VIC breath vs blood alcohol test

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Bea

Active Member
11 October 2019
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Hi everyone

Last week, I crashed my car into a parked car.
I am incredibly ashamed and remorseful of the whole thing and am just so glad I didn't seriously hurt someone or worse.

I've been driving since 2012 and have just 3 points in all those years from speeding. This was an embarrassing yet genuinely isolated incident.

About 45 mins after the crash I read 0.110 with the breath test. I was taken to hospital an they did a blood test there. I can't remember the exact time frame, but this would've been between 1.5h-2h after the first breath test.

I'm worried though that this one will read higher than the breath test. I had been at a dinner party which started at around 5pm and I left just after 11. I hadn't been slamming back shots or anything but I was definitely sipping on my glass of wine up until leaving. So I'm fairly sure the alcohol wouldn't have fully been in my system by the breath test. But it would've been my the blood test.

When it comes to court- my understanding is they'll use my blood test results. But I can't work out how this is fair since at the time of the crash I was lower.Can anyone explain this to me? thank you
 

Rob Legat - SBPL

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Because breath testing can be inaccurate for a range of reasons. It's what's used initially because it is easier to administer and less invasive than taking blood.

With breath testing:
- Just had a drink? It will be through the roof.
- Some medications, medical conditions and mouthwashes will make it higher.
- There are also a range of things which can make it appear lower. These are not readily publicised for obvious reasons.

The back up blood test is the one that will always be used. The initial test is referred to as well, as that is the reasoning used for having the second test done.
 

Scruff

Well-Known Member
25 July 2018
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If you're interested, the Wikipedia page for Blood Alcohol Content is pretty good reading.

The section titled "Test assumptions" explains the reason why breath tests can give vastly different results to blood tests.

From there on, the page has some interesting info on how the body actually processes alcohol, touching on some factors that can affect that process.
 

Bea

Active Member
11 October 2019
10
1
34
thanks for the responses so far :) I still am unclear though as to how it's "fair" that the reading from the bloodtest- 2 hours after the crash- is the official one used. It'll most likely be higher than my breath one, but at the time of the breath my last drink wouldn't have entered my blood stream yet so the level of drunk Iwas at the blood test surely isn't the level of drunk I was at the time of the crash ?
 

sammy01

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27 September 2015
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In ordinary circumstances you get pulled over... The initial test is a pass fail... But it has a margin for error. The hand held devices are much better than they used to be - back in the day where you blew in a bag... In ordinary circumstances you get taken back to the cop shop and put on their machine which is used in court
Drink driving
... But you were deemed to be in need of emergency care so you were taken to hospital....

So here is my problem with you.... You were in such a state that you needed medical attention. So the cops could not take you to the cop shop... What are the cops meant to do? run you past the cop shop first? NO... So they did what most of us would call common sense... Took you to hospital and sought a blood test. BTW given close to 2 hours had past, I reckon you're likely to get a slightly lower reading from the blood test.

You seem hung up on how is this fair? with respect, you drove, you caused the situation and the cops dealt with it as best they could. Fair enough?

regardless you'll be done for drink driving, if as you say you were sipping not slogging them down in the 30-40 min prior to the crash you just might find you blood alcohol will be reduced in the blood test... Regardless at the time of the crash you were .110. The circumstances around how you came to the attention of the police is your real problem... You were not randomly pulled over... NOPE you crashed and burned so when the magistrate makes his call it is gonna be based much more on that than whether or not you were .110 or .190
 

Scruff

Well-Known Member
25 July 2018
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The most simple answer is that the offence is to "drive with a prescribed content of alcohol in your blood", not on your breath. While breath tests are proven to be highly accurate, nothing can be more accurate than a blood test when it comes to actually measuring the level of something in the bloodstream.

Given that it's simply not possible to know a person's BAC level at the time of an accident (unless there happens to be a doctor waiting on the side of the road with a syringe), the law allows for tests to be taken within a set time frame. From memory, these time frames are generally 2 to 3 hours in most jurisdictions around the world. As that time passes, test results become less accurate in relation to the actual BAC level at the time the vehicle was last driven. The 2 to 3 hour limit exists to ensure that the test results are close enough for the purpose of law enforcement. So while you are correct in that the results do lose accuracy over time, there are time limits in place to ensure that test results are accurate enough to be acceptable as evidence in a court - and this methodology is pretty much standard across the globe.

For Victoria, the law requires that all breath, blood, oral and urine samples be taken within 3 hours of driving the vehicle (not 3 hours from the time they ask you to take the test). Once the 3 hours have elapsed, the Police can no longer require that you submit to the test. So from the info you've provided, both your tests were conducted within the legal time frame.

If your blood test does turn out to be significantly higher than the breath test (enough to push you into a higher penalty bracket), then you could certainly try to argue that your blood test is not a true representation of your BAC at the time of the crash, based on the fact that 2.25 to 2.75 hours had passed. But to have any chance of success, you would need to argue what your actual BAC was - and to do that, you would need to engage a toxicologist. The toxicologist would then need to provide expert testimony relating to "retrograde extrapolation", which is a scientific method for estimating a BAC level at a given point of time, based on the result of a test taken at a later point in time. There's plenty of info available on this subject that relates to the US, but I don't know if it's a common argument in Australian courts, or if it's even been tried here.

Given that your breath test result (already 45 mins after driving) was 0.11 and the next penalty bracket begins at 0.15 (which is a huge difference when talking about BAC levels), I'd be very surprised if your blood test result is anywhere near high enough to push you into that next penalty bracket.

The Wikipedia page above touches on retrograde extrapolation, but if you really want to read up on it, just Google it - plenty of US law firms have published blog articles on the subject.
 
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Bea

Active Member
11 October 2019
10
1
34
Hi Scruff thank you so much for your detailed answer.
I can't iamgine if it IS higher, it would be heaps higher as like I say I was honestly only sipping on my wine. It's not like I was at a bar smashing back shots.
Out of interest how many standard drinks would the difference from 0.11 and 0.15 be? I'm a 5ft5 27year old female weighing around 68lbs if that helps at all..
 

Scruff

Well-Known Member
25 July 2018
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68lb? That's only 30 odd kilos?
 

sammy01

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27 September 2015
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The whole standard drink thing is bunk especially with wine poured into a glass. A can of beer is 375ml so easy to measure standard...
Back to the main point though... like scruff said u had nearly 3 hours between crash and blood test. U also had some time between finishing drinking and crash. Mate I'm willing to bet you're gonna get a lower reading on the blood test. Keen to hear the result though...