DRINK DRIVING OFFENCE - ADVICE ON PLOD'S ANALYSIS
Discussion
I good friend of mine was stopped the other night, breathalysed and arrested for suspected 'driving while under the influence of alcohol'... He wasn't actually drunk, which even plod conceded, but had obviously had enough (two brandy's) to just tip him over, according to the police they think he was approx 82 where the limit is 80. Whilst being processed at the cop shop, another officer (not trafpol) suggested that once they get the results back from the lab, he may well be ok, as they take off 5 points for error/adjustment which should bring him back undert the threshold; the question is, is this true?; are there any trafpol on here that can give a definitive answer?. Any advice would be appreciated as he is by trade a professional driver and is wondering if he should begin looking for a new job. Just to add that he is not a DD kind of driver; for his sins, he was celebrating Arsenal's Euro win the other night...
Sounds like he has been done for blood not breath as the limit in blood is 80 whereas the limit in breath is 35.
In my force if a blood result comes in at 81 you are charged we take no points off for any errors.
Breath is different. if you blow between 35 and 39 then no charge. If between 40 and 51 you have the option of having a blood sample taken instead of us using the breath result 52 and over is straight charge.
The blood needs to be sent of to be scientifically analysed and is usually done out of force by a company called forensic alliance and there accuracy is such that there is no adjustment for error.
If it was on blood then he would not have the result then and there, usually the result takes 1 - 2 weeks to be returned to the police officer and he would be on bail untill that time.
In my force if a blood result comes in at 81 you are charged we take no points off for any errors.
Breath is different. if you blow between 35 and 39 then no charge. If between 40 and 51 you have the option of having a blood sample taken instead of us using the breath result 52 and over is straight charge.
The blood needs to be sent of to be scientifically analysed and is usually done out of force by a company called forensic alliance and there accuracy is such that there is no adjustment for error.
If it was on blood then he would not have the result then and there, usually the result takes 1 - 2 weeks to be returned to the police officer and he would be on bail untill that time.
^Slider^ said:FWIW, that is my understanding too - most (all?) forces do not charge for a breath reading below 40, whereas with a blood test there is no leeway. Where does the "they think he was approx 82" bit come from?
Sounds like he has been done for blood not breath as the limit in blood is 80 whereas the limit in breath is 35.
In my force if a blood result comes in at 81 you are charged we take no points off for any errors.
Breath is different. if you blow between 35 and 39 then no charge. If between 40 and 51 you have the option of having a blood sample taken instead of us using the breath result 52 and over is straight charge.
The blood needs to be sent of to be scientifically analysed and is usually done out of force by a company called forensic alliance and there accuracy is such that there is no adjustment for error.
If it was on blood then he would not have the result then and there, usually the result takes 1 - 2 weeks to be returned to the police officer and he would be on bail untill that time.
police state said:
[quote=^Slider^]Sounds like he has been done for blood not breath as the limit in blood is 80 whereas the limit in breath is 35.
In my force if a blood result comes in at 81 you are charged we take no points off for any errors.
Breath is different. if you blow between 35 and 39 then no charge. If between 40 and 51 you have the option of having a blood sample taken instead of us using the breath result 52 and over is straight charge.
The blood needs to be sent of to be scientifically analysed and is usually done out of force by a company called forensic alliance and there accuracy is such that there is no adjustment for error.
If it was on blood then he would not have the result then and there, usually the result takes 1 - 2 weeks to be returned to the police officer and he would be on bail untill that time.
FWIW, that is my understanding too - most (all?) forces do not charge for a breath reading below 40, whereas with a blood test there is no leeway. Where does the "they think he was approx 82" bit come from?
Thanks for the reply Slider., out of interest, which force are you in?. He has been told he will hear from then on June 7.Out of interest, bearing in mind he is 'on the border', does the blood sample degrade or lose it's BAC level whilst sitting in the lab, awating the test?
Up the Iron; that comment came from another officer at the nick who gave his 'considered opinion' with an 'estimate' based on his 'Breath Sample'
The sample can degrade if certain conditions are not met, we have to store ours in a fridge and must be kept cool. I have seen variations in 2 samples, one was stored as per our procdures and was 85 and the suspects own sample showed 82. This was due to the suspect not storing the sample correctly.
You cannot guess based on breath what the blood result will be as the persons own metabolism of alcohol will alter any readings, but i have never had a result come under the limit on blood where the suspect has blown between 40 and 51. The lowest i have had was 81.
It would also depend on wether the person was on the way up or way down and this could only be told if we was analysed an hour or so after the initial test. He could find at the time of test his reading was on the way up and if he was tested an hour later he would have been charged. Or on the other hand on his way down and he wouldent have been going through this.
Its just a waiting game really untill the 7th.
What was his level on breath??
Im TVP btw
You cannot guess based on breath what the blood result will be as the persons own metabolism of alcohol will alter any readings, but i have never had a result come under the limit on blood where the suspect has blown between 40 and 51. The lowest i have had was 81.
It would also depend on wether the person was on the way up or way down and this could only be told if we was analysed an hour or so after the initial test. He could find at the time of test his reading was on the way up and if he was tested an hour later he would have been charged. Or on the other hand on his way down and he wouldent have been going through this.
Its just a waiting game really untill the 7th.
What was his level on breath??
Im TVP btw
^Slider^ said:
The sample can degrade if certain conditions are not met, we have to store ours in a fridge and must be kept cool. I have seen variations in 2 samples, one was stored as per our procdures and was 85 and the suspects own sample showed 82. This was due to the suspect not storing the sample correctly.
You cannot guess based on breath what the blood result will be as the persons own metabolism of alcohol will alter any readings, but i have never had a result come under the limit on blood where the suspect has blown between 40 and 51. The lowest i have had was 81.
It would also depend on wether the person was on the way up or way down and this could only be told if we was analysed an hour or so after the initial test. He could find at the time of test his reading was on the way up and if he was tested an hour later he would have been charged. Or on the other hand on his way down and he wouldent have been going through this.
Its just a waiting game really untill the 7th.
What was his level on breath??
Im TVP btw
His breath was 42 and the 2nd one failed, so they took him to the nick. He was released on bail, when he got there, they wouldn't allow him a drink of water' apparently it was the doctor who took the sample that said they will make adjustment of 5 points, he seemed to infer this is a legal requirement on their part, but having read what you have said, this doesn't appear to be the case. just another point, but they made him wait a full hour before the blood test, is this standard practise or were they expecting him to be on the way up?. It was the Met btw.
police state said:
The sample can degrade if certain conditions are not met, we have to store ours in a fridge and must be kept cool. I have seen variations in 2 samples, one was stored as per our procdures and was 85 and the suspects own sample showed 82. This was due to the suspect not storing the sample correctly.
You cannot guess based on breath what the blood result will be as the persons own metabolism of alcohol will alter any readings, but i have never had a result come under the limit on blood where the suspect has blown between 40 and 51. The lowest i have had was 81.
It would also depend on wether the person was on the way up or way down and this could only be told if we was analysed an hour or so after the initial test. He could find at the time of test his reading was on the way up and if he was tested an hour later he would have been charged. Or on the other hand on his way down and he wouldent have been going through this.
Its just a waiting game really untill the 7th.
What was his level on breath??
Im TVP btw
His breath was 42 and the 2nd one failed, so they took him to the nick. He was released on bail, when he got there, they wouldn't allow him a drink of water' apparently it was the doctor who took the sample that said they will make adjustment of 5 points, he seemed to infer this is a legal requirement on their part, but having read what you have said, this doesn't appear to be the case. just another point, but they made him wait a full hour before the blood test, is this standard practise or were they expecting him to be on the way up?. It was the Met btw.
Ok, procedure is the same regardless of what force.
He failed the roadside breath test and was taken to the nick (he has not been placed on an evidential breath test yet).
He is then required to provide 2 specimins of breath on EBM one of which he fails so he has to have blood taken.
They are not allowed to drink anything because we could be accused of spiking the drink with alcohol.
The wait was only because a doctor has to take the blood sample so youll find that it can take a while before they get to the nick hence the wait, no reason for it other that waiting for a doctor to get to custody.
As i said we dont make adjustments. There is leway in breath (hence the 35 - 39 no charge rule) but nothing in blood.
When the blood is analysed at the forensic lab, they will adjust the result by taking a few points off to cater for error. When the statement is obtained by police from the lab, no further adjustment is done.
If your friend blew 42 ug%, I expect his blood reading will be over the limit and show around 82 to 84 microgrammes of alcohol in 100 millitres of blood. That is based on my experience of dealing with these sorts of offences.
If the Doctor was some time getting to your friend (1/2 hour to an hour) between the evidential breath sample and taking of the blood sample, then he may be in with a chance as the body on average gets rid of about 7 ug% per hour. That would take your friend to possibly 39 ug% or 35 ug% in breath and approx 70 to 75 microgrammes of alcohol in blood.
A risky game he has played
!
>> Edited by mg6b on Wednesday 26th April 12:27
If your friend blew 42 ug%, I expect his blood reading will be over the limit and show around 82 to 84 microgrammes of alcohol in 100 millitres of blood. That is based on my experience of dealing with these sorts of offences.
If the Doctor was some time getting to your friend (1/2 hour to an hour) between the evidential breath sample and taking of the blood sample, then he may be in with a chance as the body on average gets rid of about 7 ug% per hour. That would take your friend to possibly 39 ug% or 35 ug% in breath and approx 70 to 75 microgrammes of alcohol in blood.
A risky game he has played
! >> Edited by mg6b on Wednesday 26th April 12:27
I've got an alcohol breath tester thingy at home that once measured, displays the level of alcohol in mgs on the screen, to two decimal places, i.e.
0.80 etc
I guess the police measuring system is calibrated differently?
i.e. if the limit is 80mg, and you are tested at the roadside using a breath system that shows 41 you are pulled in for a blood sample? where as 35-40 you are OK?
0.80 etc
I guess the police measuring system is calibrated differently?
i.e. if the limit is 80mg, and you are tested at the roadside using a breath system that shows 41 you are pulled in for a blood sample? where as 35-40 you are OK?
reanimate said:
I've got an alcohol breath tester thingy at home that once measured, displays the level of alcohol in mgs on the screen, to two decimal places, i.e.
0.80 etc
I guess the police measuring system is calibrated differently?
i.e. if the limit is 80mg, and you are tested at the roadside using a breath system that shows 41 you are pulled in for a blood sample? where as 35-40 you are OK?
Don't rely on your system. They are notoriously unreliable. They are not regularly tested or calibrated as is police testing equipment. They also measure on a completely different scale from those used by police.
80 in blood is a measurement taken by methods at a forensic laboratory by the use of centrifuge procedures.
The breath reading is that equivalent to blood but in a different scale.
Blood is milligrammes per 100 millilitres
Breath is microgrammes per 100 milliltres
>> Edited by mg6b on Wednesday 26th April 13:07
Dibble said:
You cannot guess based on breath what the blood result will be as the persons own metabolism of alcohol will alter any readings,
There is a direct, proportional correlation between breath alcohol and blood alcohol - Henry's law covers this.
I failed a breath test at the side of the road and had then took a blood test. Anyway when they released me in the morning thay performed another breath test to see if I could drive home, and I failed. But I more than passed the blood test!
densham said:
You cannot guess based on breath what the blood result will be as the persons own metabolism of alcohol will alter any readings,
There is a direct, proportional correlation between breath alcohol and blood alcohol - Henry's law covers this.
I failed a breath test at the side of the road and had then took a blood test. Anyway when they released me in the morning thay performed another breath test to see if I could drive home, and I failed. But I more than passed the blood test!
So in this case, could you be nicked on the breath test results, if the blood alchol test was under the limit???
Mr F
Mr Freefall said:
You cannot guess based on breath what the blood result will be as the persons own metabolism of alcohol will alter any readings,
There is a direct, proportional correlation between breath alcohol and blood alcohol - Henry's law covers this.
I failed a breath test at the side of the road and had then took a blood test. Anyway when they released me in the morning thay performed another breath test to see if I could drive home, and I failed. But I more than passed the blood test!
So in this case, could you be nicked on the breath test results, if the blood alchol test was under the limit???
Mr F
I too am curious. I'm going to get banned in 4 weeks time for failing a breath test when I was sober, no blood was taken. I'm very doubtful about the accuracy of these things.
mg6b said:
I've got an alcohol breath tester thingy at home that once measured, displays the level of alcohol in mgs on the screen, to two decimal places, i.e.
0.80 etc
I guess the police measuring system is calibrated differently?
i.e. if the limit is 80mg, and you are tested at the roadside using a breath system that shows 41 you are pulled in for a blood sample? where as 35-40 you are OK?
Don't rely on your system. They are notoriously unreliable. They are not regularly tested or calibrated as is police testing equipment. They also measure on a completely different scale from those used by police.
80 in blood is a measurement taken by methods at a forensic laboratory by the use of centrifuge procedures.
The breath reading is that equivalent to blood but in a different scale.
Blood is milligrammes per 100 millilitres
Breath is microgrammes per 100 milliltres
>> Edited by mg6b on Wednesday 26th April 13:07
Worry not - it was bought for information's sake, not to test if I can drive. While it was expensive (£100 or so) and should be calibrated every 6 months, I would never rely on it. I was just curious about morning after readings etc (which always have shown 0!)
The question I have is about what you mentioned:
"They also measure on a completely different scale from those used by police"
I don't understand - even if it is not that accurate, say it showed 0.43 on the screen.
How is that a different scale?
Ta.
I failed a roadside breathtest years ago (young foolish trying to be one of the lads) yet passed the breath test at the station but only just.
The 2nd reading was slightly more than the 1st. The copper was ok about it, realised that I was sh*ttin' myself and had learnt my lesson.
Just gave me some friendly advice and sent me on my way.
Had to run back to my car (2 miles!) middle of nowhere in north wales at 1am.
The 2nd reading was slightly more than the 1st. The copper was ok about it, realised that I was sh*ttin' myself and had learnt my lesson.
Just gave me some friendly advice and sent me on my way.
Had to run back to my car (2 miles!) middle of nowhere in north wales at 1am.
I have always wondered about getting a device - not for checking I can drive home, you understand, but for the next morning. Whilst I never plan to drive after a skinful the night before I've had the odd occasion where its been necessary.
If I had a device I would check myself and, if even close, just pay for a cab.
Whilst I understand Police issue devices are £400 or so and undergo regular checks (as they should) I would be interested in a "domestic" model at £100...provided it measured in the same way - just not to courtroom standards.
Where did you get your device?
If I had a device I would check myself and, if even close, just pay for a cab.
Whilst I understand Police issue devices are £400 or so and undergo regular checks (as they should) I would be interested in a "domestic" model at £100...provided it measured in the same way - just not to courtroom standards.
Where did you get your device?
It is said that'hyperventilating' used to defeat the original breath test. Does this still work on the latest machines and if not, why not?
For those who don't understand, hyperventilating is where you stand and take very deep and repeated breaths whilst the officers prepare the test, then you start to feel dizzy as your have over-oxygenated the lungs and blood vessels in the lungs which 'shut-off' any further acceptance of oxygen by the blood, and thus prevent the alcohol from getting back into the lungs.
Are the patrol officers aware of this and do they act in any way to prevent an accused from 'breathing very deeply' just before the test?
About 25 years ago I had a friend who drank 4 pints of bitter then drove off and was stopped. He used this technique and the officers said he was well under the limit and allowed him to go, suggesting that he might like to get one of his rear light bulbs replaced as it had blown.
For those who don't understand, hyperventilating is where you stand and take very deep and repeated breaths whilst the officers prepare the test, then you start to feel dizzy as your have over-oxygenated the lungs and blood vessels in the lungs which 'shut-off' any further acceptance of oxygen by the blood, and thus prevent the alcohol from getting back into the lungs.
Are the patrol officers aware of this and do they act in any way to prevent an accused from 'breathing very deeply' just before the test?
About 25 years ago I had a friend who drank 4 pints of bitter then drove off and was stopped. He used this technique and the officers said he was well under the limit and allowed him to go, suggesting that he might like to get one of his rear light bulbs replaced as it had blown.
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