Marijuana legalisation and crime clearance rates: Testing proponent assertions in Colorado and Washington state

Abstract

The legalization of recreational cannabis in Washington state (I-502) and Colorado (A-64) created a natural experiment with ancillary unknowns. Of these unknowns, one of the more heavily debated is that of the potential effects on public health and safety. Specific to public safety, advocates of legalization expected improvements in police effectiveness through the reduction in police time and attention to cannabis offenses, thus allowing them to reallocate resources to more serious offenses. Using 2010 to 2015 Uniform Crime Reports data, the research undertakes interrupted time-series analysis on the offenses known to be cleared by arrest to create monthly counts of violent and property crime clearance rate as well as disaggregated counts by crime type. Findings suggest no negative effects of legalization on crime clearance rates. Moreover, evidence suggests some crime clearance rates have improved. Our findings suggest legalization has resulted in improvements in some clearance rates.