# Question about marijuana testing after an auto accident. **URL:** \ **Category:** Factual Questions\ **Created:** [June 7, 2006, 9:37pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808 "2006-06-07T21:37:11Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Don\_Logan](https://avatars.discourse-cdn.com/v4/letter/d/f07891/32.png) [@Don\_Logan](https://boards.straightdope.com/u/Don_Logan)\ **Post date:** [June 7, 2006, 9:37pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/1 "2006-06-07T21:37:11Z")
Let’s say there is a guy who drives a bus for a living. This guy, (I’ll call him Don) enjoys unwinding after a long day of bus driving by smoking the evil weed. Don never ever partakes before going to work, only partaking right after work, and finishes at least 12 hours before he starts his shift. Let’s say Don has an accident which causes him to be tested for drugs. Is the test they preform going to differentitate between Don having drugs \*in his system \* and being \*under the \* _influence,_ or does it just shows drugs in system, must have been high, etc. Case 2, let’s say Don smokes the evil weed once a month or so. Say he gets high June 7. On June 30 he has a wreck and is tested for pot, and the pot from June 7 is still in his system. Again, will the test administrator distinguish between “old” pot in the system, and pot fresh enough to have possibly played a role in the accident? ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [June 7, 2006, 9:49pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/2 "2006-06-07T21:49:44Z")
About the only thing I’ve ever seen a drug test be able to differentiate was the _level_ of the drug, not whether it was new or old. If regulations allow something other than zero tolerance, it’s up to the appropriate judge to determine whether the amount of the drug in the system contributed to the accident. ---
**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:** [June 7, 2006, 11:35pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/3 "2006-06-07T23:35:21Z")
I’ve done some drug testing, and usually the way it works is to set the bar pretty high for the initial screening, because it’s a quick and dirty test done cheaply. The detection limit of these tests might be 50 ug/ml THC metabolites in urine. GC/MS testing might lower the limit to 5 or 10 ug/ml or so. If they really want to get right down to the limit, hair testing and GC/MS might show marijuana use months after the fact. Each improvement in technique adds to the cost, so they might just use the quick and dirty dipstick for random testing, but if an accident occurred they could get pretty rigorous. ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [June 8, 2006, 2:11am UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/4 "2006-06-08T02:11:17Z")
Was Don required to take a drug test in order to qualify for the job of being a bus driver? Was a statement signed at the time of initial employment giving Don’s permission to submit to drug testing? These will sometimes state the employers drug policy and Don’s agreement to abide by them during his term of employment or be dismissed. If so, any level of pot in system after an accident would most likely be grounds for Don’s dismissal, even if they can’t prove it caused the accident. Point is, Don would be guilty of violating his employment agreement not causing an accident per say. Sucks to be Don, is he a close friend of yours? ---
**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:** [June 8, 2006, 2:14am UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/5 "2006-06-08T02:14:47Z")
In my post above, I meant ng/ml, not ug/ml. Sorry for the mistake. If you’ve got ug/ml levels of THC metabolites in your urine you’re having way too much fun. ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [June 8, 2006, 2:53am UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/6 "2006-06-08T02:53:24Z")
From what I’ve observed in NTSB reports, it is possible to determine from the level of THC metabolites in urea the last time within a reasonable window plus or minus, that the cannabis was used. Bottom line is that a bus driver needs a CDL, and the FMCSA regulations consider THC to be a prohibited substance and it’s use on or off duty is prohibited. CDL holders may be tested pre-employment; reasonable suspicion; post-accident; random; return-to-duty; and follow-up. Visit [www.fmcsa.dot.gov](http://www.fmcsa.dot.gov) for more information. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [June 8, 2006, 4:41am UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/7 "2006-06-08T04:41:03Z")
Welcome to the Dope Don. Now about your post. If your buddy “Don” has evidence of THC in his system after an accident particulary an injury accident, the shit will truely hit the fan. Doesn’t matter that it has been 12 hrs. people will be calling for your err make that “Don’s” head. My suggestion to “Don” would be to either stop smoking, or find a job where they would have more of a sense of humor about it. Driving a bus with evidence of THC in your system is an invation for an royal ass kicking. ---
**Author:** ![A.R.Cane](https://avatars.discourse-cdn.com/v4/letter/a/ee7513/32.png) [@A.R.Cane](https://boards.straightdope.com/u/A.R.Cane)\ **Post date:** [June 8, 2006, 5:06am UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/8 "2006-06-08T05:06:18Z")
To address the two questions: I have very little doubt that THC would be present after 12 hours. I’m not sure if it would be detectable after 3 weeks, but it’s a very real possibility. I think that you’re alluding to two different issues as far as the accident is concerned and it’s probably up to a jury to decide if the pot contributed to the accident, if he chooses to go the “not guilty” route If “Don” drives a bus carrying 16 or more people, then he’s required to have a CDL, class “C” license. The presence of illegal an drug in his system is grounds for revocation of the CDL, no matter how long ago he imbibed. Rick hit it on the head. Don needs to choose between smoking pot and holding down a job that forbids the use of illegal substances. It may be possible for “Don” to ask for help w/ the substance abuse problem and save his job, I’d guess that the circumstances of the accident would, in large part, dictate the success of that possibility. This is not a moral judgement, just a practical one. ---
**Author:** ![outlierrn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/outlierrn/32/3005_2.png) [@outlierrn](https://boards.straightdope.com/u/outlierrn)\ **Post date:** [June 8, 2006, 5:12am UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/9 "2006-06-08T05:12:59Z")
Since marijuana use is essentially illegal, and there’s no industry to pay taxes or bribes, there’s no motivation to determine an impaired vs unimpaired state. In our ER, there’s alcohol levels, and everything else is +/- ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [June 8, 2006, 7:37am UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/10 "2006-06-08T07:37:18Z")
There is no marijuana test that can attest to the level of intoxication at the time of the test. It is looking for the **metabolite** of the drug, the byproduct your liver spits out after helping to get you straight again. If alcohol tests worked like that, you could get falling-down-puking drunk on Saturday, and by Wedensday you’d still test drunk. ---
**Author:** ![Alex\_Dubinsky](https://avatars.discourse-cdn.com/v4/letter/a/dbc845/32.png) [@Alex\_Dubinsky](https://boards.straightdope.com/u/Alex_Dubinsky)\ **Post date:** [June 8, 2006, 9:10am UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/11 "2006-06-08T09:10:41Z")
Regarding Case 2 (your alibi?). After having smoked once, THC should be detectable for three to five days. Maybe a week. Yeah, I dunno. I’m wondering, was the urine that you gave after the accident saved? Could a more detailed analysis be conducted after the fact? There might be some specific short-term metabolite you could look for. AskNott makes an excellent point, in that the metabolites being detected may be such that a normal test may hardly be affected at all by smoking once in the past few hours if you’ve been smoking every day for a week. Only a test for short-term metabolites, or better yet THC itself, may reveal such information. Also, where do you live? Do the juries there think of weed as some insanity-inducing menace, or do they understand it for what it is? That’ll determine how much they’ll care whether or not you were intoxicated. ---
**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:** [June 8, 2006, 12:22pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/12 "2006-06-08T12:22:56Z")
> [@Rick](#): > > Welcome to the Dope Don. It sounds like Don’s been a doper for some time already. ---
**Author:** ![Kalhoun](https://avatars.discourse-cdn.com/v4/letter/k/3bc359/32.png) [@Kalhoun](https://boards.straightdope.com/u/Kalhoun)\ **Post date:** [June 8, 2006, 12:40pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/13 "2006-06-08T12:40:11Z")
> [@Alex\_Dubinsky](#): > > Regarding Case 2 (your alibi?). After having smoked once, THC should be detectable for three to five days. Maybe a week. > > Yeah, I dunno. I’m wondering, was the urine that you gave after the accident saved? Could a more detailed analysis be conducted after the fact? There might be some specific short-term metabolite you could look for. > > AskNott makes an excellent point, in that the metabolites being detected may be such that a normal test may hardly be affected at all by smoking once in the past few hours if you’ve been smoking every day for a week. Only a test for short-term metabolites, or better yet THC itself, may reveal such information. > > Also, where do you live? Do the juries there think of weed as some insanity-inducing menace, or do they understand it for what it is? That’ll determine how much they’ll care whether or not you were intoxicated. I just looked this up last night because I have a friend who is anticipating a drug test any day now. She was a regular pot smoker, and has cut down considerably over the last month. However, the site I checked said that smoking pot 2-4 times per month will take 11-18 days to clear out of your system. I think a single usage smoker takes 5-8 days to leave your body. Problem is, they don’t say how much pot you need to smoke in order to qualify for a “use.” She smoked a joint of good pot with a friend, so my guess is she’ll test dirty. Re: the bus driver gig…I’m guessing they have a zero tolerance policy due to the nature of the business. I’d say offhand that the word “fucked” will be introduced to the conversation shortly. Good luck to your friend. ---
**Author:** ![Don\_Logan](https://avatars.discourse-cdn.com/v4/letter/d/f07891/32.png) [@Don\_Logan](https://boards.straightdope.com/u/Don_Logan)\ **Post date:** [June 8, 2006, 1:18pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/14 "2006-06-08T13:18:07Z")
Thanks all for the responses. The accident was truly hypothetical- it hasn’t happened yet. This is just something I have always thought about, being a pothead and all, I have a Kafkaesque fear of being a wreck, whether at work or in my car, and be tested and found to be “under the influence” when not actually under the influence. As a follow-up (\*\*Bill Door \*\* touched on this earlier), are there “severity rules” following an accident to determine if someone gets tested for drugs? Obviously if you are acting impaired even after a fender bender you will get tested, but how “severe” does an accident have to be for a person who is acting and looking completely normal to be tested? ---
**Author:** ![Clothahump](https://avatars.discourse-cdn.com/v4/letter/c/51bf81/32.png) [@Clothahump](https://boards.straightdope.com/u/Clothahump)\ **Post date:** [June 8, 2006, 1:42pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/15 "2006-06-08T13:42:51Z")
> [@Don Logan](#): > > Obviously if you are acting impaired even after a fender bender you will get tested, but how “severe” does an accident have to be for a person who is acting and looking completely normal to be tested? All it takes is suspicion on the part of the investigating officer. Strong, friendly suggestion: get off the drugs, period. That way, you don’t need to be worrying about it and you won’t be endangering the lives of your passengers. ---
**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:** [June 8, 2006, 1:44pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/16 "2006-06-08T13:44:54Z")
> [@Don Logan](#): > > Thanks all for the responses. The accident was truly hypothetical- it hasn’t happened yet. This is just something I have always thought about, being a pothead and all, I have a Kafkaesque fear of being a wreck, whether at work or in my car, and be tested and found to be “under the influence” when not actually under the influence. That’s just how pot works, unfortunately. The question is whether you’re in a job that will test you in case of a mishap. If I recall correctly, if you’re a transport operator they do test you after any accident. There’s no way to determine whether you’re high at the time of the accident or were high earlier, so they don’t try to do so. I think this is entirely appropriate… if you’re a dishwasher or envelope-licker, go smoke your brains out, I don’t care. If you’re driving a bus, just stay off the weed. I’ve been a pothead in the past and I know that even though the buzz wears off in a few hours, the stupid lingers for days or more. ---
**Author:** ![Ensign\_Edison](https://avatars.discourse-cdn.com/v4/letter/e/7ab992/32.png) [@Ensign\_Edison](https://boards.straightdope.com/u/Ensign_Edison)\ **Post date:** [June 8, 2006, 2:08pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/17 "2006-06-08T14:08:38Z")
> [@Clothahump](#): > > All it takes is suspicion on the part of the investigating officer. > > Strong, friendly suggestion: get off the drugs, period. That way, you don’t need to be worrying about it and you won’t be endangering the lives of your passengers. Cite for how marijuana last smoked 12 hours prior to driving is a danger? ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [June 8, 2006, 2:26pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/18 "2006-06-08T14:26:53Z")
> [@Ensign Edison](#): > > Cite for how marijuana last smoked 12 hours prior to driving is a danger? Our OP’s “freind Don”. He’s a _bus driver_, where if he has to do the old “pee in a bottle” thing he’ll lose his job, \*and worse- \* but _yet he’s still puffing_. Thereby the “stupid” from Pot use must carry over! 😛 ---
**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:** [June 8, 2006, 2:46pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/19 "2006-06-08T14:46:38Z")
> [@Ensign Edison](#): > > Cite for how marijuana last smoked 12 hours prior to driving is a danger? According to [NIDA](http://www.drugabuse.gov/MarijBroch/parentpg11-12N.html) , > [@](#): > > Q: How does marijuana affect driving? > A: Marijuana affects many skills required for safe driving: alertness, concentration, coordination, and reaction time. These effects can last up to 24 hours after smoking marijuana. Marijuana use can make it difficult to judge distances and react to signals and sounds on the road. ---
**Author:** ![Ensign\_Edison](https://avatars.discourse-cdn.com/v4/letter/e/7ab992/32.png) [@Ensign\_Edison](https://boards.straightdope.com/u/Ensign_Edison)\ **Post date:** [June 8, 2006, 3:04pm UTC](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808/20 "2006-06-08T15:04:23Z")
> [@Brain Wreck](#): > > According to [NIDA](http://www.drugabuse.gov/MarijBroch/parentpg11-12N.html) , :dubious: Your own source also says: > [@](#): > > When marijuana is smoked, its effects begin immediately after the drug enters the brain and last from 1 to 3 hours. If marijuana is consumed in food or drink, the short-term effects begin more slowly, usually in 1/2 to 1 hour, and last longer, for as long as 4 hours. Is there any cite anywhere for a person getting in a car accident due to being un-coordinated or learning impaired 12+ hours after smoking marijuana? [Next page](https://boards.straightdope.com/t/question-about-marijuana-testing-after-an-auto-accident/359808.md?page=2)