Researchers have established a link between marijuana legalization and increase in traffic crashes and resultant deaths. According to researchers, states that legalized recreational marijuana saw a subsequent increase in traffic crashes and fatalities.
The study published in the Journal of Studies on Alcohol and Drugs points out that there is a cost of marijuana legalization and that cost is human lives. States wherein marijuana has been legalized for recreational use saw a 5.8% increase in the rate of traffic crash injuries and a 4.1% increase in fatal crash rates after legalization and the onset of retail sales. The researchers found no increase at the same time in a comparison group of states that did not legalize the drug.
Overall, the initial jump in the injury crash rate occurred after legalization but before retail sales began. Traffic crash injuries rose 6.5% after legalization but decreased slightly (-0.7%) after retail sales commenced. However, fatal crash rates increased both after legalization (+2.3%) and after retail sales were authorized (+1.8%).
The sharper relationship between marijuana legalization and traffic crash injuries, rather than fatalities, may be due to how some drivers compensate when impaired by marijuana. Often, drivers under the influence of marijuana slow down and maintain a larger distance between themselves and other vehicles. Impaired but at lower speeds, drivers may not be able to avoid a crash, but the crashes that occur may be less likely to be deadly.
According to the authors, earlier studies involving driving simulators have shown marijuana use to affect reaction time, road tracking, lane keeping and attention. However the current study is correlational, and increased marijuana use itself is likely not the sole cause of the increases seen.