Drug Driving (WA) | Armstrong Legal

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This article was written by Sally Crosswell

Sally Crosswell has a Bachelor of Laws (Hons), a Bachelor of Communication and a Master of International and Community Development. She also completed a Graduate Diploma of Legal Practice at the College of Law. A former journalist, Sally has a keen interest in human rights law.

Drug Driving (WA)


Prescription or over the counter medications, or a combination of drugs, can cause  side-effects that reduce a person’s ability to drive safely. These effects include slowed reaction times, inability to judge speed and visual distortion, which can increase the risk of an accident. Police can stop and charge a driver suspected of driving while impaired.

Under the Road Traffic Act 1974, it is an offence in Western Australia for a person to drive or try to drive while impaired by drugs or with an illicit drug in their system.

Driving while impaired by drugs

For a first offence, the penalty is a fine of $900 to $2500, minimum licence disqualification of 10 months.

For a second offence, the penalty is a fine of $2100 to $3500 fine or 9 months imprisonment, and a minimum licence disqualification of 30 months.

For a third or subsequent offence, the penalty is fine of $2100 to $5000 or 18 months imprisonment, and a permanent licence disqualification.

The prosecution must prove each of these factors:

  • the person drove or attempted to drive a motor vehicle;
  • one or more drugs were present in the person’s body when they were driving;
  • the conduct, condition or appearance of the person driving was consistent with that of a person who had consumed or used those drugs;
  • the conduct, condition or appearance of the person was inconsistent with the person being capable of having proper control of a motor vehicle.

It also need to be proven that the drug or drugs were present in the person’s body within 4 hours of the time of driving or trying to drive.

A person will have a defence to the charge if they can prove:

  • the drug was prescribed or administered by a doctor, nurse practitioner or dentist for therapeutic reasons; and
  • the drug had a label that did not state the drug may adversely affect the person’s ability to drive; and
  • they were not aware and could not reasonably have been expected to be aware the drug would adversely affect the person’s ability to drive.

Driving with prescribed illicit drug in oral fluid or blood

For a first offence, the penalty is a fine of up to $500. For a second or subsequent offence, the penalty is fine of $500 to $1000, and a minimum licence disqualification of 6 months.

The prosecution will need to prove that the drug or drugs were present in the person’s body within 4 hours of the time of driving or trying to drive.

It is not a defence if a person takes an illicit drug believing it to be another drug.

If a person provides instruction to a learner driver while the instructor has an illicit drug in their system, they are liable to a fine of between $300 and $500.

Drug impairment assessment

A police officer can require a person to undergo a drug impairment assessment when the officer reasonably believes:

  • the person’s driving was impaired by a substance other than alcohol;
  • the person may have been driving a motor vehicle that caused personal injury or property damage and their driving was impaired by a substance other than alcohol.

The officer can require the person to wait at a certain place, or leave a vehicle, for assessment.

A person will not be required to undergo an assessment if it is more than 4 hours since the driving, or if the person’s physical condition prevents it.

Blood and urine samples

If the assessment shows the person to be drug impaired, or the person refuses to be assessed, the police officer can require a sample of the person’s blood or urine or both for analysis. The person may have to accompany the officer to a certain place and wait there for testing. The testing must be done within 4 hours of the driving.

Preliminary oral fluid test

A police officer has the power to pull over a driver of a motor vehicle and have them undergo a preliminary oral fluid test. An officer can also require such a test for a person they reasonably believe may have been driving a motor vehicle that caused personal injury or property damage.

Oral fluid sample

If the preliminary oral fluid test indicates the person has taken a prescribed illicit drug, or if the person refuses to be tested, the officer can direct the person to provide a sample of oral fluid for drug testing. The officer can require the person to accompany them to a certain place, and wait there for testing.

A person will not be required to provide a sample if it is more than 4 hours since the driving, or if the person’s physical condition prevents it. In the latter case, the police officer can order a blood sample be taken from the person instead.

If a person refuses to provide a blood, urine or oral fluid sample without a reasonable excuse, they commit an offence and are liable to a fine and/or imprisonment and licence disqualification.

For advice or representation in any legal matter, please contact Armstrong Legal.

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