Guides · updated July 2026
Roadside drug testing is here. Prescribed patients, know your defence.
Police began oral-fluid (saliva) testing in Wellington in December 2025 and it is rolling out nationwide through 2026. Over 160,000 medicinal cannabis prescriptions were written in New Zealand last year — and THC can show up on a swab days after any effect has worn off. Here is how the system works and what the law actually says.
First, the part that matters most
If you are impaired, do not drive. Nothing on this page is a way around impaired driving — it is about what happens when a legal, prescribed, unimpaired patient returns a positive swab, which the testing technology cannot tell apart from recent use.
How the roadside test works
- A first screening test — a tongue swipe, a few minutes at the roadside.
- If positive: a saliva sample is taken for laboratory analysis, and a second screening test is run.
- Two positives = you are prohibited from driving for 12 hours. A prescription does not change this — the medical defence does not apply at the roadside.
- If the laboratory confirms one qualifying drug: $200 fine and 50 demerit points. Two or more drugs: $400 and 75 demerits.
The section 64 medical defence
Section 64 of the Land Transport Act 1998 provides a statutory medical defence: if the drug detected was prescribed to you and you took it as your prescriber directed, the infringement can be withdrawn. It covers prescribed medicinal cannabis and amphetamine-based ADHD medication, among others.
The catch: it is not automatic. You must respond to the notice with a proper application — proof of prescription, an attestation that you followed your prescriber's directions, and the Police form filled out correctly, before the due date on the notice.
We fill the application out for you
Our fast track reads your notice, completes the Police medical-defence application, and gives you a ready-to-send document — you sign it and attach your prescription.
Start the medical fast trackCommon questions
Can I drive on prescribed medicinal cannabis in NZ?
There is no legal ban on driving while taking prescribed medicinal cannabis, but you must not drive while impaired. THC can trigger a positive roadside saliva test days after any impairment has passed. If you tested positive but took your medicine as prescribed, section 64 of the Land Transport Act 1998 gives you a medical defence against the infringement.
What happens if I fail a roadside saliva test?
A first positive leads to a second saliva sample. If both are positive you are prohibited from driving for 12 hours — this applies even if you hold a prescription. A laboratory then confirms the result; a confirmed single drug means a $200 fine and 50 demerit points ($400 and 75 demerits for two or more drugs).
Does having a prescription stop the roadside 12-hour ban?
No. The medical defence does not apply at the roadside — the 12-hour prohibition stands regardless of prescription. The defence applies to the infringement notice that follows, which can be withdrawn if you show you were prescribed the medicine and took it as directed.
How do I use the section 64 medical defence?
You respond to the infringement notice with a medical-defence application: proof of your prescription, confirmation you took the medicine as your prescriber directed, and the completed Police form. GetMeOff fills out the application for you — you sign it and attach your prescription.
Which medications can trigger a positive test?
The roadside devices screen for THC, methamphetamine, MDMA and cocaine. Prescribed products that can trigger a result include THC-dominant medicinal cannabis (flower and oils) and some ADHD medications (amphetamine-based, e.g. dexamphetamine) on the lab confirmation.
Related: how to dispute a speeding ticket · how to appeal a parking ticket
Sources: NZ Police drug-driving updates, Land Transport Act 1998 s64, NZ Drug Foundation roadside testing guidance. GetMeOff.co.nz provides automated document drafting and general information only — it is not legal advice and no outcome is guaranteed. If your situation involves a criminal charge (e.g. impaired driving), see a specialist traffic lawyer.