Tested positive at a roadside drug test? This guide explains Tasmania's drug driving laws, penalties, detection windows, and the unique medicinal cannabis defence available only in this state.
If you’ve been stopped at a roadside drug test in Tasmania and returned a positive result, you’re likely facing significant uncertainty about what happens next. Perhaps you used cannabis days ago and assumed it would be out of your system, or you’re taking prescribed medication and weren’t aware it could affect your ability to drive legally. Whatever brought you here, understanding your legal position is the essential first step.
This guide explains Tasmania’s drug driving laws in detail, including the critical differences between the two main offences, the penalties you may face, the unique medicinal cannabis defence available in Tasmania, and what the prosecution must prove to secure a conviction.
Important Disclaimer: This article provides general information about Tasmanian law as at February 2026. It is not legal advice. Every situation is unique, and the application of the law depends on your specific circumstances. You should seek independent legal advice from a qualified lawyer before making any decisions.
Drug driving offences in Tasmania are governed by the Road Safety (Alcohol and Drugs) Act 1970. Unlike drink driving, where offences are determined by measurable blood alcohol concentrations with clear thresholds, drug driving law operates differently — and this difference catches many people off guard.
There are two distinct drug driving offences in Tasmania, and they carry very different penalties.
This is the more common charge and the one most people receive after a positive roadside drug test. Under section 6A of the Act, it is an offence to drive a motor vehicle while a prescribed illicit drug is present in your blood or oral fluid.
The critical point to understand is this: the prosecution does not need to prove you were impaired. They only need to prove that a prescribed drug was detected in your system while you were driving. There is no minimum threshold — any detectable amount is sufficient for a conviction.
This means you can be charged and convicted even if:
This is the more serious charge, equivalent to high-range drink driving. Under section 4 of the Act, it is an offence to drive while under the influence of a drug (or alcohol, or any intoxicating substance) to such an extent that you are incapable of having proper control of the vehicle.
For this offence, the prosecution must prove actual impairment — that the drug affected your ability to drive safely. This typically requires evidence beyond just a positive drug test, such as observations of erratic driving, being involved in a crash, or other indicators of impairment.
Tasmania Police conduct roadside oral fluid (saliva) testing that can detect several prescribed illicit drugs. As of 9 June 2023, the list of prescribed illicit drugs under the Road Safety (Alcohol and Drugs) Regulations 2018 includes:
Roadside testing primarily screens for THC, methamphetamine, and MDMA, as these are the substances the oral fluid testing devices can detect. However, if police suspect impairment from other drugs, they can require a blood test, which can detect a broader range of substances.
It’s also important to note that you can be charged with driving under the influence (section 4) for any drug that impairs your ability to drive — including prescription medications and over-the-counter drugs. Benzodiazepines, opioid painkillers, strong antihistamines, and other medications that cause drowsiness or affect concentration can all lead to charges if they impair your driving.
One of the most contentious aspects of drug driving law is the disconnect between detection and impairment. Unlike alcohol, which clears the body relatively quickly and predictably, some drugs — particularly cannabis — can remain detectable long after their impairing effects have worn off.
THC is fat-soluble, meaning it is stored in fatty tissues and released slowly over time. This creates significant variability in detection windows:
In oral fluid (saliva):
In blood:
The practical consequence is that someone who used cannabis on a Friday evening could potentially test positive on Monday morning — days after any impairing effects have passed. This is not a defence to a section 6A charge in Tasmania (or anywhere else in Australia), but it does explain why many people are genuinely surprised to receive a positive result.
These timeframes are approximations and can vary based on factors including the amount consumed, frequency of use, individual metabolism, and body composition.
Tasmania imposes some of the most significant drug driving penalties in Australia. The penalties differ depending on which offence you’re charged with and whether you have prior convictions.
First offence:
Subsequent offence:
This is treated as seriously as high-range drink driving.
First offence:
Subsequent offence:
An offence is considered a subsequent offence if you have previously been convicted of any of the following:
This means a prior drink driving conviction will result in higher penalties for a drug driving offence, and vice versa.
A court may impose a fine or disqualification period below the mandatory minimum if you can demonstrate ‘special circumstances’. However, this is a high threshold to meet and requires compelling evidence. Legal representation significantly improves your prospects of successfully arguing special circumstances.
Tasmania is currently the only Australian state or territory with a statutory defence for driving with THC in your system if you have a valid medicinal cannabis prescription. This makes Tasmania’s approach notably different from every other jurisdiction, where even lawfully prescribed medicinal cannabis users face prosecution for drug driving.
Section 6A(2) of the Road Safety (Alcohol and Drugs) Act 1970 provides:
“A person does not commit an offence against subsection (1) if the prescribed illicit drug was obtained and administered in accordance with the Poisons Act 1971.”
This means that if you can prove the THC in your system came from medicinal cannabis that was lawfully prescribed and dispensed in accordance with Tasmanian law, you have a complete defence to a charge under section 6A.
For the defence to apply, the following conditions must all be met:
Your prescription must be issued by a medical practitioner physically present in Tasmania. An interstate prescription is not sufficient. The Poisons Act 1971 defines “medical practitioner” for the purposes of Schedule 8 authorisations as one who “must be present in Tasmania and acting in the course of medical practice in Tasmania.”
Your prescriber must have obtained Section 59E authorisation from the Tasmanian Department of Health before issuing the prescription.
The medication must be dispensed by a Tasmanian pharmacy. It is an offence under section 45 of the Poisons Act to import narcotic substances, including medicinal cannabis.
You must have used the medication in accordance with your prescription. Using more than prescribed, or using it differently than directed, may void the defence.
You must not be impaired to the point of being unable to control your vehicle. The section 6A(2) defence only applies to the presence offence. If you are so affected by the medicinal cannabis that your driving is impaired, you can still be charged under section 4 (driving under the influence).
This is where many people come unstuck. A significant number of Australians access medicinal cannabis through interstate telehealth prescribers. Until very recently, these prescriptions could not be lawfully dispensed in Tasmania, and the section 6A(2) defence did not apply to them.
The case of Smith v Marshall [2024] TASMC 12 illustrates this clearly. The defendant had a valid medicinal cannabis prescription from an interstate provider. He believed he was driving lawfully. However, Magistrate Fairley found that because the prescription was not issued by a practitioner present in Tasmania, the medication was not “obtained and administered in accordance with the Poisons Act 1971” and the defence did not apply.
The defendant also argued honest and reasonable mistake of fact — that he genuinely believed he was driving lawfully. The Magistrate rejected this, finding it was a mistake of law (misunderstanding the legal requirements) rather than a mistake of fact. Importantly, the defendant’s belief was based on information from an internet chat forum rather than legal advice, which the Magistrate found was not a reasonable basis for the belief.
If you are a medicinal cannabis patient who needs to drive in Tasmania:
Ensure your prescription is from a Tasmanian doctor. If you currently have an interstate prescription, consider transferring your care to a local practitioner.
Confirm your prescriber has the required Section 59E authorisation for Schedule 8 medicines.
Obtain your medication from a Tasmanian pharmacy.
Keep documentation with you. Carry a copy of your prescription or a letter from your doctor confirming your treatment. While this won’t prevent a positive roadside test, it will assist in establishing your defence if you’re charged.
Do not drive if impaired. The defence only applies to the presence offence. If your medication affects your ability to drive safely, you can still be charged and convicted.
Seek legal advice if charged. Even with a valid Tasmanian prescription, the legal process can be complex, and you’ll need to prove your case in court.
Understanding how roadside drug testing works can help you know what to expect and what your rights are.
Tasmania Police can require any driver to submit to a roadside oral fluid test. You do not need to be driving erratically or showing signs of impairment — testing can be random, similar to random breath testing for alcohol.
The officer will ask you to place an absorbent collector in your mouth or on your tongue for a few seconds. This collects a saliva sample that is then analysed at the roadside using a screening device. The result typically takes a few minutes.
A positive roadside screening test is not enough to charge you. If the initial test indicates the presence of a prescribed drug, you will be required to undergo a second oral fluid test using a different device.
If the second test is also positive, the sample is sent to Forensic Science Service Tasmania (FSST) for laboratory analysis. You may be arrested and taken to a police station for this process.
The laboratory analysis is what forms the basis of any charges. If FSST confirms the presence of a prescribed illicit drug, you will receive a summons to appear in court.
You are entitled to have a portion of your sample independently tested by another laboratory at your own expense if you dispute the result. This must be arranged promptly, as samples are only retained for a limited period.
Refusing to provide an oral fluid sample when lawfully required is a serious offence carrying significant penalties, including mandatory licence disqualification. Unless you have a genuine medical reason that prevents you from providing a sample (which must be supported by medical evidence), refusal is not advisable.
Aside from the medicinal cannabis defence discussed above, there are limited defences available to drug driving charges. However, the prosecution must prove its case beyond reasonable doubt, and there may be grounds to challenge the evidence.
Strict procedures must be followed in collecting and analysing samples. Failures in the chain of custody, improper calibration of testing devices, or departures from prescribed procedures may provide grounds to challenge the admissibility or reliability of the evidence.
The prosecution must prove you were driving a motor vehicle at the relevant time. In some cases, this element may be in dispute.
This defence may apply in very limited circumstances — for example, if you unknowingly consumed a drug (such as a spiked drink). However, as Smith v Marshall demonstrates, a mistake about the law (believing something is legal when it isn’t) is not a defence.
For driving under the influence charges, the prosecution must prove actual impairment. Challenging the observations of the arresting officer or witnesses, or expert evidence about the effects of the drug may form part of a defence strategy.
Many people facing disqualification want to know whether they can apply for a restricted licence (sometimes called a ‘hardship licence’) to continue driving for essential purposes like work.
The short answer is: it depends on your circumstances, but many drug driving offenders are ineligible.
Under section 19 of the Road Safety (Alcohol and Drugs) Act 1970, you cannot apply for a restricted licence if:
If your offence was driving with a prescribed illicit drug present (section 6A) and none of the exclusions apply, you may be eligible to apply. However, restricted licence applications require demonstrating severe and unusual hardship — mere inconvenience is not enough.
Our comprehensive guide to restricted licence applications explains the process in detail.
While much of this article focuses on illicit drugs, it’s important to understand that legal medications can also result in drug driving charges.
Many prescription medications carry warnings about driving. Benzodiazepines (such as diazepam and alprazolam), opioid painkillers (such as oxycodone and codeine), strong antihistamines, and various other medications can impair your ability to drive.
If you’re taking prescription medication:
Unlike the section 6A offence (which only applies to ‘prescribed illicit drugs’), a section 4 charge (driving under the influence) can be laid for impairment from any drug, including lawfully prescribed medication.
If you’ve received a summons for a drug driving offence, here’s what you can expect:
You should seek legal advice as early as possible. A lawyer can review the evidence against you, advise you on the strength of the prosecution case, explain your options, and help you prepare for court.
Gather any documents that may be relevant, such as:
Drug driving matters are heard in the Magistrates Court. You will need to enter a plea of guilty or not guilty.
If you plead guilty, the court will proceed to sentencing. You (or your lawyer) will have the opportunity to make submissions about penalty, including any factors in mitigation.
If you plead not guilty, the matter will be adjourned to a contested hearing where the prosecution must prove the charge beyond reasonable doubt.
If you’re convicted, your disqualification begins immediately (or from a date specified by the court). You must not drive until your disqualification period ends and you have had your licence reissued by Service Tasmania.
A conviction for drug driving will appear on your criminal record, which may affect employment, particularly for jobs involving driving, working with vulnerable people, or requiring security clearances.
Drug driving charges are serious and carry mandatory penalties including licence disqualification. Whether you’re seeking advice about your options, representation in court, or help applying for a restricted licence, understanding your legal position is the essential first step.
At Oxley Barristers & Solicitors, we regularly represent clients facing drug driving charges throughout Tasmania. We can advise you on the strength of the prosecution case, potential defences including the medicinal cannabis defence, what outcome you might expect, and how to present your case in the best possible light.
If you’ve been charged with a drug driving offence, or you’ve tested positive at a roadside test and are waiting for laboratory results, please contact us for a confidential discussion about your situation.
This article is intended as general information only. It is not legal advice. Laws and procedures may change. Always seek advice specific to your circumstances from a qualified legal practitioner.
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