Illicit drugs & road safety

Drug-driving is a major contributor to car crashes and road fatalities in Victoria. In the last five years, around 41 per cent of all driver and motorcyclist fatalities who were tested, had illicit drugs in their system. Drivers who take illicit drugs are much more likely to be involved in a crash than drug-free drivers, and are often responsible for these crashes.

Some illicit drugs hang around for a long time

Some illicit drugs can be detected in your saliva days after drug use, even if you feel you are OK to drive. The detection time varies depending on the type of drug and amount taken, frequency of drug use, and other factors that vary between individuals. 

It is illegal to drive, attempt to drive or supervise a learner while affected by drugs. You cannot drive while impaired by any drug. These laws apply if you are on a private property or public road.

These illicit drugs* were detected in blood samples from drivers and riders killed in road crashes in Victoria between 2012 and 2014:

  • THC (active ingredient in marijuana) in 15 per cent of deceased drivers and riders
  • amphetamine (ecstasy, speed and ice) in 10 per cent of deceased drivers and riders
  • other drugs in two per cent of deceased drivers and riders.

* VicRoads 2016

Drug testing 

Victoria Police test for illegal drugs at the roadside by taking a saliva sample. If drugs are detected, then a laboratory test is done. More than one type of drug can be detected in a test, showing a combination of drugs.

It is an offence to not:

  • stop at a random drug testing station
  • provide a saliva or blood sample
  • cooperate with police who are trying to carry out a saliva, blood or urine test or
  • cooperate to take part in a drug impairment assessment.

Illicit drugs affect you in different ways:

  • depressants such as cannabis impair brain function, attention and concentration
  • stimulants such as ice, speed and ecstasy affect coordination, distance judgements and risk assessment
  • when illicit drugs wear off, you can be excessively sleepy and distracted
  • using multiple drugs makes it more difficult to predict what the effects will be, and increase your risk of causing a crash.

Cannabis and driving

All forms of cannabis, or marijuana, can contain differing levels of mind-altering (psychoactive) drugs. The major psychoactive substance in cannabis is THC (delta-9-tetrahydrocannabinol). Cannabis also contains more than 400 other chemicals.

If you take cannabis, you won’t be able to drive safely as THC will affect your:
  • alertness
  • ability to concentrate and judge distances 
  • coordination
  • reaction time.

These effects can last for many hours after taking cannabis.

Research shows that you increase your risk of crashing if you drive soon after taking cannabis, and if you combine cannabis with alcohol, the risk of crashing is higher than with either drug alone.

You cannot have any cannabis in your system while driving. There is no safe amount, and each person is affected differently by cannabis use. For information on offences and penalties, see drug-driving penalties and combined drink and drug-driving penalties

Cannabis affects everyone differently

The effects of cannabis vary depending on:

  • the amount taken
  • your experience with the drug
  • your physical and psychological state
  • when you last used cannabis.

Mixing drugs increases the danger

Using cannabis with other drugs, including alcohol, reduces your ability to drive safely. A small dose of cannabis can increase the effects of a low Blood Alcohol Concentration. Some medicines prescribed by a doctor or bought from a supermarket or pharmacy can also increase the effects of cannabis.

Plan ahead

To reduce the risk of a serious accident, do not use cannabis or other drugs if you are going to drive.

You can avoid drug-driving by planning ahead:

  • designate a non-drinking and non-drug taking driver
  • hire a taxi or ride share
  • use public transport
  • stay the night (make sure you are not still over the limit in the morning)
  • arrange for someone to pick you up
  • only accept a lift if you are certain the driver has not been drinking or using other drugs
  • always have a plan B if plan A goes amiss.

The laws in detail

The laws regarding driving with alcohol and drugs are published in the Road Safety Act 1986. Please refer to Part 5 - Offences involving alcohol or other drugs.

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