weed - in your system for a week?

[ingenieur]

hi everybody.

I don't get involved with any sorts of recreational drugs, never even tried any (I'm probably missing out!). Personally I'm wine drinker. So this is a matter of interest... not one of personal anxiety.

I was watching one of those 'police, camera, action' type programs (I forget which one precisely) and they were saying after testing some guy with a tongue swab... when he was protesting that he hadn't had any since last night... that it can stay in your system for up to a week.

I know with the issue of drinking and driving it is possible to be over the limit in the morning after a heavy one. So if you're especially cautious you would stay away from driving for the whole of the next day just to be safe and not take any chances, especially if you have to drive for a living.

With weed then... if that information was correct, is it then a good idea to stay away from driving for quite a while if the drug can still be detected on your tongue? It seems a bit excessive but how do they decide what is okay and what isn't?

[OutInTheShed]

AIUI, trace chemicals are detectable for a long time, a week is credible.
That's not the same as being under the influence.

However, it's an illegal drug and having used it can be enough to get you fired in some circles.

[ingenieur]

Well this is mostly the question.

To get a DR10 you must 'blow' over a certain level of alcohol in breath. So how do they determine whether or not having a splif a week ago was the reason you had an accident and should be charged with drug driving?

[Silvanus]

Seen (and smelt) plenty of people driving along with a spliff in hand, they obviously don't care much. I wonder what would happen if you drove along with a can of lager in hand? It always seems to be a certain kind of car and driver as well, giving plenty of warning to stay a decent distance away.

[ingenieur]

Silvanus said:

Seen (and smelt) plenty of people driving along with a spliff in hand, they obviously don't care much. I wonder what would happen if you drove along with a can of lager in hand? It always seems to be a certain kind of car and driver as well, giving plenty of warning to stay a decent distance away.

Holding anything in your hand leaves you liable for a charge of 'due care and attention' - so there's that. If you were holding a can of lager the first instinct for a cop would be to try the breathalyser. If you were under the limit because you had not drunk much they would do you for the due care instead. i.e. doubt they'd let it go.

I think where weed used to be impossible to evidence before the tongue swap people thought they could get away with it. But after watching a few episodes of these traffic cop shows it seems they check for drugs (of all kinds) as routinely as they do for drink. I'm just wondering how many habitual weed smokers realise this is the case and what they can and can't get away with?

[MustangGT]

ingenieur said:

Well this is mostly the question.

To get a DR10 you must 'blow' over a certain level of alcohol in breath. So how do they determine whether or not having a splif a week ago was the reason you had an accident and should be charged with drug driving?

Similarly, since 2015, there has been a law around drug driving. I believe the limit for cannabis is 2mg/litre.

[ingenieur]

MustangGT said:

ingenieur said:

Well this is mostly the question.

To get a DR10 you must 'blow' over a certain level of alcohol in breath. So how do they determine whether or not having a splif a week ago was the reason you had an accident and should be charged with drug driving?

Similarly, since 2015, there has been a law around drug driving. I believe the limit for cannabis is 2mg/litre.

Do they have to do a blood test if you argue with them on the evidential value of the tongue swab?

[super7]

From watching the drug tests on these programs it would appear that as soon as you get a line shown up for a particular drug, you're arrested and taken off for a blood test.....

So even if you just have trace levels in your saliva and the test detects it, you're off for a test with a needle in your arm, which I guess ruins the rest of your day.

[Vasco]

ingenieur said:

Do they have to do a blood test if you argue with them on the evidential value of the tongue swab?

I wouldn't have thought so, the equipment will have been tested and proved to be accurate - much like the breathalyser for alchohol where the formal breath test back at the police station is an accepted piece of kit. They only do blood tests if you refuse to provide a specimem.

[megaphone]

ingenieur said:

Well this is mostly the question.

To get a DR10 you must 'blow' over a certain level of alcohol in breath. So how do they determine whether or not having a splif a week ago was the reason you had an accident and should be charged with drug driving?

It's more or less the same. They do a roadside swab test, if you fail they take you back to the station and do a blood test. if the result is over the limit you get prosecuted.

[MikeGTi]

ingenieur said:

Do they have to do a blood test if you argue with them on the evidential value of the tongue swab?

AIUI the tongue swab is only indicative, as the handheld breathalyser is for drink driving, so a blood or urine sample is required for evidential purposes.

[megaphone]

The answer is, if you want to smoke weed, give up driving.

[ingenieur]

megaphone said:

The answer is, if you want to smoke weed, give up driving.

Well this seems to be the message... but it's such a popular drug... there must be millions of people out there rolling about in such a way they could be clobbered for it.

[megaphone]

ingenieur said:

megaphone said:

The answer is, if you want to smoke weed, give up driving.

Well this seems to be the message... but it's such a popular drug... there must be millions of people out there rolling about in such a way they could be clobbered for it.

Yes, all taking a risk when they drive. Only other option is to get the law changed. There are also lots of people driving around over the alcohol limit.

You can buy the tests, so I suppose that's an option before you drive. Same as you can buy alcohol breath tests to see if you're under the limit.

Edited by megaphone on Thursday 22 September 10:42

[sospan]

Alcohol stays in your system for several hours. There is a mathematical model used for estimating previous consumption. It is an AVERAGE as people have different metabolism rates to ingest and clear it from your system.
Do you trust your metabolism to clear it quickly? To quote Harry Callaghan....Do you feel lucky, punk?”
I am guessing a similar thing exists for drugs. Sports people are known to stop using in advance of possible testing ( random testing can make this risky !).
I think your hair can pick up traces as well so long hair can reveal a quite long history.

[sospan]

Alcohol stays in your system for several hours. There is a mathematical model used for estimating previous consumption. It is an AVERAGE as people have different metabolism rates to ingest and clear it from your system.
Do you trust your metabolism to clear it quickly? To quote Harry Callaghan....Do you feel lucky, punk?”
I am guessing a similar thing exists for drugs. Sports people are known to stop using in advance of possible testing ( random testing can make this risky !).
I think your hair can pick up traces as well so long hair can reveal a quite long history.

[Paul Dishman]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC35705...

Interesting article on cannabis and it’s metabolism. Looks like you’d need to be a few days cannabis free for it to be metabolised to a level safe enough to be legal

[ingenieur]

Paul Dishman said:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC35705...

Interesting article on cannabis and it’s metabolism. Looks like you’d need to be a few days cannabis free for it to be metabolised to a level safe enough to be legal

"Cannabis has a long half-life in humans (67 days). In chronic cannabis users, it is particularly difficult to determine whether a positive result for cannabis represents a new episode of drug use or continued excretion of residual drug"

So if this is true it must be really difficult to decide whether or not you can prosecute someone... or is it simple?

[MikeGTi]

I doubt the law is concerned with whether the drug use is recent or chronic, it'll be concerned with the level of whatever it is that they measure and whether it's over the limit set.

[megaphone]

ingenieur said:

Paul Dishman said:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC35705...

Interesting article on cannabis and it’s metabolism. Looks like you’d need to be a few days cannabis free for it to be metabolised to a level safe enough to be legal

"Cannabis has a long half-life in humans (67 days). In chronic cannabis users, it is particularly difficult to determine whether a positive result for cannabis represents a new episode of drug use or continued excretion of residual drug"

So if this is true it must be really difficult to decide whether or not you can prosecute someone... or is it simple?

It is simple. If you drive whilst over the prescribed limit for drugs or alcohol then you can be prosecuted. Doesn't matter when you took the drug or drank the drink.

If you are asking if an accident can be attributed to being unfit to drive through drugs taken days ago, well it all depends on the circumstances, same with alcohol. If you lose control and have an accident, likely yes.

As I posted above, if you smoke weed, you should give up driving. Or get the law changed.