker who spoke in support of the plan when it was unveiled recently by Gov. J.B. Pritzker was state Rep. Kelly Cassidy, a Chicago Democrat.

"Cannabis should be sold in venues that are highly regulated, taking the pot market out of the shadows," Cassidy said. "In states that have legalized, you see steady decreases in youth use if you do it right."

PolitiFact in recent years has assessed changes in pot use among youth while investigating claims about how legalization has affected citizens in Colorado, which became the first state in the nation to greenlight retail sales in 2014 after voters approved cannabis for adult recreational use by ballot measure in 2012.

Since 2014, the data show no statistically significant uptick in pot usage among teens so legalization hardly leads to the reefer madness some critics feared. But the numbers available for Colorado and other states that have lifted bans for adults also don’t reveal the clear pattern of decline in youth pot use that Cassidy described.

Few test cases

If lawmakers approve the plan, Illinois could become the 11th state to allow adults to use cannabis recreationally and the second in the Midwest, after Michigan, where voters in November approved a measure legalizing the drug.

So far, retail sales are up and running in seven of those states, including three in just the last three years. That makes it harder to come by comprehensive statistics.

Cassidy sent us an email promising an aide would "share the studies out of Colorado," but nothing arrived from the lawmaker’s office as of our deadline. She also didn’t explain what she meant by "do it right." Colorado and Washington were the first states to legalize retail marijuana sales, so they have the longest track records to study.

In Colorado, a 2018 report by the state Department of Public Safety's Division of Justice reviewed data from the Healthy Kids Colorado Survey, which includes answers to various health questions asked of more than 40,000 middle and high school students every other year. The survey is conducted by the state’s Department of Public Health & Environment.

Results from the survey show 19.7% of Colorado high schoolers reported using marijuana within the past month in 2013, the year before the first retail marijuana store opened. In 2015, that figure rose slightly, but experts told PolitiFact in 2016 that increase was not statistically significant. In 2017, the rate dipped to 19.4%, slightly lower than it had been in previous surveys dating back to least 2005.

But the Colorado report includes a major disclaimer. It states upfront that the majority of data related to marijuana legalization is "baseline and preliminary," making it "difficult to draw conclusions about the potential effects of marijuana legalization and commercialization on public safety, public health, or youth outcomes" due to the lack of historical data.

Jonathan Caulkins, a public policy professor at Carnegie Mellon University and former co-director of RAND’s Drug Policy Research Center, echoed that warning to PolitiFact Illinois.

"The full effects of cannabis legalization won’t be seen for a generation after national legalization, which has not even happened yet," he wrote in an email.

As for preliminary state results? Caulkins said that making recreational marijuana legal for adults has done little to affect use by youth — in large part because cannabis was already relatively easy for minors to obtain in those states.

Indeed, material included in the Colorado survey characterizes as "relatively unchanged" the slight variations in teen marijuana use since legalization.

Voters in Washington also approved recreational cannabis in late 2012, and retail sales of the drug there began in 2014, six months after Colorado.

The state conducts a biennial youth health survey similar to Colorado’s, which breaks its data down by grades. Its results show some small declines but suggest little has changed there either, with decreases of 1% between 2014 and 2016 among 8th and 10th graders who said they currently used pot, followed by 1% increases for both grades in 2018. For 12th graders, rates fell by 1% the year after retail sales began and have remained at that level, which is in line with pre-legalization rates.

"The findings with respect to youth are generally mixed and depend critically on what measures of youth use one wants to focus on," said Rosalie Pacula, a senior economist with RAND and current co-director of the Drug Policy Research Center who analyzed survey data for Washington and Colorado in several recent reports.

She explained in an email to us that studies of states where adult use is legal generally show either no effect or some decline in past-year or 30-day use rates among youth, depending on the survey data used. But results for more frequent and risky use are "a bit more mixed," she said, with some showing an uptick.

Changes in the other five states where retail sales are underway are even more difficult to evaluate than Colorado or Washington. Alaska’s state survey reported no statistically significant changes since recreational cannabis was approved for adults in 2014 and hit the market in 2016. Results in Oregon, which followed a similar timeline, were mixed. And it’s too soon to assess results out of Nevada, California and Massachusetts, which each repealed bans in late 2016 but only began allowing sales within the last two years.

Our ruling

Cassidy said, "In states that have legalized, you see steady decreases in youth use if you do it right."

She did not provide any proof to back up her statement.

Of the 10 states that allow adults to use cannabis recreationally, only four have permitted retail sales long enough to provide enough data points for a preliminary comparison. While state survey data show no spike in current marijuana use among teens, they also fall short of suggesting the downward trajectory Cassidy described.

We rate her claim Mostly False.


MOSTLY FALSE – The statement contains an element of truth but ignores critical facts that would give a different impression.

Click here for more on the six PolitiFact ratings and how we select facts to check.

Our Sources

State marijuana policies, Marijuana Policy Project, accessed May 8, 2019

State marijuana policy timeline, National Conference of State Legislatures, accessed May 8, 2019

"State Rep. Moylan on recreational marijuana: Not so fast," Chicago Sun-Times, May 6, 2019

Video, Illinois Department of Central Management Services, May 4, 2019

"Pritzker, Dems introduce bill to legalize marijuana statewide," Chicago Sun-Times, May 4, 2019

"Did marijuana use in Colorado spike after legalization?" PolitiFact, Mar. 25, 2019

"Has Colorado teen pot use not increased since legalization?" PolitiFact Arizona, Oct. 6, 2016

Email interview: Rep. Kelly Cassidy, May 8, 2019

Report: Impacts of Marijuana Legalization in Colorado, Colorado Division of Criminal Justice, October 2018

Healthy Kids Colorado Survey, Colorado Department of Public Health & Environment, accessed May 8, 2019

Email interview: Jonathan Caulkins, public policy professor at Carnegie Mellon University and former co-director of RAND’s Drug Policy Research Center, May 7-9, 2019

Healthy Youth Survey, State of Washington Office of Superintendent of Public Instruction, accessed May 8, 2019

2018 data brief, Washington State Healthy Use Survey

Email interview: Rosalie Liccardo Pacula, economist and co-director of the Drug Policy Research Center, May 7, 2019

Report: Association of State Recreational Marijuana Laws With Adolescent Marijuana Use, JAMA Pediatrics, February 2017

Report: Prevalence of Cannabis Use in Youths After Legalization in Washington State, JAMA Pediatrics, Dec. 19, 2018

2017 preliminary highlights, Alaska Youth Risk Behavior Survey

Oregon Healthy Teens Survey, accessed May 8, 2019

Nevada Youth Risk Behavior Survey, accessed May 8, 2019

Biennial Student Survey, California Department of Health Care Services, accessed May 8, 2019

Massachusetts Youth Health Survey, Massachusetts Department of Public Health, accessed May 8, 2019

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Cassidy puffs up what stats say about teen marijuana use

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