You weren’t driving
In some cases, the wrong person is charged with an offence. There are a variety of ways in which this can occur. It may be that there was an administrative error on the prosecution’s behalf, or, perhaps, the offender was carrying your identification on his person. Regardless, it is a complete defence to this charge if it can be shown that you were not driving the vehicle.
You had not consumed alcohol
In order to make out the charge of driving under the influence of alcohol, it must be shown that you were incapable of exercising effective control of your vehicle as a result of consuming alcohol. If you did not consume any alcohol, then you are not guilty of this offence.
You could control the vehicle
This offence of DUI relates directly to your ability to control your vehicle. If, despite having consumed alcohol, you are able to exercise effective control of your vehicle, then you will have a defence to this charge.
Your inability to control the vehicle was not related to alcohol
It may be the case that you experienced some difficulty in exercising control of your vehicle, however alcohol was not the cause. If there is evidence to support a claim that your inability to control your vehicle was the result of something other than the effects of alcohol, then you may have a defence o this charge.
Honest and reasonable mistake of fact (Proudman vs Dayman Defence)
If you genuinely believed that you were not under the influence of alcohol, and it was reasonable for you to hold this belief (e.g. it had been served to you without your knowledge), then you may have a defence to this charge.
Breath analysis conducted more than 2 hours after driving
Section 47K of the Road Traffic Act 1961 specifies a 2 hour period, commencing from the time of any alleged offence occurring, in which a breath analysis must occur. In the event that you are tested more than 2 hours after driving your vehicle, the results of the breath analysis will be inadmissible and, therefore, unable to be used for the purpose of proving the prosecution’s case.
The breath analysis machine was defective
Given that this charge deals with the presence of specific ranges of alcohol concentrations in the blood, evidence to show that the results yielded by the Breath Analysis Machine were inaccurate will serve as a defence.
Police did not comply with their legal obligations
The Road Traffic Act 1961 and the Road Traffic (Miscellaneous) Regulations 2014 outline a number of procedural conditions in relation to breath and blood analysis with which police must comply. In the event that they fail to comply with any of these requirements (e.g. refusing your request for a blood test), you may have a defence to this charge.