Video summary
The video argues that despite legalization in 24 states and the District of Columbia, academic studies claiming a surge in traffic accidents due to marijuana use are fundamentally flawed. The main subject is the debunking of research that suggests recreational marijuana laws have negatively impacted road safety. Instead of acknowledging that prohibition was a mistake, proponents of strict drug policies are accused of producing weak studies designed to manufacture small statistical harms. These studies often rely on press releases rather than full data sets, making it impossible to verify their conclusions or understand the context behind the numbers presented.
A significant portion of the critique focuses on specific misleading studies, such as one cited by the Wall Street Journal and another from the Insurance Institute for Highway Safety. The video explains that finding THC in a driver's blood does not prove they were impaired at the time of the crash, as the drug can remain detectable for days after use. Furthermore, the analysis of fatal crash rates shows that while some studies claimed an increase in deaths following legalization, re-charting the data as a time series reveals that the rate of increase actually slowed down after laws changed. The video emphasizes that correlation does not equal causation and that other factors likely influenced these trends rather than marijuana use itself.
The most explosive claim addressed is a Canadian study suggesting a 475% increase in marijuana-related emergency room visits, which the transcript describes as highly misleading due to several methodological errors. The actual number of cases was very small, representing only 0.1% of total traffic accident patients, and the reported percentage increase was artificially inflated by adjusting for pandemic lockdowns when driving habits were already abnormal. Additionally, the data set is tainted because it counted passengers who admitted to using marijuana and drivers whose impairment status was not confirmed, leading to a biased conclusion that legalization caused more accidents.
In conclusion, the video asserts that no researcher has successfully demonstrated a convincing causal link between marijuana legalization and a significant rise in traffic accidents or other social harms. The transcript highlights that various social indicators fluctuate for complex reasons unrelated to drug policy, and choosing one metric to study often leads to false conclusions about causality. Since states began legalizing marijuana, there have been no detectable negative consequences, disproving apocalyptic predictions of catastrophic outcomes. The real story is simply that society legalized the substance without the sky falling, validating the view that current fears are based on junk science rather than factual evidence.
Read the full video transcript
Now that 24 states in the District of
Columbia have legalized recreational
marijuana, several academic studies
claim there has been a spike in traffic
accidents because more people are
driving while high. What this body of
research actually shows is that
marijuana legalization has had no
measurable impact on traffic safety.
It's just the latest example of how drug
warriors, rather than admitting that
weed prohibition was a tragic error,
have produced weak studies designed to
tease out or manufacture small
statistical harms.
>> [snorts]
>> Last October, the Wall Street Journal
published an editorial titled, "More
marijuana users are crash dummies. How
much social and public health damage
will Americans suffer before doing a
U-turn on marijuana promotion?" The
editorial begins, "A new study finds
that more than 40% of drivers who died
in car accidents in one US county over
the last 6 years had elevated levels of
the drug in their blood." The new study
they cited was actually a short press
release describing [music] a conference
presentation of an unpublished report
with no supporting details. We tried
repeatedly to obtain a copy of the draft
study and to reach the lead author to
answer some basic questions, but the
press release alone is enough to
undermine the study's conclusions.
Testing the blood of autopsy drivers
doesn't mean they were high while
driving. [music] THC in the blood
generally indicates that someone has
used marijuana in the previous few days.
It's not proof of impairment at the time
of the deadly crash. The press release
also had no mention of a control, so we
have no idea if the driver's THC
positive rate is higher or lower than
for the general population. This study
truly proves nothing. It looked at one
county in Ohio covering data before and
after marijuana was legalized there in
[music] 2023, and there was no
significant change in the ratio of
drivers with THC [music] in their blood.
That didn't stop the Wall Street Journal
from claiming that high on drivers are
contributing to more highway accident
deaths. Another approach to assessing
the effects of legalization is to
examine changes in accident rates. The
most influential study that used this
method came from the Insurance Institute
for Highway Safety, which found that
legalization of recreational marijuana
in five western states was associated
with a 2.3% increase in fatal crash
rates. Here's how the authors presented
the data. The blue dots represent
seasonally adjusted monthly motor
vehicle fatalities before legalization.
The orange dots represent those after
legalization. And the dash lines show
the averages before and after
legalization. The 3-year average traffic
death rate in legalization states was
9.5% higher after legalization than
before. The pattern was the same in the
control states, but they had only a 6.5%
increase. After some complex
adjustments, the authors attributed a
2.3% increase to legalization, but
that's because the chart presented the
data in a misleading way. I recharted
the data and unlike the authors, I made
it into a time series, accounting for
changes in the rate of traffic deaths
during the study period. This way, you
can see the trends which undercut the
author's thesis. See how the blue line
is rising much faster than the orange
line. That shows the rate of increase in
traffic deaths slowed considerably after
legalization. Does that mean that
marijuana legalization meant fewer
highway deaths? No, because correlation
isn't causation, and we don't know what
caused the decline. But the study's
author's reverse claim is clearly
contradicted by the data. The most
explosive finding about the dangers of
legal weed comes from a study by a team
of Canadian researchers who looked at
emergency room records in Ontario before
and after legalization took effect in
October [music] 2018. As CNN summarized
it, the study found that documented
marijuana related traffic accidents
[music] that required treatment in an
emergency room was 475%
[music] between 2010 and 2021. Why is
the 475% claim misleading? For starters,
[music] the news coverage didn't mention
that we're talking about a very small
number of people. During the period when
marijuana was legalized and
commercialized, 120,569
people showed up in Ontario emergency
rooms due to traffic accidents. Just 125
people, or 0.1% of the total had
documented cannabis involvement,
according to the clinical judgment of
the on-site medical team. The tally of
125 people over 20 months works out to
about six people per month. Before
legalization, there were two people per
month showing up at emergency rooms with
marijuana involvement. That's a 200%
increase, not a 475% increase. [music]
Why did the authors claim a 475%
increase? Marijuana legalization
overlapped with the CO lockdowns. During
the pandemic, people were driving much
less, leading to a decline in total car
accidents. The authors wanted to adjust
for this unusual situation. So they
assumed that if people had been driving
normally, there would have been many
more marijuana related accidents. That
assumption along with a few other
adjustments led them to raise a 200%
increase to 475%.
This adjustment isn't valid. You can't
compare COVID lockdown data with
pre-COVID data because life was so
abnormal. School closures in Ontario
meant people were driving their kids to
school less often and many were working
from home or were unemployed. Since most
people who drive while high are less
likely to do so while heading to work or
taking their kids to school, you would
expect an increase in the proportion of
drivers on the road with marijuana in
their system during the lockdowns, even
if the absolute number stayed the same.
Another problem is that the 125 people
counted by the researchers weren't
necessarily high while driving. Just
because they were classified as cannabis
users in the ER doesn't mean they were
under the influence at the time of the
accident or that marijuana caused them
to crash their cars.
Some of those 125 people were passengers
rather than drivers, which makes the
inference that marijuana contributed to
the crashes even more dubious. If
someone who didn't use marijuana was
giving a ride to a friend because he was
too stoned to drive and they still got
into an accident, the passenger would
have been counted as a patient with
documented cannabis involvement. That
tells us nothing about whether marijuana
legalization led to more traffic
accidents. Another problem with the data
set is that many of the people were
counted because they admitted to the
doctor at the ER that they were
marijuana users. Patients would have
been more willing to admit their drug
habit after legalization than before,
which further biased the data. In the
end, the 475% figure is based on a small
absolute number, an invalid adjustment
that boosted the percentage increase,
and a tainted data set. Several other
studies have found small increases in
traffic deaths or no effect or
decreases. So far, no researcher has
demonstrated a convincing association,
let alone a causal link between
marijuana legalization and a significant
increase in traffic accidents in any
state. There is a long list of things
that legalization might affect. Traffic
fatalities, teenage pregnancy, suicides,
violent crime, property crime,
bankruptcies, high school graduation
rates, etc. These indicators go up and
down for reasons that typically aren't
well understood. If you chose one social
indicator to study, there's close to a
50% chance that it got worse after
legalization, creating opportunities to
use statistical techniques to make it
look as if there were a causal
relationship. Since states started
legalizing marijuana, there have been no
detectable social harm. Apocalyptic
prophecies that legal weed would have
catastrophic consequences have turned
out to be hyperbolic. The real story is
we legalized marijuana and the sky did
not fall. [music]
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>> [music]