Wellington will be the first location to implement the new roadside drug testing with the rest of the country to follow by mid-2026 Photo: NZ Police / Supplied
As New Zealand gets set to rollout roadside drug testing, an Australian expert says it's a scattergun approach that doesn't reliably pick up impairment.
Wellington will next month become the first location to see police use a saliva test on drivers, with the rest of the country set to follow by mid-2026.
The tests will screen four key drugs: THC, which is found in cannabis, methamphetamine, MDMA or ecstasy and cocaine.
Dr Michael White, an adjunct senior fellow at the School of Psychology at the University of Adelaide who's researched road accidents involving cannabis, says the tests are nearly worthless when it comes to picking up if someone is impaired.
One of the main issues he pointed out was that the tests detected the drugs but did not reliably assess impairment.
He said the problem was not just with the length of the detection window but how many people are actually impaired after taking drugs like cannabis.
"There's a lot of research that says regular cannabis users are not impaired even if immediately after taking it so that produces a sort of questions of justice.
It is a scattergun approach, many people who are regular users won't be impaired even if they test positive"
The government said 30 percent of all road deaths now involve an impairing drug - and that greater screening will improve road safety.
"We know that they're [drugs] a major factor in many road deaths and serious injuries," Transport Minister Chris Bishop said earlier this year.
"We're now making sure that police are equipped with roadside oral fluid screening as a road safety tool to enable the enforcement," he said.
Director of road policing Superintendent Steve Greally announced earlier this month that Australian-based company Pathtech Pty Ltd would supply the Securetec DrugWipe 3S devices, as well as oral fluid collection kits to collect samples to be sent for laboratory analysis.
"Many countries, including New Zealand, have seen a rise in the number of drivers testing positive for drugs in recent years, and the direct correlation to the number of people being seriously injured or killed on our roads," he said.
The DrugWipe detects the presence of drugs in saliva at or above a threshold that detects current or recent use.
Dr White pointed out there had been no robust evidence as to whether roadside testing has reduced drug impaired driving or accidents.
"Australia has been quite negligent on actually trying to evaluate roadside drug testing.
"They've got a very passive approach, they simply say RBT (random breath testing) for alcohol has been successful, RDT (roadside drug testing) for drugs looks a bit like random breath testing and therefore it ought to be successful. There's never been any evaluation in Australia that clearly shows that roadside drug testing actually works."
He said there were differences between how drugs and alcohol impairs drivers and testing should be based on the crash risk.
"I think policy should be based on crash risk, the crash risk from cannabis is relatively low its less than for a BAC of 0.5. So cannabis might increase your risk of crashing by up to 50 percent, alcohol at a BAC of 0.5 doubles your risk so it increases it by100 percent"
For methamphetamine, Dr White said it was more difficult as it might not actually impair a person but instead make someone more aggressive and increase their thrill seeking
The other key issue he had with the testing was with legal drugs such as benzodiazepines and opioids which he said can also result in fatal car accidents.
"Some Australian research has said that benzodiazepines account for twice as many road crash fatalities as Cannabis and opioids account for twice as many, now both of those are legal drugs.
So that's one thing that neither Australia nor New Zealand really takes into account is the damage done by legal drugs."
Pharmacist and senior lecturer in Biosciences at AUT Dr Catherine Crofts had also previously said she was worried about the lack of information on what the new testing could mean for people with prescriptions like dexamphetamine.
Dr Crofts said about 50 percent of people with ADHD in New Zealand are taking dexamphetamine or lisdexamfetamine, which is becoming increasingly popular.
"We know that some of the tests that are out there in the community do cause some cross reactivity, and I've just found that there are some that don't," she said.
"But we haven't seen anything about what the police are going to do or how it is going to be managed when somebody who is cross reacts, who is legally on these medicines."
Dr White said for subtle levels of impairment some have suggested using phone applications to assess people's reaction times.
"I'm not convinced that those apps are particularly good but at least they're trying to measure impairment which is a step in the right direction rather than measuring presence"
He also noted Australia and New Zealand did not efficiently take human rights into consideration when it came to people getting taken off the roads without showing any good cause.
"In most other countries the drug testing is associated with some sort of test of impairment, the police have to have some sort of good cause to take you off the road.
The Attorney-General's report into the legislation, written in July 2024, found it was inconsistent with parts of the Bill of Rights Act, specifically the right to be secure against unreasonable search and seizure, and the right not to be arbitrarily detained.
Minister of Defence Judith Collins had found the intrusion on privacy was not proportionate to the public interest objective.
"The intrusion on an individual's privacy that arises from the taking of a bodily sample for the first oral fluid screening test appears disproportionate where there is no basis to suspect the individual driving is under the influence of an impairing drug," she wrote.
Sign up for Ngā Pitopito Kōrero, a daily newsletter curated by our editors and delivered straight to your inbox every weekday.
