Recreational marijuana legalization and drug-related offenses in Washington State: an interrupted time series analysis with a combination of synthetic controls.

An important public concern surrounding the legalization of recreational marijuana is its impact on offenses related to hard drugs such as heroin, cocaine, and other dangerous drugs, about which competing perspectives exist. Prior research using rigorous methodology to empirically examine this issue remains limited. Based on Uniform Crime Reporting (UCR) Program data from 2007 to 2019 and a quasi-experimental research design involving interrupted time series analysis (ITSA) and the synthetic control method (SCM), this study examines the effects of recreational marijuana legalization on the rates of a variety of drug offenses including possession violations related to marijuana, heroin/cocaine and their derivatives, and other dangerous nonnarcotic drugs in Washington State (WA), which passed its recreational marijuana law (RML) in late 2012 and began legal sales in July 2014. This study found that WA has experienced decreases in the rate of possession offenses for the two categories of more harmful drugs—heroin/cocaine and their derivatives, and other dangerous nonnarcotic drugs—over the post-sale period, relative to the states that have not legalized marijuana for recreational use, offering some evidence suggesting a drug offense reduction effect of marijuana legalization. [ABSTRACT FROM AUTHOR]