All you need to know about roadside drug testing

After years in the pipeline, roadside drug testing has officially arrived in New Zealand — with Wellington becoming the first region to roll it out.

Police in and around the capital are now using saliva-based roadside drug tests, giving officers the power to randomly stop drivers and check for the presence of drugs known to impair driving. The system works much like alcohol breath testing and is being introduced in response to growing concern over drug-impaired driving.

Around 30 percent of fatal road crashes involve drivers with drugs in their system, although authorities acknowledge this does not always mean drugs were the direct cause of the crash.

How Does Roadside Drug Testing Work?

There are two stages of testing: a rapid roadside test and, if needed, a laboratory test.

At the roadside, police use PathTech saliva detection devices, the same technology used across most Australian states. A testing pad is placed on the driver’s tongue, with results returned within 10 minutes.

The rapid test screens for four recreational drugs:

• Methamphetamine

• MDMA (ecstasy)

• Cocaine

• THC (cannabis)

If the test is negative, the driver is free to go.

What Happens If You Test Positive?

If the initial roadside test is positive, police take a larger saliva sample to send to the laboratory and carry out a second rapid test.

• If the second rapid test is positive, the driver is suspended from driving for 12 hours

• If the second test is negative, the driver may continue driving, but the lab test still proceeds

The laboratory testing is carried out by PHF Science (formerly ESR), which screens for 25 high-risk drugs under the Land Transport (Drug Driving) Amendment Act 2022.

A confirmed positive result can lead to infringement notices, fines, or criminal charges, depending on the circumstances and the driver’s history.

Are the Tests Accurate?

Police say the PathTech devices meet required standards in both New Zealand and Australia.

Trials found a 5 percent false-positive rate, but only in cases where drugs were present at levels below legal thresholds. No penalties were issued in those cases, and no tests detected drugs where none were present.

What About Prescription Medications?

Some prescription drugs, including codeine, diazepam, lorazepam, and even medicinal cannabis, can be detected in laboratory testing.

Police say drivers can apply for a medical defence if a drug detected was legally prescribed. Authorities stress that prescription use alone does not automatically mean a penalty.

How Long Do Drugs Stay Detectable?

Detection times vary depending on the drug and the user:

• Cannabis: Up to 12 hours for occasional users, up to 72 hours in rare or heavy-use cases

• MDMA and meth: Up to four days

• Cocaine: Up to 48 hours

Officials say strict thresholds apply, and the system is designed to focus on road safety rather than punishment.

What If You Refuse a Test?

Drivers can refuse a roadside test — but there are immediate consequences:

• $400 fine

• 12-hour licence suspension

• 75 demerit points

Is Testing Random? And What About DNA?

Police say drivers are randomly selected, with no profiling involved. Testing can occur anywhere, anytime.

Authorities also stress that saliva samples are not used for DNA collection. All samples are destroyed after testing and are used solely for drug-driving enforcement.

What Happens Next?

From April 2026, roadside drug testing will expand beyond Wellington, with a nationwide rollout planned by mid-2026.

The message from police is clear: if you’re driving, don’t drive impaired — because roadside drug testing is now part of everyday life on New Zealand roads. 🇳🇿🚗