Michigan’s marijuana legalization law takes effect today, but some recent research raises the question of whether the new pot law will also lead to more car accidents.
Studies from the Governors Highway Safety Association (GHSA), the Insurance Institute for Highway Safety (IIHS) and Highway Loss Data Institute (HLDI) show that car crashes did increase in states that have legalized the use and sale of recreational marijuana.
It is important to point out that these studies did NOT draw any conclusions about whether a clear-cut cause and effect relationship exists between marijuana legalization and an increase in car accidents.
Impaired driving and traffic fatalities after legalization of marijuana
The GHSA study, “Traffic safety impacts of marijuana legalization,” which was published in October 2018, analyzed car crash trends after recreational marijuana was legalized in Colorado and Washington in 2012. Here’s what the study found:
- “In Washington, the proportion of suspected impaired driving cases that tested positive for THC averaged 19.1% from 2009-2012, then rose to 24.9% in 2013 . . . and to 28.0% in 2014 and 33% in preliminary data from the first four months of 2015 . . . .” [Note: The GHSA explains that THC refers to marijuana’s refers to its active component delta 9-tetrahydrocannabinol.”]
- “Marijuana-related traffic deaths increased 66% in the four-year average (2013-2016) since Colorado legalized recreational marijuana compared to the four-year average (2009-2012) prior to legalization. During the same time period, all traffic deaths increased 16%. In 2009, 9% of traffic fatalities involved drivers who tested positive for marijuana. By 2016, that number more than doubled to 21% . . . .”
Collision claims after legalization of recreational marijuana
In its study, “Recreational marijuana and collision claim frequencies,” published in April 2018, the HLDI concluded:
“[T]he legalization of retail sales [of recreational marijuana] was associated with a [combined] 6.0 percent increase in collision claim frequency” in Colorado, Washington and Oregon as compared to nearby states where marijuana remains illegal. “Collision claim frequencies in Colorado were 12.5 percent higher than in Nebraska, Utah, and Wyoming after legalization. Similarly, claim frequencies in Washington state increased by 9.7 percent compared with Idaho and Montana. Both results were statistically significant. In Oregon, the increase in collision claim frequency was not significant and less than 1 percent higher than in Idaho and Montana.”
Police-reported crashes after legalization in recreational marijuana states
The IIHS found the following in its October 2018 study, “Effect of recreational marijuana sales on police-reported crashes in Colorado, Oregon, and Washington”:
“The legalization of retail sales [of recreational marijuana] in Colorado, Washington, and Oregon was associated with a 5.2% higher rate of police-reported crashes compared with neighboring states that did not legalize retail sales.”
No firm conclusions about pot legalization being the cause of more car crashes
The GHSA noted that “[t]here are no firm conclusions on whether crash rates changed in either state” – Colorado or Washington – after they legalized recreational marijuana in 2012.
Importantly, the GHSA study noted:
- “A study comparing overall traffic fatality rates per travel mile in Colorado, Washington, and eight control states between 2009 and 2015 found that fatality rate changes in Colorado and Washington were similar to changes in the control states . . . .”
- “A study of marijuana-related traffic fatalities in Colorado, Washington, and control states between 2000 and 2016 concluded that marijuana-related fatality rates increased similarly in Colorado, Washington, and the control states . . . .”
The IIHS added:
“Although the causal link between marijuana use and crash risk remains unproven, the consistent pattern of findings in the current study and in the 2018 HLDI study suggest with reasonable certainty that crash rates in Colorado, Washington, and Oregon did indeed increase after recreational marijuana was legalized there. The extent to which these findings will generalize to other states remains to be seen.”
What must drivers know about Michigan marijuana legalization?
As I noted in my blog post, “Rules for marijuana and driving after Michigan’s new legalized marijuana law,” drivers need to know about the following in light of voters’ passage of Proposal 1, which goes into effect today, December 6, 2018:
- People over 21 can use and possess marijuana in Michigan.
- Proposal 1 “does not authorize” “[O]perating, navigating, or being in physical control of any motor vehicle . . . while under the influence of marijuana . . . .”
- Proposal 1 “does not authorize” “[C]onsuming marijuana while operating, navigating, or being in physical control of any motor vehicle . . . or smoking marijuana within the passenger area of a vehicle upon a public way.” (Proposal 1, Section 4 (1)(a) and (g)).