# Standard for pot influence **URL:** \ **Category:** Factual Questions\ **Created:** [April 28, 2012, 11:49pm UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281 "2012-04-28T23:49:03Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![etv78](https://avatars.discourse-cdn.com/v4/letter/e/d78d45/32.png) [@etv78](https://boards.straightdope.com/u/etv78)\ **Post date:** [April 28, 2012, 11:49pm UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/1 "2012-04-28T23:49:03Z")
If/when pot is decriminalized, how with impairment be measured? What kind of standard will law enforcement use? IOW, what would be the pot equivalent to BAC? ---
**Author:** ![coffeecat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/coffeecat/32/3405_2.png) [@coffeecat](https://boards.straightdope.com/u/coffeecat)\ **Post date:** [April 29, 2012, 12:11am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/2 "2012-04-29T00:11:21Z")
I don’t think stonedness is correlated with any sort of blood level. They’d probably have to directly measure impairment using some sort of driving simulator. ---
**Author:** ![etv78](https://avatars.discourse-cdn.com/v4/letter/e/d78d45/32.png) [@etv78](https://boards.straightdope.com/u/etv78)\ **Post date:** [April 29, 2012, 12:14am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/3 "2012-04-29T00:14:53Z")
How would field sobriety testing work? ---
**Author:** ![Alice\_The\_Goon](https://avatars.discourse-cdn.com/v4/letter/a/ed8c4c/32.png) [@Alice\_The\_Goon](https://boards.straightdope.com/u/Alice_The_Goon)\ **Post date:** [April 29, 2012, 12:20am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/4 "2012-04-29T00:20:05Z")
> [@etv78](#): > > How would field sobriety testing work? You could look into someone’s eyes- it’s very difficult to hide it. Pot is legal here medicinally, but illegal to drive while under the influence at all, so in that regard it would be zero tolerance, not a limit like with alcohol. ---
**Author:** ![cynyc](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cynyc](https://boards.straightdope.com/u/cynyc)\ **Post date:** [April 29, 2012, 2:46am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/5 "2012-04-29T02:46:42Z")
Read today that the Netherlands banned those weedy coffee shops due to crime. ?? And are the potheads here aware of the link between smoking the stuff and testicular cancer? Read that study on BBC news about a year ago. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [April 29, 2012, 5:48am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/6 "2012-04-29T05:48:05Z")
Huh, so a turn-your-head-and-cough sobriety field test. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [April 29, 2012, 5:58am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/7 "2012-04-29T05:58:01Z")
Offer them some Funyons. If they eat them, they’re stoned. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [April 29, 2012, 7:09am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/8 "2012-04-29T07:09:16Z")
Interesting question. Even given zero tolerance, how _do_ they test for it? Looking into the eyes isn’t remotely close to supporting a charge of driving under the influence (assuming it’s sufficient to support an arrest or further search). Is it up to the police to find/maintain a phlebotomist? Are there accepted standards for decay of levels over time (i.e. this person was under the influence within the past six hours versus someone who smoked a joint the night before and got pulled over in the morning)? ---
**Author:** ![Gagundathar](https://avatars.discourse-cdn.com/v4/letter/g/a183cd/32.png) [@Gagundathar](https://boards.straightdope.com/u/Gagundathar)\ **Post date:** [April 29, 2012, 8:22am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/9 "2012-04-29T08:22:20Z")
Well, since other drugs can be detected in the urine, I would assume that a mandatory (OK, you can always opt out but then you are declared guilty so that isn’t much of a choice) urinalysis be administered at the police office or arresting facility. Marijuana is detectable in your urine for up to 30 days depending upon your dosage. If legalized, then urine sample retention might become the standard for all late night rolling roadblocks. “I need your license, registration and a urine sample.” ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [April 29, 2012, 8:51am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/10 "2012-04-29T08:51:15Z")
I can see all sorts of problems with that. First, the key question is whether you were impaired _while driving_, not within the past 30 days. I know little of drug testing–can they detect and correlate amount of THC/metabolites detected with impairment over time? That is, can a urine sample tell beyond a reasonable doubt that someone had ingested marijuana within one hour? Five hours? Further, it’s one thing to submit a blood sample–it takes no action other than sitting there. But a urine sample? What if you just can’t go? What if you really really can’t go, especially with an angry officer standing outside the stall–or standing right behind you to make sure you don’t cheat? There are a lot of people who just can’t go under those circumstances, and it would be unconscionable to effectively criminalize shy bladders. I don’t think it’s impossible nor a new area of law enforcement. I just don’t know what the scoop is. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [April 29, 2012, 9:46am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/11 "2012-04-29T09:46:44Z")
I’ve read that a saliva test can show whether you’ve smoked cannabis in the past few hours, though I don’t know what “few” means. My understanding is that meany drunk drivers never even see a Breathalyzer. The officer pulls them over, makes them stand on one foot and recite the ABC’s backward, and if they can’t, they’re charged as driving while impaired. Combine that with a saliva test, and I would think it should be sufficient to build a case. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [April 29, 2012, 9:58am UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/12 "2012-04-29T09:58:53Z")
We’ve had some great and informative threads on field sobriety tests (which I can neither find nor accurately remember). Was failing the field test sufficient for an arrest and further search (including a blood test) or sufficient to convict at trial? ---
**Author:** ![Turble](https://avatars.discourse-cdn.com/v4/letter/t/8dc957/32.png) [@Turble](https://boards.straightdope.com/u/Turble)\ **Post date:** [April 29, 2012, 4:27pm UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/13 "2012-04-29T16:27:42Z")
Everybody so far seems to be taking it for granted that smoking pot actually does impair driving ability. I haven’t been able to find unbiased scientific support for that position. I keep finding stuff like this: “Cannabis leads to a more cautious style of driving, [but] it has a negative impact on decision time and trajectory. [However,] this in itself does not mean that drivers under the influence of cannabis represent a traffic safety risk. … Cannabis alone, particularly in low doses, has little effect on the skills involved in automobile driving.” – Canadian Senate Special Committee on Illegal Drugs. 2002. Cannabis: Summary Report: Our Position for a Canadian Public Policy. Ottawa. Chapter 8: Driving Under the Influence of Cannabis. “This report has summarized available research on cannabis and driving. … Evidence of impairment from the consumption of cannabis has been reported by studies using laboratory tests, driving simulators and on-road observation. … Both simulation and road trials generally find that driving behavior shortly after consumption of larger doses of cannabis results in (i) a more cautious driving style; (ii) increased variability in lane position (and headway); and (iii) longer decision times. Whereas these results indicate a ‘change’ from normal conditions, they do not necessarily reflect ‘impairment’ in terms of performance effectiveness since few studies report increased accident risk." – UK Department of Environment, Transport and the Regions (Road Safety Division). 2000. Cannabis and Driving: A Review of the Literature and Commentary. Crowthorne, Berks: TRL Limited. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [April 29, 2012, 4:42pm UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/14 "2012-04-29T16:42:43Z")
> [@Turble](#): > > Everybody so far seems to be taking it for granted that smoking pot actually does impair driving ability. I haven’t been able to find unbiased scientific support for that position. I keep finding stuff like this: > > “Cannabis leads to a more cautious style of driving, [but] it has a negative impact on decision time and trajectory. [However,] this in itself does not mean that drivers under the influence of cannabis represent a traffic safety risk. … Cannabis alone, particularly in low doses, has little effect on the skills involved in automobile driving.” – Canadian Senate Special Committee on Illegal Drugs. 2002. Cannabis: Summary Report: Our Position for a Canadian Public Policy. Ottawa. Chapter 8: Driving Under the Influence of Cannabis. > > “This report has summarized available research on cannabis and driving. > … Evidence of impairment from the consumption of cannabis has been reported by studies using laboratory tests, driving simulators and on-road observation. … Both simulation and road trials generally find that driving behavior shortly after consumption of larger doses of cannabis results in (i) a more cautious driving style; (ii) increased variability in lane position (and headway); and (iii) longer decision times. Whereas these results indicate a ‘change’ from normal conditions, they do not necessarily reflect ‘impairment’ in terms of performance effectiveness since few studies report increased accident risk." – UK Department of Environment, Transport and the Regions (Road Safety Division). 2000. Cannabis and Driving: A Review of the Literature and Commentary. Crowthorne, Berks: TRL Limited. On the one hand, I have a friend who has a small amount of personal experience. “He” claims that video game performance definitely goes down a notch or two after something he mysteriously referred to as “boing” hits or, and this I really don’t understand, sitting in a room with a vaporizer (why cleared sinuses would have anything to do with the marijuana is anybody’s guess). On the other hand, he also claims to be a musician of sorts, and I’ve noticed that his rhythms are definitely … enhanced (more intricate, tighter with others, creative, etc.). Though subjective, enough recordings exist of various sessions that it’s not in-the-moment inebriation that leads him to that opinion. That this level of playing requires an extraordinarily fine degree of motor control undercuts the idea that doing the marijuana impairs either focus, dexterity or … or … what was I talking about again? ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [April 29, 2012, 5:14pm UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/15 "2012-04-29T17:14:04Z")
> [@Gagundathar](#): > > (snip)Marijuana is detectable in your urine for up to 30 days depending upon your dosage. > > If legalized, then urine sample retention might become the standard for all late night rolling roadblocks. “I need your license, registration and a urine sample.” Do we really want to charge people with DUI based on a test that shows that they consumed marijuana sometime within the last thirty days? I would think something more contemporaneous would be necessary. ---
**Author:** ![Mdcastle](https://avatars.discourse-cdn.com/v4/letter/m/958977/32.png) [@Mdcastle](https://boards.straightdope.com/u/Mdcastle)\ **Post date:** [April 29, 2012, 5:29pm UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/16 "2012-04-29T17:29:34Z")
Most of the reality cop shows I watch they take a blood sample if they suspect someone is under the influence of something other than alcohol. ---
**Author:** ![Alice\_The\_Goon](https://avatars.discourse-cdn.com/v4/letter/a/ed8c4c/32.png) [@Alice\_The\_Goon](https://boards.straightdope.com/u/Alice_The_Goon)\ **Post date:** [April 29, 2012, 6:39pm UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/17 "2012-04-29T18:39:08Z")
> [@Rhythmdvl](#): > > On the one hand, I have a friend who has a small amount of personal experience. “He” claims that video game performance definitely goes down a notch or two after something he mysteriously referred to as “boing” hits or, and this I really don’t understand, sitting in a room with a vaporizer (why cleared sinuses would have anything to do with the marijuana is anybody’s guess). > > On the other hand, he also claims to be a musician of sorts, and I’ve noticed that his rhythms are definitely … enhanced (more intricate, tighter with others, creative, etc.). Though subjective, enough recordings exist of various sessions that it’s not in-the-moment inebriation that leads him to that opinion. That this level of playing requires an extraordinarily fine degree of motor control undercuts the idea that doing the marijuana impairs either focus, dexterity or … or … what was I talking about again? That kind of vaporizer is specifically for marijuana. It turns it into vapor that you suck out of a plastic bag, instead of smoke. Much easier on the lungs. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [April 29, 2012, 7:02pm UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/18 "2012-04-29T19:02:55Z")
Oh yeah! My friend says it makes a whooshing sound when you use it. 😃 (Actually, my friend has a rechargeable, portable model–bagless!) (Though he bought it to smoke flavoured tobacco) ---
**Author:** ![crowmanyclouds](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crowmanyclouds/32/19884_2.png) [@crowmanyclouds](https://boards.straightdope.com/u/crowmanyclouds)\ **Post date:** [April 29, 2012, 11:06pm UTC](https://boards.straightdope.com/t/standard-for-pot-influence/620281/19 "2012-04-29T23:06:06Z")
> [@Rhythmdvl](#): > > … urine sample? What if you just can’t go? … “Well :dubious: . . . we can always stick this here catheter in ya!” “:eek:” 😃 CMC fnord!