Clarity Law

Specialist Traffic Law Firm Queensland
Sunday, 17 December 2023 17:01

Drinking after driving but before a breath test

Written by

Drink Driving offences are offences of strict liability - effectively, if a person was suspected of driving/being in charge of or attempting to put a vehicle into motion and that person had a BAC greater than their allowed limit (See our full article on Drink Driving). Then that person is guilty of a Drink Driving offence. The Police have 3 hours from the time the defendant was suspected of driving to give them a breath or blood test.

There is, rarely a scenario which occurs where a person comes to the attention of police, they return home and consume a considerable amount of alcohol. This might looks something like this:

Cara is driving along Discovery Drive in Helensvale and clips a light post and continues home. A witness calls the police, giving a description of the vehicle and licence plate. Cara arrives home, nerves are shot and she drinks ¾ of a bottle of wine in an hour before the police arrive. Cara tells the police that she had not consumed any alcohol before she drove and that she had drunk wine after the fact.

When this occurs, there is a possibility that a defendant could raise what is called a “Dorfler Argument” which arises from the case of Davies v Dorfler; Ex parte Davies [1988] 2 Qd R 490 (this case was further followed by Leach v Commissioner of Police [2009] QDC 66.  In other words what happens if you drink after driving but before the police breath test you.


How can the defence be raised?

The defence can be raised if it can be proven that a defendant had consumed liquor after their driving and/or the prosecution cannot prove that the defendant had been under the influence of liquor at the time of driving.

It is important to note that this is not as simple as stating that you had not consumed liquor before driving and then you returned home and had a drink.

It is going to rely on a number of factors, including whether there was any visible evidence of alcohol consumption at home, your Blood Alcohol Reading measured against amount of alcohol drank and how much time has passed.

For example:

Cara has clipped the light post on Discovery Drive at 6:00pm and travelled straight home, arriving at 6:05pm. She pours herself a glass of wine and drinks it. She repeats this until ¾ of the bottle has been consumed over 1 hour. The police arrive and administer a breath test which has a positive indication for alcohol. Cara is then taken to the Coomera Police Station where on a subsequent breath test she has a BAC of .134%. 

In this example, it may be possible to raise the Dorfler Argument as a valid defence. 0.134% when measured against alcohol drank, time elapsed and other variables, it may be calculated what her BAC would have been at the time of the accident and would not have had a reading that gives rise to an offence.

If however, Cara’s reading came back as .200%, then there is some indication that Cara may have been intoxicated at the time of driving, which would negative the defence.


How would it work?

The existence of the defence does not guarantee it’s success. The prosecution will often rely on any witnesses who could provide any testimony as to a defendant’s indicia, meaning did they display signs of being intoxicated. The police can also seek a Forensic Countback be conducted. A forensic countback is a report generated by  an appropriately qualified person, such as a scientist, forensic medical officer or toxicologist.

The report will calculate the estimated BAC at the time of the commission of the offence. The report is much more detailed calculation of estimated BAC and takes into account the following:

  1. Age;

  2. Height;

  3. Weight;

  4. Gender;

  5. Amount and type of alcohol consumed;

  6. The period of time which you allege you consumed alcohol; and

  7. Your ultimate reading.

The report, while not 100% accurate, will usually be convincing in the eyes of the court. That is to say, if the report is not favourable it will remove the Dorfler Argument as an available defence. It may however, support the case theory that you put forward.

The Forensic Countback may return that a person had a prescribed concentration of alcohol in their blood, however it may determine that the estimated reading at the time of the offence was within a lower threshold. This might look like a .200%BAC at time of reading, being closer to .140%BAC at the time of driving. This has the effect of lowering mandatory penalties and potentially opening up options for an application for a restricted licence.


Do I have to take the defence to trial?

While the defence will ultimately be tested at Trial, a skilled practitioner will likely enter the case conferencing process to either seek to have the prosecution withdraw the charge or if possible, lower the reading to a lower offence threshold.

Case Conferencing the matter, as it relies on negotiating with police prior to any forensic report being prepared will also necessarily factor in a believability element. Effectively, did the defendant tell police that they had drank after getting home, whether there is any visible evidence of that fact etc etc.


Peter was driving home after work where he had consumed a light beer at approximately 5:45pm. During travel he side swipes a Tesla car, gets out and inspects the damage. He ultimately leaves the scene and continues a few minutes until he arrives home at 6:05pm. There was a witness to the incident and the police were called, and arrive at Peters house at 8:00pm. Peter had a stressful day and was now panicking about having hit a car. Peter got home and started drinking ready to drink bourbon, he drank 8 cans until the police arrived at 8:00pm. Peter admitted to driving and hitting the other car and told police he’d had one drink at 5:45pm and got home at 6:05pm when he started drinking.

Police observed numerous cans of bourbon and they take him to the station for a breath test. His ultimate test returned a reading over in excess of .177%.  Peter’s lawyer was able to negotiate with police, based on what they had witnessed, the time that had elapsed and simple calculations based off known rates of elimination to demonstrate that at the time of driving, he was likely not over a BAC of .05%.


Why doesn’t everyone do this?

The simple answer is that this is a very uncommon and difficult defence to raise. The overwhelming majority of drink driving charges arise from a police intercept or after someone has immediately gotten home.  Defences to a drink driving charge are on the whole quite rare in Queensland.

The defence will rely on the right circumstances and may required favourable calculations from any forensic countback that may be conducted.



This article is not and should not be taken as a complete explanation or legal advice regarding a forensic countback or a defence to drink driving. This article serves to give an overview on a misunderstood and uncommon defence to a very common charge.

If you are in a circumstance where you were consumed alcohol after you stopped driving and were subsequently breath tested, this is information you should bring up with your lawyer who can advise on all the facts, if there is an available defence.


How do I get more information or engage you to act for me? 

If you want to engage us or just need further information or advice then you can either;

  1. Use our contact form and we will contact you by email or phone at a time that suits you

  2. Call us on 1300 952 255 seven days a week, 7am to 7pm

  3. Click here to select a time for us to have a free 15 minute telephone conference with you

  4. Email This email address is being protected from spambots. You need JavaScript enabled to view it.

  5. Send us a message on Facebook Messenger

  6. Click the help button to the right and leave us a message


We are a no pressure law firm, we are happy to provide information to assist you, if you want to engage us then great, if not then you at least have more information about drink driving.

You won’t be chased or hounded to engage us.  Remember its critical you get advice before going to court, a drink driving charge no matter the reading will have an impact on you, your family and your employment or business.  


Need more information?

We have a range of articles on drink driving on our traffic law blog.  Some of the most recent have included:

Jack Marshall

Jack is a former soldier and now a traffic lawyer with Clarity Law.  Jack appears in courts throughout South East Queensland.

https://www.drivinglaw.com.au/about-us/our-team/281-jack-marshall.html | This email address is being protected from spambots. You need JavaScript enabled to view it.