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Federal Study Finds Stoned Driving Limits Need Adjusting

Matthias Ripp/Flickr


Federal Study Finds Stoned Driving Limits Need Adjusting

Stoned driving may not be as much of a detriment to public safety as originally believed, according to a new federal study published by the National Institute on Drug Abuse.

The government agency, which has been attempting to prove cannabis to be a useless drug for many years, issued a report that supports previous federal findings that suggests alcohol is more dangerous when used behind the wheel than its leafy counterpart.

Using the National Advanced Driving Simulator at the University of Iowa, researchers explored the intoxicating effects of cannabis and alcohol on 18 people who claimed to smoke marijuana no more than 12 times per month. These candidates were asked to either vaporize cannabis or consume alcohol, while others were given a placebo.

Interestingly, researchers found that it takes 13.1 nanograms of THC per milliliter of blood to make a driver act in the same sloppy manner as one registering a blood alcohol content of 0.08 percent – the legal limit across most of the nation.

It’s worth noting that 13.1 ug/L THC is over twice the 5 ug/L standard that is currently being used to declare impairment in Colorado and Washington.

Although these findings imply that more consistent cannabis users could likely have a higher concentration of THC in their system before displaying signs of intoxication, leader researcher Marilyn Huestis believes that more research needs to be done before the government is able to definitively establish that the current 5ug/L limit should be raised.

During a recent interview with Time Magazine, Huestis said that she believed the 5-nanogram restriction wasn’t a harsh enough limit for those with a lower tolerance.

Yet, according to Jacob Sullum, senior editor for Reason, the current inebriation cutoff really only prevents regular users, including medical marijuana patients, from being legally allowed to drive at all.

Researchers also discovered that when mixed with alcohol, cannabis had a more intoxicating effect, causing the 5-nanogram THC limit to cause swerving in a manner comparable to a BAC of 0.08 percent. Other aspects of operating a vehicle that are typically used to judge impairment, including lateral acceleration and lane departures, were not affected by marijuana.

Do you drive stoned? Tell us in the comments below.



  1. Kristen

    June 27, 2015 at 3:00 pm

    You don’t drive while driving? Reading through your comment was very painful. You are the reason stoners have a bad reputation. If your driving is anything like your English, you should not be on the road at all.

    • Neicee

      June 29, 2015 at 3:16 pm

      Stop hating go spark one and

  2. G

    June 27, 2015 at 8:45 am

    As a mmma patient I’m constantly using cannabis to treat my illnesses. As a result my husband does all the driving. I am a better driver when medicated because I can function when medicated. However, I am not willing to risk my license so we work to decriminalize cannabis in 2016. Some call for legalization and are willing to accept fines and a 5k fee to sell or produce but not myself and many others are on board. It is time to free the weed. It is safer to consume than nutmeg.

  3. T

    June 27, 2015 at 7:06 am

    I smoke around a half Oz a day and drive many times a day and my driving is not impaired. There should be no nanogram limit it’s fucking bullshit. Thc does not compare to alcohol or any other drug. Coming from somebody who has driven under the influence on every drug there is except meth. So I know where the fuck I’m coming from on the subject. High tolerance smokers like me the nanogram do not leave like a lower tolerance person. My 3rd owi was for being fucking SOBER hadn’t smoked for a entire day and my nanograms where still over 10. Get a grip government. Either way we are going to drive so go fuck yourself uncle Sam.

  4. Floyd

    June 26, 2015 at 11:14 pm

    Yo check it i smoke every day some times 3 to 4 times a day nd i still dive to work and back just fine who ever says u cant drive stoned probably hasn’t gotin hi and thats the reson they think it is dangerous


  5. Christina

    June 26, 2015 at 8:23 pm

    I always drive stoned. I love it its my perfert pass time. Driving,Ralexing and Singing. Its takes all the stress away.

  6. Abe

    June 26, 2015 at 5:59 pm

    Hahahah. I get high all day, driving is not a problem for me. I think it only depends on the person, man. Some people are totally screwed when high but on the other side some people care to be more responsible and productive when they’re high. My alcohol consumption is less, I have a limit of 3 bottles when drinking with friends. I don’t know, thc is just the thing for me. Haha

  7. Frankforgetaboutit

    June 26, 2015 at 3:10 pm

    My body consumes marijuana various times through the day. It keeps me at ease nd more focused. I would say that if it wasnt for those nice rides in the car with some relaxing music and a joint or two too relax my brain , there would be a hell of alot of road rage from this guy. Probably alot of speeding tickets too . marijuana is a beautiful medicine as i would say. It helps people like me get through the tough timea. Later

  8. Just a man

    June 26, 2015 at 1:44 pm

    I drive stoned. I’m more cautious when I do. When I’ve driven drunk I’ve gotten caught. Cause I’m not focused. Like running stop signs compared to stopping when your stoned and waiting for it to turn green

  9. jay

    June 26, 2015 at 12:49 pm

    Took drivers test twice first time sober failed second time blazed passed because I was more observant of my surrounding, signs etc. I been blazed since driving. I currently smoke a couple grams a day and still see no imparement and work stoned I focus and can concentrate to what I am doing

  10. Brodicus420

    June 26, 2015 at 12:34 pm

    I drive stoned every day. I have not been in a single accident, I pay more attention whilst stoned….. I’m not as talkative but my focus is good & my reflexes are pretty above average even when stoned…. Lol stoned driving is a piece of cake

  11. Kara

    June 26, 2015 at 11:41 am

    Personally, I drive much better when I am stoned. I will not get behind the wheel if I have had more than one beer, but I can smoke three or four bongs, get behind the wheel, and drive much slower, and much more observant to the other drivers on the road or any oncoming dangers. My tolerance is much higher than the average joe, due to the long-time, long-term smoking, therefore my blood limit is most likely over the legal limit for marijuana at all times.

  12. Jesse Baughey

    June 26, 2015 at 11:14 am

    I smoke and drive everyday. I’m a better driver of I do. I stay off my phone focus on the road and the worst that happens is I bump my music and sing along. Just like at my job if I smoke I work harder and for longer. So I don’t think there need to be a limit. As long as yur not stupid while doing it.

  13. Jim Thayer

    June 26, 2015 at 9:57 am

    I’m 66 and smoke daily. I drive stoned all the time. I feel the THC improves my ability to keep an eye on what is going on around me. I’m more aware.

  14. William Williamson

    June 26, 2015 at 9:23 am

    120 days after using cannabis the concentration of 50ng/ml is still in my bloodstream.. this effectively stops me from being able to drive.. this is insane.. we need a more accurate test method to determine driver impaired by THC.

    • wangerberry inc

      June 26, 2015 at 12:32 pm

      Fuck you ya lightweight.. You prolly never even smoked that burning bush

  15. Travis

    June 26, 2015 at 9:17 am

    Yes, I burn down when I drive and not one time have I had any trouble driving unlike if I have a few beers, in which I can feel after about 2-3 cans. I’m more alert, safe and can function better if I smoke than I am if I don’t.

  16. christine

    June 26, 2015 at 8:00 am

    As someone who uses Cannabis medically, under the current state law, my bcc (blood cannabis content) is probably 150 to 200 parts cannabis per liter. Yet, I do not get “high”. Between concentrates (RSO) at night before bed, and my daily regimen for pain, I would be thrown UNDER the jail cell for driving, but I wait at least an hour before getting behind the wheel in the first place. But feeling affects or not.. and I do not or I would not get behind the wheel… this law needs to be changed. And I have NEVER seen an accident personall nor heard of one where Cannabis was the cause. Couch surfing yes, car

  17. Eli

    June 26, 2015 at 6:46 am

    I’ve been driving for about 25 years and smokin at lest an 1/8 a day. Never had an accident that was my fault. Have no criminal background except for cannabis. Only ever been in 1 accident about 13 years ago but i got rear ended by a semi. So it doesn’t matter how much you smoke it simply matters on how you drive and who you are.To many people look for everything else to blame it on when in reality you yourself controls you at least when it comes to cannabis. I don’t drink much But when i do i can tell alcohol does impair driving And your actions. If you need some real help for cannabis testing….Let er rip!! I’m ready when you are. I don’t believe any of them test tell i see it with my own eyes.

  18. Patricia Cancelli

    June 26, 2015 at 6:41 am

    I should risk my license to drive while smoking? no… even if in an accident, I am shown not to be liable, I’ll still end up liable with a dUI because I’m a medical cannabis patient… arbitrary numbers at best… just another way for the govt to make some bucks and torment sick people

  19. Carl

    June 26, 2015 at 6:29 am

    Chronic smoker for health reasons and I smoke and drive, never had an accident.

    The article mentioned the use of alcohol and marijuana and how it intensified the effects of marijuana. I would like to point out that this only occurs if one consumes alcohol first and become slightly impaired, if marijuana is consumed in this state one becomes seriously impaired, do not do that ever. Now the kicker, if one smokes marijuana first then it matters not, one will become impaired from the alcohol at the normal rate.

    Marijuana is the best cold and flu medicine in the world. No other medicine will relieve all the symptoms of both these aliments.

    Do not live to smoke, smoke to live!

  20. TeeRex4020

    June 26, 2015 at 5:29 am

    um…i took my drivers license test 3 times. 1st time, I took my dad, who is a little bit like Vader if he were afro Latino and from Panama: I.e. intimidated me and made me nervous. I failed. horribly and ridiculously sober. 2nd time, I took my step mom, thinking she’d be less intimidating since she will always and forever remind me of Annie hall. call me woody Allen though, cuz I was hella nervous, very sober, and still failed. last time, 3rd time, I invited my friend, got super blazed, was hella relaxed and passed NY test with flying colors. #imjustsaying

  21. Tj

    June 26, 2015 at 5:14 am

    I am a daily smoker. 5 to 6 bowls a day and I have no trouble driving while under the influence of marijuana. It has no effect on my driving abilities what so ever. But say you don’t smoke regularly then I believe you can be dangerous behind the wheel. Marijuana effect everyone differently and I don’t see how they can set a limit for everyone

  22. Holly

    June 26, 2015 at 4:49 am

    I have been using cannabis for an entire decade. After 2yrs of use, I was able to smoke & drive just as I do without smoking. I do not get “messed up” from it, but a calm. I have severe anxiety & 2 rare physical conditions which cause me severe pain, muscle spams & much more. Cannabis stops all of that. I feel better smoking & driving, especially in high stress traffic.

  23. david

    June 26, 2015 at 3:18 am

    So I drive on a regular basis, I find it much more difficult to drive when not stoned. When I am sober my driving can be a little rough. I dont notice things and I tend to speed without paying attention to it .when stoned I notice things faster and can formulate a response to whatever situation arises. Not that everyone is the same,I would say it should simply depend on if they are breaking traffic laws or not.

  24. Michael

    June 26, 2015 at 1:18 am

    Yes about 3 to5 times a week I drive high this morning I am already high at 4 in the morning had to take my wife to work didn’t kill any one an I think I’m a much safe driver an I live in Athens georgai

  25. Richard young

    June 25, 2015 at 10:45 pm

    I my earlier years (I started smoking at 15 years old ) l drove a smoke at the same time. .I still smoke (I’m 51 years old now) but not as much and don’t drive while driving. .my tolerability is not as high as it use to be and the cannabis now is much stronger (depending on what you smoke ).so it depends on how much you smoke on how much you impaired. .im51m older and wise now , I still smoke and I don’t drive but these younger person doesn’t no when their had enough. .

  26. nate

    June 25, 2015 at 9:49 pm

    I passed my drivers test for my license high as a kite i drive too fast when im sober but when im high i just want to cruise

  27. The Sinned Angel

    June 25, 2015 at 4:04 pm

    Re”During a recent interview with Time Magazine, Huestis said that she believed the 5-nanogram restriction wasn’t a harsh enough limit for those with a lower tolerance.”…
    … well duh, that also applies with alcohol, but for that they have a one size fits all solution. Think of a kid on prom night with his first few drinks (ever) vs a construction worker having a few drinks after work.. is .08 applicable to them equally? NOT.. I’d much rather ride home with the construction worker! If they are going to advocate different tolerances, start with alcohol.. the kid on prom night should get lowered to .02 ..

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