The facts about roadside drug testing
Number 8.10 March 2010
Driving a motor vehicle safely is a complex task. We must be mentally alert, have clear vision and good physical coordination. This allows us to pay close attention to many things at once, and to react quickly when something unexpected happens. Taking drugs or other substances that affect the brain can reduce the ability to drive safely.
It is an offence to drive if you are under the influence of alcohol or other drugs and do not have proper control of your vehicle. Keep in mind that if you have taken alcohol or other drugs it is difficult to assess how much your own driving skills have been affected.
If you intend to drive, the safest option is not to have any alcohol or other drugs in your system at all. This includes any prescription medicines that affect your driving ability. It is also important to remember that fatigue, and the after-effects of drug use "coming down", can affect your driving skills.
This fact sheet explains drug testing of drivers in Victoria, and the steps you can take to stay safe.
What is drug testing?
Drug testing looks for traces of drugs in the body using samples of urine, breath, hair, saliva, or sweat. Testing may be used to detect illegal drug use, as well as the use of drugs not permitted while driving, or in specific workplaces or sports.
Passing a drug test may mean that either the drug is no longer in your body, or that the test cannot detect the traces that remain.
What types of types of drug tests are used?
Standard Impairment Assessment (SIA)
In Victoria, police use the Standard Impairment Assessment (SIA) to test drivers they believe may be under the influence of drugs. The test will show impairment equal to, or higher than, a blood alcohol concentration (BAC) of 0.05.
There are four parts to the assessment:
Random roadside drug testing, in Victoria and most other states and territories, uses saliva samples to detect illicit drugs.
A sample of the driver’s saliva is taken by specially-trained police officers, using an absorbent collector placed in the mouth or touching the tongue. This test takes about three to five minutes. If the test is positive, it must be confirmed by laboratory testing before charges can be laid.
In Victoria, roadside saliva tests detect drugs that contain:
Over many years, police have carried out extensive breath testing of Australian drivers to detect the amount of alcohol in their system. The procedure is straightforward—the driver is instructed to blow into a hand-held breath-testing device until deep lung air is exhaled. The BAC reading is given on a digital display.
Acceptable BAC limits vary for different types of driving licences, and in different areas of Australia. Contact your local authority or road safety agency for more details on how these laws affect you.
How long will drugs stay in my system?
Drugs and alcohol affect every person differently, so drug testing results will be unique to each individual.
Results can be affected by:
Cannabis: Random roadside drug testing can detect cannabis for at least several hours after use. Even after a small amount of cannabis you should not drive for at least five hours. Even though you may not feel the effects, the drug may still be detected in a test.
Methamphetamine ("speed", "ice") may be detected for at least 24 hours after use by random roadside drug testing. Note that the withdrawal effects of methamphetamine, such as fatigue, anxiety and irritability, can also lead to unsafe driving.MDMA (ecstasy) may be detected for at least 24 hours after use by random roadside drug testing. Taking large doses, using other drugs at the same time, and even your own particular metabolism, can affect the length of time you will feel the effects of ecstasy.
Alcohol: The liver takes an hour or more to break down the alcohol in one standard drink. A standard drink is equivalent to 10 grams of alcohol, as is found in 100ml of wine. For more information on standard drinks, see the DrugInfo fact sheet, “What is a standard drink?”.
It is important to remember that you may still be affected by alcohol the next morning. This is particularly important for drivers required to keep to a zero BAC limit.
If you are taking medication it is best to talk to your doctor about whether you are safe to drive. Also check whether your medication will be affected if you drink alcohol.
The only sure way to test negative on a drug test—other than not taking drugs—is to make sure your body has eliminated all of the drugs you have taken.
Most drugs take at least 24 to 48 hours to leave your body. This means that even if you are not drunk or stoned any more, these drugs can continue to affect your body. If you are taking more than one drug at a time (including drinking alcohol), the drugs may take even longer to be eliminated from your body.
Avoid driving whenever you have been using alcohol or other drugs. Also remember that even if you feel like you are OK to drive, you are still likely to be affected and unsafe on the roads.
If you intend to use alcohol or other drugs and need to travel, plan ahead by:
Taking more than one drug
People who have more than one drug in their system will be more impaired, and have a higher risk of having a car accident. The risk is increased when the content and purity of illicit drugs are unknown.