Random, Rapid, and Controversial: NZ’s New Roadside Drug Tests Explained

NEWS | ISSUE FOUR/20 | RONGOĀ / DRUGS

Written by Tashi Donnelly she/her | @tashi_rd | Editor

The Basics

Yes, New Zealand now has roadside drug testing. This began in Wellington in December 2025 and has been rolling out nationwide through 2026. This means that the police can stop any driver, anywhere, at any time, and administer a saliva drug test (similar to a breathalyser, which is used to test alcohol levels). You don’t need to be driving badly or suspected of impairment; testing can be completely random. 

What drugs are tested roadside?

The quick roadside test screens for four different drug types: THC (cannabis), methamphetamine, MDMA, and cocaine. The saliva test detects recent use of these substances, but does not test for impairment. 

How does the testing process work?

First, you complete the saliva test, which is just a device which they swipe on your tongue. It takes about 5-10 minutes for the result to come back. If negative: you’re free to go! If it comes back positive, you are required to do a second test. If both tests come back positive, you are banned from driving for 12 hours immediately. The saliva sample is then sent to a lab and tested for up to 25 drugs (including some prescription medications). You are NOT fined at the roadside. Penalties only happen if the lab confirms drugs above legal thresholds. 

What are the penalties?

If the lab confirms qualifying drugs, you could be subject to an infringement fine (around $200), as well as demerit points on your licence. More serious penalties can apply in other circumstances, e.g. impairment, multiple drugs, or refusing tests. If you refuse the test, you can be banned from driving for 12 hours immediately, plus receive fines and demerit points.

What about prescription drugs?

This is where the nuance truly comes into play. New Zealand law includes a “medical defence”, which means that if you test positive for a prescribed drug, so long as you followed your doctor's instructions, you will avoid penalties only after lab confirmation. So even if you were taking your prescribed medication, you can still be stopped from driving for 12 hours at the roadside. And you may still test positive even if not impaired.

But what does it all mean, Basil?

Saliva tests only detect recent drug use, and not actual impairment. So you could test positive even if you feel completely sober. Especially with cannabis (now medically legal in NZ), which can linger in saliva for up to 24 hours. 

When comparing with our current alcohol laws, you start to see why the saliva test is pretty controversial. Alcohol laws are based on measured impairment; there is a clear legal limit (250 micrograms per litre of breath for infringement, and 400+ for criminal offence), and strong scientific links between blood alcohol levels and risk of crashing. However, the new drug testing laws are based on the presence of a substance, with no clear impairment threshold, and much weaker links between test results and actual driving ability. In short, alcohol laws ask, “Are you impaired?” while drug laws ask, “Have you used something recently?”