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The Cannabis Effect on Crime: Time-Series Analysis of Crime in Colorado and Washington State

NCJ Number
Justice Quarterly Volume: Online First Dated: October 2019
Date Published
September 2019
31 pages
This article reports on a study that used a quasi-experimental, multi-group interrupted time-series design to determine whether, and how, UCR crime rates in Colorado and Washington, the first two states to legalize marijuana, were influenced by it.
Previous studies based on relatively weak analytical designs lacking contextualization and appropriate comparisons have reported that the legalization of marijuana has either increased or decreased crime. The current study recognizes the importance for public policymaking of more robust research designs in this area during a period of continuing reform of state marijuana laws. Study results suggest that marijuana legalization and sales have had minimal to no effect on major crimes in Colorado or Washington. There were no statistically significant long-term effects of recreational cannabis laws or the initiation of retail sales on violent or property crime rates in these states. (Publisher abstract modified)

Date Published: September 1, 2019