Science

Marijuana legalization sees temporary rise in traffic fatalities in some US states

Marijuana legalization sees te...
A new study reveals that traffic deaths may have slightly increased after marijuana legalization, but they returned to normal levels after about a year
A new study reveals that traffic deaths may have slightly increased after marijuana legalization, but they returned to normal levels after about a year
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A new study reveals that traffic deaths may have slightly increased after marijuana legalization, but they returned to normal levels after about a year
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A new study reveals that traffic deaths may have slightly increased after marijuana legalization, but they returned to normal levels after about a year

The United States is currently in the middle of a massive wave of marijuana legalization. Despite federal law still classifying the drug as a Schedule 1 substance, 12 states and districts have passed recreational use laws, and another 14 have decriminalized possession and use. Alongside Canada and Uruguay's nation-wide legalizations, it is clear the progressive wave of acceptance is growing.

However, there are plenty of questions surrounding the broader societal consequences of legalization that have yet to be clearly answered. One of the big issues, frequently raised by anti-legalization advocates, is the association between marijuana and traffic accidents.

As more time passes, scientists are able to gather larger sets of data, and more accurately understand the impact of marijuana legalization on traffic accidents and fatalities. A new study from two Australian researchers has collected seven years of data from Colorado, Washington, and Oregon – three of the earliest US states to legalize marijuana.

The study revealed that traffic fatalities did slightly rise in the immediate months following marijuana legalization. The researchers calculated there was about one extra traffic fatality per million citizens, per month, in the states that legalized marijuana and the neighboring jurisdictions. These spill-over effects into neighboring states were most prominent in large populations closer to the border.

"The results suggest that legalizing the sale of cannabis for recreational use can lead to a temporary increase in traffic fatalities in legalizing states," says Tyler Lane, one of the authors of the study. "This spills over into neighboring jurisdictions through cross-border sales, trafficking, or cannabis tourists driving back to their state of residence while impaired. "

The most interesting revelation in the study, however, was the finding that these traffic fatality increases seem to only be temporary. The rise in fatal incidents seemed to peak a few months into legalization, and then drop back to normal after about one year. The researchers hypothesize this rise and fall is possibly related to both a celebratory response resulting in riskier behaviors, and the increased use of marijuana by more inexperienced users who are less accustomed to the impairment effected by the drug.

Of course, this study does present some significant limitations, the biggest being that it is only taking into account overall traffic fatality numbers. There is no detail or distinction in the cause of individual fatalities. So, realistically, the increase in fatality numbers may have very little to do with marijuana use, although even if every individual extra fatal accident did have an explicit relationship with marijuana use, these are still relatively small, and most importantly, temporary increases.

Another recent study trying to determine a relationship between marijuana legalization and traffic fatalities came to a similar conclusion. That study constructed what is referred to as a "synthetic control", allowing for a relatively similar control group to be created to compare to the legalized marijuana states. That research concluded, "… since legalizing marijuana, Colorado and Washington have not experienced significantly different rates of marijuana- or alcohol-related traffic fatalities relative to their synthetic controls."

Of course, traffic fatalities are just one metric by which to examine the effects of marijuana legalization on road safety. While fatalities may not notably increase, any effect on the rates of car collisions in general and physical injuries is a different story yet to be clearly studied. More studies are certain to come soon.

The new research was published in the journal Addiction.

Source: Monash University via Medical Xpress

17 comments
Brian M
Hardly surprising - anything that interferes with alertness and decision making is going to have an effect on driving and other statistics. Other than for prescribed medical use Cannabis really is a silly thing to legalise, unless of course you are trying to subdue your population.
Martin Winlow
Just 2 *hugely* important +ve results from legalizing cannabis:- 1/ The authorities immediately lose one very robust and very overused power to stop and search people unnecessarily (certainly from a UK perspective - and if you are wondering what the connection is between the US and the UK in this context, it is simply that what happens in the US usually happens over here a few years later). No longer having this power would suddenly remove a very significant cause of friction between the police and, particularly, the Afro-Caribbean community. What hope have young British Afro-Caribbeans of growing up with an open attitude towards the police when their very first (and probably many subsequent) interactions with the police is being stopped and searched on the basis of 'suspicion of possession of cannabis'? 2/ The authorities can stop wasting vast sums of money on trying to enforce anti-cannabis legislation and concentrate instead on much more serious matters, including those that claim the lives to thousands every year (unlike cannabis use).
amazed W1
Brian M, "....unless you are trying to subdue your population." This is where the renewed interest in possible Russian and Chinese influence, working through the social websites etc, comes from. As you say the influence of pot on a habituated individual probably is small, and difficult to measure unless a severe mental condition results, but the theory is that in the concealed warfare of this sort, all you need to do to win is to lessen the overall competence of the population. This idea has been misused of course, as in the view that the reasons for teaching the "New Maths" in the UK was a plot to lessen the development of logical and mathematical abilities of a typical UK child and so of adults too.
Martin Winlow
So, has there been a similar spike (and subsequent fall) in accidents around the home?
clay
Disclaimer: I am not a pot smoker but I also do not believe self-impairment nor self-harm should be criminalized; there are plenty of laws criminalizing the downstream "effects" of being impaired. 1. " fatality increases seem to only be temporary" ...to the analyst maybe.. To the person (and his or her loved ones) getting mowed down by the stoned driver this "interesting revelation" is quite permanent. 2. Pot legalization is not a "progressive wave", it is a regressive one... In fact it was quite legal in the USA until 1937 when FDR outlawed it (among many other "Progressive wave" agenda items). 3. A review of local sheriff reports tells a much darker story. Reality is not always captured effectively with these reports: In this case these reports water down the impact by spreading the fatality spikes across a broad distribution.
piperTom
The noted increase is "about one extra traffic fatality per million"! What's the normal variance in these kinds of data? What's the margin of error? And beside that, the increase is temporary. This is nothing; it's just feed for headlines. Even if the increase is real, it might just be the result of traffic from the harsh states into the more free states. On TOP of all that, compare this one per million to the offsetting count of people killed (and lives ruined) due to enforcement of this cruel war on a weed.
f8lee
Say, @Brian - ya gotta keep the peasants distracted somehow!
fb36
I, for one, think that, marijuana should be legally treated like alcohol!
jetserf
@clay Excellent points.
Nobody
If you want to dumb down the population, this is the way to do it. Children's brain development has been found to be severely impaired by marijuana but politicians don't seem to care. If you know someone who has been using this stuff since childhood, you can easily tell how dull witted they have become.