Illegal drug market responses to state recreational cannabis laws

In the United States, 15 states and the District of Columbia have implemented recreational cannabis laws (RCLs) legalizing recreational cannabis use. We aimed to estimate the association between RCLs and street prices, potency, quality and law enforcement seizures of illegal cannabis, methamphetamine, cocaine, heroin, oxycodone, hydrocodone, morphine, amphetamine and alprazolam.

We pooled crowdsourced data from 2010-19 Price of Weed and 2010-19 StreetRx, and administrative data from the 2006-19 System to Retrieve Information from Drug Evidence (STRIDE) and the 2007-19 National Forensic Laboratory Information System (NFLIS). We employed a difference-in-differences design that exploited the staggered implementation of RCLs to compare changes in outcomes between RCL and non-RCL states.

Eleven RCL and 40 non-RCL US states.

The primary outcome was the natural log of prices per gram, overall and by self-reported quality. The primary policy was an indicator of RCL implementation, defined using effective dates.

The street price of cannabis decreased by 9.2% [β = -0.092; 95% confidence interval (CI) = -0.15-, -0.03] in RCL states after RCL implementation, with largest declines among low-quality purchases (β = -0.195; 95% CI = -0.282, -0.108). Price declines were accompanied by a 93% (β = -0.93; 95% CI = -1.51, -0.36) reduction in law enforcement seizures of cannabis in RCL states. Among illegal opioids, including heroin, oxycodone and hydrocodone, street prices increased and law enforcement seizures decreased in RCL states.

Recreational cannabis laws in US states appear to be associated with illegal drug market responses in those states, including reductions in the street price of cannabis. Changes in the street prices of illegal opioids analyzed may suggest that in states with recreational cannabis laws the markets for other illegal drugs are not independent of legal cannabis market regulation.