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March 17, 2017

Roadside drug testing

Driving a motor vehicle safely is a complex task. You 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 illegal to drive if you are under the influence of alcohol or other drugs. If you have taken alcohol or drugs it is difficult to assess how much your own driving skills have been affected.

If you intend to drive, the safest option is to have no alcohol or other drugs in your system. This includes any prescription medicines that impact driving ability. It’s also important to remember that fatigue, and the after-effects of drug use (i.e. ’coming down’), can affect your driving skills.

This page explains drug testing of Victorian drivers 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 can’t detect the traces that remain.

What types of drug tests are used?

Standard Impairment Assessment

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:

  1. Interview and observation
  2. Physical impairment test
  3. Walk and turn test
  4. One leg stand test

Saliva tests

Random roadside drug testing uses saliva samples to detect illicit drugs.

Specially-trained police officers take a sample of your saliva, using an absorbent collector placed in the mouth or on the tongue. This test takes about 3 to 5 minutes. If the test is positive, it must be confirmed by laboratory testing before charges can be laid.

Roadside saliva tests detect drugs that contain:

  • THC (Delta-9 tetrahydrocannabinol), the active component in cannabis
  • Methamphetamine, which is found in drugs such as ’speed’, ’base’, ‘ice’, and ‘crystal meth’
  • MDMA, which is known as ecstasy

These tests don’t detect the presence of legally prescribed drugs or common over-the-counter medications.

Breath tests

Alcohol breath testing is another common roadside test. Read more about blood alcohol content (BAC) testing.

How long can the drugs be detected?

Whether or not you have a positive test will depend on a number of factors: the size and potency of the dose, other drugs you may have used at the same time, and your body’s metabolism.

Cannabis: Random roadside drug testing can detect THC (the active ingredient in cannabis) for at least several hours after use. The test cannot generally detect use in previous days or weeks, although there have been reported cases of people testing positive to cannabis a few days after consuming.

Methamphetamine (‘speed’, ‘ice’):  may be detected for approximately 24 hours after use. When withdrawing or coming down from methamphetamine, people can experience fatigue, anxiety and irritability.

MDMA (‘ecstasy’):  may be detected for approximately 24 hours after use.

Medications: If you’re taking medication it’s best to talk to your doctor about the combined impact on your ability to drive.

Most drugs take 24 to 48 hours to leave your body and will continue to affect you during this time. Combinations of drugs can take even longer.

Avoid driving when you’ve been using alcohol or other drugs. Even if you feel okay to drive, you can still be affected and unsafe on the roads.

More information

DrugInfo help and support

Read more information on drugs and driving

Transport Accident Commission (TAC)