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Medicinal Cannabis & Drug Driving in WA: 2026 Laws

Strict presence offence — working group considering reform Last verified: 2026-10-18

Just tested positive? What happens next in Western Australia, step by step →

Medicinal cannabis and driving in WA: where the law stands

Western Australia is a strict presence-offence state. Under section 64AC of the Road Traffic Act 1974 (WA), driving with a prescribed drug — including THC — in your blood or oral fluid is an offence, regardless of whether you have a valid prescription.

WA also has a separate, more serious impaired-driving offence under section 64AB, and police have conducted random roadside drug testing since 2007.

A prescription authorises possession and use of the medicine dispensed to you. It does not change the driving offence, because the offence is presence, not impairment.

Is medicinal cannabis legal in Western Australia?

Yes — medicinal cannabis can be lawfully prescribed, possessed and used in WA with a valid prescription. Recreational cannabis remains a prohibited drug.

The distinction that matters for prescribed patients is that the *legality of your medicine* does not extend to the driver's seat. You can hold a current, valid prescription and still commit an offence under section 64AC the moment you drive with THC detectable — because the offence is made out by presence, not by whether your use was lawful. That gap between "legal to use" and "illegal to drive on" is precisely what the reform working group (below) is examining.

What happens at a roadside test today

Mobile drug testing in WA follows the national pattern, with state detail layered on top. See our guide, Mobile Drug Testing (MDT) in Australia, for the full multi-stage process. In brief:

1. The stop. You can be tested at a static site or by a mobile patrol. You must stop and comply with a lawful direction to test — refusing the oral fluid test is itself a serious offence.
2. The screening swab. A saliva swab screens for cannabis (THC), methamphetamine, MDMA and cocaine — all four drugs are screened in WA. It does not measure impairment, dose, or when you took your medicine.
3. The second test. A positive screen leads to a second oral fluid sample on more sensitive equipment at a bus or roadside unit. Many first-positives end here when the second test disagrees.
4. The driving ban. WA Police issue drivers who test positive for a specified drug — cannabis, ecstasy, meth or cocaine — or who refuse the roadside test with a prohibition notice banning them from driving for 24 hours. Breaching the notice is an offence, and police may issue an infringement notice with a penalty of $600.
5. Laboratory confirmation. The roadside result is indicative only. Charges typically follow laboratory confirmation, which can take weeks.

WA has run roadside drug testing longer than most states — random testing has operated since 2007 — so a WA driver is more likely to encounter it than a driver in a state that adopted the practice later. That makes the detection-window problem below especially live for prescribed patients here.

The key point for a prescribed patient: a roadside test detects the *presence* of THC in oral fluid, which correlates poorly with both impairment and time since dose. You can test positive many hours after your last dose, long after any impairing effect has passed. Under WA law, detection is enough. That mismatch is the core of the reform debate.

The two offences, side by side

It helps to understand that WA has two different drug-driving offences, and they are not the same thing:

• Section 64AC — the presence offence. Made out by the detection of a prescribed drug in blood or oral fluid, with no requirement of impairment. This is the offence a compliant, unimpaired prescribed patient can still commit.
• Section 64AB — driving impaired by drugs. A more serious offence requiring evidence you were actually impaired or under the influence. To decide impairment, police may analyse a blood sample or make you complete a driver assessment test (Legal Aid WA). A prescribed patient who drives unimpaired should not face this charge on presence alone — but driving while impaired, whatever the reason, is a serious offence with heavy penalties.

Most of the public debate about medicinal cannabis patients is really about section 64AC — the presence offence — because it is the one that catches people who are not impaired at all.

Penalties

WA penalties are set in penalty units. The s64AC figures below are verified against the consolidated Road Traffic Act 1974 (July 2026); the s64AB figures are as reported by legal practitioners. Dollar amounts are from the Road Safety Commission's published court penalty table (page updated 4 September 2026):

For a third or later impaired-driving offence the Road Safety Commission's table extends the fine to $3,150–$7,500, with 18 months imprisonment as the alternative and disqualification for life.

Three things Legal Aid WA (page last reviewed 9 September 2026) says every WA driver should know about these penalties:

• Drug driving cannot be dealt with by infringement notice in WA. Unlike low-range drink driving, there is no pay-a-fine-and-avoid-court option — a drug driving offence is dealt with in court.
• The minimums are real. Courts must impose the minimum fines and minimum disqualification periods that apply, and your licence may also be cancelled.
• Refusing a driver assessment test, oral fluid test or blood/urine sample is a separate offence with penalties comparable to the underlying charge — and refusing the roadside test also triggers the 24-hour prohibition notice.

Check the current WA penalty-unit dollar value when quoting dollar figures — they are re-indexed periodically. For how WA compares with every other state and territory, see Drug driving penalties, state by state.

What this means in practice

If you are a prescribed patient in WA, the honest position is:

• A valid prescription is not a defence. The s64AC offence is made out by presence alone. The question the court asks is whether THC was detectable, not whether you were impaired.
• Keep your prescription and dispensing records accessible. They will not prevent a charge in WA, but they matter later — for court and for the reform argument.
• Never drive impaired. Every discretion and proposed reform evaporates if you are impaired, and it is dangerous.
• If you test positive, the ban and any charge follow laboratory confirmation. See our step-by-step guide, "Tested positive in WA: what happens next", and get legal advice early.

Curious how WA stacks up against the state you learned to drive in, or where you might drive next? See every state compared on one page.

Reform status

A WA medicinal cannabis and safe driving working group has been considering evidence and potential reform, and Legalise Cannabis WA continues to campaign for change — but no medicinal cannabis driving reform has passed as of the research date.

Common questions

Is recreational cannabis legal in WA? No. Recreational cannabis remains a prohibited drug in Western Australia. Only prescribed medicinal cannabis is lawful to possess and use.

Is medicinal cannabis legal in WA? Yes, with a valid prescription. But that does not make driving with THC in your system legal — section 64AC is a presence offence, so a prescription is no defence on the road.

What is the difference between section 64AC and section 64AB? Section 64AC is the presence offence — detection of a prescribed drug is enough, with no need to prove impairment. Section 64AB is the more serious impaired-driving offence, which requires evidence you were actually affected. A compliant patient driving unimpaired is at risk under 64AC, not 64AB.

Can I be charged in WA even though my cannabis is prescribed? Yes. Section 64AC applies regardless of prescription — the offence is presence, not impairment.

Is WA going to change the law? A working group has been examining the issue and campaigners are pushing hard, but nothing has passed. Watch this page.

Will I lose my licence for a first drug driving offence in WA? Not automatically. The Road Safety Commission's court penalty table shows a first presence offence (s64AC) carries a maximum fine of $1,250 plus 3 demerit points, with no mandatory disqualification. Disqualification of at least 6 months applies from a second offence.

Can I just pay a fine and skip court for drug driving in WA? No. Legal Aid WA is explicit: it is not possible for police to issue an infringement notice for a drug driving offence. Unlike low-range drink driving, drug driving in WA is always dealt with in court.

What happens if I refuse the roadside drug test in WA? Refusing to provide a sample for drug testing is a separate offence with penalties often as serious as the underlying charge — fines, imprisonment and licence disqualification are all possible (Legal Aid WA). Police also issue a 24-hour prohibition notice, and breaching that notice is itself an offence.

Read this next

• Tested positive in Western Australia? What happens next
• How long THC stays detectable: saliva, blood and urine
• Drug driving penalties, state by state
• Every state compared on one page

Active reform items

• WA medicinal cannabis and safe driving working group considering evidence and potential reform; Legalise Cannabis WA campaigning. (No reform passed as of research date.)

Quick answers for Western Australia

Primary sources for this page

• https://www.legislation.wa.gov.au (Road Traffic Act 1974 s64AB, s64AC)
• https://www.wa.gov.au

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