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If you’ve been charged with a drink driving or drug driving offence, such as Exceed .05 or Drive Under the Influence (also called “DUI”) the consequences can be serious. As well as fines, you may face potential driving disqualifications and other penalties that can cause you expense, inconvenience and other hardships.

If you have been charged (or think you might be charged) with an offence of this kind, you may find yourself in a situation where you are considering pleading “not guilty” and defending the charge.

While it can be hard to beat a drink or drug driving charge, there are defences available. Below is a rundown of some of the instances where you may be able to defend a charge like this.

Note: Drink and drug driving laws differ from state to state, and there can be consequences for pleading “not guilty” in a case where you are later convicted. The material below is not intended as legal advice and we recommend that you consult a lawyer in your state before you are scheduled to attend court.

Power to Breathalyse

Police who administer roadside alcohol or drug tests have very broad powers, however if Police overstep the mark, they may not be able to use the test results as evidence against you. Situations where this may apply include:

  • Where police wrongly believe you were the driver of a vehicle
  • Where police wrongly believe you were involved in an accident
  • Where an amount of time has passed between your act of driving and Police administering the test.

If the Police have gone beyond their powers in breathalysing you, you may be able to successfully defend a charge of drink or drug driving.

Note: You should be aware that the consequences of refusing to submit to a test are often more serious than the consequences of failing one. If Police are requiring you to submit to a test, you should comply with their requirements, perform the test and seek legal advice afterwards.

Delay in Administering a Test

If Police have to take you to a second location to administer a breath or blood test, they have an obligation to carry out the test within a period set down by the law. This period varies from state to state but is generally two or three hours.

If there are long delays between Police taking you in to custody and a test being administered, this may be a defence to a drink or drug driving charge.

Challenging the Reading

Police drug and alcohol testing is generally carried out using technical instruments, however from time to time, these instruments may be inaccurate. They may not be properly calibrated or they may be faulty, causing them to return incorrect results. There are several ways that you may be able to challenge test results, including:

  • Checking that the instruments which Police used were correctly maintained and compliant.
  • Where a blood sample has been provided to you, having that sample re-checked by an independent analyst.
  • Providing specialist medical evidence that the test result is incorrect.

If you believe that a reading from a Police breath or blood analysis is wrong, you may be able to defend a charge of drug or drink driving.


Most of the time, being mistaken about the presence of drugs or alcohol in your blood will not be a defence to a charge. However, in rare circumstances you may be able to argue that you made an “honest and reasonable” mistake.

Circumstances where this may be available to you include:

  • Where you ingested drugs or alcohol without your knowledge.
  • Where you had a medical condition which might alter your body’s reaction to drugs or alcohol.
  • Where so much time had passed between you ingesting the substance and you driving that it was reasonable to think that you were OK to drive.

If you believe you may have made an honest and reasonable mistake with regards to a drink or drug driving incident, it is worth contacting a lawyer in your state before you attend court.

Driving Under the Influence

“Driving Under the Influence” is a more serious charge than the more common drink driving or drug driving charges, and generally carries a heavier penalty.

In some states, it is not enough for Police them to simply show that you had alcohol or drugs in your body, they also have to prove that you were incapable of properly controlling your vehicle.

If you have been charged with Driving Under the Influence, you may want to seek legal advice regarding whether you have a prospect of defending this charge.

Hardship of Extraordinary Licence Applications and Special Circumstances

Some states permit disqualified drivers to obtain an “extraordinary licence”, “restricted licence”, “hardship Licence” or “work Licence” if being unable to drive would result in special hardship. These Licences can only be obtained in certain circumstances, such as:

  • If your disqualification from driving licence would cause severe hardship to yourself or;
  • If your disqualification from driving would cause severe hardship to others around you.

Similarly some states allow a Magistrate to vary the standard penalties in “special circumstances”. If you think that this applies to you, you should seek legal advice prior to entering a plea.


It is important to remember that courts take charges of drink or drug driving very seriously. If you are considering contesting one of these charges on a technical basis, it is important that you get the right advice as soon as possible.

The contents of this blog post are considered accurate as at the date of publication. However the applicable laws may be subject to change, thereby affecting the accuracy of the article. The information contained in this blog post is of a general nature only and is not specific to anyone’s personal circumstances. Please seek legal advice before acting on any of the information contained in this post.

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