Zero alcohol... Tester accuracy.

Leroy
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Joined: Thu Aug 09, 2012 11:03 am

Zero alcohol... Tester accuracy.

Postby Leroy » Mon Aug 12, 2019 4:24 pm

This is all just academic interest, no need to devote a ton of time to it...

The academic question is, where "zero alcohol" is stated in legislation, license conditions etc, how low will a (typical) handheld breath tester give a reading? for example in NSW heavy vehicle licenses and for commercial pilots the max is 0.02BAC, has anyone ever seen a BAC reading on one of these machines below 0.02? (e.g. 0.010 BAC). I'm curious what the lowest detectable limit is?

If you were to take the term "zero" at face value, we'd all be non-zero, all the time
(ref the concept of Caesar's last breath https://www.sciencefocus.com/planet-ear ... st-breath/ interesting read is you have the time. Basically states every breath has a little of everything in it.)

Not looking for a fight here, or trying to defend any case, just curious at what point the letter of the law concedes that some particular value reflects zero. Maybe any value below the device's stated accuracy for example... Or maybe any value below a 'magic' number... idk

Gravy
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Re: Zero alcohol... Tester accuracy.

Postby Gravy » Mon Aug 12, 2019 5:29 pm

I recall reading a case where someone was trying to defend themselves against a charge of having a BAC above the prescribed limit, whereby their BAC was 0.052%. The claim went something along the lines of the limit being stated as only two decimal places, so you can't take the third decimal place into account. I don't remember how it panned out, but the point is that I specifically remember the third decimal place was in issue.

It's also important to remember that the hand-held devices are not the device on which to focus; it's a evidentiary test equipment back at the station/booze bus that you have to worry about and I'm confident they can reliably calculate better than two decimal places.

Leroy wrote:curious at what point the letter of the law concedes that some particular value reflects zero.
I've read of a legal doctrine called de minimus (from de minimis non curat lex; "the law cares not for small/trifling things"). I'm not sure it is necessarily applicable in either criminal law generally or drink driving charges specifically, though as I understand it it essentially means that if a thing is of no real, practical or perceptible affect, then the court doesn't care. A BAC of 0.002% is perhaps de minimis.

Hardy
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Re: Zero alcohol... Tester accuracy.

Postby Hardy » Mon Aug 12, 2019 10:21 pm

A reading of 0.010% or more is illegal if your limit is zero.
Under 0.010% is lawful even if it is technically over zero.
The police choose not to prosecute readings under 0.020%, so effectively you are safe below that.

Leroy
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Joined: Thu Aug 09, 2012 11:03 am

Re: Zero alcohol... Tester accuracy.

Postby Leroy » Tue Aug 13, 2019 8:46 am

Thanks Both,

This was all triggered by some conversations:
A) at work where the term "zero alcohol" gets bandied around, but nobody knows what constitutes "zero"
B) at a pub upstate where a pub checked that a lemon lime and bitters was going to an adult because they're worried about selling "alcoholic" drinks to kids. They weren't kidding, they had a sign on the wall...

My research thusfar runs to 0.02BAC or lower is "considered" effectively zero for a number of factors, and beverages are considered "non-alcoholic" below 0.5%ABV


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