A difference-in-difference analysis of five states found that cannabis decriminalization reduced youth drug-related arrests by 75% with similar effects for adults, while past-30-day cannabis use among youth showed no increase.
Read this if you are interested in whether cannabis decriminalization leads to increased youth marijuana use.
75% reduction in youth drug arrests; zero change in youth cannabis use
What the researchers found
Researchers examined the effects of cannabis decriminalization in five states (Massachusetts 2008, Connecticut 2011, Rhode Island 2013, Vermont 2013, Maryland 2014) using federal crime statistics and Youth Risk Behavior Survey data.
Decriminalization was associated with a 75% reduction in drug-related arrests for youth (95% CI: 44-89%), with similar magnitude reductions for adult arrests.
Critically, decriminalization was not associated with any increase in past-30-day cannabis use prevalence among youth. The relative change was -0.2% (95% CI: -4.5% to 4.3%), effectively zero. This finding held both overall and in each individual decriminalization state.
The results suggest that decriminalization achieved its intended consequence (reducing arrest burden) without the commonly feared unintended consequence (increased youth use).
Why it matters
This study directly addresses the central concern about cannabis decriminalization: that reducing penalties will increase use, especially among young people. The finding that arrests dropped dramatically while youth use remained unchanged provides important evidence for policy debates.
The numbers in context
75% reduction in youth drug arrests (95% CI: 44-89%). Past-30-day youth cannabis use change: -0.2% (95% CI: -4.5% to 4.3%). Five states analyzed: MA (2008), CT (2011), RI (2013), VT (2013), MD (2014). Study period: 2007-2015.
How the study worked
Difference-in-difference regression framework comparing trends in the five decriminalization states against states with no major cannabis policy changes during the observation period (2007-2015). Arrest data from federal crime statistics; youth use data from state Youth Risk Behavior Surveys.
What this study cannot tell us
The observation period may be too short to capture longer-term changes in use patterns. Youth Risk Behavior Survey data is self-reported and school-based (misses dropouts). The five states may not represent all decriminalization contexts. The difference-in-difference approach assumes parallel trends would have continued without policy change.
How to read the evidence
Well-designed difference-in-difference analysis across five states with multiple data sources provides strong quasi-experimental evidence on decriminalization effects.
When this study was published
Published in 2018 with data through 2015. Several of these states have since moved from decriminalization to full legalization.
The bigger picture
The arrest reduction has significant equity implications, as cannabis arrests disproportionately affect minority communities. The finding that these arrests can be reduced by 75% without increasing youth use challenges the deterrence argument that criminal penalties are necessary to prevent teen cannabis use.
Questions still open
- Do the effects persist beyond the initial observation period? Does decriminalization affect age of first use or frequency of use among those who do use? How do the arrest reductions distribute across racial and socioeconomic groups?
Common questions
Did decriminalization lead to more teens using marijuana?
How much did arrests decrease?
Read the original research
Cannabis decriminalization: A study of recent policy change in five U.S. states.
The International journal on drug policy, 59, 67-75
Citation
Grucza, Richard A; Vuolo, Mike; Krauss, Melissa J; Plunk, Andrew D; Agrawal, Arpana; Chaloupka, Frank J; Bierut, Laura J. (2018). Cannabis decriminalization: A study of recent policy change in five U.S. states.. The International journal on drug policy, 59, 67-75. https://doi.org/10.1016/j.drugpo.2018.06.016