Drug driving offences are prosecuted with increasing frequency in Victoria. There are two distinct categories of offence under the Road Safety Act 1986 (Vic): driving with a prescribed illicit drug present in your system, and driving while impaired by a drug. Importantly, the presence offence is one of strict liability — impairment does not need to be established.

Drug driving matters are heard in the Magistrates’ Court of Victoria. Like drink driving offences, they carry mandatory licence disqualification and can result in fines or imprisonment depending on the circumstances and a person’s prior history. At Angus Cameron and Partners, we have extensive experience representing clients charged with drug driving and related traffic offences.

If you have been charged with a drug driving offence, obtaining legal advice early is essential. The evidentiary and procedural requirements for drug testing are complex, and there may be defences available depending on the circumstances of your matter.

The Offences

There are two main drug driving offences under the Road Safety Act:

Driving with a prescribed illicit drug present

A person commits this offence where they drive or are in charge of a motor vehicle and have a prescribed illicit drug present in their oral fluid or blood. The prescribed drugs currently covered include:

  • THC (the active component of cannabis)
  • Methamphetamine (speed and ice)
  • MDMA (ecstasy)
  • Cocaine

The prosecution must prove beyond reasonable doubt that:

  • the accused was driving, or in charge of, a motor vehicle;
  • a prescribed illicit drug was present in the accused’s oral fluid or blood; and
  • the testing procedures complied with the requirements under the Road Safety Act.

Crucially, the prosecution does not need to establish that the accused was impaired. The mere presence of the drug is sufficient.

Driving while impaired by a drug

A person commits this offence where they drive or are in charge of a motor vehicle while impaired by a drug — including prescription medications and substances not covered by the "presence" offence. The prosecution must prove that the accused was driving or in charge of a vehicle and that their driving was impaired by the drug. Impairment is assessed by reference to observable signs and, where applicable, blood analysis.

In charge of a motor vehicle

Both offences extend to being “in charge” of a motor vehicle, not only driving. Whether a person is in charge depends on all the circumstances, including proximity to the vehicle, possession of the keys, and their intention with respect to driving.

Testing Procedures

Police may conduct roadside drug testing using an oral fluid (saliva) test. If the preliminary test returns a positive result, a second confirmatory sample is taken and sent to a laboratory for analysis. A charge is laid on the basis of the laboratory result, not the roadside screening result.

Blood samples may also be taken following an accident or where an oral fluid test cannot be completed. The chain of custody and handling of blood samples must comply with strict legislative requirements.

Detection periods vary by drug and individual. THC, for example, may remain detectable in oral fluid for a number of hours after use, but can be detected in blood for considerably longer depending on the frequency of use.

Defences

Being charged with a drug driving offence does not necessarily mean you will be convicted. There are a number of defences that may apply depending on the circumstances.

Challenging testing procedures

The Road Safety Act sets out detailed requirements for the conduct of oral fluid and blood testing. If those requirements were not followed — for example, if the required observation period was not observed, or if there was a break in the chain of custody of a sample — there may be grounds to challenge the admissibility or reliability of the test results.

Prescription medication

Where a person is charged with driving while impaired, a lawfully prescribed medication may in some circumstances provide a defence or at least a mitigating explanation. Whether this argument is available will depend on the particular drug involved and the evidence of impairment.

Not driving or in charge

If the prosecution cannot establish beyond reasonable doubt that you were driving or in charge of the vehicle at the relevant time, the charge may not be made out. This may be relevant where there is uncertainty about who was driving, or where you had no realistic intention of driving.

Disputing the result

The laboratory analysis of oral fluid or blood samples is not infallible. There may be grounds to challenge the accuracy of the result, including through expert evidence about the testing methodology or the handling of the sample.

FAQs

Do police need to prove I was impaired?

Not for the "presence" offence. The mere presence of a prescribed illicit drug in your oral fluid or blood is sufficient, regardless of whether your driving was affected. For the separate offence of driving while impaired by a drug, impairment must be established.

How long do drugs stay detectable?

Detection periods vary depending on the drug, the testing method, and individual factors such as metabolism and frequency of use. THC may be detectable in oral fluid for several hours after use, but can remain in blood for much longer in regular users. We recommend seeking legal advice specific to your situation.

Will I lose my licence if charged with drug driving?

Yes. Drug driving offences carry mandatory minimum licence disqualification periods in Victoria. The length of disqualification depends on whether it is a first or subsequent offence and the nature of the charge, along with your particular circumstances.

Can I be charged with drug driving for taking prescription medication?

Prescription medications are not covered by the "presence" offence, which targets specific illicit drugs. However, if a prescription medication impairs your driving, you may be charged with the impaired driving offence. It is important to follow medical advice about driving when taking any medication that may affect your ability to drive safely.

What is the difference between the roadside test and the laboratory analysis?

The roadside oral fluid test is a preliminary screening tool. A positive result triggers the taking of a second, confirmatory sample that is sent to a laboratory. Any charge is based on the laboratory result, not the roadside reading. The laboratory analysis must meet strict scientific standards, and there may be grounds to challenge the result in some circumstances.

Do I need a lawyer if I’m charged with drug driving?

Yes. Drug driving charges involve complex evidentiary and procedural issues, and the consequences — including mandatory licence disqualification — are significant. An experienced criminal lawyer can identify whether any defences apply, advise on the prospects of contesting the charge, and ensure the best possible outcome at sentencing.

Can I get bail if charged with drug driving?

Drug driving matters are generally dealt with by way of summons rather than arrest. Where a person is taken into custody — for example, following an accident — bail can usually be obtained. We are available to assist with urgent bail applications where needed.

Related Guides

You may also find the following guides useful:

  • Guide to Drink Driving — a related offence involving driving with a blood alcohol concentration exceeding the legal limit