Behind the Wheel - Detecting Marijuana Impairment
 

I recently overheard a conversation between young people where they discussed the daily use of marihuana - on their way to and from school and in their cars. They said it did not affect their ability to drive and that it went undetected by parents, teachers, employers and the police. Could you please discuss what methods are available, if they are being utilized to identify drivers under the influence of marihuana and how effective it is.

I did not receive Drug Recognition Expert (DRE) training during my traffic enforcement service, but I was able to work alongside others who had been trained and learned enough to be confident of my decisions when I issued 24 hour prohibitions for the use of marihuana.

A driver under the influence of marihuana is more difficult to detect than most other illegal drugs, but it does produce the following symptoms: blood shot eyes, accelerated heart rate (tachycardia), muscle tremors and forgetfulness. Marihuana impairments include: difficulties with judgement, depth perception and the ability to maintain attention. All of these skills are necessary for the safe operation of a motor vehicle.

How effective are Drug Recognition Experts? A driver may be convicted of driving while impaired by a drug based on driving or care and control evidence and the impairment evidence given at trial by the DRE. Recent amendments to the Criminal Code have significantly expanded the use of the DRE by making it a requirement for a suspected impaired driver to submit to an exam rather than voluntarily participate.

Reference Links

I am astonished to hear that you feel that just because you worked beside someone who has received training that you felt you were trained as well. I hope all officers do not follow this method!! How can you possibly feel that just because you work with someone who received training to be on par??

Secondly the impairments you listed sound like you watched a little too much reefer madness. I would love to see how the VPD or RCMP came up with these results. I wonder if a doctor was ever considered, or real world testing. I do agree that no one should be driving while stoned, but there have been many test done out of the UK that show marijuanan imparment is the least hazardous compared to alcohol and lack of sleep.

Do you have testing for people high on prescription drugs? Opiates and all that other garbage that the pharm companies issue?

Skid and I are SFST trained and part of that training is to detect drugs. We can detect impairment but to decide what it is that is causing the ipmairment, take a DRE. The DRE course is long, highly demanding and requiures frequent recertification. It is recognized, like the SFST, by the courts in Canada and the US. The SFST is a week long and requires several exams and repeated practical tests with real impaired subjects. It ain't just theory. The theory is based on tested, sound medical observations by medical professionals. Who cares if it is prescription downers or uppers or crack, symptoms of impairment are just that.

I can tell you have been drinking and are impaired by alcohol...but I can't tell if it was beer or scotch. Based on experience I can offer an opinion on your level of impairment but it takes a Datamaster reading to say what it is officially. The DRE can offer a trained, expert opinion, accepted and recognized by the legal system. It's good enough for them, if it isn't good enough for you.

free booze? sign me up to be a test dummy .. :D

Hey Zulutango,

Cool good to know. I know testing for marijuana is extremely hard. Since it stays in your system for 2-6 months it is almost impossible to tell if you smoked 5 min ago, or 2 months ago. Its not like with booze where you can blow into a tube and get a blood alcohold reading. All the reports I have read out of the UK and Europe where marijuana is more openly accepted are the total opposite of what the US and CAD Police organizations are claiming. I am not condoing smoking weed and driving, but I am curious to see where these results came from. Most reports state that against common knowledge or hearsay marijuana is not an imparing drug. I am sure you didn't toke up and drive, I should think that more indepth testing should be done. Especially now with marijuana closer than ever to become legalized.

http://www.duiblog.com/2009/04/23/do...iving-ability/

I remember a car mag back a couple of decades ago ( with grass THC about 2%) doing a closed track test with a drunk and a stoner. They gave them a demanding skill course and monitored their driving, looking at things like lap times, the # of cones etc hit. The results were that both drivers got impaired. Their lap times and cone count went up. The biggest differences on the effect of the ipmairment was that the drunks knew they were impaired and tried to avoid the cones and do better. The stoners didn't admit their impairment and things went bad because they just didn't care that they were messing up. Ever seen anyone stoned? My experience has been that, that is excatly how they react...car or no car. The big caveat these days is that 15-20+% TCH is available often and that would give you 7 to 10 times the level of impairment potential.

If you are of the belief that having a few "reefers" is not a problem, would you feel the same way if you knew the Brain Surgeon about to operate on you, or Pilot about to do a high risk landing in your plane had indulged to your "safe level"...and really mean that?

The roadside check you get is not to see if you have any 2 month old "sidestream" smoke in your blood...it's to see if you are "impaired" by drug or alcohol. So far, it's not like a Lance Armstrong post-Tour De France test. I think if you look at real, unbiased, independant medical testing, you will find that it is an impairing drug that causes harm in areas other than driving ability as well. The website you linked to could hardly be considered "unbiased" in any sense of the word. The

Hey Zulutango,

With that being said, how can you tell me that fellow officers are not unbiased in their teachings and courses. Marijuana has been proven over and over again to not be as bad as it has been assumed to be. Some studies actually show that it increases awareness. I never condoned stoned driving.

To knock that site as being biased, I can easily say that your teachings are extremely biased. See you tell me that THC is higher, but do you really know what gets you stoned when you smoke? Do you know what other things come into effect? THC is not the only determining factor. Some weed makes you sleepy and hungry, while others can give you a more head high.

Alcohol is legal, however it is still illegal to drink and drive.

The Police are not "biased" in their tecahings and courses...the medical information in the traini ng is valid and accepted by the highest courts of law in both countries. I'm not the only one who would accept that, over anectodal circumstances being experienced and reported by persons, who by definition, are consuming medically and legally-defined harmful and impairing substances. Ask the medical experts, THEY say that THC is the substance that causes the impairment and "gets you stoned when you smoke". Go back & look at that site & its links and then truthfully tell me that there is no bias? Re-read your own post to see how you contradict yourself. Your quarrel is not with me, it's with the medical and legal opinions that say you are wrong.

WTF IS THIS driving high on weed is not illegal it doesnt efect anythin i do it all the time and i actualy drive safer belive it or not

If you can't tell the difference between someone who is currently blitzed out of their skull... and someone who smoked it two months ago (?????), then you need some vision correction ;)


I was out walking the dog yesterday afternoon. I spotted a guy smoking a big fat joint (all by himself) in the parking lot of the park... then he got into his truck and drove off. So I called 911 to report an impaired driver.

On my way to work, about half an hour later, I saw the same truck being towed away about a kilometer down the road. Guess they got him!

Stupid pothead, no driving for you.

Just like having a few drinks or a ton of drinks you register a blood alcohol level, with marijuana there is no way to tell how stoned someone is. Where did I condone driving stoned? You counter my statement with a totally different argument. There is no way to legaly prove that you were stoned at that time. They have to prove he was stoned at the time he was driving. If he tests positive, there is no way to tell if that was 5 min ago, or 2 months ago. Unless they found weed on him, or he was caught in the act its not going to stick. Cops have to prove he was stoned at the time. Thats why when they test for your blood alcohol level, it proves you were drunk at this time.

Follow me? Or do you need some vision correction.

Wow, major reading fail.

See what happens when you smoke too much reefer, kids?

well they actually could. they can use sweat tests. you'll need a min of 15mg of THC to show a positive. The test is effective for up to 1wk. ie. if you smoked within the past week, it'll catch it. if you smoked 2wks ago..it will show negative.

And if they REALLY ....like i mean REALLY REALLY REALLY wanted to trust me when i say they'll find an expensive way to show beyond ANY doubt you were impaired while driving.

But now the question becomes, knowing that there are methods to find out, would you be willing to consent to them?

But none of this is even important. You might get a ticket, big deal. a hundred bucks or soemthing. I dont know.

What happens if you get in an accident and cause a big mess. ICBC will easily throw in the impaired argument and you're no longer covered as you broke the contract. Now you're on the line for it.

See what happens when cop thinks he is qualified because his buddy passed a course? What don't you understand?

Just because you work along someone long enough does not qualify you for a course. They wouldn't have the course available and have something called an exam, inorder to say that you are infact "DRE" certified.

I don't understand where he claimed he was "trained" or "qualified". He said he was confident in his own judgment based on his experience... that's not the same thing, nor does he claim it to be.

Isn't paranoia another sign of drug abuse? Cuz you seem to have plenty to go around...

Pretty sure anyone in their right mind would be able to smell it, but I forget sometimes that I'm arguing with people on here who don't use their minds...

Vision works too... look at the bloodshot eyes. I can recall many a road check where I was asked if I'd been "smoking the wacky tobacco" because of my bloodshot eyes.. (I wear contacts... they dry out.. gives me bloodshot eyes... so..)

Are you seriously this stupid? Next time you're cruising around looking for a grocery store to buy pizza pops, you might just run over someone at a cross walk.

Oh, and don't smoke before posting. Your spelling is dropping my IQ.

My concern is that there is an existing prejudice for police officers to assume impairment. How many officers have detected or assumed marijuana usage, and consequently charged or threaten to charge the person with impaired driving without actually checking to see if they were significantly impaired? I'd bet willing to be a few have done so. All you have to do is report that the vehicle and driver smelled of marijuana and that the driver had blodshot eyes, and maybe in your opinion, they seemed forgetful and sluggish, and BAM, that's pretty much enough for an impairment charge. Even if it doesn't stand up in court, it'll still show up on the CPIC screen for 5 years!!

BAC testers have made life a bit easier for cops as it gives them a black & white way to test for "legally impaired" drunk drivers. However in reality impairment is not a YES or NO answer. It's a shade of grey, and you can still be charged with impaired driving even if your BAC is well within the limit! (and that's actually a good thing folks, because some people can be totally wasted while still within the legal BAC for driving)

The same goes for weed, however, on the other end of the spectrum, I might smell like weed and have bloodshot eyes, and be tired, and suddenly I can be accused of being impaired, when in fact, I am absolutely NOT impaired. That's not right and currently it's leaves a bit too much liberty for the police in that case. There should be some sort of BWC (breath weed content, lol) tester!

You're all forgetting that being "impaired" doesn't require substance use or abuse of any kind. Someone who's falling asleep at the wheel is also legally impaired. Yes, the BAC machine makes it a lot easier to prove beyond just the officer's judgement... doesn't mean their ability to tell if someone shouldn't be on the road is completely invalid either. And no, it doesn't REQUIRE special training, either.

The problem is that establishing a "breath weed content" is that it sets a precedent that using marijuana would be "legal" to a certain degree.

y would i tell a cop how to catch me driving stoned?

Could you please elaborate on why being able to tell what kind of drug the user has taken requires such an intensive course, when all you need to know is if the user is drugged or not?

i tried it once and from that day on i have NEVER driven stoned, it effected my ability to judge distance and it caused me to run a red light.

Did I say anything about being on par? I said that I learned enough to be confident to issue a 24 hour prohibition based on what the DRE taught me. There is no way I would consider myself anywhere near qualified to be a DRE.

They didn't come up with these. Scientific experts in the field did. Did you do any research yourself, or is this just a knee jerk response to the column?

That is part of DRE training, but the question that prompted the column only asked about marihuana.