In just a few weeks, roadside drug testing will start rolling out in the New Zealand city of Wellington, with nationwide coverage expected by mid-2026. This poses risks for medical cannabis users, including those with a prescription.

In March this year, legislation to enable police to conduct random roadside drug testing passed its third and final reading in NZ’s Parliament.

The saliva screening test will detect the presence of cannabis (THC), cocaine, methamphetamine, and MDMA. If a test is positive, a driver will need to take a second saliva test. If this also tests positive, the driver will be barred from driving for 12 hours. Furthermore, another saliva sample will undergo further testing at a lab to determine whether any of 25 drugs are detected. If they are, the driver will receive an infringement offence notice, with demerit points and a fine.

The laboratory detection of one drug will result in an infringement offence notice that carries a $200 fine and 50 demerit points. Where 2 or more drugs are detected in a saliva sample, an infringement offence notice will be sent, carrying a $400 fine and 75 demerit points. Refusing to provide a saliva sample is also an offence, accompanied by a $400 fine.

Unlike Australia, current NZ law provides a medical defence against an infringement notice for medical cannabis users with a prescription . But the medical defence does not apply immediately at the roadside, meaning an impacted driver can still be directed to not drive for 12 hours.

Complicating matters is that THC can be detected long after ingested and any impairment. Some say THC can stay in the body up to three days, others up to a couple of weeks. And adding to the stress of such a situation is the application for a medical defence can only be completed via the Police website after an infringement offence notice has been issued. Users of cannabidiol (CBD) preparations also need to be cautious, as many of these preparations may contain THC in trace amounts.

For further information, New Zealand’s Drug Foundation has compiled a comprehensive guide on New Zealand’s roadside drug testing, which notes NZ Police are having operational discussions regarding how the medical defence will be handled.

In related news, NZ Police have selected the Securetec DrugWipe 3 S device for roadside drug-impaired driver screening, supplied by Australia’s Pathtech Pty Ltd; which will also provide “Oral Fluid Collection Kits” (i.e. saliva-collection kits) for samples to send for lab analysis

Since New Zealand’s Medicinal Cannabis Scheme was fully implemented in 2020, Kiwis have been increasingly embracing accessing medicines via legal channels. The New Zealand Drug Trends Survey (NZDTS) 2024 indicated 37 per cent of medical cannabis users had a prescription, up from just 9 per cent in 2022/23.