
Stoned drivers are safer than drunk ones, new federal data show - pkaeding
https://www.washingtonpost.com/news/wonk/wp/2015/02/09/stoned-drivers-are-a-lot-safer-than-drunk-ones-new-federal-data-show/
======
JPKab
As a full supporter of cannabis legalization, I'm also a big supporter of a
technology that can instantly detect whether someone's reflexes are impaired
by cannabis.

Notice that I'm focusing on whether or not they are impaired, as opposed to
the amount in their bloodstream. The point being that people that use cannabis
regularly for medical reasons don't seem to be impaired by it at all, while
newer or more occasional users are certainly impaired.

It would be fascinating to see what kind of technologies could be used to
achieve this that folks on HN are aware of.

~~~
Broken_Hippo
Right now, there is none. Obviously the measurable amount isn't reliable - but
that has been known to general users for years. And so much of it is personal
- a person going out on the weekend and smoking a lot (much like drinking most
weekends or occasionally) is going to be really impaired. A regular smoker,
who keeps a slight buzz and gets used to it would have very little effect most
times. People around them don't have a clue.

I honestly think the best solution would be to regulate the current traffic
laws better - including things such as speed limits, yeilding to pedestrians,
keeping distance ahead of you (don't know if that is a law) and other things.
Not only is this going to help catch people too impaired to be driving, but
folks that are simply not paying attention to the road and trying to multi-
task while driving.

~~~
bnegreve
> Right now, there is none. ... a person going out on the weekend and smoking
> a lot (much like drinking most weekends or occasionally) is going to be
> really impaired.

I think the article is pretty misleading but the conclusion is clear: " _There
's plenty of evidence showing that marijuana use impairs key driving skills.
If you get really stoned and then get behind the wheel, you're asking for
trouble._".

The problem is that the legal thresholds for THC are so low that "stone
drivers" are not actually stone, making the whole federal study flawed.

Here: " _Several states have passed laws attempting to define "marijuana-
impaired driving" similarly to drunk driving. Colorado, for instance, sets a
blood THC threshold of 5 nanograms per milliliter. But that number tells us
next to nothing about whether a person is impaired or fit to drive. _"

If you look at the data, "any illegal drug" is also not correlated with more
accidents.

~~~
gnaritas
> but the conclusion is clear: "There's plenty of evidence showing that
> marijuana use impairs key driving skills. If you get really stoned and then
> get behind the wheel, you're asking for trouble.".

While the conclusion is clear, it's also misleading. No one disputes that you
can get too stoned to drive, that isn't the issue that matters. What matters
is whether those too stoned to drive drive anyway like they do on alcohol.
Anecdotally from decades of experience I can say they don't, pot doesn't
destroy your ability to judge your state of mind so there's no reason to treat
it with special exceptions like we do for alcohol. Most long term smokers
drive while high, but not while impaired. High != impaired just as drinking
one beer doesn't destroy your ability to drive safely.

------
kdamken
Do not read this and think it's okay to drive high. It's not. Do not drive
high. Call an uber or something.

I worry that people read studies like this and suddenly justify going out and
driving while impaired. Driving is an incredibly dangerous activity on its
own. Doing it when you're stoned is a stupid and risky move, and comparing it
to how much more dangerous drunk driving is doesn't make it less stupid.

If you've never smoked pot, you don't understand how it feels and affects your
thinking/reactions/perception of time and reality. If you smoke pot everyday,
it may affect you less due to tolerance, but it's still affecting you, much
like a functional alcoholic.

I have nothing against usage and I strongly encourage legalization, but I
don't think it's okay to pretend that it's safe to get high and go driving.

~~~
dubcanada
It's also not safe to drive while tired, on any medication at all (including
over the counter drugs), while texting, while on the phone, while not looking
at the road, with glasses (they could fall off and you'd be blind), with a
heart condition, etc etc.

I think it's safe to assume you drive very often with things that affect your
driving. If pot is proven to not affect your driving to a measurable degree,
then the only thing that is different between that and random over the counter
medication is one is called pot.

~~~
scarecrowbob
I don't really mess with cannabis any more, but I think that a lot of folks
have strange ideas about how it affects people.

If my only experience with the drug were the first couple of times in college
where we were taking bong hits, then yeah, I can see why people would be
shocked that you could drive in that state. It took a me a couple of years
before I discovered that most of the folks (especially the folks in their 50s
- 60s I hang out with) really are just getting a little bit at a time.

It's possible (and I think for many long-term users, more normal) to have only
enough to modify your mood and outlook on events without becoming glued-to-
the-couch high.

Pro tip: there is also a difference between having a beer with dinner and
chugging vodka shots all night long. :D

~~~
georgemcbay
"Pro tip: there is also a difference between having a beer with dinner and
chugging vodka shots all night long. :D"

True, which points to the fact that it would be useful to have a well-
understood BAC-like scale for marijuana usage, especially as the drug becomes
more and more legal to use.

Clearly there's a difference between having one beer and driving an hour later
compared to getting behind the wheel while nearly passed-out drunk. Lots of
people have a decent approximate sense of what 0.08 BAC is when it comes to
alcohol consumption, but everyone who is "high" is just "high" without some
sort of well-defined scale.

~~~
oxide
tolerance comes into account, which is why comparing driving on marijuana and
driving on alcohol is akin to comparing apples and oranges.

they're entirely, exponentially, infinitely different.

~~~
pklausler
As a mathematician, I'm going to have to go ahead and disagree with you on
"exponentially" and "infinitely" there.

~~~
oxide
it's hyperbole, not science. fair enough, though.

------
beat
Alcohol has two synergetic problems for drivers... it reduces reflexes and
increases confidence, simultaneously. Less capable, and more aggressive. No
wonder it's so awful for drivers.

Marijuana doesn't significantly impair reflexes (as generations of musicians
have shown). As for judgment, it tends to make users more cautious, not more
aggressive. They're not trying to get around that car in front of them to blow
through the used-to-be-yellow light - they're trying to make sure they
remember where they're going...

~~~
mankyd
> Marijuana doesn't significantly impair reflexes (as generations of musicians
> have shown).

As an aside, is music really reliant on reflexes like this? I would assume
that the beat of a song gives one plenty of forewarning as to when a melody
might change.

And that assumes that the rhythm of a melody doesn't put you in am altered,
hypnotic state in other ways.

~~~
beat
The original association of marijuana and music is in jazz, and playing while
stoned is still as much norm as exception among jazz musicians. Jazz is a form
of structured improvisation. The raw music actually isn't that complex. What's
complex is trying to make a new statement with that music on the fly, while
simultaneously listening closely to other musicians in the band, who are
making their own statements. Done right, it feels like two (or more) minds
thinking as one.

So yes, in addition to the physical reflexes needed to play difficult
instruments gracefully, there's a lot of in-the-moment reflex in responding to
the music and your fellow musicians.

~~~
sampo
> while simultaneously listening closely to other musicians in the band, who
> are making their own statements

Ostensibly, yes. In practice, usually only one person at a time is playing a
solo over a predetermined and repeating chord progression.

~~~
beat
Oh, no. That's not jazz at all! The soloist isn't the only person improvising.
The rest of the band is supporting the soloist _by improvising_. The chords
themselves aren't simple, static devices. There is plenty of room for
expression and communication. A soloist needs to be on their toes, ready for
the drummer to just rework the groove for laughs. A bass player needs to catch
on to some rhythmic motif the soloist is using, and be ready to drive them
home when the soloist does.

Even within totally composed music, a lot of attention is required to keep
timing in sync. Performing live music in a group setting requires a great deal
of attention to what's going on outside your own mind.

------
oarsinsync
> "At the current time, specific drug concentration levels cannot be reliably
> equated with a specific degree of driver impairment"

Massively leading title given the statement actually issued, and their own
remarks later on:

> There's plenty of evidence showing that marijuana use impairs key driving
> skills[0]. If you get really stoned and then get behind the wheel, you're
> asking for trouble.

[0][http://www.ncbi.nlm.nih.gov/pubmed/23220273](http://www.ncbi.nlm.nih.gov/pubmed/23220273)

~~~
MadManE
But if they told the truth, they wouldn't get upvoted to the front page.

------
iconjack
From the comments here, it seems like people either didn't read the article,
or just don't believe the study, because it pretty much says it is ok to smoke
and drive.

    
    
      For marijuana, and for a number of other legal and illegal
      drugs including antidepressants, painkillers, stimulants
      and the like, there is no statistically significant change
      in the risk of a crash associated with using that drug
      prior to driving.

~~~
notahacker
From your comment, you clearly read neither the article nor the study. I mean,
the article states "There's plenty of evidence showing that marijuana use
impairs key driving skills. If you get really stoned and then get behind the
wheel, you're asking for trouble" and the study itself cites plenty of other
studies which have found strong positive associations between marijuana use
and driving impairments.

What it _actually_ shows is that for one particular study the increase in
crashes resulting from users testing positive for marijuana (i.e. have used up
to a week ago) becomes statistically insignificant when controlling for user
demographics. It also threw up anomalies like a [statistically insignificant]
_improvement_ in drivers under the influence of smaller amounts of alcohol
over no alcohol or drugs, so I wouldn't exactly herald it as definitive.

To argue that they "pretty much says it is ok to smoke and drive" is a
grotesque distortion of the actual research.

~~~
mcbits
So, we have "impairs key driving skills" versus "no statistically significant
change in the risk of a crash". It sounds a bit like _in vitro_ vs. _in vivo_
results. At the end of the day, I'm more concerned about risk factors that
actually lead to accidents on the roads.

Why doesn't "key driving skill" impairment from marijuana appear to increase
the risk of a crash? My best guess is that stoned drivers are concerned about
being pulled over and are able to compensate more than 1) someone impaired but
not aware/concerned enough to compensate (e.g. tired or distracted drivers) or
2) someone worried about getting pulled over but unable to compensate as well
for their impairment (e.g. drunk drivers).

~~~
notahacker
I suspect drivers under the influence being cautious is _a_ factor.

I suspect _majority of drivers testing positive for cannabis were not actually
remotely close to being stoned at the time they were driving_ plays a huge
role too (possibly also overzealous demographic controls). That's consistent
with the study authors' observations that other studies based on accidents
which rely on self-reported cannabis use show it to have a large effect on
accident rates, and studies which rely on testing to show it has little or no
discernible impact on accident rates. They consider the studies relying on
testing to be superior in construction. Based on the well-established fact
that cannabis use tends to show up in standard tests days after its main
effects have worn off, I beg to differ.

------
mywittyname
I can't argue with this data, but I have to wonder how much
tolerance/individuality plays a role in this. I know that I personally could
not drive high on THC, my propensity to zone out would almost certainly result
in an accident, but I (used to) have friends who drove regularly during and
after partaking and I was completely confident in their abilities.

Personally, I think prohibitionists/law enforcement is looking for an easy
money-grab and are hunting for justification of their desires rather than
responding to an actual harmful issue that society is facing.

~~~
lukeschlather
The headline is simply a lie. The study basically showed that you cannot
measure whether someone is stoned by testing their blood for THC. The blood
test only proves they were stoned at some point in the past few weeks.

The study did not show that it's safe to drive while stoned, and if you read
the entire article they're fairly clear about that.

~~~
mywittyname
> The study did not show that it's safe to drive while stoned, and if you read
> the entire article they're fairly clear about that.

Which is exactly what I can't argue with. My point was in reference to the
conclusion of the article, which states,

> So, should we all assume that we're safe to blaze one and go for a joyride
> whenever the whimsy strikes us? Absolutely not. There's plenty of evidence
> showing that marijuana use impairs key driving skills. If you get really
> stoned and then get behind the wheel, you're asking for trouble.

We apparently cannot map concentrations of THC to driver impairment. Which
agrees with my anecdotal experience in the matter, that the effects THC vary
greatly with individuals.

------
hristov
This means nothing. The big difference between alcohol and other drugs is that
there is a relatively straightforward correlation between the amount of
alcohol in the bloodstream and the current effect of alcohol on the brain.

Somebody testing positive for marijuana may not be stoned at all. It could be
they were stoned last week and tested positive.

Furthermore, alcohol testing is much easier and is the only type of testing
really done by police in the field. Police will try to get you to admit being
impaired by other drugs if they stop you, but they do not have anything like
the breathalyzer to test for other drugs.

Current data comparing driving impairment of various drugs and alcohol is
almost entirely an artifact of the difference in testing methods.

~~~
vasilipupkin
Yes, the only thing anyone should take away from this data is, we currently do
not have reliable data on impairment vs intoxication on THC. Need controlled
studies to collect it

------
Symmetry
I remember an article on this in New Scientist back in the 90s that went into
a lot more depth. A study showed that while alcohol impaired multiple aspects
of driving skill marijuana mostly impaired just time judgement. And stoned
drivers tended to overestimate their level of impairment and slow down while
drunk drivers tended to underestimate how impaired they were. They actually
found that drivers who were moderately drunk and stoned were less likely to
crash than drivers who were just moderately drunk because they slowed down
even though they were more impaired.

~~~
webXL
Right, there's more involved than just the impairment itself. I was just about
to ask if this had something to with stoned drivers driving more carefully
just to avoid harsher penalties for possession. Data from states where pot is
legal would be interesting.

~~~
Symmetry
In this case the subjects were given substances in a lab and then used a
driving simulator.

------
dimino
I'm going to upgrade my view of this article to linkbait title. The title
should be, "THC found to not correlate with impairment in the same way that
blood alcohol concentration does".

From the article:

> The study's findings underscore an important point: that the measurable
> presence of THC (marijuana's primary active ingredient) in a person's system
> doesn't correlate with impairment in the same way that blood alcohol
> concentration does.

The story here is that there is no "THC impairment" test like there is a blood
alcohol test, not that driving while stoned is safer.

------
curiousgeorgio
You can distort the data all you want, or in this case, put it in an absurd
context to try and prove a point, but the fact remains - the legalization of
marijuana is _not_ without negative consequences.

I'm surprised no one here has mentioned AAA's findings (legalization followed
by a 2x increase in fatal marijuana-related crashes):
[http://newsroom.aaa.com/2016/05/fatal-road-crashes-
involving...](http://newsroom.aaa.com/2016/05/fatal-road-crashes-involving-
marijuana-double-state-legalizes-drug/)

EDIT: Link to the study [PDF]: [http://publicaffairsresources.aaa.biz/wp-
content/uploads/201...](http://publicaffairsresources.aaa.biz/wp-
content/uploads/2016/04/Prevalence-of-Marijuana-Involvement-Report-FINAL.pdf)

~~~
rudolf0
Driving while high should definitely be banned, but it kind of seems like
they're making a big assumption here.

>The percentage of drivers involved in fatal crashes who recently used
marijuana more than doubled from eight to 17 percent between 2013 and 2014.

How are they ruling out the fact that since it's been legalized, more people
in general are using marijuana?

~~~
curiousgeorgio
> How are they ruling out the fact that since it's been legalized, more people
> in general are using marijuana?

That's exactly the point. No one is trying to say that driving high has gotten
more dangerous as a result of legalization - just that it's _inherently_
dangerous (and a certain percentage of marijuana users are going to be driving
either way), so legalization only contributes to more usage, leading to more
irresponsible decisions on the road.

~~~
rudolf0
My point is: They're getting this data by doing drug tests of drivers in fatal
car crashes after the crash has occurred. Previously, 8% of those drivers had
cannabis detected. Now, 17% have it detected.

What evidence is there that the increased cannabis use is _causing_ these
crashes, considering you have to control for the fact that more people in
general are using cannabis, so in almost _any_ population (drivers in fatal
car crashes; fast food employees; school teachers; whatever) you could expect
to see an increase in use.

~~~
curiousgeorgio
Ah, I understand what you're saying now. Still, I think it'd be a stretch to
assume that none of those fatalities were actually related to the marijuana
use. But I agree, it doesn't necessarily imply causation, just a correlation
(which as you say, could in part be coincidental).

~~~
deelowe
It's a fine assumption. We could also assume that marijuana use discourages
use while under the influence due to increased paranoia. Neither have been
demonstrated yet.

All we know from this is that there was a increased detection of thc for
people involved in fatal accidents. The reason for this seems obvious to me
and I assume it correlates with general increased use among the population. I
still conject that "fatal" accidents are used here to push a particular
narrative. I don't see any significance in "fatal" versus cumulative accidents
or DUI arrests.

If the intent is to prove that there is an increased hazard on the road due to
marijuana use, then they need to prove that it's use significantly increases
this hazard AND that the rate of drivers under influence has increased. Those
are two separate and independent studies.

I'm still waiting to see those studies.

------
binarymax
I'm on vacation in Colorado right now, and you can point out the stoned
drivers. They tend to drive slow and passive, they fear the merge, and spend
lots of time stopped at stop signs making sure they really are stopped and not
going to crash. The impression I have is that their judgement and reactions
are definitely impaired, but in a stark contrast to the invincibility and
carelessness of alcohol induced drivers.

~~~
hfourm
You noticed this just on vacation eh?

As a CO resident, maybe you just haven't noticed how shitty our drivers are ;)

~~~
sosborn
> As a CO resident, maybe you just haven't noticed how shitty our drivers are
> ;)

I've lived in many places, including Colorado, and let me tell you – drivers
are shitty everywhere :)

------
vlunkr
That chart has sections for both "Any Legal Drug" and "Any Illegal Drug", and
both bars are barely visible. Are they claiming that all drugs, legal or not,
don't affect driving?? Because that would be an incredibly stupid claim.

------
breatheoften
Are there any ways to directly measure impairment rather than using chemical
trace detection as a proxy for the affect?

Maybe a driver could take a short impairment test on their cellphone or in car
computer prior to starting their drive -- if they pass the test then they
would have an argument against impairement should they become subsequently
involved in an accident... If they fail the test and drive anyway then there's
an even stronger argument that they made an irresponsible decision for which
they must take responsibility.

------
samsonradu
I was watching a documentary the other day about life in a Delhi prison and I
was thinking to myself if there's the slightest possibility for me to ever end
up in prison for one reason or another, considering of course that I don't
have the slightest intention of committing a felony. Then I realized that a
driving mistake has the best odds of causing such a thing. It's crazy how many
don't take such a high-responsibility task seriously, texting, drinking,
smoking while driving.

------
green_lunch
It's studies like this that have caused people in my city to support legally
driving while high. I've seen so many people that somehow think there is no
effect on driving skills.

I'm all for legalization, but I will not support the potential of endangering
other people.

------
skuunk1
The title seems misleading. People with marijuana in their bloodstream !=
stoned drivers. Marijuana use is detectable for a long time past the point of
impairment and the data only reflects that they HAVE used marijuana vs being
stoned at the point of driving.

Maybe instead of breathalysers and drug detection kits we should have
standardised attention/reaction tests to determine if someone is safe to drive
(you could probably even run them on a tablet). This would also weed out (pun
intended) tired drivers.

------
zymhan
This is from February of 2015. Nothing about this data is new anymore.

------
brickmort
> Stoned drivers are _less dangerous_ than drunk ones

------
slipperyp
KIRO TV in Seattle did a small test of impairment on a closed course with
participants using varying amounts of marijuana a few years ago around the
time Washington voters were choosing to legalize pot and found similar
results:

[http://www.kiro7.com/news/stoned-drivers-hit-test-
course/139...](http://www.kiro7.com/news/stoned-drivers-hit-test-
course/139144424)

------
jacquesm
The only valid comparison is with a driver that is sober.

------
_dark_matter_
I wonder if, as public perception changes on the issue, stoned drivers will be
in even less accidents as their own perception changes - i.e. "I'm high on
cannabis, but that doesn't impair driving, so my own driving isn't impaired",
and thus they drive better. Compared to before, "I'm high, high drivers are
bad drivers, so my own driving is impaired".

~~~
MaxfordAndSons
I can't imagine that's how cognition and an activity like driving interact.
It's not like negative reinforcement in a social setting (getting demoted at
work and as a result getting discouraged and becoming a worse performer, for
example) - most people realize driving is an inherently dangerous activity,
and most people don't want to die (even if they're doing moderately risky
things like driving stoned), so they're not going to have an emotional
reaction like "Welp! Guess I'm just fated to drive like shit since I'm stoned
right now, hope I make it home, but first lets do some donuts." No, they're
going to overcompensate and drive more safely.

If anything, I'd be concerned the opposite effect would occur - data
suggesting that driving stoned is safe will cause stoned drivers to lower
their guard and not compensate for their impairment as much, and thus raise
stoned driving accident rates.

------
exodust
"Safer than drunk" is a poor choice or words, irresponsible even.

If you drive within an hour or two or three of smoking sticky buds, the risk
is not reflexes or reaction time, it's getting distracted by your own
thoughts, or zoning out. That can easily translate into driving through a red
light. The mind wanders when stoned, which is the opposite of what you want
when operating machinery.

------
bunkydoo
I'm a bit curious if the "any illegal drug" column includes LSD or
hallucinogens. Part of me thinks most people have the common sense not to
drive while on such a substance, part of me thinks there would be no way to
gather data

------
musgrove
I think a lot of people could have told them that. Including, most likely,
some of the researchers themselves as well as a few presidents, especially our
current one, and most Kennedys.

------
WelcomeToHeaven
Was federal data really needed to determine stoned drivers are safer than
drunk ones? I thought it would be known that drunk driving is more dangerous
than stoned driving.

------
RichardCA
Carl Sagan had some things to say about this topic.

[http://marijuana-uses.com/mr-x/](http://marijuana-uses.com/mr-x/)

------
mjhm2539
"Neighbor beats his wife less often than other neighbor, new federal data
shows"

------
chipotle2
Maybe they get in fewer accidents because they are driving like 8 miles per
hour.

------
cphoover
Confirming what everyone already knew.

Also... Driving impaired in anyway is a big mistake.

------
return0
Both should only be allowed to drive self-driving cars.

------
kalehrishi
They must be smoking good stuff when they decided to publish this article :D

------
elcapitan
On the other hand, studies have shown that red wine is good for the heart and
chocolate as well. So the best of all worlds is to get stoned, drink a lot of
red wine and then drive while eating chocolate. Why is there no study yet
showing that?

------
riggins
But what about their propensity to drive really slow?

~~~
JoeAltmaier
Slowing down is the single most effective thing to reduce traffic accidents
and injury. Not good for efficiency or smooth flow, sure. But can't claim its
not safer.

~~~
bryanlarsen
Slowing down is not safer because it significantly reduces the number of
traffic accidents.

Slowing down is safer because it significantly reduces the severity of the
traffic accidents that do happen.

~~~
JoeAltmaier
Both; as shown by the statistics (I posted below).

------
draw_down
If anything is true about how this country acts with cannabis, it's that facts
and data are pretty much 100% ignored.

------
ck2
I've had two friends killed by drunk drivers in two different decades and I
have to run on the side of the road

If you are on anything, legal or illegal that influences you, I hope you get a
nice long prison sentence for driving impaired.

If you see someone step out of a bar or whatnot that is either drunk or high
and goes to drive, please call the police and possibly save someone's life -
you don't have to call 911, call the anonymous number for your city.

