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Defending Drink or Drug Driving Charges

Winning defences can be raised in many prosecutions for drink or drug driving

The consequences of a drink or drug driving conviction can be severe. In some cases, they involve a sentence of incarceration. They always involve a serious fine and a licence disqualification. Conditions may be imposed on licence reinstatement that prevent drivers from driving any vehicle that is not equipped with an alcohol interlock.

Drivers often feel that the situation is hopeless when they are charged with a drink or drug driving offence. You should always consult with a lawyer, however, because it may be possible to challenge the evidence and to defeat the charge.


Driving under the influence of alcohol or a drug is the most serious charge. It also affords the most opportunities for a defence. The offence requires proof that you were incapable of exercising effective control of your vehicle due to the consumption of drugs or alcohol. Incapacity to control a vehicle can be established by proving that your physical or mental capabilities were impaired because you used drugs or drank alcohol.

The mere presence of a drug in your system does not necessarily mean you were under the influence of that drug. If the offence is charged in the absence of a chemical test for alcohol (or if your test result was relatively low), it may be difficult for the prosecution to prove that any observations the officer made about your behaviour (such as weaving while driving) were caused by drug or alcohol consumption as opposed to fatigue or stress. A speech impediment may explain the officer’s conclusion that your speech was slurred while a bad back or bum leg may explain why you staggered.


A charge based on exceeding the prescribed concentration of alcohol (0.05 for most drivers) can be challenged in several ways. The test may have been taken too long after you stopped driving. You may have consumed alcohol after you stopped driving but before you were tested. The officer may not have followed proper procedures, resulting in a contaminated breath sample. You may have burped so that the machine measured mouth alcohol rather than the deep lung air required for a valid result. Whether any of these defences apply in your case is something you can only determine by talking to an experienced drink driving lawyer.


If you refused a chemical test, you may have a defence if you had a legitimate reason for refusing. You will have an even stronger defence if you tried to take a breath test but were unable to produce a sufficient breath sample for the machine to register. The police may claim you deliberately avoided blowing into the machine, but asthma and other medical conditions often prevent people from blowing hard enough and long enough to submit a valid breath sample. Again, a lawyer can help you understand whether you have a defence to a refusal charge.

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